Copy of Copy of MP

8/11/2019 Copy of Copy of MP

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Table of Contents

Chapter Title Page No.

I Introduction 1-2

II Principles of mix design 3-62.1. The principles of proportioning 4

2.2. Design requirements 5

III Ingredients of mix design 7-93.1. Cement 8

3.2. Aggregate 8

3.3. Water 93.4. Admixture 9

IV Tests on ingredients 10-174.1. Tests on cement 11

4.1.1. Fineness test 11

4.1.2. Specific gravity test 124.2. Tests on aggregates 12

4.2.1. Fineness modulus of coarse 12

and fine aggregates

4.2.2. Specific gravity and water absorption 15of coarse and fine aggregates

V IS code method of mix design 18-285.1. Theory 19

5.2. Factors affecting choice of mix proportions 205.3. Mix proportions designation 21

5.4. Procedure for mix design 21

VI Superplasticizer used for mix design 29-31

(Sikament 170)6.1. Description 30

6.2. Uses 306.3. Advantages 30

6.4. Method of use 31

6.5. Dosage 316.6. Compressive strength results (typical) 31

6.7. Effect on workability (typical) 31


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VII Results 32-337.1. Results of standard mix 33

7.2. Results after adding superplasticizer 33

VIII Conclusion 34-35

Bibliography 36-37

Appendix 38-42


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ChapterI

Introduction


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CONCRETE MIX DESIGN BY IS CODE METHOD USING SUPER PLASTICIZER-

(Mix- M20)

Ingredient of mixes-

The selection of right kind of ingredients having properties which help toachieve desirable properties of concrete is of utmost importance:-

The ingredients are:-

Cement.

Coarse aggregate.

Fine aggregate.

Superplasticizer.

Water.

Testing of cement: -

fineness test

Specific gravity

Testing of coarse aggregate: -

Specific gravity.

Water absorption test.

Fineness test

Testing of fine aggregate: -

Fineness test.

Water absorption test.

Specific gravity test.

After testing all the materials, the properties of different ingredients

are obtained and after that the mixing of these ingredients is done in which super plasticizer is

also used and a wet mix is obtained and than the SLUMP TESTis done on this wet mix and

then after the hardening of concrete in the cube, the compressive strength test is done on the

concrete cube and then its compressive strength is found in terms of 7days,14days and 28days

strengths.


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ChapterI I

Principles of mix design


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2.Principles of mix design:-

2.1. The Principles of Proportioning:

The fundamental object in proportioning concrete or mortar mixes is

the production of a durable material of requisite strength, water tightness, and other essential

properties at minimum cost. To achieve these objectives, careful attention must be given to the

selection of cement, aggregate, and water to the following considerations:

1. The mix must be workable so that it can be placed and finished without undue labour.

2. Since cement is the most costly ingredient in the mix, the proportion used should be as small

as is consistent with the attainment of desired properties.

Within wide limits, experiments have shown:

(a) The strength and degree of water tightness of mixes, having like constituent materials,

density, and workability, increase with the cement content.

(b) With the cement content, materials, and workability all constant, the strength and degree of

water tightness increase with the density of the mix.

(c) For usual methods of placement, the strength and degree of water tightness of well-cured

concrete and mortar are greatest when the mix is plastic (has a slump of approximately 50 mm).Drier mixes, although frequently as strong, are likely to be porous unless compacted by

pneumatic rammers or electrically driven vibrators. Increasing the water content beyond that

required for plasticity causes the strength to decrease rapidly.

(d) Concrete with 47 per cent, by volume, entrained air made by using an air-entraining cement

or by adding air-entraining admixtures is more resistant to freezing and thawing action and also

to scaling due to the use of salt for ice removal than concrete made with regular cement and

without air-entraining admixtures.

In addition to the above, the following statements appear to be justified by the results of

experience and tests:

(e) To proportion concrete for the maximum resistance to fire, a porous non-combustible

aggregate of high specific heat together with cement sufficient to provide the requisite strength

should be thoroughly mixed and placed with as little ramming as possible to produce a porous

concrete.


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(f) In proportioning concrete or mortar which is to be subjected to freezing temperatures shortly

after placement, a minimum amount of water and a quick-setting cement should be used.

(g) Concrete for road construction should be made from a carefully graded, hard tough aggregate

bound together with as small a proportion of rich mortar as is consistent with the required

workability, strength, and imperviousness. In locations where resistance to freezing and thawing

is required, the concrete should have 36 per cent of entrained air.

The principal methods used in scientific

proportioning of mixes are based upon relationships between properties and ratio of cement to

voids in the mix, or on the relationship between properties and the ratio of water to cement in the

mix.

2.2. Design Requirements:

Before the engineer can begin to design a concrete mix the following

information form the site of work is required:

(i) Grade of concrete: The grade M 20, connotes characteristic strength, fck of 20 N/mm2,

respectively, and standard deviation based on the degree of control to be exercised on site.

