Concrete Pavement Section 600

601. DRY LEAN CEMENT CONCRETE

SUB-BASE

601.1. Scope

601.1.1. The work shall consist of construction of dry lean concrete subbase for
cement concrete pavement in accordance with the requirements of these specifications
and in conformity with the lines, grades and cross-sections shown on the drawings or as
directed by the Engineer. The work shall include furnishing of all plant and equipment,
materials and labour and performing all operations, in connection with the work, as
approved by the Engineer.

601.1.2. The design parameters of dry lean concrete sub-base, viz., width,
thickness, grade of concrete, details of joints, if any etc. shall be as stipulated in the
contract drawings.

601.2. Materials

601.2.1. Source of Materials: The contractor shall indicate to the Engineer the
source of all materials with relevant test data to be used in the lean concrete work
sufficiently in advance and the approval of the Engineer for the same shall be obtained at
least 45 days before the scheduled commencement of the work. If the contractor later
proposes to obtain the materials from a different source, he shall notify the Engineer for
his approval at least 45 days before such materials are to be used.

601.2.2. Cement: Any of the following types of cement may be used with prior
approval of the Engineer:

(i) Ordinary Portland Cement IS: 269

(ii) Portland Slag Cement IS: 455
(iii) Portland Pozzolana Cement IS:1489

If the subgrade is found to consist of soluble sulphates in a concentration more than

0.5 per cent used shall be sulphate resistant and shall conform to IS: 6909.

Cement to be used may preferably be obtained in bulk form. It shall be stored in

accordance with stipulations contained in Clause 1014 and shall be subjected to
acceptance test prior to its immediate use.

601.2.3. Aggregates:

601.2.3.1. Aggregates for lean concrete shall be natural material complying with
IS:383. The aggregates shall not be alkali reactive. The limits of deleterious materials
shall not exceed the requirements set out in IS:383. In case the Engineer considers that
the aggregates are not free from dirt, the same may be washed and drained for at least 72
hours before batching, as directed by the Engineer.

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601.2.3.2. Coarse aggregate: Coarse aggregates shall consist of clean, hard,

strong, dense, non-porous and durable pieces of crushed stones or crushed gravel and
shall be devoid of pieces of disintegrated stone, soft, flaky, elongated very angular or
splintery pieces. The maximum size of the coarse aggregate shall be 25 mm. The coarse
aggregate shall comply with Clause 602.2.4.2.

601.2.3.3. Fine aggregate: The fine aggregate shall consist of clean, natural sand
or crushed stone sand or a combination of the two and shall conform to IS: 383. Fine
aggregate shall be free from soft particles, clay, shale, loam, cemented particles, mica,
organic and other foreign matter. The fine aggregate shall comply with Clause 602.2.4.3.

601.2.3.4. The coarse and fine aggregates may be obtained in either of the
following manner.

(i) In separate nominal sizes of coarse and fine aggregates and mixed together
intimately before use.
(ii) Separately as 25 mm nominal single size, 12.5 mm nominal size graded
aggregates and fine aggregate of crushed stone dust or sand or a
combination of these two.

The material after blending shall conform to the grading as indicated in Table 600-1

TABLE 600-1. AGGREGATE GRADATION FOR DRY LEAN CONCRETE

Sieve Designation Percentage Passing the
sieve by weight
26.50 mm 100
19.00 mm 80-100
9.50 mm 55-75
4.75 mm 35-60
600.00 micron 10-35
75.00 micron 0-8

601.2.4. Water: Water used for mixing and curing of concrete shall be clean and
free from injurious amounts of oil, salt, acid, vegetable matter or other substances
harmful to the finished concrete. It shall meet the requirements stipulated in IS:456.

601.2.5. Storage of materials: All materials shall be stored in accordance with

the provisions of Clause 1014 of these specifications and other relevant IS specifications.
All efforts must be made to store the materials in proper so as to prevent their
deterioration or contamination by foreign matter and to ensure their satisfactory quality
and fitness for use in the work. The storage place must also permit easy inspection,
removal and storage of materials. All such materials even though stored in approved
godowns must be subjected to acceptance test immediately prior to their use. The
requirement of storage yard specified in clause 602.2.9 shall also be applicable.

