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General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 181
DIVISION 6
SUBBASE AND AGGREGATE BASES
6.1 Description:This Division includes materials and execution methods required for the
construction of Subbases and aggregate Base courses, which includes:
-
Production and storage of aggregate materials.
- Aggregate Subbase.
- un-treated aggregate base.
- Cement treated aggregate base.
-
Asphalt treated aggregate base.
6.2 Production and storage of aggregate materials:
6.2.1 Description:This section includes production methods, transportation and stockpiling of
natural, crushed, or screened materials used in construction of roads and relevant
structures. Contractor shall provide the aggregate conform to the quality and gradation
requirements indicated in the special specifications, drawings, contract documents or
these general specifications.
6.2.2 Material Sources:
Unless otherwise the material sources are shown on the drawings or in the
special specifications, the contractor should specify those sources whether they are new
queries or authorized existing crushers.
Contractor, in cases, prior starting production or supplying the aggregate
materials by a period not less than 30 days, shall submit to the Engineer a technical
report, which includes:
1. Source (s).
2.
Types and approximate quantities of available rocks and materials.
3. The results of test on representative samples according to the type of work on
which these material proposed to be used, according to the requirement
indicated in the relevant divisions and sections of these general specifications or
special specifications.
4.
Machines, equipments and methods of crushing, screening and transporting of
rocks.5. Sites and methods of aggregate stockpiles.
6. The written agreement from the related agency and property owner for the new
suggested locations of material production and stockpiling.
Contractor is not allowed to start the production of aggregate materials before
the approval of the Engineer for the source. This approval is considered preliminary.
The final approval shall be made based on the test results for the materials actually
supplied to the project.
The contractor shall enable the Engineer to reach sites of the works, inspect
equipments, production and storing methods at any time during the construction. TheContractor shall obtain a new approval for the source as mentioned above whenever the
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 182
source or production methods were changed or when the Engineer notices a significant
change in the supplied materials properties.
When contract documents contain information about the available sources and
specifications of materials, this information are considered as guides and does not
release the Contractor from the responsibility for providing materials conforming to thespecifications. The Contractor shall make his own studies to estimate the construction's
prices, regardless of the source and available materials. The Engineer has the right,
according to test results, to reject materials and to require from the Contractor to change
the source(s) if the materials were not technically acceptable the Contractor has no right
to claim any additional costs resulting from this.
6.2.3 Aggregate materials production:
This work shall consists of site preparation, provision of machines, equipments
and required arrangements for producing natural or crushed aggregate and screening of
the materials to the required sizes to obtain the required gradations, transportation,
storage of acceptable produced aggregate, disposal of extra materials and un-acceptablematerials at the approved sites. The produced aggregate shall achieve all the
requirements indicated for the specified works.
Contractor shall, at all work phases, follow the approved environmental
standards regarding to noise levels, air pollution and dust and he shall make all the
required arrangements to limit environmental pollution in all its forms.
6.2.3.1 Site Preparation:
Aggregate materials shall be produced at the approved sources according to item
(6.2.2) requirements of this section. Contractor, after the approval of the Engineer for
the source(s), shall remove overburden, waste and unsuitable materials covering the
aggregate or rock layers proposed to produce crushed aggregate, and transport all
removed and waste materials to sites approved by the Engineer. The removal and
clearing works are considered for charged only with other items and no payment for
them shall be made to the Contractor.
6.2.3.2 Machines and equipments:
Contractor shall provide all the machines and equipments required for the
production of crushed and natural aggregate according to the approved specifications
and it includes central or mobile crushers, suitable sieves sizes, belt conveyor,
excavation, loading, and transporting machines and all equipments needed for producing an aggregate conform to specifications of the required work item.
6.2.3.3 Production of Natural Aggregate:
Contractor shall produce natural aggregate conforming to the specification's of
the specified works in the sources approved by the Engineer.
The production operation shall include removal of all unsuitable materials including the
sizes larger than the maximum size required, and disposal of soil materials and other
undesirable materials using suitable methods including screening and/or washing.
Contractor shall prepare a work plan for disposal of unsuitable materials from
the material's source, separate aggregate materials into sizes and transport each sizeseparately to the stockpiles.
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 183
6.2.3.4 Production of Crushed Aggregate: Crushed aggregate production shall be made from the approved sources
according to the types and specifications of the available rock materials, using the
crushing methods, which achieve the requirements for number of crushed faces and
shape of particle.
Contractor shall sieve the materials before crushing process through vibratory
sieves of suitable capacity to remove all the soil and rock materials of small sizes.
Contractor shall use the suitable crushers according to the rock types, select the
production capacity and calibrate the crusher to match the required gradations, screen
all the produced materials and apply a periodical inspection for blocked or wearied and
broken sieves.
The produced aggregate shall be separated into different sizes, which provide
the required gradation conform to the aggregate requirements according to the work
type.
Contractor on his expense shall wash the aggregate if indicated in the special
specifications or when the clay materials and dust exceed the allowable limits.
The production process shall be stopped when the crushing and screening
method does not fulfill aggregate specifications requirements. The contractor has no
right to commence aggregate production before the Engineer approval for the required
repair, modification procedures taken and verification of the produced aggregate
quality.
6.2.4 Aggregate Transportation:
Contractor shall load and transport aggregate from production centers or
stockpile by loaders and covered trucks using method which ensures no particle
segregation occurs or contamination of aggregate with soil or any deleterious materials.
It is not allowed to take aggregate from the 30 cm in contact with the ground from the
aggregate stockpile except when the storing floor is concrete. The aggregate shall be
taken from the bottom upwards to maintain the uniformity of aggregate gradation.
6.2.5 Aggregate Stockpiling:
Contractor shall transport and store the produced aggregate at the sites shown on
the drawings or other contract documents or sites approved by the Engineer. Contractorshall obtain a written agreement from the site owners for its use before starting of
aggregate transportation to these sites, Contractor shall clear and level those sites to a
leveled surfaces and provide water drainage facility at those sites.
Contractor shall store aggregate materials in separated stockpiles according to
sizes in distance apart or using concrete walls to avoid mixing of different sizes, and he
shall transport, discharge and store each size of aggregate in layers in such a way that
prevents particle segregation. The height of the stockpile shall not exceed 8 meters.
It is not allowed to use bulldozers or any other chain machines lead to breaking
or fracturing of aggregate during stockpiling process.
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 185
Ministry has the right to review contractor’s quality control records and compare
them statistically with quality assurance results to insure quality according to division
17 of these general specifications. And it has the right to inspect the contractor’s
laboratory and its equipments, its technical staff, methods of testing and construction to
insure the efficiency of the contractor’s technical staff and equipments and conformity
of investigation, testing and construction methods with the approved methods.
The Engineer has the right at anytime to stop the Contractor's production or
stockpiling process when he notices that suitable production or stockpiling conditions
according to specifications is not available, or when the contractor does not follow the
environmental protection standards, or when the produced materials do not achieve the
required specifications. The Engineer has the right to change the production source
when the available materials not conform to the specifications and the Contractor has no
right to claim any additional payments for this.
6.2.9 Measuring and Payment:
Measurement shall be made only for determining the produced and availablequantities but payment shall be done according to the work items in which aggregate
materials are used and the aggregate price shall be included in the prices of those items
unless otherwise indicated in the contract documents that payment shall be made for the
aggregate materials separately.
6.3 Aggregate Subbase:
6.3.1 Description:
This section includes material requirements and construction methods for the
aggregate Subbase includes supply, wetting, spreading, leveling and compaction of the
materials conformed to the approved technical specifications and finishing surfaces
according to the dimensions, levels and slopes shown on the drawings, special
specifications, contract documents and these general specifications.
6.3.2 Materials:
Contractor shall use, for the construction of Subbase layer, the aggregate that
conform to gradation and quality requirements indicated in the special specifications or
in this section.
The materials shall be capable of forming a durable and stable Subbase layer
after being wetted and compacted. The aggregate shall be solid water resistant materials
from natural sources or crushed rock, clean, free from impurities and friable materialssuch as organic materials, clay lumps, soluble salts and metals and it is not allowed to
use materials susceptible to disintegration when subjected to wetting or drying.
Aggregate shall fulfill the quality requirements specified in Table (6.3.1) unless
otherwise indicated in the special specifications. The blended aggregate shall achieve
one of the graded shown in Table (6.3.2) or any other gradation stipulated in the special
specifications within the variation allowed in the approved design job mix formula
indicated in Table (6.3.3).
