Tranning Report Civil Enggineering

Construction of an Interchange at 0-00 km at

Yamuna Expressway Project

A Practical Training Report

On Yamuna expressway project, Noida

From 15.05.2010 to 14-06-2010

Submitted in Partial Fulfillment of the Requirements

for

the Degree of

BACHELOR OF TECHNOLOGY

in Civil Engineering

Submitted to: Submitted by:

Vimal Gahlot Abhishek Mathur

Reader & Head Civil- Final year

Department of Civil Engineering

COLLEGE OF ENGINEERING & TECHNOLOGY BIKANER

Bikaner 334001, INDIA

AUGUST, 2010





From 15.05.2010 to 14-06-2010


for

the Degree of









AUGUST, 2010





From 15.05.2010 to 14-06-2010


for

the Degree of









AUGUST, 2010

i

Abstract

This report is a summer internship report submitted in partial

fulfillment of the requirements for the degree of Bachelor of

Technology in Civil Engineering as per norms of Rajasthan Technical

University Kota. The author visited the site for construction of trump

interchange structure, at Yamuna expressway, Noida in his training

period and attained technical knowledge during the course, after which

he was able to compile this report. The report consists of brief study

and description of materials, equipments and procedures used at site

for construction of an interchange. Author put his best to elaborate the

actual site conditions, and problem faced at site and the tactics used to

deal with them.

The main objective of this report is to present a systematic text on the

execution of construction of an interchange based on the Indian

Standard codes. The report also covers the fundamental aspects of

practical requirement such as safety, feasibility and economy at site.

In this report the objective was to introduce, wherever necessary,

material which embodies the most recent methodologies.

Chapter 1 discusses introduction to organization profile, management

structure, products, plants, capacity, turnover, market share, problem

definition (objectives, deliverables etc), and the main conclusions.

Chapter 2 deals with materials and equipments used at site, literature

review. Chapter 3 contains description of the process plant/site where

practical training was undertaken including block diagrams for showing

process scheme, major operations and process equipments, stream

compositions, site conditions governing the process control. Chapter 4

discusses summary of the project with main findings and conclusions,

the method of adoption of the proposed solution by the organization

ii

and expected benefits (technical and financial) Chapter 5 presents the

results obtained after the tests performed on site proceeding with their

conclusion.

In spite of every care taken, it is possible that some errors might have

been left unnoticed. The author sincerely welcomes the constructive

criticism for improving the report.

iii

iv

Certificate

It is certified that the work contained in this training report titled

“Construction of interchange at 0-00 km at Yamuna Expressway

project, Noida" is the original work done by Abhishek Mathur

(07ECTCE003) and has not been submitted anywhere.

(Vimal Gahlot)

Date: Reader & Head

Place: Department of Civil Engineering

College of Engineering &

Technology

Bikaner 334001

v

Acknowledgment

I take immense pleasure in thanking Prof. R.C Gaur, Principal,

College of Engineering & Technology, Bikaner and Mr.Vimal Gahlot,

(Reader, civil department) for having permitted me to carry out this

training.

I wish to express my deep sense of gratitude to my teachers, Mr.

Surender beniwal, Mrs Pratibha Choudhary, Mrs. Karanjeet

kaur, civil department, for their able encouragement and useful

suggestions, which helped me in completing the training work, in time.

Needless to mention that Mr.Ramesh Kamboj,(Vice President

projects V.N.C) and Mr.K Mohan (project manager V.N.C), who

had been a source of inspiration and for his timely guidance in the

conduct of my training. I would also like to thank Mr.Rajesh pustry,

Mr.Sudarhan Murty, Mr. Garurav Maroo and Mr.Dinesh Pawar of

for all their valuable assistance during training.

Words are inadequate in offering my thanks to the Project team of

Vijay Nirman Construction company for their guidance and cooperation

in carrying out the training work.

Finally, yet importantly, I would like to express my heartfelt thanks to

my beloved parents for their blessings, my friends/classmates for their

help and wishes for the successful completion of this training.

vi

Table of Contents

Abstract i

Certificate from company iii

Certificate iv

Acknowledgement v

Chapter 1: Introduction 1-9

1.1 Company’s Profile 1

1.2 Project Profile 3

1.3 Interchange 6

Chapter 2: Material & Equipment 10-33

2.1 Materials

2.1.1 Cement 10

2.1.2 Coarse aggregate 11

2.1.3 Fine aggregate 11

2.1.4 Reinforcement bar 12

2.1.5 Water 14

2.1.6 Admixture 17

2.1.7 RMC 19

2.2 Equipments 20

2.2.1 Batch Mix Plant 20

2.2.2 Transit mixer 23

2.2.3 Post tensioning 23

2.2.3.1 Duct 23

2.2.3.2 Bearing plate 24

2.2.3.3 Wedges 25

2.2.3.4 Jack 27

2.2.3.5 Meter Gauge 28

2.2.4 Grouting 28

vii

2.2.4.1 Mixer 29

2.2.4.2 Storage Hopper & screens 29

2.2.4.3 Grout pumps 30

2.2.4.4 Pressure gauge 31

2.2.4.5 Hoses 31

2.2.5 Auto Level 31

Chapter 3: Structural Components 34-79

3.1 Sub Structure

3.1.1 Foundation 34

3.1.2 Pile cap 36

3.1.3 Piers 38

3.2 Super Structure

3.2.1 Piers cap 39

3.2.2 Bearing 46

3.2.3 Precast Girder 52

3.2.4 Diaphragm wall 75

Chapter 4: Results & Discussions 80-88

4.1Test for Aggregate 80

4.2Test for Reinforcement 83

4.3Test for Concrete 85

Chapter 5: Construction management 89-95

5.1 Basic concept 89

5.2 Choice of technology & method 90

5.3 Work task 91

5.4 Relationship among activities 91

5.5 Estimating activity duration 92

5.6 Resource requirement 93

5.7 Reporting 93

5.8 Safety 93

viii

Conclusion 96

Appendix 97-109

Appendix I 97

Appendix II 100

Appendix III 105

Appendix IV 108

Reference 110

Suggestions

1

1.1 Company’s Profile

VIJAY NIRMAN COMPANY was established in the year 1982 by Dr. S.

Vijaya Kumar. The company started its operation from Visakhapatnam,

port city of Andhra Pradesh, India with construction of Industrial

structures and Pile foundations. Over the years, Vijay Nirman Company

has expanded into the fields of marine work (Berths/Jetties), power

projects, road and bridges, electrical sub stations, residential and

commercial buildings, and water works. Vijay Nirman has also executed

silos & chimneys involving slip form technology.

Vijay Nirman has completed more than 350 projects to date, and

maintains an arbitration–free record, with all over India and an Annual

turnover of ` 400 cores, projected for the year 2010-2011

Corporate social responsibility environment philosophy they believe is

that as long as we are in harmony with nature, it will provide us with

everything in abundance, at the appropriate time

1.1.1 Turnover

`610 `940 `811 `870

`2700

`4500

`6450

01000200030004000500060007000

2004-05 2005-06 2006-07 2007-08 2008-09 2009-10 2010-11

Rs.inMilions

1Chapte rINTRODUCTION

2

1.1.2 Major Projects Completed by Vijay Nirman

Industrial/DefenseProjects

Workshops building at NYC site A at Naval Dockyard,Visakhapatnam, involving 6000MT of structural steelfabrication & erection; Sulphur Recovery Unit for HPCL,Visakhapatnam; Aluminum alloy wheel plant at Duvvada,Visakhapatnam; Wet Process unit for Transworld Garnet India,Visakhapatnam.

Roads &Bridges

Western Transport Corridor Tumkur-Haveri NH4 project; RailBridge across Lakshamanteertha river,Mysore; R.B. acrossriver Pennaiyar 600 mt, Melpattambakkam; Road over bridgenear Pakur Station, Jharkand; Main Carriage Way of elevatedhighway of Hosour road; Underpasses & ROBsconstruction/strengthening of existing two lane Tindivanam-Ulundurpet section of NH45.

PowerPlants

208MW combined cycle power plant at Kakinada, involving 5cell RCC cooling tower; 1x300MW Captive Power Plant forARYAN Coal Benefications Pvt Ltd; captive power plant atBhadrak; 30 MW Diesel Power Plant near Visakhapatnam.

MarineWorks

Construction of Jetty for ONGC in Fisheries’ harbor,Visakhapatnam; Construction of sea Water Intake System andapproach jetty, Srikakulam; Construction of Pipe bridge oftotal length 2200 Kakinada; Pile foundation for Matsya Dock atNaval Dockyard, Visakhapatnam; Upgradation and renovationof Fishing Harbor at Visakhapatnam.

BuildingsWorks

Construction of new building for Bharat Electricals, Bangalore;Expansion of Chinnaswamy Cricket Stadium, Bangalore; HIGHIQ luxury apartment, Bangalore; Construction of IndependentVillas, Housar road, Bangalore; Chaulukya Holidays Resort,Bangalore; Sea Valley Resorts,

MaterialHandlingProjects

Construction of Wagon Tippler & other facilities for handlingiron ore and coal a Ganagavaram Port; Expansion of Aluminahandling Facilities at Nalco’s Port facility, Visakhapatnam.

3

1.2 Project Profile

‘Yamuna Expressway Project’ at a glance

The Government of Uttar Pradesh has been working proactively to

improve the connectivity of the National Capital Region to improve tourist

attraction of Taj Mahal at Agra through the new 6 lanes (extendable to 8

lanes) Access Controlled Expressway with brand name of Yamuna

Expressway (erstwhile Taj Expressway).

Almost everyone who comes to India makes it a point to make a trip to

the Taj Mahal, Agra. Presently Agra is about 210 km from Delhi by road.

It takes normally nine to ten traveling hours on a return trip between

Delhi and Agra which leaves very less time in Agra to see the Taj and

other places of historical importance. The concept of the Yamuna

Expressway (erstwhile Taj Expressway proposes a 160 km Expressway

between Greater Noida and Agra thus reducing the travel time to 100

minutes only.

For implementing the Yamuna Expressway Project and allied development

in the region, Government of UP constituted Taj Expressway Industrial

Development Authority (TEA) vide its Notification No.697/77-4-2001-

3(N)/2001 dated 24th April, 2001, under U.P. Industrial Area

Development Act, 1976 (U.P. Act No.6 of 1976). The main

responsibilities of TEA, inter alia, included:

Execution of Yamuna Expressway.

Acquisition of land for construction of Expressway.

Preparation of Zonal/Master plan for planned development along

the Expressway.

4

Development of drainage, feeder roads, electrification and other

facilities in the area.

Approx. 334 villages of District Gautam Buddh Nagar, Bulandshahar,

Aligarh, Mahamaya Nagar (Hathras), Mathura and Agra are Notified under

Yamuna Expressway Industrial Development Authority vide various

Notifications of Government of UP.

1.2.1 Project Map

Fig. 1.1: Map of Yamuna Expressway

5

Table 1: Quick Facts about Yamuna Expressway

Length 165.537Km

Right of Way 100m

Number of lane 6 lane, extendable to 8 Lanes

Type of Pavement Rigid (Concrete)

Cost `1400 millions

Structures

Interchange 7

Main Toll Plaza 3

Toll Plaza on interchange loop 7

Underpass 35

Rail Over Bridge 1

Major Bridge 1

Minor Bridge 42

Cart Track Crossing 68

Culverts 204

6

1.3 Interchange

Fig. 1.2: A typical interchange

In the field of road transport, an interchange is a road junction that

typically uses grade separation, and one or more ramps, to permit traffic

on at least one highway to pass through the junction without directly

crossing any other traffic stream. It differs from a standard intersection,

at which roads cross at grade. Interchanges are almost always used when

at least one of the roads is a limited-access divided highway (expressway

or freeway), though they may occasionally be used at junctions between

two surface streets.

At rotary intersection weaving is an undesirable situation in which traffic

veering right and traffic veering left must cross paths within a limited

distance, to merge with traffic on the through lane. In the worst

circumstances, a large portion of through traffic must change lanes to

stay on the same roadway. Weaving creates both safety and capacity

7

problems. Some interchanges use collector/distributor roads to deal with

weaving-while doing so does not eliminate the problem entirely.

Collector/distributor roads separate the weaving traffic from the

highway's main lanes or carriageway, thus improving traffic flow. Some

areas that had such bad junctions have gone through the expensive

process of ‘unweaving the weave’ to improve traffic flow. Another way to

avoid weaving is to have braided ramps, in which an on-ramp passes over

or under an off-ramp using an overpass structure such as interchange.

8

1.3.1 Types of Interchange

1.3.1.1 Four-way interchangesCloverleaf

Stack

Clover stack

Turbine

A cloverleaf interchange is typically a two-level,four-way interchange whereby all left turns arehandled by loop ramps (right turns if traveling onthe left). To go left, vehicles first cross over orunder the targeted route, then bear right onto asharply curved ramp that loops roughly 270degrees, merging onto the interchanging road fromthe right, and crossing the route just departed.

A stack interchange is where left turns are handledby semi-directional flyover/under ramps. Vehiclesfirst turn slightly right (on a right-turn off-ramp) toexit, and then complete the turn via a ramp whichcrosses both highways, eventually merging with theright-turn on-ramp traffic from the oppositequadrant of the interchange. A stack interchange,then, has two pairs of left-turning ramps, of whichcan be stacked in various configurations above orbelow the two interchanging highways.