(ii) Type of cement: The grade of Ordinary Portland Cement (OPC) such as 33, 43, or 53 grade.

Portland Pozzolana Cement (PPC) to relevant IS specifications.

(iii) Type and size of aggregate: Natural sand, crushed stone, gravel etc. conforming to IS:383

1970, quoting the source of supply.

(iv) Nominal maximum size aggregate (MSA): 40 mm, 20 mm, 10 mm, as per IS:3831970.

(v) Maximum/minimum cement content (kg/m3): This is required for durability/considerations.

(vi) Type of mixing and curing water: Whether fresh potable water, seawater, ground water is to

be used.

(vii) Maximum free water-cement ratio by weight: This is required for considerations of strength

and/or durability for different exposures and to meet appearance and other requirements.

(viii) Degree of workability of concrete: This is dependent on placing and compaction

conditions.


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(ix) Air content: This is inclusive of entrained air.

(x) Type of admixture used.

(xi) Maximum/ minimum density of concrete.

(xii) Maximum/minimum temperature of fresh concrete.


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ChapterI I I

I ngredients of mix design


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3. Ingredients of mix design:-

Concrete is essentially a mixture of cement, water, coarse and fine aggregates which consolidates

into a hard mass due to chemical reaction between cement and water. Each of the four

constituents has a specific function. Besides most optimum use of ingredients, the selection ofright kind of ingredients having properties which help to achieve desirable properties of concrete

is of utmost importance. A brief discussion about the ingredients follows.

3.1. Cement:-

The cement used should have a minimum compressive strength at different ages

according to the relevant IS specificationIS:2691987 (33 grade OPC), IS: 81121982 (43

grade OPC), IS:122691987 (53 grade OPC), IS:122301988 (Sulphate resisting cement),

IS:1489-1976 (Portland

Puzzolana cement), IS:4551976 (Portland slag cement). All types of Portland cements are

interchangeable for mix design, and the most commonly used ones are OPC, PPC, PSC, andSRC.

After water is added to the cement hydration occurs and continues

as long as the relative humidity in the pores is above 85 per cent and sufficient water is available

for the chemical

reactions. On an average, 1 g of cement requires 0.253 g of water for complete hydration. As

hydration proceeds, the ingress of water by diffusion through the deposit of hydration products

around the original cement grain becomes more and more difficult, and the rate of hydration

continuously decreases. In mature paste, the particles of calcium-silicate hydrates form an

interlocking network which is a gel having a specific surfaceof about 200 m2/g. This gel is

poorly crystalline, almost amorphous, and appears as randomly oriented layers of thin sheets or

buckled ribbon. The gel is the heart of the concrete and is a porous mass. The interstitial spaces

in the gel are called gel pores. The strength giving properties and phenomena, such as creep

and shrinkage are due to the porous structure of the gel, and the strength is due to the bond

afforded by the enormous surface area.

3.2. Aggregate:-

The size of the aggregate, particle shape, color, surface texture, density

(heavyweight or lightweight), impurities, all of which have an influence on the durability of

concrete, should conform to IS: 3831970.

During the process of hydration the products of hydration completely

surround and bind together the aggregate particles in a solid hardened mass. Aggregates

constitute nearly 7075 percent of the total volume of concrete.


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The strength of concrete is governed by the weakest element, be it the cement paste, the

aggregate or the interface of the aggregate-cement paste. Strong aggregates are also more sound

and durable in aggressive environments. The strength at the aggregate mortar interface is perhaps

more critical, hence the shape, size and texture of the coarse aggregate is important. The

aggregate should be clean, hard, strong, and durable, free from chemicals or coatings of clay or

other fine material that can affect the bond with the cement paste.

3.3. Water:-

Water is required primarily for hydration of cement and to give fluidity to the

plastic mass. Water should be clean and free from impurities. The permissible limits for solids in

mixing and curing water as specified in IS:4562000 are:

Chlorides

For RC work 500 mg/l

For plain concrete 2,000 mg/l

Sulphates 400 mg/l

Inorganic matter 3,000 mg/l

Organic matter 200 mg/l

Suspended matter 2,000 mg/l

3.4. Admixtures:-

Based on the properties admixture imparts to the concrete, a selection can be

done and the manufactures instructions followed for its method of use. The Bureau of Indian

Standards has also brought out a standard for admixtures, IS: 9103.


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Chapter I V

Test on ingredients


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4. Test on ingredients:-

4.1. Tests on cement:

4.1.1. Fineness test:

Object-To determine the fineness of cement by dry sieving.

Apparatus- a) Standard balance with 100 gm weighing capacity.

b) IS: 90 micron sieve confirming to IS: 460-1962 and a brush.