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601.3. Proportioning of Materials for the Mix

601.3.1. The mix shall be proportioned with a maximum aggregate cement ratio of
15:1. The water content shall be adjusted to the optimum as per Clause 601.3.2 for
facilitating compaction by rolling. The strength and density requirements of concrete
shall be determined in accordance with Clause 601.6 by making trial mixes.

601.3.2. Moisture content: The right amount of water for the lean concrete in the
main work shall be decided so as to ensure full compaction under rolling and shall be
assessed at the time of rolling the trial length. Too much water will cause the lean
concrete to be heaving up before the wheels and picked up on the wheels of the roller and
too little will lead to inadequate compaction, a low in-situ strength and an open-textured
surface.

The optimum water content shall be determined and demonstrated by rolling during
trial length construction and the optimum moisture content and degree of compaction
shall be got approved from the Engineer. While laying in the main work, the lean
concrete shall have a moisture content between the optimum and optimum + 2 per cent,
keeping in view the effectiveness of compaction achieved and to compensate for
evaporation losses.

601.3.3. Cement content: The minimum cement content in the lean concrete shall
not be less than 150 kg/cu.m. of concrete. If this minimum cement content is not
sufficient to produce concrete of the specified strength, it shall be increased as necessary
without additional cost compensation to the contractor.

601.3.4. Concrete strength: The average compressive strength of each

consecutive group of 5 cubes made in accordance with clause 903.5.1.1 shall not be less
than 10 MPa at 7 days. In addition, the minimum compressive strength of any individual
cube shall not be less than 7.5 MPa at 7 days. The design mix complying with the above
clauses shall be got approved from the Engineer and demonstrated in the trial length
construction.

601.4. Subgrade

The subgrade shall conform to the grades and cross sections shown on the drawings
and shall be uniformly compacted to the design strength in accordance with these
specifications and specification stipulated in the contract. The lean concrete subbase shall
not be laid on a subgrade softened by rain after its final preparation; surface trenches and
soft spots, if any must be properly back-filled and compacted to avoid any weak or soft
spot. As far as possible, the construction traffic shall be avoided on the prepared
subgrade. A day before placing of the sub-base, the subgrade surface shall be given a fine
spray of water and rolled with one or two passes of a smooth wheeled roller after a lapse
of 2-3 hours in order to stabilise loose surface. If Engineer feels it necessary, another fine
spray of water may be applied just before placing sub-base.

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601.5. Construction

601.5.1. General: The pace and programme of the lean concrete sub-base
construction shall be matching suitably with the programme of construction of the cement
concrete pavement over it. The sub base shall be overlaid with cement concrete pavement
only after 7 days after sub-base construction.
601.5.2. Batching and mixing: The batching plant shall e capable of
proportioning the materials by weight, each type of material being weighed separately in
accordance with Clause 602.9.3.2. The cement from the bulk stock shall be weighed
separately from the aggregates. The capacity of batching and mixing plant shall be at
least 25 per cent higher than the proposed capacity for the laying arrangements. The
batching and mixing shall be carried out preferably in a forced action central batching
and mixing plant having necessary automatic controls to ensure accurate proportioning
and mixing. Other types of mixers shall be permitted subject to demonstration of their
satisfactory performance during the trial length. The type and capacity of the plant shall
be got approved by the Engineer before commencement of the trial length. The weighing
balances shall be calibrated by weighing the aggregates, cement, water and admixtures
physically either by weighing with large weighing machine or in a weigh bridge. The
accuracy of weighing scales of the batching plant shall be within + 2 per cent in the case
of aggregates and + 1 per cent in the case of cement and water.

The design features of Batching Plant should be such that the shifting operations of
the plant will not take very long time when they are to be shifted from place to place with
the progress of the work.

601.5.3. Transporting: Plant mix lean concrete shall be discharged immediately

from the mixer, transported directly to the point where it is to be laid and protected from
the weather by covering the tippers/dumpers with tarpaulin during transit. The concrete
shall be transported by the tipping trucks, sufficient in number to ensure a continuous
supply of material to feed the laying equipment to work at a uniform speed and in an
uninterrupted manner. The lead of the batching plant to paving site shall be such that the
travel time available from mixing to paving as specified in Clause 601.5.5.2 will be
adhered to.