Partial cloverleaf interchange (parclo) is designmodified for freeway traffic emerged, eventuallyleading to the clover stack interchange. Its rampsare longer to allow for higher ramp speeds, and loopramp radii are made larger as well. For countriesusing right hand-drive, the large loop rampseliminate the need for a fourth, and sometimes athird level in a typical stack interchange, as only twodirections of travel use flyover/under ramps.

Another alternative to the four-level stackinterchange is the turbine interchange (also knownas a whirlpool). The turbine/whirlpool interchangerequires fewer levels (usually two or three) whileretaining semi-directional ramps throughout, andhas its left-turning ramps sweep around the centerof the interchange in a spiral pattern in right-handdriving.

9

(a) Windmill (b) Diverging windmill (c) Full diamond

Fig. 1.3: Various other types of interchanges

1.3.1.2 Three-way interchanges

Trump

Directional

T – Bone

Trumpet interchanges have been used whereone highway terminates at another highway.These involves at least one loop rampconnecting traffic either entering or leaving theterminating expressway with the far lanes of thecontinuous highway.

Directional T interchange uses flyover/underramps in all directions at a three-wayinterchange. A semi-directional T does thesame, but some of the splits and merges areswitched to avoid ramps to and from thepassing lane. Directional T interchanges arevery efficient, but are expensive to buildcompared to other three-way interchanges.They also require three levels, which can be aneyesore for local residents.

¾-volley Half-Clove

10

10

2.1Materials

2.1.1Cement

Portland cement is composed of calcium silicates, aluminates and

aluminoferrite. It is obtained by blending predetermined proportions

limestone clay and other minerals in small quantities which is pulverized

and heated at high temperature – around 1500 deg centigrade to produce

‘clinker’. The clinker is then ground with small quantities of gypsum to

produce a fine powder called Ordinary Portland Cement (OPC). When

mixed with water, sand and stone, it combines slowly with the water to

form a hard mass called concrete. Cement is a hygroscopic material

meaning that it absorbs moisture. In presence of moisture it undergoes

chemical reaction termed as hydration. Therefore cement remains in good

condition as long as it does not come in contact with moisture. If cement

is more than three months old then it should be tested for its strength

before being taken into use.

The Bureau of Indian Standards (BIS) has classified OPC in three different

grades The classification is mainly based on the compressive strength of

cement-sand mortar cubes of face area 50 cm2 composed of 1 part of

cement to 3 parts of standard sand by weight with a water-cement ratio

arrived at by a specified procedure. The grades are

2Chapt erMATERIAL & EQUIPMENT

11

1. 33 grade

2. 43 grade

3. 53 grade

The grade number indicates the minimum compressive strength of

cement sand mortar in N/mm2 at 28 days, as tested by above mentioned

procedure. Nowadays good quality fly ash is available from Thermal

Power Plants, which are processed and used in manufacturing of PPC.

2.1.2 Coarse aggregate

Coarse aggregate for the works should be river gravel or crushed stone.

It should be hard, strong, dense, durable, clean, and free from clay or

loamy admixtures or quarry refuse or vegetable matter. The pieces of

aggregates should be cubical, or rounded shaped and should have

granular or crystalline or smooth (but not glossy) non-powdery surfaces.

Aggregates should be properly screened and if necessary washed clean

before use. Coarse aggregates containing flat, elongated or flaky pieces

or mica should be rejected. The grading of coarse aggregates should be

as per specifications of IS: 383-1970.

After 24-hrs of immersion in water, a previously dried sample of the

coarse aggregate should not gain in weight more than 5%.Aggregates

should be stored in such a way as to prevent segregation of sizes and

avoid contamination with fines.

2.1.3 Fine aggregate

Aggregate which is passed through 4.75 mm IS Sieve is termed as fine

aggregate. Fine aggregate is added to concrete to assist workability and

to bring uniformity in mixture. Usually, the natural river sand is used as

12

fine aggregate. Important thing to be considered is that fine aggregates

should be free from coagulated lumps.

Grading of natural sand or crushed stone i.e. fine aggregates shall be

such that not more than 5 percent shall exceed 5 mm in size, not more

than 10% shall IS sieve No. 150 mm not less than 45% or more than

85% shall pass IS sieve No. 1.18 mm and not less than 25% or more

than 60% shall pass IS sieve No. 600 micron.

Table 2.1: Limits Of Fineness Moduli in aggregate

Maximum size of aggregate Fineness modulus

Max. Min.

Fine aggregate 2.0 3.5

Coarse aggregate 20 mm 6.0 6.9

40 mm 6.9 7.5

75 mm 7.5 8.0

150mm 8.0 8.5

Mixed aggregate 20 mm 4.7 5.1

25mm 5.0 5.5

32 mm 5.2 5.7

40 mm 5.4 5.9

75 mm 5.8 6.3

150 mm 6.5 7.0

2.1.4 Reinforcement Bras

Steel reinforcements are used, generally, in the form of bars of circular

cross section in concrete structure. They are like a skeleton in concrete

body. Plain concrete without steel or any other reinforcement is strong in

13

compression but weak in tension. Steel is one of the best forms of

reinforcements, to take care of those stresses and to strengthen concrete

to bear all kinds of loads.

Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel high

strength deformed bars conforming to IS:1786 (grade Fe 415 and grade

Fe 500, where 415 and 500 indicate yield stresses 415 N/mm2 and 500

N/mm2 respectively) are commonly used. Grade Fe 415 is being used

most commonly nowadays. This has limited the use of plain mild steel

bars because of higher yield stress and bond strength resulting in saving

of steel quantity. Some companies have brought thermo mechanically

treated (TMT) and corrosion resistant steel (CRS) bars with added

features.

Bars range in diameter from 6 to 50 mm. Cold-worked steel high strength

deformed bars start from 8 mm diameter. For general house

constructions, bars of diameter 6 to 20 mm are used.

Transverse reinforcements are very important. They not only take care of

structural requirements but also help main reinforcements to remain in

desired position. They play a very significant role while abrupt changes or

reversal of stresses like earthquake .They should be closely spaced as per

the drawing and properly tied to the main/longitudinal reinforcement.

Steel has an expansion coefficient nearly equal to that of modern

concrete. If this were not so, it would cause problems through additional

longitudinal and perpendicular stresses at temperatures different than the

temperature of the setting. Although rebar has ribs that bind it

mechanically to the concrete, it can still be pulled out of the concrete

under high stresses, an occurrence that often precedes a larger-scale

collapse of the structure. To prevent such a failure, rebar is either deeply

14

embedded into adjacent structural members (60-80 times the diameter),

or bent and hooked at the ends to lock it around the concrete and other

rebar. This first approach increases the friction locking the bar into place;

while the second makes use of the high compressive strength of concrete.

Common rebar is made of unfinished tempered steel, making it

susceptible to rusting.

2.1.5 Water

Water is one of the most important elements in construction but people

still ignore quality aspect of this element. The water is required for

preparation of mortar, mixing of cement concrete and for curing work etc

during construction work. The quality and quantity of water has much

effect on the strength of mortar and cement concrete in construction

work. It has been observed that certain common impurities in water

affect the quality of mortar or concrete. Many times in spite of using best

material i.e. cement, coarse sand, coarse aggregate etc. in cement

concrete, required results are not achieved. Most of

Engineers/Contractors think that there is something wrong in cement, but

they do not consider quality of water being used. Some bad effects of

water containing impurities are following:

1. Presence of salt in water such as Calcium Chloride, Iron Salts,

inorganic salts and sodium etc. are so dangerous that they reduce

initial strength of concrete and in some cases no strength can be

achieved. There is rusting problem in steel provided in RCC.

2. Presence of acid, alkali, industrial waste, sanitary sewage and water

with sugar also reduce the strength of concrete.

3. Presence of silt or suspended particle in water has adverse effect on

strength of concrete.

15

4. Presence of oil such as linseed oil, vegetable oil or mineral oil in

water above 2 % reduces the strength of concrete up to 25 %.

5. Presence of algae/vegetable growth in water used for mixing in

cement concrete reduce of the strength of concrete considerably

and also reduce the bond between cement paste and aggregate.

It has been observed at various places that cement concrete start falling

down in pieces after rusting mild steel from RCC slab, which is due to use

of bad quality/salty water in RCC slab. All this is due to negligence or

ignorance which creates great problems and also bears a heavy loss. It is

advisable that the water must be tested before using in construction

work.

Limits of Solids

Table 2.2: Limits of Solids

Organic 200 mg/L

Inorganic 1000 mg/L

Sulphate: 400 mg/L

Chloride 500 mg/L for RCC work and 2000 mg/L for concrete not

containing steel.

Suspended

matter

2000 mg/L

16

Main disadvantages of mixing too much water in mortar and

concrete

The water occupies space in sand and it evaporates to create voids.

Moreover the water voids will be more and this will reduce the

density, strength and durability of mortar or concrete.

When more water is used in concrete excess water brings a mixture

of excess cement paste with water floating on the surface. This

material forms a thin layer of chalky material on the surface which

reduces proper bonding with second layer of cement concrete in

case of water tank and dams etc. This will affect the strength of

concrete.

When more water is used, the cement slurry starts coming out from

cement concrete mix. The excess slurry formed by water and

cement comes out through shuttering joints. This makes concrete

of less cement and reduces the strength of concrete.

When more water is used, proper compaction is not achieved and

there is bleeding, large voids and more shrinkage, less durability

and less strength.

When more water is mixed in cement concrete, the problem of

segregation of material is faced at the time of laying the mix. As a

result Coarse Aggregate and cement paste separate from each

other.

Hence strict control should be kept on water cement ratio for preparing

the mortar or concrete for qualitative finish/ strength.

17

2.1.6 Admixtures

Water Reducing Admixtures

The water reducer admixture improves workability of concrete/mortar for

the same water cement ratio. The determination of workability is an

important factor in testing concrete admixture. Rapid loss of workability

occurs during first few minutes after mixing concrete and gradual loss of

workability takes place over a period from 15 to 60 minutes after mixing.

Thus relative advantages of water reducing admixture decrease with time

after mixing. These admixtures increase setting time by about 2 to 6 hrs

during which concrete can be vibrated. This is particularly important in

hot weather conditions or where the nature of construction demands a

time gap between the placements of successive layers of concrete.

Advantages

It can reduce 10% of water consumption.

It can improve mixture of cement concrete for workability.

Compression strength improves by more than 15 %.

It can reduce initial stage of cement heat hydration by large

margin.

It has no function of corrosion reinforcing bars.

It increases workability, density and strength without increasing the

quantity of cement.

18

Table 2.3 Type of admixture

Type of admixture Performance

Water reducing/plasticizing Water reduction at equal consistence

Water Reduction ≥ 5%

High-range water

reducing/superplasticizing

Water reduction at equal consistence

Increase in consistence at equal w/c

ratio


Slump increase ≥ 120 mm

Water retaining Reduction in bleeding

Shrinkage Reduction ≥ 50%

Water resisting Reduction in capillary absorption

Reduction ≥ 50% by mass

Air entraining Air void characteristics in hardened

concrete

Spacing factor ≤ 0.200 µm

Set accelerating Reduction in initial setting time

Initial setting time Reduction ≥ 40%

at 5°C

Hardening accelerating Compressive strength at 1 day

Increase ≥ 20% at 20°C

Compressive strength at 2 days

Increase ≥ 30% at 5°C

19

Set retarding Increase in initial and final setting time

Initial setting time increase≥ 90 min.

Final increase ≤ 360 min

Set retarding/water

reducing/plasticizing


Increase in initial and final setting time


Initial setting time increase≥90min.

Final setting time increase≤ 360 min.

Set retarding/high-range

water reducing/superplasticizing


Increase in consistence at equal

w/c ratio

Increase in initial and final setting time

at equal consistence


Slump increase ≥120 mm

Initial setting time increase ≥ 90 min.

Final setting time increase≤ 360 min.

Set accelerating/water

reducing/plasticizing

Water reduction at equal

Consistence

Reduction in initial setting time

Reduction ≥5%

Reduction ≥ 30 min. at 20°C and ≥

40% at 50C

2.1.7 Ready Mix Concrete (RMC)

Ready-mix concrete is a type of concrete that is manufactured in a

factory or batching plant, according to a set recipe, and then delivered to

a work site, by truck mounted transit mixers. This results in a precise

mixture, allowing specialty concrete mixtures to be developed and

20

implemented on construction sites. Concrete itself is a mixture of Portland

cement, water and aggregates comprising sand and gravel or crushed

stone. In traditional work sites, each of these materials is procured

separately and mixed in specified proportions at site to make concrete.

Ready Mixed Concrete is bought and sold by volume - usually expressed

in cubic meters. RMC can be custom-made to suit different applications.

Table 2.4: Mix design adopted at RMC plant

S.No. GRADE SAND CEMENT WATER GRIT

(10mm)

GRIT

(20mm)

ADMIXTURE

2 M-15 626.00 310.00 169.88 627.00 627.00 0.00

3 M-20 630.00 350.00 189.00 579.25 579.25 0.00

4 M-25 580.35 365.00 169.88 627.30 627.80 4.20

5 M-30 450.00 400.00 172.00 487.00 730.00 0.00

6 M-35

CAP

601.70 436.00 174.00 571.00 571.00 3.50

7 M-35

PILE

596.00 442.00 179.00 565.00 565.00 4.20

8 M-40 465.50 470.00 174.00 632.15 632.15 5.17

9 M-45 414.00 488.00 179.00 599.00 732.00 4.80

Sour ce: RMC p lant

21

2.2 Equipments

2.2.1 Batch Mix Plant

A concrete plant, also known as a batch plant, is a device that combines

various ingredients to form concrete. Some of these inputs include sand,

water, aggregate (rocks, gravel, etc.), fly ash, potash, and cement. There

are two types of concrete plants: ready mix plants and central mix plants.