When construction is made in areas with high or fluctuated water level or in
salty environment, the aggregate material types shall be suitable and water resistanthaving a soundness not exceeding 25 % according to AASHTO T-104 test by using
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 186
sodium sulphate and their plasticity index shall not exceed 4 according to AASHTO T-
90 test. When the special specifications require using of open gradation aggregate, the
gradation indicated in the special specifications shall be used otherwise the gradation
No. 5 in Table (6.3.2) of this section shall be used.
Table 6.3.1: Quality requirements for Subbase layer aggregate
Property Test Designation Value
Los Angles Abrasion test % AASHTO T-96 50% (Maximum)
Soundness by Na SO4, 5 cycles AASHTO T-104 25% (Maximum)
Liquid limit%
Plasticity index %
AASHTO T-89
AASHTO T-90
25% (Maximum)
6 % (Maximum)
CBR % ASTM D-1883 50% (Minimum)
Table 6.3.2: Gradation Requirements for gravel Subbase layers
Percent Passing Sieves
GradationSieve size
(mm)(1) (2) (3) (4)
(5)
(open graded)
75 (3") 100 100
62.5 (2.5") 100 100
50 (2") 97-100 100 90-100 70-100
37.5 (1.5") 97-100 70-100 50-85
25 (1") 65-79 -
19 (
3
/4") 50-85 15-5512.5 (1/2") 45-59 -
9.5 (3/8")
6.3 (1/4") 0-20
4.75 (No. 4) 28-42 40-60 30-60 35-70 -
2.36 (No. 8) 0-10
0.425 (No. 40) 9-17
0.3 (No. 50) 0-8
0.075 (No. 2000 4-8 0-12 0-10 0-15 0-5
Table 6.3.3: Allowable variation in Aggregate Subbase Gradation
Sieve size, mm Tolerance limits
9.5 mm (3/8 inch) or larger ± 10 %
4.75 mm (No. 4) ± 7 %
0.075 mm (No. 200) ± 4 %
6.3.3 Design job mix formula:
1. Job mix requirements
The materials used shall achieve the quality requirements specified in Table
(6.3.1) unless otherwise indicated in special specifications, and the total gradation shallconform to the approved gradation in the special specifications or these general
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 187
specifications or those approved by the Engineer within the tolerance limits indicated in
Table (6.3.3).
2. Job mix formula acceptance:
Contractor, prior starting of Subbase materials supply by a period not less than
30 days, shall submit to the Engineer a technical report of the design job mix formulaincluding:
1. Source(s) and gradation of the aggregate for each aggregate size or type and
blending percents of various sizes and the combined gradation.
2. Quality test results required in the special or general specifications for the
aggregate to be used in Subbase layer.
3. The method used for the production of each mix.
4.
Date of starting aggregate production of Subbase material.
The Engineer shall review the proposed job mix formula and if it does not contain
the required information, it shall be returned within 7 days to the Contractor to complete
the information and data required, and then resubmitted to the Engineer for approval.
If the job mix formula includes all the required information it shall be reviewed
within 14 days and accepted or rejected and returned to the Contractor to prepare and
submit a new job mix formula which fulfills the specified requirements and a new date
for starting production should be proposed.
When the test result and technical reports indicates that the proposed job mix
formula is conform to specification requirements, the Engineer shall issue a written
approval for it and the Contractor shall start the mix, production. It is not allowed to
start the aggregate production for Subbase mix before a written approval from the
Engineer for the job mix formula.
The Engineer approval for the design job mix formula does not release the
Contractor from responsibility for supplying materials conform to approved
specifications and construct Subbase according to drawings and contract documents or
these general specifications. The final approval shall be based on the test results of the
actually used materials.
The approved job mix formula is considered a basis for evaluating all materials
and constructed work in the subsequent phases of construction and the tolerance limits
of gradation shall be taken on the bases of same job mix formula.
Contractor has no right to make any modification in the approved job mix
formula unless a new job mix formula submitted and accepted according to
requirements indicated previously in this paragraph. The Contractor shall submit a new
job mix formula whenever the source of the materials actually supplied to the project or
production methods or materials properties and gradation is changed.
6.3.4 Equipments:
Contractor shall provide all the machines and equipments required for
collecting, mixing, screening, loading, transporting, spreading, leveling, wetting and
compacting the aggregate materials and finishing the Subbase according to the specialspecifications, drawings, contract documents and these general specifications. The
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 188
machines and equipments shall be in good technical condition and in numbers and types
sufficient for constructing the work according to the work plan approved by the
Engineer. The contractor shall provide the required arrangements to lessen dust, noise
and pollution according to the environmental protection requirements.
The machines and equipments shall include, loading and hauling machines andequipments such as loaders and trucks, spreading, grading, compaction and leveling
machines such as graders and rollers and tankers provided with water distributors,
which can be calibrated. It is not allowed to use chain machines, sheep foot rollers, and
any other machines, which leads to fracturing or breaking of aggregate particles.
6.3.5 Experimental Section:
when special specifications indicates or the Engineer requires that, Contractor
prior to starting of construction, shall, construct an experimental section not less than
200 meters long for the purpose of verifying the efficiency of the machines, equipments,
possibility of construction according to approved specifications, to determine the
number of the required compaction passes, the quantity of water to be applied to reachthe suitable moisture content, and the thickness of the layer before and after
compaction.
Contractor shall modify the work plan or replace the machines and equipments
if the construction of Subbase layer not possible according to the Contractor's plan or
equipments. If the results of the experimental section are acceptable on the basis of the
test results then the construction method followed shall be approved, and Contractor has
not the right to make any modifications or replace machines or equipments without the
written approval from the Engineer.
6.3.6 Construction:
Prior to starting construction of Subbase, Contractor shall verify the completion,
finishing and handing over and approval of Subgrade layer by the Engineer and
according to the requirements of section 5.5. The Contractor shall verify that the
Subgrade was not damaged and when the period from Subgrade finishing and starting of
Subbase construction exceeds 15 days he shall verify the moisture content and
compaction degree and perform the required repair works when necessary. Contractor
shall not be paid any additional costs for this work.
Contractor shall remove all the loose materials, repair all the defects and adjust
levels of the parts not conforming with the final levels of Subgrade and achieve therequired cross slopes using method accepted by the Engineer for removing surplus
materials or adding new materials conforming to requirements of the Subbase while
adhering to construction requirements and compacting materials up to required degree
of compaction. Contractor has no right to claim any additional costs for repair works
and no right to start Subbase material supply and construction before obtaining the
written approval of the Engineer for the surfaces on which construction shall be made.
Contractor shall mix aggregate materials in central mixing plants and supply to
the site ready mix conforming to gradation requirements approved in the design job mix
formula. It is possible, if approved by the Engineer, to mix aggregate materials of
different sizes on special mixing pads or on site providing that the Contractor shall
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 189
verify the possibility of obtaining a gradation conforming to required gradation without
any deleterious aggregate materials.
The Engineer has the right, when the required gradation not achieved or
Contractor fail to prevent mixing Subbase material with other unsuitable materials or
when mixing on the road causes damage to the previously constructed layers, to stop thework and require modifying and mixing method or providing of technically acceptable
materials from plants.
Materials shall be transported in wet or dry conditions by trucks having metal
boxes and discharged to the paver hopper or deposited on the surface considering that
the loading and unloading of the materials shall not cause segregation and the heaps
shall be distributed in distances that give a layer of required thickness before
compaction. The spreading of the heaps shall be made using graders, and it is not
allowed to use bulldozers. Spreading and leveling process shall continue until a layer
with uniform thickness and moisture content for the full depth is obtained with
approved cross fall.
Unless otherwise indicated in the special specifications, construction shall be in
layers suitable for the used compaction machines and equipments and the individual
layer thickness shall not be more than 20 cm. When the thickness of the Subbase layer
exceeds the maximum indicated thickness these layer shall be constructed in
approximately equal layers providing that the thickness of each layer does not exceed
20 cm.
Contractor before starting compaction shall verify the layer surface is smooth
with no depressions or pockets of extra moisture content or particle segregation, when
such distresses were noticed the required arrangements should be made for repairing,
using method accepted by the Engineer.