601.5.4. Placing: Lean concrete shall be laid/placed by a paver with electronic

sensor. The equipment shall be capable of laying the material in one layer in an even
manner without segregation, so that after compaction the total thickness is as specified.
The paving machine shall have high amplitude tamping bars to give good initial
compaction to the sub-base.

The laying of the two-lane road sub base may be done either in full width or lane by
lane. Preferably the lean concrete shall be placed and compacted across the full width of
the road, by constructing it in one go or in two lanes running forward simultaneously.
Transverse and longitudinal construction joints shall be staggered by 500-1000 mm and
200-400 mm respectively from the corresponding joints in the overlaying concrete slabs.

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601.5.5. Compaction

601.5.5.1. The compaction shall be carried out immediately after the material is
laid and leveled. In order to ensure thorough compaction which is essential, rolling shall
be continued on the full width till there is no further visible movement under the roller
and the surface is closed. The minimum dry density obtained shall be 97 per cent of that
achieved during the trail length construction vide Clause 601.7. The densities achieved at
the edges i.e. 0.5 m from the edge shall not be less than 95 per cent of that achieved
during the trail construction vide Clause 601.7.

601.5.5.2. The spreading, compacting and finishing of the lean concrete shall be
carried out as rapidly as possible and the operation shall be so arranged as to ensure that
the time between the mixing of the first batch of concrete in any transverse section of the
layer and the final finishing of the same shall not exceed 90 minutes when the concrete
temperature is above 25 and below 30 degree Celsius and 120 minutes if less than 25
degree Celsius. This period may be reviewed by the Engineer in the light of the results of
the trial run but in no case shall it exceed 2 hours. Work shall not proceed when the
temperature of the concrete exceeds 30 degree Celsius. If necessary, chilled water or
additional of ice may be resorted to for bringing down the temperature. It is desirable to
stop concreting when the ambient temperature is above 350C. After compaction has been
completed, roller shall not stand on the compacted surface for the duration of the curing
period except during commencement of next day’s work near the location where work
was terminated the previous day.

601.5.5.3. Double drum smooth-wheeled vibratory rollers of minimum 80 to 100

kN static weight are considered to be suitable for rolling dry lean concrete. In case any
other roller is proposed, the same shall be got approved from the Engineer, after
demonstrating its performance. The number of passes required to obtain maximum
compaction depends on the thickness of the lean concrete, the compactibility of the mix,
and the weight and type of the roller etc., and the same as well as the total requirement of
rollers for the job shall be determined during trial run by measuring the in-situ density
and the scale of the work to be undertaken.

601.5.5.4. In addition to the number of passes required for compaction there shall
be a preliminary pass without vibration to bed the lean concrete down and again a final
pass without vibration to remove roller marks and to smoothen the surface.

Special care and attention shall be exercised during compaction near joints, kerbs,
channels, side forms and around gullies and manholes. In case adequate compaction is
not achieved by the roller at these points, use of plate vibrator shall be made, if so
directed by the Engineer.

601.5.5.5. The final lean concrete surface on completion of compaction and

immediately before overlaying, shall be well closed, free from movement under roller
and free from ridges, low spots, cracks, loose material, pot holes, ruts or other defects.
The final surface shall be inspected immediately on completion and all loose, segregated
or defective areas shall be corrected by using fresh lean concrete material laid and
compacted as per Specification. For repairing honeycombed surface, concrete with

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aggregates of size 10 mm and below shall be spread and compacted. It is necessary to

check the level of the rolled surface for compliance. Any level/thickness deficiency
should be corrected after applying concrete with aggregates of size 10 mm and below
after roughening the surface. Similarly the surface regularity also should be checked with
3m straight edge. The deficiency should be made up with concrete with aggregates of
size 10 mm and below.
601.5.5.6. Segregation of concrete in the dumpers shall be controlled by premixing
each fraction of the aggregates before loading in the bin of the batching plant, by moving
the dumper back and forth while discharging the mix on it and other means. Even paving
operation shall be such that the mix does not segregate.