A concrete plant can have a variety of parts and accessories, including

but not limited to mixers (either tilt-up or horizontal or in some cases

both), cement batchers, aggregate batchers, conveyors, radial stackers,

aggregate bins, cement bins, heaters, chillers, cement silos, batch plant

controls, and dust collectors (to minimize environmental pollution).

A central mix plant combines some or all of the above ingredients

(including water) at a central location. The final product is then

transported to the job site. Central mix plants differ from ready mix

plants in that they offer the end user a much more consistent product,

since all the ingredient mixing is done in a central location and is

computer-assisted to ensure uniformity of product. A temporary batch

plant is similar to the central batch plant but it can be constructed on a

large job site.

22

Fig 2.1 Batch Mix Plant

All the feeder bins have pneumatic operated gates. The four bins

combined have a storage capacity of 7.5 m³.The gates are radial type for

coarse/fine discharge. Sand bin is also provided with discharge.

Aggregates are discharged into Gathering Conveyor. Is suspended on 6

load cells as soon as the desired recipe accumulates, gathering conveyor

discharges the mix on to the slinger conveyor. Gathering conveyor and

slinger conveyor are provided with idler rollers and return rollers.

Weighing hopper is mounted on 3 load cells with butterfly valve for

discharge. Cement weighing hopper capacity 500 kg is provided with

pneumatic vibrator and two inlets for two screw conveyors. Water tank

supported on load cells and it has gate with rubber gasket at the bottom.

Additives comprise of admixture flask of capacity 10 liters with feeding

pump. Cement is fed from SILO to the cement weighing hopper.

Temporary storage hopper is provided with vibrator and it is utilized for

holding the batch of 4 aggregates before feeding into the mixture Pan

Type Mixture comes in capacity of 1 m³ and is fixed on the basic

23

structure of the plant. Mixer having 7 arms and shell is reinforced with

replaceable high wear resistance NI hard liners. The aggregates, cement,

water ad additives are discharged to the Pan Mixer.

After proper and homogenous mixing the batch is ready to be discharged

by hydraulic system. Fully computerized cabin with SCADA based

controller are a standard on ATLAS DM Series plant. Software which is

very user friendly ensures top notch performance. Proxy switches are

available for each control panel. Display of the entire process of control

parameters is available and provision for printing entire data like-Mix

Proportion, Batch Weigh, Total No. of Batches, Sub Total, Gross Total,

etc. Preset batch controls the number of batches for Transit Mixer. There

is provision to store, edit production details, and mix proportions up to 99

recipes. Auto and manual control can be accessed. Cabin is fabricated

with M. S. Structured frame and insulated by wood. Strategic location of

seat ensures complete view of the plant.

2.2.2 Transit Mixer

Transit Mixer are made to transport and mix concrete from a plant to the

construction yard more modern plants load the truck with 'Ready Mixed'

concrete. With this process, the material has already been mixed, and

then is loaded into the truck. The ready mix truck maintains the

material's liquid state, through agitation, or turning of the drum, until

delivery. The interior of the drum on a concrete truck is fitted with a

spiral blade. In one rotational direction, the concrete is pushed deeper

into the drum. This is the direction the drum is rotated while the concrete

is being transported to the building site. This is known as ‘charging’ the

mixer. When the drum rotates in the other direction.

24

2.2.3 Post Tensioning

2.2.3.1 Duct

Corrugated plastic duct (Figure 2.2) to be completely embedded in

concrete should be constructed from either polyethylene or

polypropylene. The minimum acceptable radius of curvature should be

established by the duct supplier according to standard test methods.

Polyethylene duct should be fabricated from resins meeting or exceeding

the requirements of Indian Specification The duct should have a minimum

material thickness of 2.0 mm + 0.25 mm. Ducts should have a white

coating on the outside or should be of white material with ultraviolet

stabilizers.

Fig2.2 Corrugated Plastic Duct

2.2.3.2 Bearing Plate

A basic bearing plate is a flat plate bearing directly against concrete.

Covered by this definition are square, rectangular, or round plates,

sheared or torch cut from readily available steel plate. Basic bearing

plates are used in conjunction with galvanized sheet metal or plastic

25

trumpets to transition from the strand spacing in the wedge plate to the

duct.

Fig 2.3: Bearing Plate

2.2.3.3 Wedges

Wedge performance is critical to the proper anchoring of strands.

Different wedges have been developed for particular systems and

applications such that there is no single standard wedge. However, all are

similar. The length is at least 2.5 times the strand diameter, with a 5° to

7° wedge angle and serrated teeth for gripping the strand. They are of

case-hardened low carbon or alloy steel. A wedge assembly typically has

2 or 3 part wedges with a spring wire retainer clip in a groove around the

thick end.

Wedges are case hardened with a ductile core, in order to bite into the

strand and conform to the irregularity between the strand and wedge

hole. In so doing, the surface may crack. This is normally acceptable and

does not affect performance so long as wedges do not break completely

into separate pieces. Often, it is only the portion outside the retainer ring

that cracks Wedges and Strand-Wedge Connection Wedge performance is

26

critical to the proper anchoring of strands. Different wedges have been

developed for particular systems and applications such that there is no

single standard wedge. However, all are similar. Wedges are case

hardened with a ductile core, in order to bite into the strand and conform

to the irregularity between the strand and wedge hole. In so doing, the

surface may crack. This is normally acceptable and does not affect

performance so long as wedges do not break completely into separate

pieces. Often, it is only the portion outside the retainer ring that cracks.

Fig 2.4 Arrangement of wedges and bearing plate

2.2.3.4 Strands

Uncoated stress relieved low relaxation seven ply strands. The seven wire

strand shall have a centre wire at least 14 percent greater in diameter

than the surrounding wires enclosed tightly by six helically placed outer

wires with a uniform length of lay of at least 12 times but not more than

16 times of the nominal diameter of the strand. The length of lay for the

two and three wire strands shall be uniform throughout and shall be 24 to

36 times the diameter of element wire. The wires in the strand shall be so

formed that they shall not unravel when the strand is cut and they shall

27

not fly out of position when the strand is cut without seizing. After

stranding, all strands shall be subjected to a stress-relieving. Stress

relieving shall be carried out as a continuous process on a length of

strand by uncoiling and running through any suitable form of heating to

produce the prescribed mechanical properties. Temper colours, which

may result from the stress-relieving operation, shall be considered normal

for the finished appearance of the strand.

Fig 2.5: Strands for Post tensioning

2.2.3.5 Jack

Multi-Strand Jacks

Multi-strand post-tensioning tendons are usually stressed as an entire

group, using very large custom made jacks. This ensures that all strands

are tensioned together and avoids the risk of trapping an individual

strand. Stressing jacks are generally of the center-hole type i.e. tendons

pass through a hole in the middle and are attached at the rear of the jack

(Figure 2.6). Post-stressing jacks must be very accurate which is difficult

to achieve. Stressing jacks have more wearing surface and packing than

a conventional jack of the same capacity. This, and the necessity of a

long jack stroke, increases the potential for variations in the accuracy of

28

the applied force. Other factors that affect the accuracy and efficiency of

stressing jacks are: use of dirty oil, exposure of the system to dust or

grit, eccentric loading, type of packing, ram position, oil temperature,

hydraulic valves, ram and packing maintenance, and readout equipment.

Fig 2.6: Post tensioning jack

2.2.3.6 Master Gauge

The master gauge measures hydraulic pressures accurately. The load cell

operates on the principle that changing pressure results in a

corresponding change in electrical resistance. The readouts are made with

a so-called Transducer Strain Indicator.

Gauge readings should not be taken while the ram is retracting or in a

static condition as hysteresis will likely result in erroneous values. The

calibration curves and master gauge readings are only valid when the

ram is extending. If there is any indication of damage to the gauge, the

stressing system should be checked with the master gauge. For this

29

reason, the master gauge should be kept locked away in a safe place so

that it is always in good working order.

2.2.4 Grouting

2.2.4.1 Mixer

The mixer should be capable of continuous mechanical mixing to produce

a homogeneous, stable, grout free of lumps or un-dispersed material that

it supplies continuously to the pump. Mixers are of two main types: vane

(or paddle) mixers with a speed of about 1,000 rpm or high- speed shear

(colloidal) mixers with a speed of about 1,500 rpm. The high speed mixer

distributes cement more uniformly, improves bleed characteristics and

minimizes cement lumps.

A high-speed mixer is recommended for pre-bagged grouts.

2.2.4.2 Storage Hopper and Screen

Most grouting equipment has a mixing (blending) tank which discharges

through a screen into a storage hopper or tank mounted over the grout

pump (Figure 2.7). The storage hopper should also have a mixing rotor

to keep the grout agitated for continuous use and should be kept

partially full at all times. The screen should contain openings of 3mm

maximum size to screen lumps from the mix. The screen should be

inspected periodically. If lumps of cement remain on the screen, then the

mix is not suitable.

30

Fig 2.7: Grout Mixing and Pumping Equipment

2.2.4.3 Grout Pump

Grout pumps should be of the positive displacement type and able to

maintain an outlet pressure of at least 1MPa (145psi) with little

variation. The pump, hoses and connections should be able to

maintain pressure on completely grouted ducts. A shut-off valve

should be installed in the line so that it can be closed off under

pressure, as necessary.

Pumps with a variable output capability are adaptable to delivery

demands of different duct diameters or to group grouting. However,

the grouting pressure should be limited to help prevent blow-outs in the

equipment, protect operators, prevent excessive segregation or bleed

and prevent possible splitting of concrete by over-pressurizing the

ducts.

Pumps should have a system for re-circulating the grout when pumping is

31

not in progress and should have seals to prevent oil, air or other

foreign substance entering the grout or prevent loss of grout or water.

At the pump, grout piping should incorporate a sampling tee with a

stop valve. The number of bends and changes in size should be

minimized.

2.2.4.4 Pressure Gauge

A pressure gage with a full scale reading of not more than 2MPa (300

psi) should be attached between the pump outlet and duct inlet. For

short lengths (say less than about 10m (30 feet) of grout hose, the

gauge may be placed near the pump - for long lengths, at the inlet.

For hose lengths over 30m (100 ft), a gage near the pump and one

at the inlet may help identify whether sudden pressure build-ups are

in the hoses or the ducts.

2.2.4.5 Hoses

The diameter and pressure rating of hoses should be compatible with

the pump and anticipated maximum pressures. All hoses should be

firmly connected to pump outlets, pipes and inlets. It is recommended

that grout hoses be at least 20mm inside diameter for lengths up to

about 30m (100 ft) and that a reduction in size at connectors be

avoided. Also, narrow openings should be avoided. Both can lead to

pressure build-up and possible risk of blockage.

2.2.5 Auto Level

An Auto Level machine is the equipment used for all surveying and

engineering level applications. They are suitable for obtaining accurate

levels during surveys even if the ground is not levelled. For this, an

automatic level comes complete with an internal compensator

mechanism which is a swinging prism. When this mechanism is set

close to level, it automatically removes any remaining variation from

32

level. This reduces the requirement to set the instrument truly level

even when it is a dumpy or tilting level. It is, therefore, a self-levelling

instruments designed by auto level manufacturers for accuracy, ease

of operation and rugged dependability. Auto level is now the preferred

instrument on building sites, construction and surveying due to ease of

use and rapid setup time. They also give maximum portability. Most of

the auto levels are supplied with aluminium telescopic tripod stand.

With the rising popularity of auto levels for surveying and other

engineering application, the auto level manufacturers have included

many useful features in today's automatic levels. The popular features

of any auto level include:

Most of the auto levels are provided with aluminum telescopic

tripod stand.

They are rigidly constructed and ensure accuracy for years under

severe conditions.

Available in various types of models.

They can be set up very easily.

Includes hard shell carrying case with dual latches, plumb bob,

Allen wrench, adjusting pin, and instruction manual.

Ensures accurate leveling.

The equipment has easy adjusting features.

They are portable.

Functions of Auto Level Instrument

Auto level has dominated the most of the market due to the useful

features they provide for surveying and engineering work. Some of the

important functions performed by an auto level include:

Conducting research work smoothly in extreme weather

conditions.

Ensuring accuracy to the test performed.

33

Making telescopic magnification possible through the apparatus.

Applications of Auto Level Instrument

Auto Level equipment is mainly used to obtain accurate leveling while

surveying, engineering and other such works. Some of the applications

of auto level include:

Excavation

Optical Surveys

Topographic Surveys

Construction (Buildings, Roadways, etc.)

Mapping

2.2.6 Jacks

The adjustable base plate stirrup heads provide a method of

adjustment which can be used at either the top or bottom of a scaffold

support structure. It is in conjunction with foreheads and adapter and

can accept the full loading capacity of cup lock when fully braced.