Layer compaction shall begin from the outer edge towards the road center line
while achieving the required overlapping between adjacent compaction passes, using
the machines and equipments suitable for the materials and layer thickness, the
compaction shall continue until the degree of not less than 100% of the maximum dry
density specified by AASHTO T-180 modified Proctor test at a uniform moisture
content not differ by more than 2% from the approved optimum moisture content.
Contractor shall provide the equipments capable of compacting areas whichcan't be compacted by normal rollers including manual operation equipments or
vibratory plate and shall change the thickness of compacted layers in these areas to suit
the used rollers so that uniform compaction degrees may be obtained for the full
constructed layer thickness and width.
The field density for each layer shall be determined by sand cone method
according to (AASHTO T-191) test or the nuclear method according to AASHTO T
310-01 or any other approved non-destructive test. The test shall be carried for the full
depth of the layer. The minimum number of readings when using nuclear or non-
destructive method at each location shall be not less than three (3) taken at each area in
different direction, and the average of these three readings is considered as the fielddensity of that location.
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 190
For the purpose of determination of payment factor, the previous mentioned
required density values shall be reduces by 2% using statistical method.
Contractor shall level the final Subbase layer surface and spread materials so
that thickness before compaction shall be greater than the target thickness by
approximately 20-25% of the target thickness. The contractor shall continue levelingand removal process until achievements of the finishing requirements regarding
thickness, slopes and levels.
Each layer of the Subbase shall be measured at the beginning of construction
and during construction, the thickness measurements shall accepted when the final level
of the Subbase does not exceed tolerance limits of the levels indicated on the drawings
and in the contract documents, providing that the material requirements and compaction
degrees for the full depth of each layer is achieved.
The thickness used for determining payment factor shall be the specified
thickness minus 20 mm if the subsequent layer was aggregate and 10 mm if it wasasphalt or 90 % of the thickness shown on the drawings whichever is lesser.
6.3.7 Protection of Constructed layers:
Contractor shall maintain the constructed layers surface, free from any
deleterious or loose materials, and take the required arrangements to maintain moisture
content, compaction degree and water drainage until the subsequent layer is laid. When
the constructed layer is damaged for any reason, Contractor before subsequent layer
construction shall carry out the required repair works including re-pulverization,
spreading, wetting, compaction and finishing without any additional costs and the costs
shall be included on the other construction items.
6.3.8 Finishing requirements:
The Subbase layer shall be constructed according to the dimensions, slopes, and
thickness indicated on the drawings and special specifications.
The final surface levels of the Subbase shall not vary from the level shown on the
drawings or approved by the Engineer by more than 10 mm if the subsequent layer is of
asphalt or concrete or by not more than 20 mm if the subsequent layer is aggregate.
The final surface of Subbase shall be verified by taken cross sectional levels at
25 meters intervals providing that the number of the sections is not less than 5 in each
2000 square meters of the constructed layer. Measurement shall be done at each crosssection in 5 points at least.
The final surface smoothness shall be verified using straight edge 3 meters long
and the gap between the bottom surface of the straight edge and the surface between any
two contact points in any direction shall not exceed 10 mm when the subsequent layer is
aggregate or 6 mm when it is asphalt or concrete.
6.3.9 Acceptance:
Contractor shall control the quality of Subbase through performing all the
required measures to insure the used materials, methods of construction and the
completed works meet the quality requirements specified in these specifications andother contract documents.
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 191
The Ministry has the right to ensure the quality by verifying Contractor's quality
control procedures either, through direct supervision of quality control activities or
performing quality assurance procedures neutrally, on a sufficient number of
representative samples to determine the level of construction and to accept or reject the
constructed work on detailed bases in division 17 of this specifications except otherwise
indicated in the special specifications and other contract documents.
1. Quality control:
Contractor shall control the quality of materials and constructed works, monitor,
record and analyze results, draw quality charts for critical properties and perform all
required tests and measurements in Table (6.3.4).
Contractor shall submit to the Engineer with copies of all the measurements, reports
tests results and he shall apply all the articles stated in item 17.1.1 of this specifications.
2.
Quality assurance:
The Ministry has the right to ensure the quality of materials and completed
works through carrying out or ordering others under its direct supervision to carry outthe necessary tests and measurements, and checking the completed work for each or
some of quality control items specified in Table (6.3.4).
Ministry has the right to review contractor’s quality control records and to
compare these records statistically with the results obtained by quality assurance as
specified in division 17 of these specifications, and inspect contractor’s equipments,
technical staff, and measurement and construction methods, to determine the degree of
compliance of measurements and constructed methods with the approved requirements.
Works shall be accepted with the prices specified in the contract or with lower
prices or might be rejected according to the quality levels by applying the statistical
method specified in division 17 of these specifications except otherwise specified by the
special specifications.
6.3.10 Measurements:
The Subbase layer shall be measured in cubic meters or as specified in the
special specifications, after being laid and compacted according to the specified
thickness and within the dimensions and levels shown on the drawings or according to
the Engineer's instructions.
6.3.11 Payment:
Payment shall be made for actually constructed and technically accepted works
within the approved limits, dimensions and prices indicated in the contract or reduced prices results from applying of quality assurance procedure.
The paid amounts are considered full compensation for the extraction, supply,
mixing, transporting, spreading, wetting, compacting of materials and finishing the
works, provision and operation of machines and equipments, labor, tests, measurements
benefits, revenues, fees, third party payments and all other requirements to construct the
works in accordance with the drawings, special and general specifications. Payment
shall be according to the item indicated in Table (6.3.5) without contradiction with
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 193
6.4 Aggregate Bases:
6.4.1 Description:
This section contains material requirements and constructed methods for the
construction of the un-treated aggregate Base according to the dimensions, levels,
thickness and slopes shown on the drawings and other contract documents.
6.4.2 Materials:
Contractor shall provide the aggregate materials conform to requirements of the
special specifications or these general specifications, these materials shall be crushed
coarse and fine aggregate or natural aggregate or furnace slag after being broken and
screened to achieve the required gradation and verify its density.
The materials used shall be clean, free from impurities, organic materials, friable
particles and clay lumps, and not more than 10% of thin and elongated particles. The
materials, after being spread, wetted and compacted, shall form a sound and stable base,
which complies with the special technical specifications or these general specifications.
The untreated aggregate Base shall achieve, unless otherwise indicated in thespecial specifications, the quality and gradation requirements indicated in Table (6.4.1)
and Table (6.4.2) considering the following:
1. Category (A) aggregate, type (1) gradation shall be used for arterial roads,
highways, industrial areas and heavy vehicles parking areas,
2.
Category (B) aggregate, gradation (2) shall be used for collective roads.
3. Category C aggregate, using gradation (3) shall be used for secondary roads at
residential areas.
When the specifications require using of open gradation aggregate it shall
conform to one of the gradations indicated in Table (6.4.3) and the quality of the
materials shall be from category (A) as shown in Table (6.4.1). Open gradation
materials shall be treated, when constructing main roads and streets, industrial area
roads and heavy vehicles parking areas, with cement or any other method stipulated in
the special specifications or the technical study.
Table 6.4.1: Quality Requirements for Aggregate Bases
Contractor shall select the aggregate material source(s) and perform the
preliminary tests to verify achievement of the specifications quality requirement, the
possibility of mixing to obtain the required gradations and the quantities available at
each source.
The Base materials, unless otherwise indicated in special specifications shall
achieve the quality requirements indicated in Table (6.4.1), and the combined gradation
shall conform to approved gradation in special specifications or these general
specifications or the gradation approved by the Engineer within the tolerance limits
indicated in Table (6.4.4).
2. Job mix formula acceptance procedures:
Prior to starting supply of the untreated Base materials by a period not less than30 days, Contractor shall submit to the Engineer a technical report including the job mix
formula for the aggregate materials conform to requirements indicated in the special
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 196
6.4.4 Equipments:
Contractor shall provide all machines and equipments required for producing the
aggregate materials and construct untreated Base according to drawings, special
specifications or these general specifications.
These machines and equipments shall be in the numbers, types, good technical
condition and capable to construct the works according to the approved time schedule.
The equipments shall include mixing, transporting, spreading, leveling, wetting
and compacting machines such as aggregate mixers, loaders, trucks, graders, spreaders,
adjustable water distributors and rollers, It is not allowed to use chain machines and
sheep foot rollers or any machines or equipments cause damage to the materials and
affect their properties and gradation.