Procedure- a) Break down any air-set lumps in the cement sample with hand.

b) Weigh accurately 100 gm of cement and place it on a standard 90 micron sieve.

c) Continuously sieve the sample for 15 minutes.

d) Weigh the residue left after 15 minutes of sieving. This completes the test.

Result-

The percentage weight of residue over the total sample is reported.

Weight of the sample retained on the sieve

% weight of residue =

Total weight of the sample

= (8.47/100) X 100

= 8.47%

Result- The percentage residue is well within the prescribed limit.

Limits- The percentage residue should not exceed 10%.

Precautions-Sieving shall be done by holding the sieve in both hands and gentle wrist motion,

this will involve no danger of spilling the cement, which shall be kept well spreadout on the screen. More or less continuous rotation of the sieve shall be carried out

throughout sieving.


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4.1.2. Specific gravity test:

Object- To determine the specific gravity of cement using Le Chatelier flask or specific gravity

bottle.

Apparatus- a) Le Chatelier flask or specific gravity bottle- 100 ml capacity.

b) Balance capable of weighing accurately upto 0.1 gm.

Procedure- Weigh a clean and dry Le Chatelier flask or specific gravity bottle with its stopper

(W1). Place a sample of cement upto half of the flask (about 50 gm) and weight

with its stopper (W2). Add kerosene to cement in flask till it is about half full. Mix

thoroughly with glass rod to remove entrapped air. Continue stirring and add more

kerosene till it is flush with graduated mark. Dry the outside and weigh (W 3).

Entrapped air may be removed by vacuum pump, if available. Empty the flask,

clean it refills with clean kerosene flush with the graduated mark wipe dry the

outside and weigh (W4).

Calculations-

Specific gravity = ( W2 - W1 )

(W2- W1) - (W3- W4) X 0.79

Where, W1= weight of empty flask.

W2= weight of flask + cement.

W3= weight of flask + cement + kerosene.

W4= weight of flask + kerosene.

0.79= specific gravity of kerosene.

Limit- Specific gravity of cement = 3.15 g/cc.

4.2 Tests on aggregate:

4.2.1. Fineness modulus of fine and coarse aggregate:

Object- To obtain the fineness modulus of fine and coarse aggregate samples.

Apparatus- - Sample of fine aggregate.

- Sample of coarse aggregates.

- Digital weighing scale.


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- Sieve sifter for fine aggregates.

- Sieve sifter for coarse aggregates.

- Various cleaning brushes (point and wire).

Procedure- Part 1: Sieve Analysis of fine aggregate

Step 1:Take 500g sample of fine aggregate (as per IS code provisions, the aggregates

must be completely dry). This is determined by weighing the material on a

digital scale. Also weigh each sieve of the mechanical sifter, and the pan, and

record the weights.

Step 2:Place the aggregate in the top sieve of the well-cleaned mechanical sifter (sieves

used are 4.75mm, 2.36mm, 1.18mm, 900mic, 600mic, 300mic, 150mic,less than

150mic). This apparatus is used for shaking the aggregates (similar to theprinciple used in a paint-mixing machine) and sieving them. The mechanical sifter

has a bottom pan and a lid to close the sifter during the test. After placing the lid

on the sifter, agitate the sifter for about 10 minutes.

Step 3: Determine the weight of aggregates that are retained in each of the sieves, by

weighing each of the sieves (along with the retained aggregates), and subtracting

the weight of each sieve. Also record all the weights of aggregates retained in

each of the sieves. To ensure that all materials are collected, clean each sievecarefully using the proper type of brush. Use the paint brush for the finer sieves,

the copper brush for intermediate sieves and the steel wire brush for the coarse

sieves. Also verify whether the sum of weights of aggregates, retained in all the

sieves, and the bottom pan is equal to the initial weight of the aggregates taken.

Step 4:Tabulate the data and determine the percent retained in each sieve. From these

values calculate the (cumulative) percentage of material that would have been

retained in the sieve if the whole volume of material was to be sifted in that sieve

alone. Then add the percentage of material retained in all the sieves and divide by

100 to get the fineness modulus. Also prepare a column to determine the

cumulative percentage passing through the sieve to plot the fineness modulus

curve.


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Procedure- Part 2: Sieve Analysis of coarse aggregate

Step 1: Take 5000 grams of coarse aggregates by weighing the material in a digital scale.

Weigh each of the clean sieve, along with the bottom pan, and record their

weights.

Step 2: Place the aggregates in the mechanical sifter (sieve sizes used are 80mm, 40mm,

20mm, 10mm, 4.75mm). This apparatus is used for shaking the material (similar

to the principle of a paint-mixing machine) and sieving it.

Step 3: Determine the aggregates that are retained in each individual sieve, as mentioned

earlier in Part I, and record the data. To ensure that all materials are collected,

use the steel brush to clean each sieve.

Step 4: Tabulate the data and determine the percent retained, and the percentage that

would have been retained in each sieve, if that sieve alone was used to sieve the

whole volume. The fineness modulus is obtained by adding the percentage of

material retained in all the sieves and dividing it by 100.