601.5.6. Joints: Contraction and longitudinal joints shall be provided as per the
drawing.

At longitudinal or transverse construction joints, unless vertical forms are used, the
edge of compacted material shall be cut back to a vertical face where the correct
thickness of the properly compacted material has been obtained.

601.5.7. Curing: As soon as the lean concrete surface is compacted, curing shall
commence. One of the following two methods shall be adopted:
(a) The initial curing shall be done by spraying with liquid curing compound. The curing compound
shall be white pigmented or transparent type with water retention index of 90 per cent when
tested in accordance with BS 7542. Curing compound shall be sprayed immediately after rolling
is complete. As soon as the curing compound has lost its tackiness, the surface shall be covered
with wet hessian for three days.
(b) Curing shall be done by covering the surface by gunny bags/hessian, which shall be kept
continuously moist for 7 days by sprinkling water.

601.6. Trial Mixes

The contractor shall make trial mixes of dry lean concrete with moisture contents
like 5.0, 5.5, 6.0, 6.5 and 7.0 per cent using cement content specified and the specified
aggregate grading but without violating the requirement of aggregate-cement ratio
specified in Clause 601.3.1. Optimum moisture and density shall be established by
preparing cubes with varying moisture contents. Compaction of the mix shall be done in
three layers with vibratory hammer fitted with a square or rectangular foot as described in
Clause 903.5.1.1. After establishing the optimum moisture, a set of six cubes shall be cast
at that moisture for the determination of compressive strength on the 3rd and the seventh
day. Trial mixes shall be repeated if the strength is not satisfactory either by increasing
cement content or using higher grade of cement. After the mix design is approved, the
contractor shall construct a trial section in accordance with Clause 601.7.

If during the construction of the trial length, the optimum moisture content
determined as above is found to be unsatisfactory, the contractor may make suitable
changes in the moisture content to achieve a satisfactory mix. The cube specimens
prepared with the changed moisture content should satisfy the strength requirement.
Before production of the mix, natural moisture content of the aggregate should be

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determined on a day-to-day basis so that the moisture content could be adjusted. The mix
finally designed should neither stick to the rollers nor become too dry resulting in
raveling of surface.

601.7. Trial Length

601.7.1. The trial length shall be constructed at least 14 days in advance of the
proposed date of commencement of work. At least 30 days prior to the construction of the
trial length, the contractor shall submit for the Engineer’s approval a “Method Statement”
giving detailed description of the proposed materials, plant, equipment, mix proportion,
and procedure for batching, mixing, laying, compaction and other construction
procedures. The Engineer shall also approve the location and length of trial construction
which shall be a minimum of 60m length and for full width of the pavement. The trial
length shall contain the construction of at least one transverse construction joint involving
hardened concrete and freshly laid sub-base. The construction of trial length will be
repeated till the contractor proves his ability to satisfactorily construct the subbase.

601.7.2. In order to determine and demonstrate the optimum moisture content

which results in the maximum dry density of the mix compacted by the rolling equipment
and the minimum cement content that is necessary to achieve the strength stipulated in
the drawing, trial mixes shall be prepared as per Clause 601.6.

601.7.3. After the construction of the trial length, the in-situ density of the freshly
laid material shall be determined by sand replacement method with 20 cm dia density
cone. Three density holes shall be made at locations equally spaced along a diagonal that
bisects the trial length; average of these densities shall be determined. These main density
holes shall not be made in the strip 50 cm from the edges. The average density obtained
from the three samples collected shall be the reference density and is considered as 100
per cent. The field density of regular work will be compared with this reference density in
accordance with Clauses 601.5.5.1 and 903.5.1.2. A few cores may be cut as per the
instructions of the Engineer to check segregation or any other deficiency.

601.7.4. The hardened concrete shall be cut over 3 m width and reversed to inspect
the bottom surface for any segregation taking place. The trial length shall be constructed
after making necessary changes in the gradation of the mix to eliminate segregation of the
mix. The lower surface shall not have honey-combing and the aggregates shall not be
held loosely at the edges.

601.7.5. The trial length shall be outside the main works. The main work shall not
start until the trial length has been approved by the Engineer. After approval has been
given, the materials, mix proportions, moisture content, mixing, laying, compaction plant
and construction procedures shall not be changed without the approval of the Engineer.