6.4.5 Experimental Section:
Contractor, when special specifications or the Engineer requires that, shall
construct experimental section not less than 200 meters long, to verify his capability for
constructing aggregate Base conform to drawings, special specifications or thesegeneral specifications and to determine the water quantity required to be added, the
required compaction passes and thickness required before compaction, Using
construction method and available equipments.
When test results show that, the work plan and available machines and
equipments are capable to construct the required works, results are approved and
Contractor shall follow the approved construction method and has no right to make any
changes in machines or that method without a written approval from the Engineer.
However, if the results of the experimental section were not technically
acceptable, Contractor shall make the required modifications in the construction method
or machines to achieve the approved specifications.
6.4.6 Construction:
6.4.6.1 Surfaces preparation:
Prior Contractor start materials supply and construction of aggregate Base all
previous works shall be completed and handed over according to drawings, special
specifications and these general specifications. It is necessary to insure these layers have
not been subjected to any damages or loose or change in their compaction degree or
moisture content.
Contractor on his own expense shall remove all deleterious and loose materials
and repair all surfaces' defects and has no right to claim any additional costs for this
work.
When the period between the previous layer construction and the beginning of
Base construction exceeds two weeks the compaction degree and moisture content of
the constructed layer shall be verified by field density test, if the test results obtained
show a change in compaction degree, Contractor on his expense shall rewet and
compact that layer up to required compaction degree.
The Contractor is not allowed to start materials supply and aggregate Baseconstruction before receiving a written approval of the Engineer.
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 197
The Subbase or Subgrade shall be wetted before placing the aggregate Base to ensure
layers bonding.
6.4.6.2 Mixing and Transportation:
Water and aggregate shall be fully mixed in calibrated plant mixer capable to
control feeding and mixing of different material sizes to provide mix conform toapproved gradation in the design job mix formula and it is not allowed to mix materials
on site.
Water shall be applied to the aggregate during mixing using calibrated
distributor to obtain a mix of uniform moisture content closed to optimum moisture
content determined by Modified Proctor Test, considering the percent of evaporation
during transportation and spreading.
The mixed aggregate shall be loaded and transported by covered trucks. The loading
and discharging process shall be performed in a method that prevents particles
segregation of materials.
6.4.6.3 Spreading and Compaction:
The aggregate Base shall be constructed in layers with thickness that suits the
materials used and the available compaction equipments on the basis of the
experimental section results and the thickness of each layer shall not exceed 20 cm.
The materials shall be supplied to the site in wet condition with moisture content
closed to optimum moisture content. The Base materials shall be spread using
mechanical spreader or shall be placed in distributed heaps on surface to provide, after
spreading a uniform layer conform to the approved thickness before compaction.
Consideration shall be made to avoid particle segregation during transportation, loading
and spreading. When these materials have been exposed to segregation, Contractor shall
remove all segregated materials and replace them with other acceptable materials.
Moreover, the additional grading can be done using motor grader.
The spread materials shall achieve the thickness, slope and approved cross
section, and the layer shall be leveled without depressions or particle segregated
materials or pockets in which water may collect.
Compaction shall be executed using approved work plan rollers and according to
experimental section results, those rollers shall be capable of compacting the layers forfull thickness up to required compaction degrees without leading to particle fracturing
or grinding.
The layer thickness before compaction indicated in Table (6.4.5) can be used
according to rollers, however, the approved thickness shall be determined based on test
section's results of field density and Engineer's comments during construction.
When total thickness of constructed Base is greater than thickness approved for
compaction according to available equipment, the construction shall be performed in
layers providing that the thickness of each layer shall not exceed the suitable thickness
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Table 6.4.5: Suitable Layer Thickness According to Roller Type
Roller type Layer thickness after compaction, cm
Vibratory, more than 12 tons 20
Vibratory, (10-12) Ton 15
Normal rollers 10
Contractor shall start compaction of each layer longitudinally, from the outer
side in the cross section to inner side with adequate overlapping distance between
adjacent passes, which shall be less than 15 cm.. Compaction shall continue up to
degree of not less than 100 % of the maximum dry density, determined by Modified
Proctor Test AASHTO T-180 for the same materials, at uniform moisture content not
differs by more than 2 % from optimum moisture content.
During compaction, Contractor shall compensate for water evaporation usingsuitable distributor allow regular and uniform spraying.
Contractor shall remove loose materials and carry the required remedies for
depressed and cavity areas existed in the Base layer surface, treat and re-compact these
sections as directed by the Engineer, to obtain stable layer capable to sustain the
subsequent layers. Contractor has no right to claim any additional cost for this work.
Prior starting construction of the subsequent layer the first layer shall be finished
and compacted to required degrees and handed over and sprayed with water to provide
the required bond between layers.
The compaction degree shall be determined using field density test as percent of
maximum dry density obtained from Proctor modified test for the used material and the
minimum compaction degree for determination of pay item using statistical procedure is
the above acceptable level minus 2 %. The field density test shall be done using sand
cone method according to AASHTO T-191 or nuclear method according to AASHTO
T-310-01or any other non-destructive testing method. The field density test shall be
performed for the full thickness of the layer. When using nuclear method or any non-
destructive test a minimum of three readings shall be taken at each location the average
of three readings should be the density of that location.
Base layer thickness shall be measured before construction and during
construction and the final level of the Base accepted if it does not exceed the tolerance
limits of levels shown on the drawings and contract documents, providing that the
materials requirements and compaction degrees for the full depth of each layer has been
achieved. The thickness shown on the drawings minus 10 mm shall be taken to
determine the quality index and payment factor.
The final Base layer shall be finished according to the dimensions, thickness and
slopes shown on the drawings, special specifications or these general specifications.
Consideration shall be given to spreading and leveling of the final layer materials and
the final levels can be verified using stakes or any other guiding method accepted by theEngineer. The materials shall be spread so that their thickness before compaction is
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
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greater than the specified thickness by approximately 20-25%. Leveling shall continue
until the final layer surface conformed to approved level and cross section.
6.4.7 Maintaining the constructed layers:
Contractor shall maintain the constructed layers free from any deleterious and
loose materials and perform all required procedures to maintain moisture content,compaction degree and drains until lying of the subsequent layer. When any damage is
occur in the constructed layer Contractor shall perform the required repair works
including re-plowing, spreading, wetting, compaction and finishing, before commences
construction of the next layers, and Contractor has no the right to claim any additional
cost for this work and the cost shall be included on other construction item.
6.4.8 Finishing requirements:
The Base shall be finished according to the dimensions, slopes and thickness
shown on the drawings and special specifications.
The final surface levels of the Base shall not differ from the level shown on the
drawings or approved from the Engineer by more than 10 mm if the next layer was anasphalt or concrete layer.
Verification of the levels shall be on basis of final measurements performed in at
least 5 points of each cross section taken in interval of 25 meters providing that the
number of the sections shall not be less than 5 for each 2000 square meter.
The surface of the final layer of Base shall be smooth and conform to slope and
level shown on the drawings or special specifications. The smoothness shall be
inspected using straight edge 3 meters long. The clearance between bottom of straight
edge and the surface of the layer in any direction between any two contact points shall
not exceed 6 mm.
6.4.9 Acceptance:
Contractor shall control the quality of aggregate Base through performing all the
required measurements to insure used materials, methods and the completed works meet
the quality requirements specified in these specifications and other contract documents.
The Ministry has a right to ensure the quality by verifying contractor's quality
control procedures either, through direct supervision or carrying out quality assurance
procedures, neutrally on a sufficient number of representative samples to determine the
level of construction, and to accept or reject constructed work on basis detailed in
division 17 of this specifications, except otherwise indicated in the specialspecifications and other contract documents.
1. Quality Control:
Contractor shall apply control the quality of materials and constructed works,
monitor record and analyze the results, draw the quality charts for critical properties and
perform all tests and measurements indicated in Table (6.4.6).
Contractor shall submit to the Engineer copies of all tests and apply all
requirements indicated in item 17.1.1 of these general specifications.
2. Quality Assurance:
The Ministry has the right to ensure the quality of materials and completedworks through carrying out or ordering others under its direct supervision to carry out
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 200
the necessary tests and measurements, and checking the completed work for each or
some quality control items specified in Table (6.4.6).