Calculations are shown in Appendix 7.


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4.2.2 Specific gravity and water absorption of fine and coarse aggregates:

Object- To determine the specific gravity and water absorption of given sample of coarse

aggregates.

Apparatus- A balance or scale of capacity not less than 3 kg, readable and accurate to 0.5 g and of

such a type and shape as to permit the basket containing the sample to be suspended from

the beam and the weighed in water.

A well ventilated oven thermostatically controlled to maintain a temperature of 100oC to

110oC.

A wire basket of not more than 6.3 mm mesh or a perforated container of convenient size.

Two dry soft absorbent cloths each not less than 7545 cm.

A shallow tray of area no less than 650 cm

2

.

Procedure-

Asample of 2000 g of aggregate is used for conducting the test. Aggregate which

have been artificially heated should not normally be used. The sample is thoroughly washed to

remove finer particles and dust, drained and then placed in the wire basket and immersed in

distilled water at a temperature between 22-32C with a cover of at least 50 mm of water above

the top of the basket. Immediately after immersion the interrupted air is removed from the

sample by lifting the basket containing it 25 mm above the base of the tank and allowing it to

drop 25 times at the rate of about one drop per second. The basket and aggregate are kept

completely immersed during the operation and for, 1 period of 24 1/2 hours afterwards. The

basket and the sample are jolted and weighed in water (weight A1). These are then removed from

the water and allowed to drain for a few minutes, after which the aggregate are gently emptied

from the basket on to one of the dry clothes. and the empty basket is returned to the water, jolted

25 times and weighed in water (weight A2).The aggregate placed on the dry cloth are gently

surface dried with the cloth, and are completely surface dried. The aggregate art' then weighed

(weight B). The aggregate are there after placed in an oven at a temperature of 100-110oC and

maintained at this temperature for 24 1/2 hours. It is then removed from the oven, cooled in the

air-tight container and weighed (weight C). The computations are as under-

Specific gravity = C/(B-A)= 2400/(2410-(2300-800)

= 2.63

Water absorption(percent in dry weight) = ((B-C)/C) X 100= ((2410-2400)/2400) X 100

= 0.41%


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Where, A = the weight in g of the saturated aggregate in water (A1- A2).

B = the weight in g of the saturated surface dry aggregate in air.

C = the weight in g of oven-dried aggregate in air.

Object- To determine the specific gravity and water absorption of given sample of fine

aggregates.

Apparatus-

A balance of capacity not less than 3kg ,readable and accurate to 0.5 gm and of such atype as to permit the weighing of the vessel containing the aggregate and water .

A well ventilated oven to maintain a temperature of 100C to 110C

Pyconometer of about 1 liter capacity having a metal conical screw top with a 6mm hole

at its apex . The screw top shall be water tight.

A tray of area not less than 32cm.

Filter papers and funnel.

Procedure-

A pycnometer is used for determining specific gravity. A sample about 1000 g

for 10 mm to 4.75 mm or 500 g if finer than 4.75 mm, is placed in the tray and covered with

distilled water at a temperature of 22-32C. Soon after immersion, air entrapped in or bubbles on

the surface of the aggregate are removed by gentle agitation with a rod. The sample is kept

immersed for 24 1/2 hours. The water is then carefully drained from the sample through a filter

paper, any material retained being returned to the sample. The aggregate including any solid

matter retained on the filter paper should be exposed to a gentle current of warm air to evaporate

surface moisture and stirred at frequent intervals to insure uniform drying until no free surface

moisture can be seen and the material just attains a free-runningcondition. The saturated and

surface dry sample is weighted (weight A). The aggregate is then placed in the pycnometer

which is filled with distilled water. The pycnometer is dried on the outside and weighed (weight

B). The contents of the pycnometer are emptied into the tray. The pycnometer is refilled with

distilled water to same level as before, dried on the outside and weighed (weight C). The water is


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then carefully drained from the sample by decantation through a filter paper and any material

retained is returned to the sample. The sample is placed in the oven at a temperature of 100 to

110C for 24 1/2 hours, during which period it should be stirred occasionally to facilitate

drying. It is then cooled in the air-tight container and weighed (weight D).

Specific gravity = D/A-(B-C)= 540/550-(2000-1650)

= 2.70

Water absorption (percent in dry weight) = ((A-D)/D) X 100

= ((550-540)/540) X 100= 1.85%

Where, A = weight in g of saturated surface-dry sample.

B = weight in g of pycnometer containing sample and filled with distilled

water.C = weight in g of pycnometer filled with distilled water only.

D = weight in g of oven-dried sample.


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ChapterV

IS code method of mix design


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5. IS code method of mix design:-

5.1. Theory:-

This method, now widely used in the country, is recommended for designing

mixes for general types of construction, using the ingredients of concrete normally available. The

design is carried out for a specified compressive strength and workability of concrete using

continuously graded aggregates.