Fig 2.8: Adjustable Stirrup Head

Range of adjustable stirrup heads available with us come in standard

sizes of:

32 mm diameter, 225 mm adjustment



34

3.1 Sub-Structure

3.1.1 Foundation

Pile Foundation

A deep foundation is a type of foundation distinguished from shallow

foundations by the depth they are embedded into the ground. There

are many reasons a geotechnical engineer would recommend a deep

foundation over a shallow foundation, but some of the common

reasons are very large design loads. Deep foundations can be installed

by either driving them into the ground or drilling a shaft and filling it

with concrete, mass or reinforced. They are also called as caissons,

drilled shafts, drilled piers, Cast-in-drilled-hole piles (CIDH piles) or

Cast-in-Situ piles.

Rotary boring techniques offer larger diameter piles than any other

piling method and permit pile construction through particularly dense

or hard strata. Construction methods depend on the geology of the

site. In particular, whether boring is to be undertaken in 'dry' ground

conditions or through water-logged but stable strata i.e. 'wet boring'.

Boring is done until the hard rock or soft rock layer is reached in the

case of end bearing piles. If the boring machine is not equipped with a

rock auger, then socketing of the hard rock layer is done with the help

of a heavy chisel which is dropped from a height of about 1.5

m(depends on the weight of the chisel and design requirements) by

3Chapte r

STRUCTURAL COMPONENT

35

suspending it from a tripod stand attached to a winch crane. The

socketing is carried out until the desired depth within the rock layer

has been attained. Usually, the required depth within the rock layer is

considered to be equal to the diameter of the pile in hard rock layers

and is taken to be equal to 2.5 times the diameter of the pile in soft

rock layers.

'Dry' boring methods employ the use of a temporary casing to seal the

pile bore through water-bearing or unstable strata overlying suitable

stable material. Upon reaching the design depth, a reinforcing cage is

introduced; concrete is poured in the bore and brought up to the

required level. The casing can be withdrawn or left in situ.

'Wet' boring also employs a temporary casing through unstable ground

and is used when the pile bore cannot be sealed against water ingress.

Boring is then undertaken using a digging bucket to drill through the

underlying soils to design depth. The reinforcing cage is lowered into

the bore and concrete is placed by tremmie pipe, following which,

extraction of the temporary casing takes place.

The reinforcement cage may need to be lapped with another cage if

the depth of the pile exceeds 12m as that is the standard length of

reinforcement bars of diameter 16mm and above.

In some cases there may be a need to employ drilling fluids (such as

bentonite suspension) in order to maintain a stable shaft. Rotary auger

piles are available in diameters from 350 mm to 2400 mm or even

larger and using these techniques, pile lengths of beyond 50m can be

achieved.

Such piles commonly fail due to the collapse of the walls of the shaft

resulting in the formation of a reduced section which may not be able

to bear the loads for which it had been designed. Hence at least a third

of piles in projects with a large number of piles are tested for

36

uniformity using a ‘Pile Integrity Tester’. This test relies on the manner

in which low intensity shock waves are affected as they pass through

the pile and are reflected to judge the uniformity and integrity of the

pile. A pile failing the integrity test is then subjected to a pile load test.

3.1.2 Pile cap

Foundations relying on driven piles often have groups of piles

connected by a pile cap (a large concrete block into which the heads of

the piles are embedded) to distribute loads which are larger than one

pile can bear. Pile caps and isolated piles are typically connected with

grade beams to tie the foundation elements together; lighter structural

elements bear on the grade beams while heavier elements bear

directly on the pile cap.

Sequence for construction of pile cap

3.1.2.1 Excavation

At road locations the pit shall be excavated to the dimensions

providing working space all around the pile cap. Proper side slope or

shoring shall be provided depending upon the suitability of the soil

found in the area. The last 200mm excavation shall be carried out

manually.

3.1.2.2 Fixing of shuttering and formwork

After excavation the proper shuttering is fixed with supporting form

work according to drawing and maintaining the size of pile cap.

3.1.2.3 Removal of laitance

After excavation the laitance of the piles shall be removed by using

pneumatic jack hammer minimum sever days after casting of pile or

manually minimum. Three days after casting of pile. The top of pile

after striping shall project 300m above the cut-off level.

37

Fig.3.1: Removal of Laitance

3.1.2.4 P.C.C Laying

After leveling the bottom, the pit shall be watered to keep the soil

moist, mix concrete used as a P.C.C and transported for batching plant

to the P.C.C Laying site through transit mixer. The concrete shall be

directly poured by chute & shall be spread, leveled manually to the 150

mm thickness.

3.1.2.5 Pile cap reinforcement

The reinforcement bar shall be cut in a proper length and bend

according to bar bending schedule. The bar shall be provided with

inhibitor treatment by applying inhibitor solution mixed with cement in

a ration of 600ml: 1 kg of cement and stacked for drying under shed

for 24 hrs.

The reinforcement bar is fixed in a proper location according to

drawing over the P.C.C and tied with 1mm diameter Galvanizing iron

binding wire. 75 mm clear cover is provided at the bottom both side

38

and upper face of rebar cage. The vertical reinforcement of pier is also

tied with pile cap reinforcement and crash barrier reinforcement also

tied.

Refer drawing for Dimension Details of Pile Foundation & Pile cap.

3.1.3 Piers

Piers are constructed above the footings. They provide vertical support

to the bridge superstructure Pier construction begins once the footings

are in place. The forms are typically constructed to cast/build

segments of the pier vertically, and moving the forms upward as the

pier construction takes place. Many different shapes of the piers are

possible; the most economical shape would have a consistent cross

section. The size and frequency of piers depends on the type of super

structure and spans they are supporting. Concrete is the most likely

construction material to be used. Twin Piers are constructed to

facilitate balanced cantilever construction technique. Steel form used

to construct oblong pier shape, Steel rebar extending from pile cap is

continued in piers up to pier cap. Steel forms are used to place around

rebar cage to cast concrete.

3.1.3.1 Reinforcement

Fabricated and tie the pier reinforcement cut and bend the

reinforcement bar for tie reinforcement according to drawing bar

bending Schedule. The bar shall be provided with inhibitor treatment

by applying inhibitor solution mixed with cement in ratio of 600ml: 1kg

of cement and stacked for drying under shed form 24 hrs. Tie

reinforcement tied with the vertical reinforcement through galvanized

iron binding wire according to drawing.

39

3.1.3.2 Shuttering and Formwork for Pier

Shuttering and form of pier formwork fixed the pier shuttering and

form proper formwork is fixed form supporting the pier shuttering

according to drawing.

3.1.3.3 Concreting

Completion of shuttering concreting would be started with the help of

concrete pump. Before pouring concrete we check the slump. The

range of slump is 100 –120mm. The drop height of the concrete should

not more than 1.5m. At one time we can concrete max 2m and

compacted by needle vibrator 60mm full of concreting should be done

continuously one pour. Total concreting time 6-8 hrs. In the pier 5-6

layer of concrete should be sufficient. The max range of concrete

temperature is 40°C.

3.1.3.4 Curing

Curing of pier concrete is done with the help of wet jute cloth for min 7

days.

3.2 Super Structure

3.2.1 Pier Cap

Sequence work for pier cap

3.2.1.1 Scaffolding

Scaffolding is a temporary structure used to support people and

material in the construction or repair of buildings and other large

structures. It is usually a modular system of metal pipes or tubes. The

key elements of a scaffold are standards, ledgers and transoms. The

standards, also called uprights, are the vertical tubes that transfer the

entire mass of the structure to the ground where they rest on a square

concrete base plate to spread the load. The base plate has a shank in

its centre to hold the tube and is sometimes pinned to a sole board.

40

Ledgers are horizontal tubes which connect between the standards.

Transoms rest upon the ledgers at right angles. Main transoms are

placed next to the standards. The height of strands and ledger

available are 0.5m, 1m, 1.5m, 2m, 2.5m, 3m, 4m etc.

Fig.3.2: Scaffolding for pier cap

3.2.1.2 Level transferred to pier

After completion of pier, the levels as per drawings are transferred to

the pier with the help of auto level (see appendix IV) the bottom level

of pier cap is marked on the pier and scaffolding is erected up to that

level, some space is left for bottom shutter plat and IS Medium Beam

125 to support the dead load of pier cap before it attains its full

strength. Adjustable stirrup head are placed between the ISMB 125

and top of scaffolding to adjust the top level of bottom shutter plate.

41

Fig 3.3: Arrangement of shutter plate, ISMB, Adjustable stirrup head

After fixing of bottom shutter plate the top level of bottom shutter

plate are checked by auto level (see appendix IV) the top surface of

shutter plate should be in a same level, so that the bottom of pier cap

is to be casted should be smooth.


The reinforcement bar is to be placed as per drawings and bar bending

schedule. Rebar cages are fabricated either on the project site

commonly with the help of hydraulic benders and shears, however for

small or custom work a tool known as a Hickey or hand rebar bender,

is sufficient. The rebars are placed by rod busters or concrete

reinforcing ironworkers with bar supports separating the rebar from

the concrete forms to establish concrete cover and ensure that proper

embedment is achieved. The rebars in the cages are connected by

welding or tying wires. Welding can reduce the fatigue life of the rebar,

and as a result rebar cages are normally tied together with wire.

Besides fatigue concerns welding rebar has become less common in

developed countries due to the high labor costs of certified welders.

42

There are different types of ties used for securing rebars. It is better to

use two twisted strands of annealed 0.9 to 1.6 mm diameter wires.

3.2.1.4 Concreting

Concreting at a higher altitude is a difficult task, so concrete pump is

required concrete pump is attached to a truck. It is known as a trailer-

mounted boom concrete pump because it uses a remote-controlled

articulating robotic arm (called a boom) to place concrete with pinpoint

accuracy. Boom pumps are used on most of the larger construction

projects as they are capable of pumping at very high volumes and

because of the labour saving nature of the placing boom. They are a

revolutionary alternative to truck-mounted concrete pumps. The bends

in the pipes conveying concrete from the pump should be minimal in

order to avoid losses. In addition, these should not be sharp. Each 10o

bend is equivalent to an extra length of pipe of 1 m. The pipe diameter

should be at least 3 times the maximum aggregate size. Large

aggregates can especially tend to get blocked near the bends.

The economy of pumping depends on the number of interruptions.

Each time, the priming of the pipes using mortar is required (0.25

m3/100 m of 6 inch pipe), and the pipe also has to be cleaned.

Aluminum pipes should be avoided, as the Al reacts with alkalis in the

cement, and leads to the evolution of hydrogen gas. These gases tend

to introduce voids in the concrete, which reduce the efficiency of

pumping.

Pumping enables concreting of inaccessible areas. Moreover, the direct

conveyance of concrete from the truck to formwork can avoid double

handling of the concrete.

43

Requirements for pumped concrete

Concrete mixture should neither be too harsh nor too sticky;

also, neither too dry nor too wet.

A slump between 50 and 150 mm is recommended (note that

pumping induces partial compaction, so the slump at delivery

point may be decreased).

If the water content in the mixture is low, the coarse particles

would exert pressure on the pipe walls. Friction is minimized at

the correct water contents. The presence of a lubricating film of

mortar at the walls of the pipe also greatly reduces the friction.

High cement content in concrete is generally beneficial for

pumping.

Water is the only pump able component in the concrete, and

transmits the pressure on to the other components.

Two types of blockage to efficient pumping could occur:

Water can escape from the mixture if the voids are not small

enough; this implies that closely packed fines would be needed

in the mixture to avoid any segregation. The pressure at which

segregation occurs must be greater than that needed to pump

concrete.

When the fines content is too high, there could be too much

frictional resistance offered by the pipe. The first type of

blockage occurs in irregular or gap-graded normal strength

mixtures, while the second type occurs in high strength mixtures

with fillers. In order to avoid these two types of failure, the

mixture should be proportioned appropriately.

Other mixture factors that could affect pumping are the cement

content, shape of aggregate, presence of admixtures such as

44

pumping aids or air entrainment. Air entrainment is helpful in

moderate amounts, but too much air can make pumping very

inefficient.

When flowing concrete is being pumped, an over-cohesive

mixture with high sand content is recommended. For lightweight

aggregate concrete, pumping can fill up the voids in the

aggregate with water, making the mixture dry.

Fig.3.4: Boom placer concreting pier cap

3.2.1.5 Compaction

It is important that concrete be vibrated at the correct frequency to

fluidise the mix, to coat the aggregate with cement paste and to

release trapped air. The operating frequency of internal vibrators may

45

be less than specified values, which may have been measured with the

vibrator operating in air. A reduction in frequency results in an energy

reduction, which in turn reduces the effective compaction area. It is

important to introduce the vibrator in a systematic way, so that the

compaction areas overlap and all the concrete is compacted. An

internal vibrator with an electric motor and electronic speed control

has been developed. This gives controlled energy input and has the

added benefit of a lighter, more flexible cable.

Fig.3.5: Needle vibrator for Compaction

3.2.1.7 Finishing

When the concrete compaction and screeding is done, the slab is

roughly floated with a trowel to give a smooth surface. After floating,

slab is left to set hard. Free water (bleed water) will rise to the surface

of the slab after it is leveled. Wait until the surface water dries before

doing the final float or trowel finishing. On a cold day the bleed water

may have to be dragged off by pulling a rope or hose over the surface.

Never spread dry cement or sand over the slab to absorb the bleed

water as this will make the finished surface weak and dusty. Wood or

steel hand-floats and trowels do a good job too; the whole surface

should be worked over twice. Save finishing time by finishing the

46

girder only to the standard needed for the type of finish to be used,

the top surface is finished smooth.