Ministry has the right to review contractor’s quality control records and to
compare these records statistically with the results obtained by quality assurance as
specified in division 17 of these specifications, and inspect contractor’s equipments,technical staff, and measurement and construction methods, to determine the degree of
compliance of measurements and constructed methods with the approved requirements.
Works shall be accepted with the prices specified in the contract or with lower
prices or might be rejected according to the quality levels by applying the statistical
method specified in division 17 of this specifications except otherwise specified by the
special specifications.
6.4.10 Measurements:
The Base quantities shall be measured in cubic meters, unless otherwise indicate
special specifications and contract documents.
The measurements for payment shall include the actually constructed works
indicated on the drawings or contract documents, measurement shall not be done for
payment purposes for works constructed outside approved areas in drawings or
specified by the Engineer, and the quantities of these work items shall be calculated and
paid according to contract documents.
6.4.11 Payment:
Payment shall be made for actually executed and technically accepted work
quantities within the approved limits and dimensions according to contract rates or
reduced prices as a result of quality assurance works when contract documents call for
this.
The paid amounts are considered as full compensation for extraction,
transportation, spreading, wetting and compaction of the materials regardless of their
source, according to these general specifications, special specifications and other
contract documents. Plus provision, operation of machines, equipments and labor, tests,
measuring and all requirements to execute the works in accordance with drawings,
special and general specifications, benefits, revenues, fees and third party payments.
Payment shall be according to the item indicated in Table (6.4.7), withoutcontradicting the contract documents.
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6. Cement content in the mix, and water-cement ratio.
7. Mixture density at the proposed water-cement ratio on basis of (AASHTO T-
134) test method.
8.
Quality properties of the mixture such as unconfined compressive strength and
any other quality properties indicated in the special specifications.
9.
Results of all tests show materials conformity and mixture to requirements ofspecial specifications or these general specifications.
10. Type and percent of admixtures and additives in mixture on the basis of cement
dry weight and method of application and mixing.
11. Method of production, construction and curing of cement- treated Base.
The Engineer shall review the report of design job mix formula proposed by
Contractor, if not all required information is complete the Engineer shall return the
report within 7 days and Contractor shall complete the information and resubmit it to
the Engineer. If the information and data were complete, the Engineer shall verify
materials conformity to quality and gradation requirements and approve or reject the job
mix formula within 14 days from the date of its submission.
Contractor shall provide the adequate quantities of aggregate and all the mix
components and verify the availability of suitable water in adequate quantities for
production and wetting before starting production. It is not allowed for the Contractor to
change the sources and specifications of the materials used in preparing design job mix
formula without submitting a new design job mix formula approved by the Engineers.
The approval of design job formula by the Engineer shall be considered only
preliminary. The mix production and construction shall be verified to achieve the
requirements indicated in these specifications or special specifications based on tests
results of constructed experimental section, production quality control, and tests results
of field samples taken from the site during the first working day and quality control
procedure. When the Engineer notice significant in material or mix properties or in
constructed works shall require from contractor to stop the work and to take the
required arrangements to remove unsuitable materials and works and reconstruct these
works according to these general specifications, special specifications and Engineer's
instructions. Contractor shall be responsible for all the costs results from this and has no
right to claim any additional costs.
6.5.4 Equipments:
Prior to start construction, Contractor shall submit a list of proposed equipmentsfor cement-treated Base construction. These equipments shall be in good technical
condition, and in numbers, types conform to work plan requirements and time schedule
submitted by the Contractor, accepted by the Engineer, and capable of constructing and
finishing cement treated Base according to the drawings, special specifications and
these general specifications.
Equipments shall include central plant or mobile mixers, trucks, pavers, graders,
rollers and cement distributors, water distributor, asphalt distributor and all
requirements for constructing the work according to the specifications. Types and
numbers shall be selected according to the approved work plan, mix method and time
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6.5.5 Construction:
6.5.5.1 Surface preparation:
Before starting construction of cement treated Base, all previous works shall be
completed, tested and handed over. The surfaces on which cement treated aggregate
Base will be constructed shall be free from deleterious and loose materials, level,durable to receive cement treated base and capable to sustain traffic movement of
construction equipments and machines without causing any deformations.
Contractor should carry out all required works and arrangements to repair all
defects and surfaces deformations for the layer that receive cement treated Base. The
surface repair shall include removing deleterious, loose and waste materials, and
adjusting layer's levels. The layer's level shall be adjusted by removing of waste
materials, or adding new materials having same quality of repaired layer, and spreading,
leveling and compacting them according to the requirements of that layer, or by, re-
wetting and compacting the layer providing that the final surface shall achieve the
thickness, compaction, leveling and slope requirements indicated on the drawings or thespecial specifications or these general specifications and according to the Engineer's
instructions. Contractor has no right to claim any additional costs for this work.
Contractor not allowed to starts material supply or spread the cement treated
Base before the approval from the Engineer's for surface preparation works.
Prior to start spreading of the cement treated base, Contractor shall uniformly wetting
the previous layer's surface without excessive water causing log or week areas unable to
sustain movement of spreading and compaction equipments or lead to an increase of
moisture content to limits which do not allow a uniform mixing of materials with
cement when use on road mixing.
6.5.5.2 Weather Limitations:
Contractor shall not construct cement treated Base during bad weather
conditions which tend to increase water evaporation or change cement ratio in the mix
or affect mix properties or cement hardening and limiting the gained strength required.
Cement treated aggregate Base shall not be spread when temperature is less than
5 c°, or expected to reach this degree in the next day of spreading and compaction, or
when temperature is higher than 35 c°. It is possible according to a written approval
from the Engineer to ignore the above weather limitations limits if Contractor takes the
required precautions to maintain the mix and constructed works to decrease waterevaporation and cooling of the mix or its components without affecting the quality of
the treated base or its efficiency after construction. Contractor shall be responsible for
any results caused from this works, and he shall carry out on his expense all repair
works when necessary including re-construction of all sections conforming to
specifications. It is not allowed to construct cement treated Base during rainfall or dust
storms or when wind speed exceeds 25 km/hr or when wind speed may leads to cement
scattering during road mixing. The Contractor shall be responsible for maintaining the
surface on which the treated layer shall be laid in a technically acceptable condition
during all weather conditions, and dispose all materials or mix or works performed in
unsuitable weather conditions without having the right to claim any additional costs for
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6.5.5.3 Mixing: Cement, water, and admixtures indicated in the special specifications and design
job mix formula shall be applied according to approved percent and mixed until a
consistent mix were achieved for whole areas and thickness of treated layers. Unless
otherwise indicated in special specifications, the cement treated Base mix shall be
produced in central mixing plants.
When constructing small size works or approved from Ministry mixing may be
performed on road using mobile mixers if the Contractor proves that the produced mix
conform to required specifications and approved work plan. When approved by the
Engineer, the cement treated Base material may be mixed on the road surface using
motor grader for limited quantities when necessary and for not more than 50 linear
meters.
Contractor is fully responsible for producing a mix conforming to specifications
and design job mix formula regardless of the applied mixing method.
1. Mixing in Central Plant:
The cement treated Base mixes shall be produced in Batch plants mixers or
continuous mixers.
The mixers used shall be capable of producing uniform mix conforming to
requirements indicated in technical specifications and approved design job mix formula.
Mixers shall be calibrated and provided with all required control devices for feeding
aggregate according to approved gradation and feeding cement within tolerance limits
not exceed 5% and feeding water within tolerance limits not exceed 2% of the accepted
percentages in the approved design job mix formula.
Contractor shall submit with the design job formula a list shows type and site of
the plant proposed to use. Contractor not allowed starting mix production before the
Engineer's approval for the plant used. The produced mix shall be verified whether
conforming to specifications based on the first day production. When the produced mix
does not achieve the specified requirements, the production shall be stopped and the
required precautions shall be taken to calibrate the mixer or modify the design job mix
formula.
Contractor shall set out a plan to transport the mix according to a time schedule
for production and transportation, in which the time period from applying water toaggregate-cement mixture, spreading and starting of compaction shall be within the
allowed periods. The period from water application to starting of compaction shall not
exceed 30 minutes, unless otherwise allowed in the special specifications. The mix shall
be transported in specialized transportation equipments. The mix shall be discharged
from the plant to the trucks, transported and deposited in to spreader, without any
particles segregation, and all required arrangements shall be taken to lessen the loss in
moisture content.