The method can be used for both, reinforced and pre stressed concretes. The

method is not to be used for the design of mixes for flexural strength, or when gap graded(not

continuously graded) aggregates, or when pozzolana, or admixtures are used .The basic

assumption made in the IS method is that the compressive strength of concrete is based on the

water-cement ratio of the concrete mix. Further, for a given type, shape, size and grading of

aggregates, the amount of water determines the workability for normal concretes.

However, there are other factors which also affect the properties of concrete,

for example, the quality and quantity of cement, water and aggregates; method of transporting,

placing, compacting and curing of the concrete. Hence, the proportions arrived at for the mix

design

should be considered only as a basis for a trial, subject to modification in the light of experience

and the actual materials that will be used at site.

In the IS method the general principles and requirements of basic data remain

unchanged. That is, specifying characteristic strength, workability recommendations in terms of

compacting factor Vee-Bee time or slump, type and grade of cement, maximum size of aggregate

used, grading of aggregates according IS: 3831970, and durability requirements in terms of

minimum cement content and maximum water-cement ratio for various exposure conditions.


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5.2. Factors affecting the choice of mix proportions:-

The various factors affecting the mix design are:

1.Compressive strength:

It is one of the most important properties of concrete and influences many other describable

properties of the hardened concrete. The mean compressive strength required at a specific age,

usually 28 days, determines the nominal water-cement ratio of the mix. The other factor affecting

the strength of concrete at a given age and cured at a prescribed temperature is the degree of

compaction. According to Abrahams law the strength of fully compacted concrete is inversely

proportional to the water-cement ratio.

2. Workability:

The degree of workability required depends on three factors. These are the size of the section to

be concreted, the amount of reinforcement, and the method of compaction to be used. For the

narrow and complicated section with numerous corners or inaccessible parts, the concrete must

have a high workability so that full compaction can be achieved with a reasonable amount of

effort. This also applies to the embedded steel sections. The desired workability depends on the

compacting equipment available at the site.

3.Durability:

The durability of concrete is its resistance to the aggressive environmental conditions. High

strength concrete is generally more durable than low strength concrete. In the situations when the

high strength is not necessary but the conditions of exposure are such that high durability is vital,

the durability requirement will determine the water-cement ratio to be used.

4.Maximum nominal size of aggregate:

In general, larger the maximum size of aggregate, smaller is the cement requirement for a

particular water-cement ratio, because the workability of concrete increases with increase in

maximum size of the aggregate. However, the compressive strength tends to increase with thedecrease in size of aggregate.

IS 456:2000 and IS 1343:1980 recommend that the nominal size of the aggregate should be as

large as possible.


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5.Grading and type of aggregate:

The grading of aggregate influences the mix proportions for a specified workability and water-

cement ratio. Coarser the grading leaner will be mix which can be used. Very lean mix is not

desirable since it does not contain enough finer material to make the concrete cohesive.

The type of aggregate influences strongly the aggregate-cement ratio for the desired workability

and stipulated water cement ratio. An important feature of a satisfactory aggregate is the

uniformity of the grading which can be achieved by mixing different size fractions.

6.Quality Control:

The degree of control can be estimated statistically by the variations in test results. The variation

in strength results from the variations in the properties of the mix ingredients and lack of control

of accuracy in batching, mixing, placing, curing and testing. The lower the difference between

the mean and minimum strengths of the mix lower will be the cement-content required. Thefactor controlling this difference is termed as quality control.

5.3. Mix proportion designations:-

The common method of expressing the proportions of ingredients of a concrete mix is in the

terms of parts or ratios of cement, fine and coarse aggregates. For e.g., a concrete mix of

proportions 1:2:4 means that cement, fine and coarse aggregate are in the ratio 1:2:4 or the mix

contains one part of cement, two parts of fine aggregate and four parts of coarse aggregate. The

proportions are either by volume or by mass. The water-cement ratio is usually expressed inmass.

5.4. Procedure for mix design:-

The Bureau of Indian standards, recommended a set of procedure for design of concrete mix

mainly based on the work done in national laboratories. The mix design procedures are covered

in IS 10262-82. The method given can be applied for both medium strength and High strength

concrete.

Before we proceed with describing this method step by step, the following short comings

in this method are pointed out. Some of them arisen in view of the revision of IS 456-2000. The

procedure for concrete mix design needs revision and at this point of time (2000AD) a

committee has been formed to look into the matter of mix design.

1. The strength of cement has available in the country today has greatly improve since 1982.

The 28-days strengths of A, B, C, D, E, F, category of cement is to be reviewed.


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2. The graph connecting, different strength of cement and W/C ratio reestablished.

3. The graph connecting 28-days compressive strength of concrete and W/C is to be

extended up to off 80Mpa, this graph is to be cater for high strength concrete.