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601.8. Tolerances for Surface Regularity, Level, Thickness, Density and

Strength

The tolerances for surface regularity, level, thickness, density and strength shall
confirm to the requirements given in Clause 903.5. Control of quality of materials and
works shall be exercised by the Engineer in accordance with Section 900.

601.9. Traffic

No heavy commercial vehicles like trucks and buses shall be permitted on the lean
concrete sub-base after its construction. Light vehicles if unavoidable may, however, be
allowed after 7 days of its construction with prior approval of the Engineer.

601.10. Measurements for Payment

The unit of measurement for dry lean concrete pavement shall be the cubic metre of
concrete placed, based on the net plan areas for the specified thickness shown on the
drawings or as directed by the Engineer.

601.11. Rate

The contractor unit rate payable for dry lean concrete sub-base shall be payment in
full for carrying out the required operations including full compensation for all labour,
materials and equipment, mixing, transport, placing, compacting, finishing, curing,
testing and incidentals to complete the work as per Specifications, all royalties, fees,
storage and rents where necessary and all leads and lifts.

602. CEMENT CONCRETE PAVEMENT

602.1. Scope

602.1.1. The work shall consist of construction of unreinforced, dowel jointed, plain
cement concrete pavement in accordance with the requirements of these Specifications
and in conformity with the lines, grades and cross sections shown on the drawings. The
work shall include furnishing of all plant and equipment, materials and labour and
performing all operations in connection with the work, as approved by the Engineer.

602.1.2. The design parameters, viz., thickness of pavement slab, grade of concrete,
joint details etc. shall be as stipulated in the drawings.

602.2. Materials

602.2.1. Source of materials: The contractor shall indicate to the Engineer the
source of all materials to be used in the concrete work with relevant test data sufficiently
in advance, and the approval of the Engineer for the same shall be obtained at least 45

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days before the scheduled commencement of the work. If the contractor later proposes to
obtain materials from a different source, he shall notify the Engineer for his approval, at
least 45 days before such materials are to be used with relevant test data.

602.2.2. Cement: Any of the following types of cement capable of achieving the
design strength may be used with prior approval of the Engineer, but the preference
should be to use at least the 43 Grade or higher.

(i) Ordinary Portland Cement, 33 Grade, IS : 269.

(ii) Ordinary Portland Cement, 43 Grade, IS : 8112.
(iii) Ordinary Portland Cement, 53 Grade, IS : 12269.

If the soil around has soluble salts like sulphates in excess of 0.5 per cent, the
cement used shall be sulphate resistant and shall confirm to IS: 12330.

Guidance may be taken from IS: SP: 23, Handbook for Concrete Mixes for
ascertaining the minimum 7 days strength of cement required to match with the design
concrete strength. Cement to be used may preferably be obtained in bulk form. If cement
in paper bags are proposed to be used, there shall be bag-splitters with the facility to
separate pieces of paper bags and dispose them of suitably. No paper pieces shall enter
the concrete mix. Bulk cement shall be stored in accordance with Clause 1014. The
cement shall be subjected to acceptance test prior to its use.

602.2.3. Admixtures: Admixtures confirming to IS:6925 and IS:9103 shall be

permitted to improve workability of the concrete or extension of setting time, on
satisfactory evidence that they will not have any adverse effect on the properties of
concrete with respect to strength, volume change, durability and have no deleterious
effect on steel bars. The particulars of the admixture and the quality to be used, must be
furnished to the Engineer in advance to obtain his approval before use. Satisfactory
performance of the admixtures should be proved both on the laboratory concrete trial
mixes and in trial paving works. If air entraining admixture is used, the total quantity of
air in air-entrained concrete as a percentage of the volume of the mix shall be 5 + 1.5 per
cent for 25 mm nominal size aggregate.

602.2.4. Aggregates

602.2.4.1. Aggregates for pavement concrete shall be natural material complying

with IS : 383 but with a Los Angeles Abrasion Test result not more than 35 per cent. The
limits of deleterious materials shall not exceed the requirements set out in IS : 383.