3.2.1.7 Curing

Approved curing compounds may be used in lieu of moist curing with

the permission of the engineer-in charge. Such compounds shall be

applied to all exposed surfaces of the concrete as soon as possible

after the concrete has set. Water covering closely the concrete surface

may also be used to provide effective barrier against evaporation. For

the concrete containing portland cement, portland slag cement or

mineral admixture, period of curing may be increased.

Fig.3.6: curing of pier cap

3.2.2 Bearings

POT bearings for incrementally launched bridges have a dual function.

First, they provide low friction sliding surfaces over piers as the deck is

launched during construction. Thereafter, they become permanent

bearings for the completed bridge. A POT bearing serving both

functions is shown in the picture above. During construction, a fixing

device avoids relative movement between sliding plate and pot

cylinder. POT bearing for bridge the sliding plate is supplied with a

47

second stainless steel sheet on top. Inserting neoprene-teflon pads

between deck and bearings allows the launching operation to be

carried out. Pads, second stainless steel sheet and fixing device are

removed after launching. To achieve this, the deck is lifted by means

of hydraulic jacks placed on top of the piers. Once this operation is

achieved, the deck is lowered to its final position, the jacks are

removed and the sliding plate is connected to a previously embedded

steel plate in the deck. Finally, the fixing devices used for

transportation are released, thus the bearing is in its final service

position. For the correct design of these bearings, it is very important

to know the loads during launching, because, they have major

influence in the actual length and thickness of the sliding plates.

Although the cost of this type of bearing is higher than the standard

ones, their use represents a saving for the job because:

Temporary launching bearings are not required

Demolition and replacement of the temporary bearings by

permanent ones, is costly and time consuming therefore avoided

Fig. 3.7: POT bearings

48

Site Installation

3.2.2.1 Preparation of the piers

Build the piers leaving on them the required recesses according to the

dimensions indicated on the drawings. Pedestal reinforcement is

anchored during the formation of mesh of reinforcement of pier cap.

Fig. 3.8: Reinforcement for pedestal

3.2.2.2 Levelling of bearings

Fig. 3.9: Plan view Fig. 3.10: Elevation

49

Place the pot bearing in its position levelling it with Steel wedges. It is

important to ensure that the X-axis of the bearing is aligned in the

longitudinal direction of the bridge and that the X and Y directions are

accurately horizontal. For bearings allowing horizontal displacements it

should be checked that the arrow painted on the slide plate is pointing

in the correct direction.

Install the form for grouting the space between pier and pot bearing.

Grout the space between pier and pot bearing. Fill in the recesses

checking that the level is the correct.

3.2.2.3. Formwork for diaphragm wall

The formwork of the deck is placed embedding the upper dowels of the

bearing

Fig. 3.11: Formwork for Diaphragm wall

3.2.2.4 Removal of fixing plates

Once the formwork has been removed, the bearing is definitively

installed. Remove the lateral fixing plates of the bearing in order to

allow its free movement.

50

Fig. 3.12: Removal of fixing plates

3.2.2.5 Types of Bearing for joints of girder on pier cap

Fixed joint

Fig. 3.13: Bearing for fixed joint

51

Expansion joint

Fig. 3.14: Bearing for expansion joint

Free joint

Fig.3.15: Bearing for free joint

52

3.2.3 Precast Girder

3.2.3.1 P.C.C

The plane cement concrete strip of cement mix 1:6 is laid and a strip

of length and breadth about 1.4 times than that of dimension of

precast girder and thickness of 20 mm. A constant level line is

maintained throughout the strip by help of auto level and its top

surface is leveled by flat trowels.

3.2.3.2. Runner

At some intermediate distance C shaped steels bars of diameter 16

mm and length 1.2 times width of precast girder are placed across the

length of P.C.C strip. Runners are provided to stop skidding the

shuttering plates in outward direction due to force produced by

concrete placement and compaction of concrete.

Fig 3.16: P.C.C for casting girder

3.2.3.3 Flats

Steel plates of 5 mm thick are placed over the P.C.C strip to provide

smooth bottom of precast girder.

53


Steel reinforcements are used, generally, in the form of bars of circular

cross section in concrete structure. They are like a skeleton in human

body. Plain concrete without steel or any other reinforcement is strong

in compression but weak in tension. Steel is one of the best forms of

reinforcements, to take care of those stresses and to strengthen

concrete to bear all kinds of loads.

Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel

high strength deformed bars conforming to IS: 1786 (grade Fe 415

and grade Fe 500, where 415 and 500 indicate yield stresses 415

N/mm2 and 500 N/mm2 respectively) are commonly used. Grade Fe

415 is being used most commonly nowadays. This has limited the use

of plain mild steel bars because of higher yield stress and bond

strength resulting in saving of steel quantity. Some companies have

brought thermo mechanically treated (TMT) and corrosion resistant

steel (CRS) bars with added features.

Bars range in diameter from 6 to 50 mm. Cold worked steel high

strength deformed bars start from 8 mm diameter. For general house

constructions, bars of diameter 6 to 20 mm are used.

Transverse reinforcements are very important. They not only take care

of structural requirements but also help main reinforcements to remain

in desired position. They play a very significant role while abrupt

changes or reversal of stresses like earthquake etc.

They should be closely spaced as per the drawing and properly tied to

the main/longitudinal reinforcement.

54

Terms used in Reinforcement

3.2.3.5 Bar-bending-schedule

Bar-bending-schedule is the schedule of reinforcement bars prepared

in advance before cutting and bending of rebars. This schedule

contains all details of size, shape and dimension of rebars to be cut.

(Refer Appendix II).

3.2.3.6 Lap length

Lap length is the length overlap of bars tied to extend the

reinforcement length. Lap length about 50 times the diameter of the

bar is considered safe. Laps of neighboring bar lengths should be

staggered and should not be provided at one level/line. At one cross

section, a maximum of 50% bars should be lapped. In case, required

lap length is not available at junction because of space and other

constraints, bars can be joined with couplers or welded (with correct

choice of method of welding).

3.2.3.7 Anchorage length

This is the additional length of steel of one structure required to be

inserted in other at the junction. For example, main bars of beam in

column at beam column junction, column bars in footing etc. The

length requirement is similar to the lap length mentioned in previous

question or as per the design instructions.

3.2.3.8 Cover block

Cover blocks are placed to prevent the steel rods from touching the

shuttering plates and thereby providing a minimum cover and fix the

reinforcements as per the design drawings. Sometimes it is commonly

seen that the cover gets misplaced during the concreting activity. To

prevent this, tying of cover with steel bars using thin steel wires called

binding wires (projected from cover surface and placed during making

55

or casting of cover blocks) is recommended. Covers should be made of

cement sand mortar (1:3). Ideally, cover should have strength similar

to the surrounding concrete, with the least perimeter so that chances

of water to penetrate through periphery will be minimized. Provision of

minimum covers as per the Indian standards for durability of the whole

structure should be ensured.

Shape of the cover blocks could be cubical or cylindrical. However,

cover indicates thickness of the cover block. Normally, cubical cover

blocks are used. As a thumb rule, minimum cover of 2” in footings,

1.5” in columns and 1” for other structures may be ensured.

Table 3.1: Minimum cover to reinforcement

Structural element Cover to reinforcement (mm)

Footings 40

Columns 40

Slabs 15

Beams 25

Retaining wall 25 for earth face

20 for other face

3.2.3.9 Things to Note

Reinforcement should be free from loose rust, oil paints, mud etc. it

should be cut, bent and fixed properly. The reinforcement shall be

placed and maintained in position by providing proper cover blocks,

spacers, supporting bars, laps etc. Reinforcements shall be placed and

tied such that concrete placement is possible without segregation, and

compaction possible by an immersion vibrator.

56

For any steel reinforcement bar, weight per running meter is equal to

d2/162 kg, where d is diameter of the bar in mm. For example, 10 mm

diameter bar will weigh 10×10/162 = 0.617 kg/m.

Three types of bars were used in reinforcement of a slab. These

include straight bars, crank bar and an extra bar. The main steel is

placed in which the straight steel is binded first, then the crank steel is

placed and extra steel is placed in the end. The extra steel comes over

the support while crank is encountered at distance of one fourth of

span from the supports.

For providing nominal cover to the steel in beam, cover blocks were

used which were made of concrete and were casted with a thin steel

wire in the center which projects outward. These keep the

reinforcement at a distance from bottom of shuttering. For maintaining

the gap between the main steel and the distribution steel, steel chairs

are placed between them.

For details of reinforcement refer to drawing no 3.1.1.

Profiling

Duct Installation

3.2.3.10 Alignment

Correct duct alignment and profile is of paramount importance for

proper functioning of a post-tensioning tendon, whether that tendon is

internal or external to concrete. Duct alignment and profile should be

clearly and sufficiently defined on the plans and approved shop

drawings by dimensions to tangent points, radii, angles and offsets to

fixed surfaces or established reference lines and by entry and exit

locations and angles at anchorage or intermediate bulkheads.

Alignment, spacing, clearance and details should be in accordance with

Indian Specifications.

57

General recommendations for fabrication are that ducts should be:

Installed with correct profile (line and level) within specified

tolerances.

Tied and properly supported at frequent intervals.

Connected with positively sealed couplings between pieces of

duct and between ducts and anchors.

Aligned with sealed couplers at temporary bulkheads.

Positively sealed at connections made on-site and in cast-in-

place splice joints.

The elevations and alignments of ducts should be carefully

checked.

Installed to connect correct duct location in bulkhead with correct

duct location in matchcast segment.

Correctly aligned with respect to the orientation of the segment

in the casting cell and the direction of erection.

Elevations and alignments of longitudinal and transverse ducts

should be carefully checked.

Fig. 3.17: Profiling of Ducts

58

3.2.3.11 Local Zone Reinforcement

Regardless of the type of anchor, it is essential to provide

reinforcement in the local anchor zone – this is the region directly

behind the anchor bearing plate(s).

For longitudinal strand, tendons comprise a spiral shape (Fig 3.18).

Local zone reinforcement should be placed as close as possible

(i.e.12mm maximum) to the main anchor plate in all applications. A

series of relatively rectangular stirrups is normally provided to

reinforce the general anchor zone (region around and beyond the local

zone) until the local anchor force has dispersed to the full effective

depth of the section. Typically, for an I-girder, this extends over a

length approximately equal to the depth of the beam from the anchor.

Local anchor zones for transverse deck slab tendons anchored in the

relatively shallow depth at the edge of segments are most effectively

reinforced by multiple-U shaped bars placed in alternating up and

down arrangement, beginning very close to the anchor plate. This

arrangement has been found to be very effective for intercepting

potential cracks that might originate at the top or bottom corner of the

anchor bearing plate and travel diagonally through the adjacent

surface – apart from the classical splitting stress along the line of the

tendon itself.

Fig. 3.18: General and Local Anchor Zone in end of I-Girder

59

3.2.3.12 Shuttering

Shuttering or formwork is the term used for temporary timber,

plywood, metal or other material used to provide support to wet

concrete mix till it gets strength for self support. It provides supports

to horizontal, vertical and inclined surfaces or also provides support to

cast concrete according to required shape and size. The formwork also

produces desired finish concrete surface. Shuttering or formwork

should be strong enough to support the weight of wet concrete mix

and the pressure for placing and compacting concrete inside or on the

top of form work/shuttering. It should be rigid to prevent any

deflection in surface after laying cement concrete and be also sufficient

tight to prevent loss of water and mortar form cement concrete.

Shuttering should be easy in handling, erection at site and easy to

remove when cement concrete is sufficient hard. The shuttering plates

are pre designed as per dimensions from drawing. The plates are

cleaned and lubricating oil is polished on the surface of plate in contact

with concrete. A layer of liquid proofing material is applied between the

two plates the plates are bolted together till the settling of concrete.

Shuttering is supported by the manual jacks.

Alignment of Shuttering

Fig. 3.19: Shuttering of girder

60

When shuttering plates are fixed they are not vertical. Thus the final

shape of girder will not be smooth and linear. So the alignment of

shuttering is to be done. A thread is tied along the length of girder at a

fixed distance (x) outward from shuttering plates, at the last plate near

to end face of girder a plumb bob is placed and verticality of the plates

is checked by measuring the distance of thread of plumb bob from

plate, this distance should be same to the distance (x), the distance is

checked both at top of plate and bottom of plate, if distance is larger

than that of fixed at bottom of plate then upper jack supporting the

plate is tightened or vice versa, this procedure is repeated on every

plate to check the alignment of plate.

Fixing of anchor cone

Anchor Cone is made of steel. It is a steel guide embedded in concrete,

while providing shuttering on face of girder, one end of anchor cone is

fixed on shuttering plate through bolts and at other end of it,

sheathing is mounted. It is covered by the spiral rebar. It provides a

firm base to jack for post tensioning and protect concrete from

bursting.

Fig. 3.20: Anchor cone

61

3.2.3.13 Concreting

Concrete is ordered by strength-grade and slump. Never use concrete

less than M20 grade (20 MPa of strength, with 20 mm nominal

maximum aggregate size and 80 mm slump). The concrete grade used

for girder was M45 as per design. Reject the concrete with a slump of

more than 100 mm. In fact 80-mm slump is better. It may be slightly

harder to work into place, but it can be finished sooner and will shrink

less. The slump of concrete is a rough measure of the amount of water

in the mix. If water is added the mix will become sloppy and easier to

work into place – but the concrete will be weaker, more cracks will be

there and have a poor surface finish. For this reason no water should

be added to concrete during the placement and finishing operations.