4.

As per revision of IS 456-2000,the degree of workability is expressed in terms of slump

instead of compacting factor. This result in change of value of estimating approximate

water and sand content for normal concrete up to of 35Mpa and high strength of concrete

above 35Mpa .the table giving adjustment of value in water content and sand percentage

for other than standard conditions, require appropriate change and modification.

5. In view of above and other changes made in the revision of IS 456-2000,the mix design

procedure as recommended in IS 10262-82 is required to the modified to the extent

considered necessary and examples of mix design is work out.

However, in the absence of revision of IS on method of mix design,the existing method i.e. IS 10262-82 is describe below step by step.

1. Design stipulations:

Characteristics compressive strength Required in the

field at 28 days :20MPa

Maximum size of aggregate :20 mm(angular)

Degree of workability :0.90 compacting factor

Degree of quality control :Good

Type of exposure :Mild

2. Test data for Materials:

Specific gravity of cement :- 3.15

Compressive Strength of cement at 7 days :- Satisfies the requirement of IS: 269-1989

Specific gravity of C.A. :- 2.60

Specific gravity of F.A. :- 2.60

Water absorption:-

1. Coarse aggregate :- 0.50%

2. Fine aggregate :- 1.0%


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Free(Surface) moisture:- 1. Coarse aggregate :- Nill

2. Fine aggregate :-2.0%

Coarse aggregate

SieveSize (mm)

Analysis of coarseaggregate fractions (%

passing)

Percentage of differentfractions

Remark

I II I II combined

60% 40% 100%

20 100 100 60 40 10 Conforming to gradingZone III of table 4 IS:

385-1970

10 0 71.20 0 28.5 28.5

4.75 9.40 - - 3.7 3.7

2.36 - - - - -

Fine aggregate

Sieve Size Fine aggregate (% passing) Remarks

4.75mm 100 Conforming to grading

2.36mm 100

1.18mm 93 Zone III of table 4 IS:

600micron 60

300micron 12 385-1970150micron 2

3. Target mean strength of concrete:

The target mean strength for specified characteristics cube strength is

Fck= fck+ ts

Fck= 20+1.65x4

Fck=26.6 Mpa

Where f ck = characteristics compressive strength of 28 days.

S = standard deviation, given in Appendix 2.

t = a statistical value depending on expected proportion of low results (risk factor), given

in Appendix 1


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4. Selection of Water-Cement ratio:

From Appendix 3, the water cement ratio required for

the target mean strength of 26.6Mpa is 0.50. This is lower than the maximum value of

0.55 prescribed for Mild exposure (refer table 3) adopt W/C ratio of 0.50.

5. Selection of Water and sand content:

From Appendix 4, for 20mm maximum size aggregate

,Sand conforming to grading zone II.

Water content per cubic meter of concrete = 186kg and

Sand content as percentage of total agg.

By absolute volume = 35%

From Appendix 6, for change in value in W/c ratio, compacting factor, for sandbelonging to Zone III, following adjustment is required:-

Therefore required sand content as percentage of total aggregate by absolute

volume

= 35 - 3.5 = 31.5%

Required Water content = 186 + 5.58 =191.6 l/m3

6. Determination of sand content:-

Water-Cement ratio = 0.50

Water =191.6 liters

Change in condition % adjustment required

(See table 5 ) Water content sand in total

aggregate

For decrease in water cementRatio by(0.60-0.50) that is 0.1 0 -2.0

For increase in compacting factor

(0.90-0.80), that is 0.10 +3 0

For sand conforming to Zone III

Of table 4, IS: 383-1970 0 -1.5Total +3 -3.5


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Cement =

= 383 kg/m3

From Appendix 5, this cement content is adequate for MILD exposure conditions.

7. Determination of coarse and fine aggregate contents: From table 1, for the specified

maximum size of aggregate of 20mm, the amount of entrapped air in the wet concrete is 2 %.

Taking this in to account and applying the given equation:-

Where

V = Absolute volume of concrete, which is equal to

Gross volume (m3) minus the volume of

Entrapped air,

W = mass of water (kg)/m3

of concrete,

C = mass of cement (kg)/m

3

of concreteSc = Specific gravity of cement

P = Ratio of FA to total aggregate by absolute volume

fa,Ca= Total masses of FA and CA (kg)/m3of concrete

Respectively and

Sfa, Sca= Specific gravities of saturated, surface dry FA & CA.