The mix shall be spread using mechanical spreader or special spreading boxes
and if available space was not adequate for using one of above mentioned methods it is
possible, when necessary, to spread the mix using motor grader. Spreading, regardlessof the used method, shall be executed with required compacted thickness of the layer
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 207
within the allowed variation and in one pass of spreading machine. The produced
surfaces shall be uniform, level, free from particles segregation and conform to the
slopes and cross sections shown on the drawings or in the specifications within the
allowed variation limits.
When the mix allowed to be spread on more than one lane simultaneously, the period between spreading the mix on the constructed lane and staring of spreading on
the adjacent lane shall not exceed 30 minutes, otherwise construction joints shall be
constructed.
2. On site mixing:
Road mix construction method by mobile or traveling mixers can be used after a
written approval from the Ministry, while mixing and spreading by motor grader shall
only used after a written approval from the Engineer for construction of limited
quantities of cement treated Base and for a distance not more than 50 meters. When
using any of the on site mixing methods, Contractor shall, on basis of practical
experimental results, prove that the test results of mix are uniform, achieve allrequirements and do not differ from design strength of the mix by more than 20%.
- Mixing by Mobile Mixers:
Mixing may be done on site by mobile mixers when the available areas were
enough for the operation of such mixers. These mixers shall be capable of producing a
mix conformed to approved specifications and shall be equipped with control systems
for cement and water application. The supplied aggregate materials shall conform to
approved gradation and quality requirements, when discharged in to the mixer, whereas
cement shall be applied in dry state, with the approved rate, and mixing it with
aggregate materials until a uniform mix is obtained, then water is applied with the
specified percent and the mixing shall continue until the final mix conformed to
specifications. The mix shall be transported to the construction site using approved
means of transportation and discharged in the spreader or spreading box then spread
according to the specified thickness, slope and cross section, compacted and finished.
- Mixing by Traveling Mixers:
When mixing on road by traveling mixers these mixers shall be capable of
picking all spread materials to be treated over the road, without contamination with any
other surface materials or deleterious materials. These mixers shall be capable of
applying cement within tolerance limits, and not more than 5 % of the specified rate in
the design job mix formula, then mixing it uniformly with the treated material andapplying water within variation limits not more than 2 % of the specified percent in the
design job mix formula.
Cement treated Base materials shall be spread on the prepared and approved
surface and leveled to thickness conformed to the approved technical specifications.
Transportation and spreading of aggregate materials shall be performed without causing
particles segregation or aggregate fracturing, according to slopes, cross sections and
thickness shown on the drawings or specifications and approved work plan.
The spread materials shall be wetted before applying cement by one day, and the
period between wettings and applying cement shall not be less than 12 hours. The
spreading process shall not lead to formation of weak areas or areas with excessive
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 208
moisture content or formation of cement lumps some extend that may restrict the
uniformity of cement and aggregate mixing for full depth.
It is possible to apply cement in one batch or many batches, without formation
of cement lumps, and mixing continuously until a uniform mix in color and gradation
were obtained, at the specified cement rate before water application. Immediately aftercompletion of aggregate and cement mixing, water shall be applied in specified rate and
mixing shall continue until uniform moisture content is obtained for the whole mix.
- On surface mixing:
When special specifications allow that or when constructed limited quantities of
works, it is possible to distribute the cement over spread materials surface using a
distributor machine capable of applying cement uniformly on the material surface
within tolerance limits, and not more than 5% of the specified rate. The distributor
openings shall be as near as possible to the treated surface and covered from all sides to
prevent cement scattering. Spreading of cement also, can be performed by distribution
of bags on surface in forms of rows at calculated intervals, then the bags shall be openedand the cement distributed in the transverse directions. Finally, distribution process shall
be completed using equipments accepted by the Engineer, so that a uniform cement rate
is obtained for the whole area and thickness of the layer to be treated. The materials on
which cement is distributed shall be dry.
After cement is distributed, it shall be mixed in dry state with the aggregate
materials using plowing, pulverizing and mixing equipments, equipped with plowing
and pulverizing arms, teeth and rotating screw plows capable of pulverizing the
materials all over the layer and treated area and mixing the materials properly with
cement until a uniform mix is obtained in one pass. Then water shall be applied in
specified rates and plowing and pulverizing shall be repeated until a uniform mixture is
obtained according to the required cement rate and moisture content for the whole depth
of constructed layer materials shall be spread according to approved slopes, levels and
smoothness.
When constructing limited quantities of works it is possible, with approval of the
Engineer, to use automatic steering grader capable of pulverizing, uniformly mixing and
spreading materials according to the slopes, thickness and smoothness shown on the
drawings or in the special specifications or these general specifications. Motor grader
mixing shall not lead to materials contamination with Subgrade or Subbase materials or
any deleterious materials during mixing and spreading. The produced mix shall conformto approved design job mix formula. Cement shall be applied in a dry state pulverized
and consciously mixed with aggregate for the full depth of the constructed layer, until a
uniform color and gradation of the mix is obtained at the specified cement rate. Water
shall be applied, pulverized and mixed until a according to specified moisture content,
then the mixture is spread in one pass according to thickness, slopes and smoothness
shown on the drawings or special specifications.
Levels and thickness of spread layers shall be controlled using fixed stakes that
allows construction according to approved slopes and levels.
The period between cement and water application and starting of compaction shall not
exceed 30 minutes and all compaction and finishing processes shall be completedduring a period not more than 2.5 hours from cement and water applications.
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6.5.5.4 Compaction and Finishing: Compaction operations shall be started immediately after finishing of spreading
using smooth steel rollers of suitable weight ranged from 6-10 tons, or vibratory rollers
after disconnecting vibration system, these rollers shall be capable of compacting the
cement treated aggregate Base to compaction degree not less than 98% of the density
determined by AASHTO T-134 test for the full depth. Compaction shall not lead to breaking aggregate particles. The period between spreading completions and starting of
compaction shall not exceed 30 minutes considering the prevailing air temperature,
while the period between water application to aggregate-cement mixture and
completion of compaction shall not exceed 2.5 hours.
Contractor shall take all the necessary measures for eliminating formation of
random cracks through controlling the cement rate used, such that it does not exceed the
approved minimum limit in the design job mix formula and water ratio control. Also,
carrying out the works at the suitable climatic conditions when temperatures are getting
lower as far as possible and taking the required arrangements for construction in hot
weather and care about mostening throughout the curing period. When some randomcracks appear, he should carry out the required repair works according to the engineer's
instructions and filling cracks with the suitable materials. Except otherwise stipulated in
the special specifications for a specific type, filler materials shall comply with ASTM D
(3405, 3406). Also, he shall remove all parts in which cracks of more than 3 mm wide
cracks appear when the cracked area exceeds 15% of any 30 m2 area and to replace it
with another area technically accepted. As an alternative to removal and replacement,
contractor, according to a technical report prepared by a specialized agency and with the
acceptance of the engineer, may construct an asphalt layer absorbing to stresses.
Contractor has no right to claim any additional cost for that.
Compaction degree shall be determined for each constructed layer by taking
random samples at time interval immediately after completing compaction using sand
cone method, AASHTO T-191 test or the rubber balloon method according to
AASHTO T-205 test or nuclear method according to AASHTO T-310 or any other
approved nondestructive test method. When using nuclear method or any non-
destructive test a minimum of three readings shall be taken at each location and the
average of three readings should be the density of that location.
Compaction degree shall be calculated by dividing field density with maximum
dry density determined from AASHTO T-134 test.
The minimum limit of accepted compaction degree for determining the payment
factor using statistical method shall be the indicated degree in the beginning of this
paragraph minus 2%.
The unconfined compressive strength shall be determined by taking samples at
random time intervals from the mix, preparing, maintaining and testing them according
to AASHTO T-(134, 126, 22).The minimum allowed limit for calculating the payment
factor is 80% of the value obtained in the design job mix or the minimum strength
specified in the special specifications whichever is greater.
The applied cement rate shall be verified on field samples using AASHTO T-211 test this rate shall not differ from the approved percentage by more than 10% of the
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 210
rate specified in the design job mix formula providing that the total difference should
not exceed, 0.5 % whichever is lesser.
Thickness of each constructed layer shall be measured after verification of
compaction by taking five random core samples and it is possible to use the field
density test hole for this purpose. The thickness accepted for determining paymentfactor shall not be less than the approved thickness minus 2 cm or 10 % of the thickness
shown on the drawings whichever is lesser.