Place each batch of concrete next to the previous batch. Start from

one end and work along the girder making sure that each new batch is

well mixed into the batch before.

Do not let concrete free-fall more than 1m from a chute, pipe or

bucket when it is being placed. Level the surface of the concrete with a

screeding board. It is important to move the screeding board with a

sawing and chopping motion as this helps to compact the concrete.

3.2.3.14 Compaction

A needle vibrator is used to compact the concrete. Poke the vibrator

into the concrete every half m over the length of the beam and hold it

in place until the concrete settles and bubbles stop rising to the

surface. Hold the vibrator straight up and be careful not to move the

steel reinforcement, or damage the underlay or formwork. Curing

should be done.

3.2.3.15 Post-tensioning

Principle of Post-tensioning

The function of post-tensioning is to place the concrete structure under

compression in those regions where load causes tensile stress. Tension

62

caused by the load will first have to cancel the compression induced by

post-tensioning the before it can crack the concrete. Fig. 3.21 shows a

plainly reinforced concrete simple-span beam and fixed cantilever

beam cracked under applied load.

Fig. 3.21: Reinforced concrete beam under load

By placing the post-tensioning low in the simple-span beam and high

in the cantilever beam, compression is induced in the tension zones;

creating upward camber.

Fig. 3.22 shows the two post-tensioned beams after loads have been

applied. The loads cause both the simple-span beam and cantilever

beam to deflect down, creating tensile stresses in the bottom of the

simple-span beam and in top of the cantilever beam. The bridge

designer balances the effects of load and post-tensioning in such a way

that tension from the loading is compensated by compression induced

by the post-tensioning. Tension is eliminated under the combination of

the two and tension cracks are prevented. Also, construction materials

(concrete and steel) are used more efficiently; optimizing materials,

construction cost. Post-tensioning can be applied to concrete members

in two ways, by pre-tensioning or post-tensioning.

In pre-tensioned members the pre-stressing strands are tensioned

against restraining bulkheads before the concrete is cast. After the

concrete has been placed, allowed to harden and attain sufficient

63

strength, the strands are released and their force is transferred to the

concrete member.

Pre-stressing by post-tensioning involves installing and stressing pr-

stressing strand or bar tendons only after the concrete has been

placed, hardened and attained a minimum compressive strength for

that transfer.

Fig. 3.22: Comparison of reinforced and post-tensioned concrete beams

Tendon Installation

Multi-strand tendons are the most frequent choice for main longitudinal

tendons in bridges. All the strands of one tendon are tensioned

together using a multi-strand jack. The sequence in which tendons are

stressed and the ends from which they are stressed should be clearly

shown on the contract plans or approved shop drawings and must be

followed.

Anchoring Tendons

A bearing plate is fixed having holes equal as no of strands and an

anchorage body for anchoring tendons with wedges, having a central

passage or bore for the tendon, at least one part or section of which

passage widening conically from the inlet end to the outlet end in order

to form a seat for wedges, said anchorage body presenting at the inlet

end of said passage a projection integral with the remaining part of the

64

body and having also a passage or bore for the tendon to form a

holding means for a sealing element surrounding the portion of a

tendon near the anchoring body.

Fig. 3.23: Anchor set or wedge set

Jacking Methods

When the tendons are very long, losses over the length of the tendon

due to friction and wobble become large. Stressing the tendon from

the second end results in a higher force in the tendon than if only

stressed from one end. Also, for symmetrical tendons two-end

stressing becomes effective when the effect of anchor set at the

jacking end affects less than half of the tendon (Fig. 3.23). Stressing

from the second end should not be done if the calculated elongation is

less that the length of the wedge grip. Re-gripping in a portion of the

old grip length should be avoided. ‘Two End Stressing’ results in

symmetrical stresses, and, in longer tendons, higher stress levels.

65

Fig. 3.24: Stresses along tendon for Two End Stressing

Fig. 3.25: Arrangement of post-tensioning Jack

The force required in each tendon is determined by the designer and is

given on the approved shop drawings or job stressing manual. Also,

the corresponding elongations are predetermined taking into account

all losses due to curvature friction, wobble, wedge set, and friction

within the anchor and jack, as necessary (refer to Appendices III). For

post-tensioning, measurement of elongations serves as a check of the

anticipated jacking force primarily given by the gauge pressure and

66

calibration chart. The stressing operation should constantly be

monitored by an inspector. There are two basic pieces of information

that need to be recorded: tendon elongations and gauge pressures.

Both will give an indication whether the tendon is stressed to the force

required. The gauge pressure is a direct measurement of the force at

the jack and the elongation will give an indication how the remainder

of the tendon is being stressed. Normally the tendon will be stressed to

a predetermined gauge pressure, representing a certain force in the

tendon at the stressing end. The elongation measured at this point is

compared to the theoretically determined elongation.

Measuring Elongations on Strand Tendons

When stressing a tendon a certain portion of jack extension will be

needed to remove the slack. This gives a false initial elongation that

should not be part of the real elongation measurements. For this

reason, the first step is to stress the tendon an initial force of

approximately 20% of the final force to remove the slack. From this

point up to 100% of the required load, the extension of the jack will

cause pure elongations of the tendon. At the end of the operation, a

correction can be made for the unmeasured portion of the elongation

by straight extrapolation. The accuracy of the determination of the

elongation obtained during the first step, i.e. tensioning up to 20% of

the jacking force, can sometimes be improved by recording elongations

at intermediate gauge readings of 40%, 60% and 80% and plotting

results on a graph. Ideally, the graph should be a straight line.

Intermediate elongations must be recorded if a long tendon has to be

stressed using two or more pulls on the jack when the required

elongation is greater than the available stroke For short, mono or

multi-strand tendons it may suffice to check the elongation for the

stressing range between 20% and 100% load against the calculated

value for this range. Short tendons are those generally less than about

30m (100 feet) long where the expected elongation is only about 0.2m

67

(8 inches) or less and is easily made with a single, steady and

continuous stroke of the jack. Elongation may be measured by the

extension of the cylinder beyond the barrel of the jack. However, this

is acceptable only if the wedge pull-in of the internal wedges that grip

the strand inside the jack is reliably known; it is deducted from the

measured extension on the cylinder to give the actual strand

elongation. This method is often preferred for convenience.

Strand End Cut-off

The ends of the strands should only be cut off if the jacking forces and

elongations are satisfactory. If there is any doubt that might require

verification by a lift-off test or additional jacking, strands should not be

cut. Preferably, strands should be trimmed as soon as possible, so that

permanent grout caps can be placed over the wedge plate to seal the

tendon until grouting. Strands should be cut off at the wedges leaving

approximately 12 to 20mm (½” to ¾”) of strand projecting but no

greater than that which can be accommodated by any permanent non-

metallic grout cap supplied for installation with the post-tensioning

system. Strands should be cut only with an abrasive cutting tool.

Under no circumstances should flame cutting be used as the heat can

soften the strands and wedges and lead to loss of strands. Recently,

plasma cutters have become available; their use should only be with

strict inspection and approval of the Engineer.

After strand tails have been cut-off, the ends of the tendon should be

temporarily protected in an approved manner until the tendon has

been grouted. Preferably, a non-metallic (plastic) grout cap should be

placed over the strands and wedges.

3.2.3.16 Grouting

The purpose of grouting is to provide permanent protection to the

post-tensioned steel against corrosion and to develop bond between

the post-tensioned cables and the surrounding structural concrete.

68

Grouting shall be carried out as early as possible, but generally not

later than two weeks of stressing. Whenever this stipulation cannot be

completed with for unavoidable reasons adequate temporary

protection of the cables against corrosion by methods or products,

which will not impair the ultimate adherence of the injected grout shall

be ensured till grouting.

Verification of Post-Tensioning Duct System Prior to Grouting

Check for Water and Debris

Prior to grouting, tendon ducts, grout inlets and outlets, and anchors,

should be examined and a water jet is injected at pressure of

50kg/cm2 to remove debris and water to avoid blockages or dilution.

Inlets, Outlets and Connections

Connections from grout hose to inlets and outlets should be airtight

and free from dirt. Inlets and outlets should be provided with positive

shut-offs capable of withstanding the maximum grouting pressure. The

required grouting pressure should take into account the pressure head

for vertical changes in profile.

Appropriate repairs should be made to any damaged inlets and outlets

prior to grouting.

Fig. 3.26: Arrangement of grout cap, inlets & outlets

69

Pressure Check of Duct System

Prior to grouting, it is recommended that the post-tensioning ducts be

tested using compressed air to verify if any duct connections, joints or

fittings require sealing or repair. Compressed air should be clean, dry

and free from any oil or contaminants.

A possible test would be to consider the duct system satisfactory if,

after pressurizing to an initial pressure (e.g. 0.7MPa (100 psi)) the

pressure loss over five minutes is less than 10% (e.g. 0.07MPa, In any

case, it would be necessary to temporarily seal the ends of ducts. This

could be done with anchor grout caps. Testing to 0.7MPa (100 psi)

before concrete placement, connections and fittings or using a suitable

sealant approved by the manufacturer of the PT duct system and

acceptable to the Engineer. Leaks at match-cast joints could be sealed

by epoxy injection or other acceptable means. In no case should duct

tape be used as a seal; however, it may be used to provide temporary

support or restraint.

Batching and Mixing

The proportions in the mix should be based upon the mix approved

prior to grouting is begun whether for a mix to be blended on site or

for a pre-qualified, pre-bagged grout. Dry powder and pre-bagged

grout materials should be batched by weight to an accuracy of ±2%.

Water and liquid admixtures may be batched by weight or volume to

an accuracy of ±1%. Any water content in any liquid admixtures should

be counted towards the quantity of water.

The materials should be mixed to produce a homogeneous grout

without excessive temperature rise (limiting up to 10ºC) or loss of

fluid properties (flow cone). The mix should be continuously agitated

until it is pumped. Water must not be added to increase fluidity if it

has decreased by delayed use of the grout. Typically, the mix time for

70

grout should be in accordance with the qualification trials and

generally not more than 4 min for a vane mixer or 2 min for a high-

speed shear mixer.

Unless otherwise specified by the manufacturer, the constituents maybe added as follows:

For a vane mixer: all the water, about 2/3 cementitious material,the admixture and the remaining water.

For a high speed shear (colloidal) mixer: water, admixture andcementitious material.

Condensed, dry compacted silica fume should not be added to a mix as

it agglomerates and does not blend well, leading to a poor mix.

Injection of Grout

Pumping

Grout pumping methods should ensure complete filling of the ducts

and encasement of post tensioning steel. Grout should be pumped in a

continuous operation and be ejected from the first, and subsequent

outlets, until all visible slugs of water or entrapped air have been

removed prior to closing each outlet in turn. At each outlet and final

grout cap, pumping should continue until the consistency of the

discharged grout is equivalent to that being injected at the inlet. At

least 7.5 liters (2 gallons) of good, consistent, quality grout should be

discharged through the final anchor and cap before closing them.

Limiting Grout Injection Pressures

For normal operations grout should be injected at a pressure of less

than 0.52 MPa (75psi) at the inlet. Pumping pressures should not

exceed 1MPa (145 psi). Although higher pressures than this might be

sustained by internal ducts of HDPE or steel or external ducts of steel

pipe, higher pressures are not recommended for grouting. Sometimes

an initial temporary higher pressure may be needed to mobilize a

71

thixotropic grout, but, once flowing, pumping pressures should be the

same as for normal grout.

Vacuum Grouting Operation

Vacuum grouting generally involves the following activities:

Pressurize void and check for leaks.

Seal leaks (tighten all caps and seal leaks with epoxy or epoxy

injection).

Measure the volume of the void to determine the necessary

quantity of grout.

Mix sufficient grout for use and for testing, record quantity of

mixed grout.

Test the grout using the flow-cone or modified flow-cone

method.

Evacuate air from the voids.

Switch valve and inject grout into voids under pressure.

Record quantity of grout remaining and calculate the amount

injected.

Seal grout injection inlets.

Clean equipment, area of operations on structure and properly

discard unused grout.

Record and report vacuum grouting operations.

Sealing of Grout Inlets and Outlets

It is recommended that threaded plastic caps be used to seal all grout

inlet and outlet pipes and that threaded plugs be installed in

anchorages and grout caps once the grout pipe and shut-off valve have

been removed (Fig. 3.27). Where an inlet or outlet is permanently

recessed within the concrete, provision should be made to

accommodate the threaded plastic cap at clear depth of at least 25mm

(1”) by means of a formed recess. The recess should be cleaned and

completely filled with an approved epoxy material. The surface of the

72

recess should be prepared to receive the epoxy material in accordance

with the recommendations of the manufacturer of the epoxy.

Fig. 3.27: Sealing of grout inlets and outlets

3.2.3.17 Erection of girder

Stool Fixing

Fig. 3.28: Stool for girder

Stools are temporary arrangements for resting of girder on pier cap

they are made of high strength steel, they are fixed on pier cap with

73

the help of high strength friction grip bots having gross dia of 22.5

mm, there bottom plate is fixed on pier cap and its top surface has

arrangement for adjustment of level below it. Thus the top plate of

stool can be adjusted accordingly to required level or chamber of

bridge (see Appendix IV).

Erection of the precast concrete girders must be done accurately and

carefully, as shown on the drawings and in a manner that will prevent

damaging the girders.