Table 1:- Approximate Entrapped air content

Maximum size of Entrapped air, as percentage of Aggregate(mm)

Volume of concrete10 3.0

20 2.040 1.0

V

x

Ca =


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Ca=

The mix proportion the becomes:-

Water Cement Fine aggregate Coarse aggregate

191.6 383 546 1188

0.50 1 1.425 3.10

8. Actual quantities required for the mix per bag of cement:

The mix is 0.50 : 1.0 :1.425 :3.10. For 50 kg of cement, the quantity of

materials is worked out as below;

1. Cement = 50 kg

2. Sand = 71.0kg

3. Coarse aggregate(CA) = 155 kg Fraction I =60% = 93 kg

i. Fraction II =40% = 62 kg

4. Water

For w/c ratio of 0.50, quantity=25 liters of water.

a)

Extra quantity of water to be added for absorption in case of CA, at 0.5 percent mass =

0.77 liters.

b) Quantity of water to be deducted for moisture present in sand, at 2 per cent by mass = 1.42

liters.

c) Actual quantity of water required to be added

= 25.0 + 0.77 - 1.42 = 24.35 liters.

fa= 546kg/m

Ca= 1188kg/m


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d) Actual quantity of sand required after = 71.0 + 1.42

Allowing for mass of free moisture = 72.42 kg.

e) Actual quantity of CA required

Fraction I = 93 - 0.46 = 92.54 kg.

Fraction II = 62 - 0.31 =61.69 kg.

Therefore the actual quantities of different constituents required for one bag mix are

Water : 24.35 kg

Cement : 50.00 kg

Sand : 72.72 kg

CA

1. Fraction I : 92.54 kg

2. Fraction II : 61.69 kg


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Trial mix

A typical trial mix test program is given in table below:

Quantity of materials per cubic meter of concrete Concrete characteristics

Mix

No.

Cement Water Sand C

Type

I

A

Type

II

Workab

-ility

(CF)

Visual

Observ-

ation

28 days

compre-

ssivestrengt-h

1 2 3 4 5 6 7 8 9

(Kg) (L) (kg) (kg) (Kg) N/mm2

1 383

191.6

w/c = 0.5

546

(31.5%)

712 475 0.80 Under

sanded _

2 394.6197.3w/c=

0.5

564(33%)

687 458 0.91 Cohesive 28.8

3 358.7

197.3

w/c=

0.55

591

(34%)

688 459 0.90 Cohesive 26.0

4 438.4

197.3

w/c=

0.45

535

(32%)

682 455 0.89 Cohesive 31.2


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ChapterVI

Superplasticizer used for mix design


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6. Sikament 170 (High Performance Plasticizer):-

6.1. Description:

Sikament 170 is a purpose designed material which is a chemical combination of

Modified Lignosulphonates. Sikament 170 allows the manufacture of economic high quality concrete without

undesirable side effects.

Sikament 170 is a ready to use liquid for producing a more uniformly cohesive quality

concrete to meet the specifications and needs of Architects, Consulting Engineers and

Contractors.

Complies with EN 934 Part 2 Table 3.1/3.2 - High Range Water

Reducing/Superplasticising Admixtures.

6.2. Uses:

Readymix concrete

Precast concrete

Pumped concrete

Lightweight concrete

Wet shotcrete

Semi-dry concrete

6.3. Advantages:

Improved workability/reduces w/c ratio

Flexible high performance plasticizer

High resistance to segregation/reduces bleeding

Improved surface finish

Reduces shrinkage cracking potential

Higher initial and ultimate compressive strengths Higher durability concrete


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6.4. Method of use:

For maximum dispersion Sikament 170 should be added with the mixing water, on no account

should it be added to the dry cement. Where concrete is being mixed by ready mixed trucks,

Sikament 170 can be added at the batching plant but the trucks must rotate their drums until a

uniform mix is achieved. To produce flowing concrete a well proportioned pump mix should beused.

6.5. Dosage:

The dosage rate of Sikament 170 is best found after initial site trials, which will take into

consideration the best performance/dosage rate. As a guide an addition rate of between 0.30.5%

by weight of cement is recommended (i.e. 0.150.25 liters per 50 Kg).

6.6. Compressive Strength Results (typical):

Admixture Dose(ml/50 Kg

Cement)

w/c ratio Slump(mm)

Air content%

28 daycompressive

strength

(N/mm2)

Control None 0.65 75 0.8 42.5

Sikament 170 200 0.59 80 1.5 54

6.7. Effect on workability (typical):

Admixture Dose(ml/50 Kg

Cement)

w/c ratio Slump(mm)

Air content%

28 daycompressive

strength

(N/mm2)

Control None 0.65 75 0.8 42.5

Sikament 170 200 0.65 Collapsed 1.5 43.0


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ChapterVI I

Results


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7. Results:-

7.1 Results of standard mix:

Cubes Dial gaugereading(KN)

Surface area of cube Strength of cube in days7 14 28

1. 350 15cm x 15cm 15.55

2. 360 15cm x 15cm 16.00

3. 390 15cm x 15cm 17.33

Average strength of concrete in 7 days is= 16.30 N/mm

2

Average strength of concrete in 14 days is= N/mm2

Average strength of concrete in 28 days is= N/mm2

7.2 Results of mix after adding super Plasticizer:

Cubes Dial gauge

reading(KN)