6.5.5.5 Construction of Joints:
Joints shall be executed between adjacent sections constructed in consecutive
days or when constructing adjacent sections finished more than 30 minutes ago. Joint
construction shall be done by cutting edge of constructed layer straight and
perpendicular to a distance that extends up to the area where the surface regular with
constant slope and the cut width shall be not less than 10 cm. These cut faces shall be
wetted properly before starting the spreading of the new materials. The prepared joints
shall be protected at the end of each working day by wooden boards or other materialsaccepted by the Engineer.
When the pavement surface is asphalt concrete, transverse contraction joints
shall be performed for the full width of layer, with at interval not more than 10 meters,
and filled with the required filler materials. No need for performing contraction joints
when using a cement concrete surface layer. The cutting of contraction joints shall be
within the first five days after finishing of compaction, and joints shall be cleaned from
loose materials, and filled with filler material, providing that the level of sealing
materials shall not exceed the level of layer surface. The selection of filler type and
method of construction shall be in accordance with the requirements of division 14 of
these general specifications.
6.5.5.6 Curing:
Cement treated base surface shall be kept in wet state by water spraying for a
period not less than 7 days providing that spraying shall start immediately after
finishing of compaction process and the layer curing can be done using soaking method
after making confining water perms on its surface or covering it with wetted sacks.
These sacks shall be rewetted using water for minimum two days and recovered with
the plastic sheets after each wetting process.
Moisture content of constructed layer surface can be maintained, by coveringthat surface with emulsified asphalt curing membrane composed from equal percent of
asphalt and water conforming to requirements indicated in paragraph (6.5.2.5) of this
section. The asphalt curing membrane shall be sprayed in a rate of 0.9-1.13 Litre/m2
based on the experimental section. Prior construction of asphalt curing membrane the
constructed surface shall be wetted with water for a minimum 24 hours period.
The asphalt curing membrane shall be executed according to construction
requirements of asphalt Base indicated in the division eight (8) of these general
specifications. Contractor shall be responsible for repairing any damage caused to
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6.5.6 Traffic Control:
Contractor shall take all necessary requirements for traffic control during
construction and curing periods, and prevent movements of any equipment over the
treated layer before, the end of curing period, except water distributors are allowed to
pass providing that it should not cause any damage in the treated layer. Contractor shall
be responsible for maintenance and repair until construction of the next layer is allowed.
6.5.7 Finishing Requirements:
Cement treated Base shall be constructed according to dimensions, slopes and
thickness indicated on drawings and special specifications, providing that the difference
between constructed layer thickness and required thickness shall not exceed 2 cm or 10
% of the approved thickness whichever is lesser.
The final surface levels of constructed layer shall not differ from the specified
levels by more than 10 mm. The final levels shall verified on basis of 5 points cross
section measurements taken every 25 m interval, providing that the number of the
sections shall not be less than 5 for each 2000 square meters of constructed layer.
The surface smoothness shall be verified visually and by using straight edge, 3
meters long in five (5) locations, and the clearance between straight edge bottom and
the constructed surface between any two adjacent points shall not exceed 6 mm.
6.5.8 Acceptance:
Contractor shall control the quality of cement treated base through performing
all the required arrangements to insure that materials, methods and the completed works
meet the quality requirements specified in these specifications and other contract
documents.
The Ministry has the right to ensure quality of constructed works by verifying
contractor's quality control procedures either, through direct supervision of quality
control activities, or through performing quality assurance procedures, neutrally, on a
sufficient number of representative samples, to determine the level of construction and
to accept or reject the constructed work, on basis detailed in division 17 of this
specifications except otherwise indicated in the special specifications and other contract
documents.
1. Quality Control:
Contractor shall control the quality of materials and constructed works, andmonitor, record and analyze results, draw quality charts for critical properties and
perform all required tests and measurements indicated in Table (6.5.3).
Contractor shall submit to the Engineer with copies of all the measurements,
reports tests results and he shall apply all the requirements stated in item 17.1.1 of this
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 214
6.6 Emulsified Asphalt Treated Base:
6.6.1 Work description:
This Section consists of furnishing and cold-mixing aggregate and emulsified
asphaltic material, hauling, spreading, compacting and finishing the emulsified asphalt
treated base to the lines, grades and thickness shown on the plans, all in accordance withthe these General Specifications, Special Specifications, and as directed by the
Engineer.
There are three of emulsified asphalt treated base mixes, which are classified
according to aggregate gradation used in these mixes as shown in Table (7.3.5) in these
General Specifications. They are type-I (open graded), type-II (dense graded), and type-
III (sand graded).
Type-I emulsified asphalt treated base mix is produced at ambient temperature
(cold-mix) and only by central mixing. However, the emulsified asphalt treated base
mixes Type-II and type-III may be produced in the ambient temperature (cold-mix) byone of the following three methods:
• Central mixing in a continuous mixing pugmill.
• Central mixing in a batch plant.
• Mix on-road by using a mobile mixing unit.
6.6.2 Materials:
Asphalt material: the material shall be from emulsified asphalt categories MS-2 or
MS-2h or CMS-2 or CMS-2h or SS-1h or CSS-1 or CSS-1h so that it complies with the
quality requirements indicated in Tables (7.2.5) to (7.2.7) in these General
Specifications. The selected asphaltic materials shall provide the required coating
requirements stated in Item 6.6.3.
Aggregate: Aggregate gradations 1 (open-graded), 2 (dense-graded), and 3 (sand-
graded) from Table 7.3.5 in these General Specifications, shall be used for preparing the
emulsified asphalt treated base mixes provided that they achieve the quality
requirements indicated in Table (7.3.1) (Types 4, 5, 6) in these General Specifications.
The combined aggregate shall achieve the approved gradation requirements within the
allowed variation limits indicated in Table (6.6.1).
Water: Water shall be free of matter deleterious to the quality of the emulsified asphalt
treated mixture.
Cement: It shall be from Portland cement type (I) or (II) which is compliant with the
requirements indicated in Item 7.3.4 in these General Specifications
Table 6.6.1: Allowable tolerance limits for total aggregate
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 215
6.6.3 Emulsified Asphalt Treated Base Mix:
6.6.3.1 Job Mix Formula:
Contractor, before starting the execution of the Emulsified asphalt treated base
by thirty (30) days, shall submit to the Engineer a full technical report prepared by an
approved specialized agency including the mix design and job mix formula (JMF)which should be prepared according to the basic asphalt emulsion guide (MS-19)
published by the American Asphalt Institute using and ASTM D-1559 unless otherwise
stated in the Special Specifications. The JMF shall conform to the requirements shown
in Table (6.6.2).
Table 6.6.2: Quality requirements for emulsified asphalt treated mixes (MS-19)
Property Minimum limit Maximum limit
Marshall stability. Kilogram ASTM D 1559 227 -
Stability loss, percent % - 50
Air voids, percent 2 8Absorbed moisture rate after 4 soaking days, % - 4
Aggregate coating, percent ASTM D 244 % 50 -
The Contractor shall submit the JMF together with the following information:
1. Necessary data on aggregate source, gradation, and properties related to
crushing, gradation and other quality requirements stated in Item 6.6.2.
2. Type and grade of the emulsified asphalt materials to be used.
3.
All test results of the trial experimental mixes and mix design.
4. Asphalt content based on the total dry weight of the mix.
5.
Percentage of the Portland cement, as required, of the total dry weight of themix.
6.
Percentage of additional mixing water on the basis of the total dry weight of the
mix.
7. Total liquid percentage (asphalt material and water) at compaction based on the
dry total weight of the mix.
8. Maximum theoretical density according to ASTM D-2041.
9.
Type and site of mixer intended for use in preparing each mix to be submitted.
10. Date of commencing production of the emulsified asphalt treated base mixes.
11. A list for all the equipment to be used.
The Engineer shall be provided access to the materials sampling and testingoperations at all times.
Contractor shall supply to the Engineer one hundred (100) kilogram samples of
each individual aggregate size, eight (8) liters of asphaltic material and, when used,
sufficient quantities of mineral filler and chemical admixture to check design JMF and
all representing materials which the Contractor proposes to furnish.