Contractor must clean the bearing surfaces and the surfaces to

be in permanent contact before the members are assembled.

Check the elevations, camber, and girder alignment and ensure

that the diaphragms are completely connected. Take profiles of

the girder tops so that camber adjustments may be determined

with particular emphasis on the differential camber between

adjacent girders.

When the girders are satisfactorily erected and approved, ensure

that the lifting devices are cut off, all lifting pockets are filled

with grout, and lifting holes on exterior girders are filled with

grout.

Inspect the girders for cracks, chips or other damage, which may

have occurred during erection.

Report any damaged girders noted to the Bridge Project

Engineer.

If post-tensioning of the girders is required, discuss the

procedures and all aspects of the inspection required with the

Bridge Project Engineer.

74

Fig. 3.29: Erection of girder

3.2.4 Diaphragm Wall

3.2.4.1 Formwork

The formwork shall be designed and constructed so as to remain

sufficiently rigid during placing and compaction of concrete, and shall

be such as to prevent loss of slurry from the concrete. For further

details regarding design, detailing, etc. reference may be made to IS

14687. The tolerances on the shapes, lines and dimensions shown in

the drawing shall be within the limits given below:

Table 3.2 limits of tolerances on the shapes, lines and dimensions

a) Deviation from specified dimensions

of cross-section of columns and beams

12±6 mm

b) Deviation from dimensions of footings

1) Dimensions in plan 50±12mm

2) Eccentricity 0.02 times the width

of the footing in the

direction of

75

deviation but not

more than 50mm

3)Thickness + 0.05 times the

specified thickness

These tolerances apply to concrete dimensions only, and not to

positioning of vertical reinforcing steel or dowels.

The number of props left under, their sizes and disposition shall be

such as to be able to safely carry the full dead load of the slab, beam

as the case may be together with any live load likely to occur during

curing or further construction.

3.2.4.2 Cleaning and treatment of formwork

All rubbish, particularly, chippings, shavings and sawdust shall be

removed from the interior of the forms before the concrete is placed.

The face of formwork in contact with the concrete shall be cleaned and

treated with form release agent. Release agents should be applied so

as to provide a thin uniform coating to the forms without coating the

reinforcement.


Reinforcement shall be bent and fixed in accordance with procedure

specified in IS 2502. The high strength deformed steel bars should not

be re-bendor straightened without the approval of engineer-in charge.

Bar bending schedules shall be prepared for all reinforcement work. All

reinforcement shall be placed and maintained in the position shown in

the drawings by providing proper cover blocks, spacers, supporting

bars, etc. Crossing bars should not be tack-welded for assembly of

reinforcement unless permitted. Welded joints or mechanical

connections in reinforcement may be used but in all cases of important

connections, tests shall be made to prove that the joints are of the full

strength of bars connected. Welding of reinforcements shall be done in

76

accordance with the recommendations of IS 275 1 and IS 9417. Where

reinforcement bars up to 12 mm for high strength deformed steel bars

and up to 16 mm for mild steel bars are bent aside at construction

joints and afterwards bent back into their original positions, care

should be taken to ensure that at no time is the radius of the bend less

than 4 bar diameters for plain mild steel or 6 bar diameters for

deformed bars. Care shall also be taken when bending back bars, to

ensure that the concrete around the bar is not damaged beyond the

band. Reinforcement should be placed and tied in such a way that

concrete placement be possible without segregation of the mix.

Reinforcement placing should allow compaction by immersion vibrator.

Within the concrete mass, different types of metal in contact should be

avoided to ensure that bimetal corrosion does not take place.

3.2.4.3 Concreting

The concrete shall be deposited as nearly as practicable in its final

position to avoid re-handling. The concrete shall be placed and

compacted before initial setting of concrete commences and should not

be subsequently disturbed. Methods of placing should be such as to

preclude segregation. Care should be taken to avoid displacement of

reinforcement or movement of formwork. As a general guidance, the

maximum permissible free fall of concrete may be taken as 1.5 m.

3.2.4.4 Compacting

Concrete should be thoroughly compacted and fully worked around the

reinforcement, around embedded fixtures and into comers of the

formwork Concrete shall be compacted using mechanical vibrators

complying with IS 2505, IS 2506, IS 2514 and IS 4656. Over vibration

and under vibration of concrete are harmful and should be avoided.

Vibration of very wet mixes should also be avoided. Whenever

vibration has to be applied externally, the design of formwork and the

77

disposition of vibrators should receive special consideration to ensure

efficient compaction and to avoid surface blemishes.

3.2.4.5 Curing

Curing is the process of preventing the loss of moisture from the

concrete whilst maintaining a satisfactory temperature regime. The

prevention of moisture loss from the concrete is particularly important

if the water cement ratio is low, if the cement has a high rate of

strength development, if the concrete contains granulated blast

furnace slag or pulverised fuel ash. The curing regime should also

prevent the development of high temperature gradients within the

concrete. The rate of strength development at early ages of concrete

made with super sulphated cement is significantly reduced at lower

temperatures. Super sulphated cement concrete is seriously affected

by inadequate curing and the surface has to be kept moist for at least

seven days.

3.2.4.6 Stripping time of form work & finishing

Forms shall not be released until the concrete has achieved strength of

at least twice the stress to which the concrete may be subjected at the

time of removal of formwork. The strength referred to shall be that of

concrete using the same cement and aggregates and admixture, if

any, with the same proportions and cured under conditions of

temperature and moisture similar to those existing on the work.

While the above criteria of strength shall be the guiding factor for

removal of formwork, in normal circumstances where ambient

temperature does not fall below 15°C and where ordinary Portland

cement is used and adequate curing is done.

Where the shape of the element is such that the formwork has re-

entrant angles, the formwork shall be removed as soon as possible

after the concrete has set, to avoid shrinkage cracking occurring due to

the restraint imposed.

78

Fig.3.30: Diaphragm wall

80

Tests for Materials

4.1 Tests for Aggregates

Table 4.1: Physical properties

S. No. PropertiesNominal Size

20 mm 10 mm

1 Specific Gravity 2.65 2.64

2 Impact Value 23.0 % ----

3 Abrasion Value 21.0 % ----

4 Bulk Density (Compacted) 1.64 gm/cc 1.53 gm/cc

5 Water Absorption 0.77 % 0.85 %

6 Free Surface moisture Nil Nil

Source: VNC

Table 4.2: Gradation of Coarse Aggregates

Source: VNC

4Chapte r

RESULTS & DISCUSSIONS

81

4.2 Tests for Fine Aggregate

Fine Aggregate Gradation (Sieve Analysis)

Specific Gravity : 2.63

Bulk Density : 1.83 gm/cc

Free Surface Moisture : 0.20 %

Gradation : As per table 4.3

Fineness Modulus : 2.41

Silt Content : 0.80 %

Table 4.3: Gradation of fine aggregate

Source : VNC

82

4.3 Tests for Reinforcement:

Reinforcement is very important and essential part of any construction

work there are some important tests are conducted at VNC Lab. Test

result of these are given below in the table 4.4

Table 4.3: Tests on reinforcement bars of different diameter

Test Required: Tensile strength, Yield stress, % Elongation, Nominal mass, Bend test,

Rebend test

S.No. Name of test Standard

specification

Actual sample

results

Remarks

1 Nominal Dia. 10mm

All samples

confirm to

IS:1786-1985

for Fe 415 grade

with respect to

test performed

Tensile strength Min. 485 MPa 721.0 MPa

Yield stress Min. 415 MPa 556.0 MPa

% Elongation Min. 14.5 % 20.2 %

Nominal mass 0.617 kg/m 0.620 kg/m

Bend Test There shall not be

any transverse

crack

No transverse crack

observed

Rebend Test There shall not be

any fracture in

bent portion

No fracture

observed in bent

portion

2 Nominal Dia. 12mm

All Samples

confirm to

IS:1786-1985

Grade Fe-415 in

respect of test

performed

Tensile strength Min. 485.0 MPa 612.0 MPa

Yield Stress Min. 415.0 MPa 525.0 MPa


Nominal Mass 0.888 kg/m 0.908 kg/m

Bend Test There shall be not

any transverse

crack

No transverse crack

observed


any fracture in

bent portion

No fracture

observed in bent

portion

83

3 Nominal Dia. 16mm

All Samples

confirm to

IS:1786-1985

Grade Fe-415 in

respect of test

performed

Tensile strength Min. 485.0 MPa 593.0 MPa

Yield Stress Min. 415.0 MPa 524.0 MPa


Nominal Mass 1.580 kg/m 1.58 kg/m

Bend Test There shall be not

any transverse

crack

No transverse crack

observed


any fracture in

bent portion

No fracture

observed in bent

portion

Source: VNC

84

4.4 Tests for Concrete

Mix Design (M25)

Target Avg. comp. strength (fck) (IS: 10262-1982 Clause 2.2)

The target average strength required to be achieved by the designed mix

in the laboratory

Fck = fck + t x s = 25 + 1.65 x 5.3 = 33.75 N/mm2

where,

Fck = Target average compressive strength at 28 days (N/mm2)

fck = Characteristic compressive strength in 28 days (N/mm2)

t = Statistical factor depending upon no. of tests and acceptable low

results

s = Standard deviation

Fck =33.75 N/mm2

Quantity of materials for the mix (IS: 10262-1982, Clause-3)

Corresponding to the design strength of concrete mix the following ratio

and quantities are obtained as per standard guidelines.

(i) Water Cement Ratio : 0.465

(ii) Water : 169.73 L/m3

(iii) Cement : 365.0 kg/m3

(iv) Sand Content : 580.35 kg/m3

(v) Coarse Agg(10 mm) : 627.80 kg/m3

(20 mm) : 627.80 kg/m3

(vi) Slump : 82.0 mm

(vii) Filling Frequency : 3 Cubes on (5m3-10m3)

(viii) Curing : 7 – 28 days

85

Fig. 4.1: Cube curing by ponding

4.4.1 Compressive Strength Test

Following table shows the test results of concrete cube after 28 days.

Table 4.6: Compressive strength test results

Source: VNC

86

Fig. 4.2: Compressive strength testing machine

4.4.2 Slump Test

Following table shows the slump test result

Table 4.7: Result of slump test

Source: VNC

87

Different Grades of Concrete

These various kind of concrete grades were used for concrete work at

site. Following shows the properties and these mix gradients.

Table 4.8: Constituents of different grades of concrete

S.No. Water

(kg/m3)

w/c

Ratio

Aggregate Sand Cement

(kg/m3)

Slump

(mm)

Admixture

20 mm 10 mm

M-45 179.10 0.367 % 732.00 599.00 414.0 488 105 1%

M-40 174.84 0.367 % 632.15 632.15 465.3 470 105 1%

M35

(Cap)

174.40 0.400 % 571.16 571.16 601.6 436 70 1%

M35

(Pile)

179.01 0.405 % 565.76 565.76 596.7 442 130

M-30 172.00 0.430 % 730.00 487.00 450.0 400 90

M-25 169.73 0.465 % 627.80 627.80 580.3 365 82

M-20 189.70 0.542 % 579.25 579.25 630.0 350 44

M-15 169.88 0.548 % 627.75 627.75 626.2 310 66

Source: VNC

89

Construction Planning

5.1 Basic Concepts in the Development of Construction Plan

Construction planning is a fundamental and challenging activity in the

management and execution of construction projects. It involves the

choice of technology, the definition of work tasks, the estimation of the

required resources and durations for individual tasks, and the

identification of any interactions among the different work tasks. A

good construction plan is the basis for developing the budget and the

schedule for work. Developing the construction plan is a critical task in

the management of construction, even if the plan is not written or

otherwise formally recorded. In addition to these technical aspects of

construction planning, it may also be necessary to make organizational

decisions about the relationships between project participants and

even which organizations to include in a project.

For example, the extent to which sub-contractors will be used on a

project is often determined during construction planning. In developing

a construction plan, it is common to adopt a primary emphasis on

either cost control or on schedule control as illustrated in Fig. 5.1.

Some projects are primarily divided into expense categories with

associated costs. In these cases, construction planning is cost or

expense oriented. Within the categories of expenditure, a distinction is

5Chapte r

CONSTRUCTIONMANAGMENT

90

made between costs incurred directly in the performance of an activity

and indirectly for the accomplishment of the project. Scheduling of

work activities over time is critical and is emphasized in the planning

process. In this case, the planner insures that the proper precedence’s

among activities are maintained and that efficient scheduling of the

available resources prevails.

Fig. 5.1 Alternative emphases in construction planning

5.2 Choice of Technology and Construction Method

In selecting among alternative methods and technologies, it may be

necessary to formulate a number of construction plans based on

alternative methods or assumptions. Once the full plan is available,

then the cost, time and reliability impacts of the alternative

approaches can be reviewed. This examination of several alternatives

is often made explicit in bidding competitions in which several

91

alternative designs may be proposed or value engineering for

alternative construction methods may be permitted

5.3 Work Tasks

The definition of appropriate work tasks can be a laborious and tedious

process, yet it represents the necessary information for application of

formal scheduling procedures. Since construction projects can involve

thousands of individual work tasks, this definition phase can also be

expensive and time consuming. Fortunately, many tasks may be

repeated in different parts of the facility or past facility, construction

plans can be used as general models for new projects.

5.4 Defining Precedence Relationships among Activities

Once work activities have been defined, the relationships among the

activities can be specified. Precedence relations between activities

signify that the activities must take place in a particular sequence.