Surface area of cube Strength of cube in days

7 14 281. 400 15cm x 15cm 17.77

2. 380 15cm x 15cm 16.90

3. 380 15cm x 15cm 16.90

Average strength of concrete in 7 days is = 17.20 N/mm2

Average strength of concrete in 14 days is = N/mm2

Average strength of concrete in 28 days is = N/mm2


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ChapterVI I I

Conclusion


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8. Based on the analysis of the above results of mix design, following conclusions can be

drawn:

We are carrying out the CONCRETE MIX DESIGN BY IS CODE METHOD

USING SUPER PLASTICIZER-(M20), the project has provided the excellent

opportunity to gain the knowledge about the various aspects of mix design of concrete

while working on this project many new concepts and technical details have been

encountered.

We have concluded that the result obtained from the standard mix is less when compared

to the mix design with super plasticizer. The 7 day strength of standard mix was 16.30

N/mm2, where as the 7 day strength of mix after adding super plasticizer was 17.20

N/mm2.

We have also seen that the workability of standard mix was less than the workability of

the mix with super plasticizer. The slump value of standard mix was found to be 20mm,

where as the slump value of the mix with super plasticizer was 25mm which is more than

the standard mix.


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Bibliography


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B I B L I O G R A P H Y

Books :

(1) Prof. M.S. Shetty, Concrete Technology, S. Chand publications, New Delhi.

(2) A.M. Neville and J.J. Brook, Concrete Technology, Pitman Publishing Limited,

London.

(3) S.K. Duggal, Building materials, New age publications, New Delhi.

Codes :

(1)IS 10262 Concrete Mix Design

Websites :

(1)www.engineeringcivil.com


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Appendix


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Appendix 1:- Values of Tolerance Factor (t) (Risk Factor)

Tolerance Level

No of samples 1 in 10 1 in 15 1 in 20 1 in 40 1 in 100

10

20

30

infinite

1.37

1.32

1.31

1.28

1.65

1.58

1.54

1.50

1.81

1.72

1.70

1.64

2.23

2.09

2.04

1.96

2.76

2.53

2.46

2.33

Appendix 2:- Assumed Standard Deviation as per IS 456-2000

Grade of concrete Assumed Standard

Deviation N/mm2

M 10

M 15

M 20

M 25

M 30

M 35

M 40

M 45

M 50

3.5

4.00

5.00


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Appendix 3:- Relation between free water cement ratio and concrete compressive strength

Appendix 4:- Relation between free water cement ratio and concrete compressive strength

W/C =0.60, Workability =0.80 C.F.

(Slump 30mm approximately)

(Application for concrete upto grade M35)

Maximum Size Water content including Sand as percent of

Of aggregate surface water per cubic Total aggregate

(mm) Metre of concrete (kg) by absolute volume10 200 4020 186 35

40 165 30


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Appendix 5:- Minimum cement content, Maximum W/C ratio and Minimum grade of

concrete for different exposures with normal Weight Aggregate of 20mm Nominal

maximum size . IS:456-2000

Sl. Exposure Plain concrete Reinforced concrete

No.

Minimum

cement

contents

kg/m3

Maximum

free W/C

ratio

Minimum

grade of

concrete

Minimum

cement

contents

kg/m3

Maximum

free W/C

ratio

1. Mild 220 0.60 - 300 0.55 M 20

2. Moderate 240 0.60 M 15 300 0.50 M 25

3. Severe 250 0.50 M 20 320 0.45 M 30

4. Very

severe

260 0.45 M 20 340 0.45 M 35

5. Extreme 280 0.40 M 25 360 0.40 M 20


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Appendix 6:- Adjustment of value of Water content and sand percentage for other

conditions

Change in conditions Adjustment required inStipulated for tables Water content % sand in total

Aggregate

For sand conforming to grading Zone I +1.5 for

Zone IZone III or Zone IV of Table 4,IS: 0 -1.5% for

Zone III383-1979 -3% forZone IVIncrease or Decrease in the value ofCompacting factor by 0.10 +3% 0Each 0.05 increase or decrease in Water

-cement ratio 0 +1%For Rounded aggregate -15 -7%

Appendix 7:- Fineness modulus of coarse and fine aggregate

Coarse Aggregate-

IS Sieve size Percent retained Cumulative percent

retained

Percentage passing

40mm 0.00 0.00 100.00

20mm 0.60 0.60 99.40

10mm 73.50 74.10 25.90

4.75mm 22.90 97.00 3.00

Fine Aggregate-

IS sieve size Percent retained Cumulative percent

retained

Percentage passing

10mm 0.00 0.00 100.004.75mm 5.20 5.20 94.80

2.36mm 3.00 8.20 91.80

1.18mm 8.60 16.80 83.20

600micron 25.80 42.60 57.40

300micron 32.80 75.40 24.60

150micron 20.70 96.10 3.90


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