6.6.3.2 Job Mix Formula Acceptance Procedures:
After Contractor submits the proposed job formula with all its appendices as
indicated in the previous item, the Ministry shall review the job mix according to the
General Specifications of Urban Roads Construction Division 6- Subbase and Aggergate Base
Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 217
6.6.6.2 Aggregate Preparation:
Aggregate shall be stockpiled and transported from stockpiles according to the
requirements of Item 7.3.6 in these General Specifications
6.6.6.3 Central Mixing:
Unless the Special Specifications allow, all emulsified asphalt treated base types(I, II, and III) may be produced in a central mixing plant. Aggregate, the emulsified
asphalt material, added water, Portland cement, and other additive materials, when
required, may be proportioned by approved JMF. Mixing shall be executed according
to the following steps:
1. The aggregate shall be fed from storage to the mixing chamber using a belt
feeder equipped with devices by which the rate of aggregate feed can be
determined while the plant is in full operation. Aggregate feed and the asphaltic
emulsion material-metering pump shall be mechanically or electrically
interlocked in a manner that maintains a constant ratio of aggregate and
asphaltic emulsion material.
2.
Portland cement, when required, shall be introduced into the dry aggregate onthe belt feeder and shall be mixed thoroughly before adding water or emulsified
asphalt.
3. Mixing water, when required, shall be introduced into the aggregate through a
spray bar mounted at such a point that the water is added as the aggregate enters
into the mixing chamber.
4.
The asphaltic emulsion material shall be introduced into the mixing chamber
through a spray bar that can be adjusted to vary mixing times between five and
thirty (5-30) seconds.
5. The aggregate, water and Portland cement as required, and asphaltic emulsion
material shall be mixed until the aggregate has been coated and a uniform and
homogeneous mixture has been obtained.
6. Type (I) open-grade emulsified asphalt treated base mix shall be discharged
directly into hauling equipment or stored in bins or silos. Type (I) open-graded
emulsified asphalt treated base mix shall not be stored on the ground.
7. Type (II) and Type (III) emulsified asphalt treated base mixes may be
discharged directly into hauling equipment or stored. Type (II) and Type (III)
base mixes shall not be stored for periods longer than forty-eight (48) hours
without prior written approval from the Engineer.
6.6.6.4 Road Mixing:
When the Special Specifications allow, types (II) and (II) of the emulsifiedasphalt treated base mixes may be mixed using a propelled mobile mixing plant. The
travel plant shall be capable of producing a uniform, properly coated, emulsified asphalt
material-aggregate mixture conforming to the requirements of the JMF. Emulsified
asphalt material and aggregate proportioning devices shall be keyed to the rate of
forward travel of the mixer, or interlocked to ensure a constant asphaltic emulsion
material-aggregate blend. Multiple passes of the travel plant may be required for higher
emulsified asphalt material contents to achieve required uniformity of mix.
6.6.6.5 Spreading and Compaction:
The surface to receive emulsified asphalt treated base shall conform to the
compaction and other requirements for the material involve. When the surface does not
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 218
conform to compaction and other requirements for the material involved, the
Contractor, at his own expense, shall correct all deviations.
When the surface to receive emulsified asphalt treated base is a soil subgrade,
aggregate subbase or aggregate base, and the total thickness of the asphaltic emulsion
treated base and surface course is less than ten (10) centimeters, the surface shallreceive a prime coat in accordance with the requirements specified in Section 8.3 in
these General Specifications. The prime coat shall be allowed to cure for at least forty-
eight (48) hours before placement of emulsified asphalt treated base.
Type (I) open-graded emulsified asphalt treated base shall be spread using a
self-propelled paving machine. The maximum thickness of one lift shall not exceed ten
(10) centimeters. Immediately after spreading, each lift shall be compacted with (1) one
coverage of a steel-drum tandem roller weighing not less than ten thousand (10,000)
kilograms. After the initial coverage, choke stone shall be uniformly spread across the
surface of the open-grade base at a rate between seven and thirteen (3-5) kilograms per
square meter using a self-propelled spreading device. Immediately after spreadingchoke stone, the open-graded base shall receive three (3) additional coverages with a
steel-drum tandem roller weighing not less than ten thousand (10,000) kilograms. After
completion of compaction, surplus choke stone shall be removed by sweeping. Each lift
of open-graded base shall be allowed to cure for a period not less than seventy-two (72)
hours before spreading successive lifts.
Type (II) and Type (III) emulsified asphalt treated base may be spread using a
self-propelled paving machine, aggregate base spreader, or other device which results in
a base that is smooth, has a uniform texture, conforms to planned and specified
thickness, and is within the lines and grade shown on the plans. The maximum
thickness of one lift shall not exceed ten (10) centimeters unless otherwise approved by
the Engineer provided sufficient Portland cement is added to the mixture to accelerate
curing and the Contractor demonstrates that curing is effective.
Each lift shall be compacted using a steel-drum tandem roller weighing not less
than ten thousand (10,000) kilograms until the relative compaction is at least ninety-one
(91) percent of the theoretical maximum density determined from test method ASTM
D-2041.
Each lift of Type (II) and Type (III) emulsified asphalt base shall be allowed to
cure for the period specified in the Special Specifications, or for three to five (5) days,
or, when Portland cement is added to the mixture, for such shorter period as approved by the Engineer. In all cases, the next layer shall not be placed and the traffic shall not
be allowed before the emulsified asphalt treated base is cured.
6.6.6.6 Finishing:
When it is shown on the drawings or specified in the specifications, the
emulsified asphalt treated base layers of all types shall be covered with a layer of
asphalt slurry seal type (3) sand compliant with the requirements of item 10-3 of these
General Specifications.
When the surface is tested by a four (4) meter straight edge, the deviations shall
not be more than five (5) millimeters in the longitudinal direction or ten (8) millimetersin the transverse direction are allowed.
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Ministry of Municipal & Rural Affairs – Kingdom of Saudi Arabia 219
6.6.7 Traffic control:
The Contractor shall take effective action to control all traffic in accordance
with the “Manual of Traffic Control through Work Zones” issued by the Ministry of
Municipalities and Rural Affairs in 1421H (2001).
6.6.8 Work Acceptance:The Contractor shall apply quality control procedures for emulsified asphalt
treated base works to ensure that the materials used and the executed work conform to
these General Specifications and other Contract’s Documents.
The Ministry shall assure the quality of production by checking that the
Contractor is performing the quality control procedures in correct manners. The
Ministry may have a direct supervision on the quality control system or by applying
quality assurance procedures in an independent unbiased way, on adequate number of
samples to judge the execution level and decide whether to accept or reject the work.
Division 17 in these General Specifications shall be used for this purpose, unless stated
otherwise in the Special Specifications or Contract’s Documents.
6.6.8.1 Quality Control:
The Contractor shall perform all required tests and measurements, and shall
collect, document, and draw the critical property diagrams to ensure that the raw
materials at source, materials while work execution, emulsified asphalt treated base
produced, and the executed work are within acceptable limits. The tests may be
performed at The Contractor’s laboratory or at an independent laboratory, approved by
the Ministry. The Contractor shall submit copies of all test results to the Engineer.
Table (6.6.4) shows the tests that the Contractor shall perform on raw materials and
mixes, the frequency of these tests, and the allowance limits. The Contractor shall
submit copies of all tests to the Engineers and shall apply all requirements detailed in
Item 17.1.1 in these General Specifications.
6.6.8.2 Quality Assurance:
The Ministry reserves the right, at any time, to assure the quality of materials
and executed work by performing or ordering the Contractor to perform, under its direct
supervision, some or all quality control tests that are shown previous Sub item. The
Ministry has also the right to inspect all Contractors' quality control test records and
compare them with its quality assurance test done according to Division 17 in these
General Specifications. Ministry may inspect Contractor's laboratory, devices, technical
staff, and testing methods to assure the full adequacy and capability of the Contractor toexecute the work according to standard approved methods.
6.6.9 Measurements:
Each type of the emulsified asphalt treated base shall be measured in cubic
meters according to its position and its compaction according to the specified thickness
and within the lines and levels shown on the drawings and according to the Engineer's
instructions. It is not allowed to perform any measurements for the materials laid
outside the allowed limits for payment purposes.
Mineral fillers, chemical admixtures and asphalt modifiers used by the
Contractor to meet the Job Mix Formula (JMF) requirements will be consideredsubsidiary to the construction of the emulsified asphalt treated base and shall not be