Numerous natural sequences exist for construction activities due to

requirements for structural integrity, regulations, and other technical

requirements. For example, design drawings cannot be checked before

they are drawn. Diagrammatically, precedence relationships can be

illustrated by a network or graph in which the activities are

represented by arrows as in (Fig. 5.2). The arrows in Fig.5.2 are called

branches or links in the activity network, while the circles marking the

beginning or end of each arrow are called nodes or events. In this

figure, links represent particular activities, while the nodes represent

milestone events.

Fig. 5.2 Illustrative Set of Four Activities with Precedences

92

More complicated precedence relationships can also be specified. For

ex ample, one activity might not be able to start for several days after

the completion of another activity. As a common example, concrete

might have to cure (or set) for several days before formwork is

removed. This restriction on the removal of forms activity is called a

lag between the completion of one activity (i.e., pouring concrete in

this case) and the start of another activity (i.e., removing formwork in

this case). Many computers based scheduling programs permit the use

of a variety of precedence relationships.

5.5 Estimating Activity Durations

In most scheduling procedures, each work activity has associated time

duration. These durations are used extensively in preparing a

schedule. For example, suppose that the durations shown in Table 5.1.

The entire set of activities would then require at least 8 days, since the

activities follow one another directly and require a total of 2.0 + 2 +

3+ 1.0 = 8 days. If another activity proceeded in parallel with this

sequence, the 8 day minimum duration of these four activities is

unaffected. More than 8 days would be required for the sequence if

there was a delay or a lag between the completion of one activity and

the start of another.

Table 5.1 Durations and Predecessors for a Four Activity Project

Illustration

Activity Predecessor Duration (Days)

Excavate trench

Place formwork

Place reinforcing

Pour concrete

---

Excavate trench

Place formwork

Place reinforcing

2

2

3

1

93

A probability distribution indicates the chance that particular activity

duration will occur. In advance of actually doing a particular task, we

cannot be certain exactly how long the task will require.

5.6 Estimating Resource Requirements for Work Activities

In addition to precedence relationships and time durations, resource

requirements are usually estimated for each activity. Since the work

activities defined for a project are comprehensive, the total resources

required for the project are the sum of the resources required for the

various activities. By making resource requirement estimates for each

activity, the requirements for particular resources during the course of

the project can be identified. Potential bottlenecks can thus be

identified, and schedule, resource allocation or technology changes

made to avoid problems.

The initial problem in estimating resource requirements is to decide the

extent and number of resources that might be defined. At a very

aggregate level, resources categories might be limited to the amount

of labor (measured in man-hours or in do), the amount of materials

required for an activity, and the total cost of the activity. At this

aggregate level, the resource estimates may be useful for purposes of

project monitoring and cash flow planning.

5.7 Reporting

Day to day work should be reported with accuracy in measurement in

prescribed format

5.8 Safety

As with all the other costs of construction, it is a mistake for owners to

ignore a significant category of costs such as injury and illnesses.

While contractors may pay insurance premiums directly, these costs

94

are reflected in bid prices or contract amounts. Delays caused by

injuries and illnesses can present significant opportunity costs to

owners. In the long run, the owners of constructed facilities must pay

all the costs of construction.

During the construction process itself, the most important safety

related measures are to insure vigilance and cooperation on the part of

managers, inspectors and workers. Vigilance involves considering the

risks of different working practices. In also involves maintaining

temporary physical safeguards such as barricades, braces, guy lines,

railings, toe boards and the like. Sets of standard practices are also

important, such as:

Requiring hard hats on site.

Requiring eye protection on site.

Requiring hearing protection near loud equipment.

Insuring safety shoes for workers.

Providing first-aid supplies and trained personnel on site

While eliminating accidents and work related illnesses is a worthwhile

goal, it will never be attained. Despite these peculiarities and as a

result of exactly these special problems, improving worksite safety is a

very important project management concern.

95

5.9 Recommendat ions

Cons truc ti on of any work shou ld star t on ly af te r taking

al l measures of sa fe ty li ke proper li gh ti ng ar rangemen t,

re fl ec ti ve sa fe ty tapes et c.

Traf fi c pl anning fo r GO & FRO Vehi cl es shou ld be

di ve rt ed , el im inat ing Tr af fi c jams .

Pl anning of such proj ec ts shou ld be comp le te ly

suppor ted by a fi rm po li ti ca l wi ll invo lv ing al l user s and

af fe cted agencies or pe rsons.

Al l sa fe ty measures as pe r sa fe ty codes shou ld be

ensu red by execut ing as we ll as supe rv is ing agencies to

avoi d loss of li fe and proper ty .

Al l mandatory te st s shou ld be conduc ted and proper

re co rds ma in ta ined fo r the fu ll li fe of such proj ec ts .

Te st s fr om ou ts ide agenci es shal l on ly be go t done from

accred ited labs on ly .

When such projec ts are taken in urban area s comp le te

de ta il s of unde rg round wa te r, el ec tr ic , sewage ,

te lephone li ne s must be ob ta ined to avoi d traf fi c jams

and inconven ience to publ ic .

No compromi se shou ld be made wi th Qual it y Cont ro l

no rms la id down in vari ou s codes to avo id lo ss of

proper ty and li fe . There shou ld be a comp le te

coordi na ti on be tween desi gner s and executor s. Pu tt ing

up blames on each othe r is a ma jo r lo ss to the

engi neer ing commun ity as a whol e.

97

Appendix I

(Illustrative example on concrete Mix Design)

An example illustrating the mix design for a concrete of M 20 grade is

given below:

DESIGN STIPULATIONS

Grade Designation = M40

Type of cement = O.P.C 43 grade

Brand of cement = XXX

Admixture = XXX

Fine Aggregate = Zone-II

Sp. Gravity Cement = 3.15

Fine Aggregate = 2.61

Coarse Aggregate (20mm) = 2.65

Coarse Aggregate (10mm) = 2.66

Minimum Cement (As per contract) = 400 kg /m3

Maximum water cement ratio (As per contract) = 0.45

Mix Calculation: -

1. Target Mean Strength = 40 + (5 x1.65) = 48.25 MPa

2. Selection of water cement ratio

Assume water cement ratio = 0.4

3. Calculation of cement content: -

Assume cement content 400 kg /m3

(As per contract Minimum cement content 400 kg /m3)

98

4. Calculation of water

400 X 0.4 = 160 kg

Which is less than 186 kg (As per Table No. 4, IS: 10262)

Hence o.k.

5. Calculation for C.A. & F.A.: – As per IS: 10262, Cl. No. 3.5.1

V = [W + (C/Sc) + (1/p)x(fa/Sfa) ] x (1/1000)

V = [W + (C/Sc) + {1/(1-p)}x(ca/Sca) ] x (1/1000)

Where

V = absolute volume of fresh concrete, which is equal to gross volume

(m3) minus the volume of entrapped air,

W = mass of water (kg) per m3 of concrete,

C = mass of cement (kg) per m3 of concrete,

Sc = specific gravity of cement,

(p) = Ratio of fine aggregate to total aggregate by absolute volume ,

(fa) , (ca) = total mass of fine aggregate and coarse aggregate (kg) per

m3 of Concrete respectively, and

Sfa, Sca = specific gravities of saturated surface dry fine aggregate and

Coarse aggregate respectively.

(As per Table No. 3, IS-10262),

for 20mm maximum size entrapped air is 2% .

Assume F.A. by % of volume of total aggregate = 36.5 %

0.98 = [160 + (400 / 3.15) + (1 / 0.365) (Fa / 2.61)] (1 /1000)

99

Fa = 660.2 kg ≈ 660 kg.

0.98 = [160 + (400 / 3.15) + (1 / 0.635) (Ca / 2.655)] (1 /1000)

Ca = 1168.37 kg ≈ 1168 kg.

Considering 20 mm: 10mm = 0.6: 0.4

20mm = 701 kg

10mm = 467 kg

Hence Mix details per m3

Cement = 400 kg

Water = 160 kg

Fine aggregate = 660 kg

Coarse aggregate 20 mm = 701 kg

Coarse aggregate 10 mm = 467 kg

Admixture = 0.6 % by weight of cement = 2.4 kg

Recron 3S = 900 gm

Water: cement: F.A.: C.A. = 0.4: 1: 1.65: 2.92

Observation

A. Mix was cohesive and homogeneous.

B. Slump = 110mm

C. No. of cube casted = 12 Nos.

7 days average compressive strength = 51.26 MPa.

28 days average compressive strength = 62.96 MPa which is

greater than 48.25MPa

Hence the mix is accepted.

100

Appendix II

Bar bending Schedule of diaphragm wall as per drawing

101

102

103

104

105

Appendix III

Level Transferred to Pier for Casting of Pier cap

To mark the bottom level of pier cap on the pier the bottom level of pier

cap should be known that will attained by reducing the thickness of

wearing course ,deck slab, diaphragm wall and thickness of pier cap.

All dimensions are in m

106

198.695 pier cap bottom level (as per drawing)

- 195.00 zero level

3.695

+ 1.500 height of zero level form ground level

5.195 height of pier cap bottom from ground level

- 0.300 adjustable margin

4.895 scaffolding had to be provided up to this height from G.L

Thus scaffolding is to be provided leaving a margin space of 300mm for

ISMB125, 0.125 m

adjustable jack 0.170 m

shutter plate 0.005 m

0.300 m

107

Appendix IV

Calculation for leveling bearing

The level of bearing were fixed as per drawings, the top level of pier cap

was known by drawing and calculations so firstly set a auto level ,level

and center it take back sight as the top level of the pier cap determine

the height of instrument.

All dimensions are in m

108

Suppose H.I of the instrument is 1.48

203.14 + 1.48 = 204.62

-203.14 + 0.45 = 203.59

1.03m

Now place the staff on the top surface of bearing ,the actual reading

appear on staff is to be 1.03m,else shift the top of bearing up or down as

if actual reading on staff is greater than theoretical reading then shift the

top of bearing downward or vice versa until the actual reading and

theoretical reading do not concede.

Repeat same procedure for levellling of stool for girder.

109

References

List of IS codes Referred

IS 456 -2000 Plain & Reinforced concrete code of practice

IS 383-1993 Specification for Coarse and Fine Aggregate from

natural

sources for concrete

IS: 383 Zone-III- specifications for Coarse & Fine Agg. From natural

sources for Concrete.

IS 1786 -1985 Specification for High strength Deformed steel bars

and wires for Concrete Reinforcement

IS 2386 (Part - II) 1991 Method for Test for aggregates for

concrete Part - II Estimation of deleterious materials and organic

impurities

SP-34 Hand Book on concrete reinforcement and Detailing

SP-23 Hand Book on concrete Mix.

IS 9103 1979 Specification for admixtures for concrete

IS-383-1970.The grading of coarse aggregates should be as per

specifications

110

IS 2751 and IS 9417 Welding of reinforcements in accordance with

the recommendations

IS: 1786 1985 Test to be performed in Respect of Fe 415

IS: 10262 1982 Recommended Guidelines for Concrete Mix Design.

IS: 516 1959 Methods of tests for Strength of Concrete.

Books

General Theory of Bridge Construction by Hermann Haupt

Design and construction of bridge approaches by Harvey E. Wahls

Bridge engineering: construction and maintenance by Wai-Fah Chen

Design Of R.C.C. Structural Elements by S.S. Bhavikatti

Significance of tests and properties of concrete by Joseph F.

Lamond, J. H. Pielert

Materials in construction: an introduction by Geoffrey D. Taylor

Advances in Construction Materials 2007 by Christian U. Grosse

Reinforced concrete: a fundamental approach by Edward G. Nawy

111

Corrugated plastic ducts for internal bonded post-tensioning

Fédération internationale du béton

Post-tensioning manual by Post-Tensioning Institute

Practical handbook of grouting: soil, rock, and structures by James

Warner

Aggregates: sand, gravel and crushed rock aggregates for By Mick

R.Smith,

Aggregates in concrete by Mark G. Alexander, Sidney Mindess

Manual of ready-mixed concrete by J. D. Dewar, R. Anderson

Construction management: new directions by W. D. McGeorge,

Angela Palmer, Kerry London

Formwork for concrete by Mary Krumboltz Hurd

Bridge bearings and expansion joints by David John Lee

Structural bearings - Page 62 byHelmut Eggert, Wolfgang Kauschke

E- sources

112

Suggestions

113

Suggestions

96

Conclusion

The primary objective of this report is a description of practical knowledge. I

attained on construction site of an interchange structure during my summer

internship training. In the period of training, i closely studied the aspects of

practical application of various methodologies and learnt the art of being

pioneer in solving practical problem faced at site; during the course of my

study i attained the following conclusions:

There are differences between theoretical and practical approach to

execute various construction process. Theoretical knowledge is

insufficient to commence task at site.

The quality of construction work was at priority with respect to

time. Various check were formatted at each step of construction to

ensure the quality of work.

After the consecutive revisions of drawing, they are finally revised

to fulfil the requirements of site.

The various factors such as climatic conditions, man power,

availability of resources and methods involved in construction plays

a crucial role in an optimised completion of project.

Safety measures were taken to avoid injuries and accidents on site.

This report elaborates the sequence of work for construction of structural

components in a bridge. The report contains the characteristics of

materials and technique used in construction of RCC bridge. It gives a

brief introduction to construction planning.

Tranning Report Civil Enggineering

Documents