The aggregates shall be free from chert, flint, chalcedony or other silica in a form
that can react with the alkalies in the cement. In addition, the total chlorides content
expressed as chloride ion content shall not exceed 0.06 per cent by weight and the total
sulphate content expressed as sulphuric anhydride (SO3) shall not exceed 0.25 per cent by
weight.

602.2.4.2. Coarse aggregate: Coarse aggregate shall consist of clean, hard, strong,
dense, non-porous and durable pieces of crushed stone or crushed gravel and shall be
devoid of pieces of disintegrated stone, soft, flaky, elongated, very angular or splintery

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pieces. The maximum size of coarse aggregate shall not exceed 25 mm for pavement
concrete. Continuously graded or gap graded aggregates may be used, depending on the
grading of the fine aggregate. No aggregate which has water absorption more than 2 per
cent shall be used in the concrete mix. The aggregates shall be tested for soundness in
accordance with IS : 2386 (Part-5). After 5 cycles of testing the loss shall not be more
than 12 per cent if sodium sulphate solution is used or 18 per cent if magnesium sulphate
solution is used.

Dumping and stacking of aggregates shall be done in an approved manner. In case

the Engineer considers that the aggregates are not free from dirt, the same may be washed
and drained for at least 72 hours before batching as directed by the Engineer.

602.2.4.3. Fine aggregate: The fine aggregate shall consist of clean natural sand or
crushed stone sand or a combination of the two and shall confirm to IS : 383. Fine
aggregate shall be free from soft particles, clay, shale, loam, cemented particles, mica and
organic and other foreign matter. The fine aggregate shall not contain deleterious
substances more than the following:

Clay lumps 4.0 per cent

Coal and lignite 1.0 per cent
Material passing IS Sieve No. 75 micron 4.0 per cent

602.2.5. Water: Water used for mixing and curing of concrete shall be clean and
free from injurious amount of oil, salt, acid, vegetable matter or other substances harmful
to the finished concrete. It shall meet the requirements stipulated in IS: 456.

602.2.6. Mild steel bars for dowels and tie bars : These shall confirm to the
requirements of IS : 432, IS : 1139 and IS : 1786 as relevant. The dowel bars shall
confirm to Grade S 240 and tie bars to Grade S 415 of I.S.

602.2.7. Premoulded joint filler: Joint filler board for expansion joints which are
proposed for use only at some abutting structures like bridges and culverts shall be of 20-
25mm thickness within a tolerance of + 1.5 mm and of a firm compressible material and
complying with the requirements of IS: 1838, or BS Specification Clause No. 2630 or
Specification for Highway Works, Vol. I Clause 1015. It shall be 25 mm less in depth
than the thickness of the slab within a tolerance of + 3 mm and provided to the full width
between the side forms. It shall be in suitable lengths which shall not be less than one
lane width. Holes to accommodate dowel bars shall be accurately bored or punched out to
give a sliding fit on the dowel bars.

602.2.8. Joint sealing compound: The joint sealing compound shall be of hot
poured, elastomeric type or cold polysulphide type having flexibility, resistance to age
hardening and durability. If the sealant is hot poured type it shall confirm to AASHTO
M282 and cold applied sealant shall be in accordance with BS 5212 (Part 2).

602.2.9. Storage of materials: All materials shall be stored in accordance with the
provisions of Clause 1014 of the Specifications and other relevant IS Specifications. All
efforts must be made to store the materials in proper places so as to prevent their
deterioration or contamination by foreign matter and to ensure their satisfactory quality

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and fitness for the work. The platform where aggregates are stock piled shall be leveled
with 15 cm of watered, mixed and compacted granular sub-base material. The area shall
have slope and drain to drain off rain water. The storage space must also permit easy
inspection, removal and storage of the materials. Aggregates of different sizes shall be
stored in partitioned stack-yards. All such materials even though stored in approved
godowns must be subjected to acceptance test as per Clause 903 of these Specifications
immediately prior to their use.

602.3. Proportioning of Concrete

602.3.1. After approval by the Engineer of all the materials to be used in the
concrete, the contractor shall submit the mix design based on weighed proportions of all
ingredients for the approval of the Engineer. The mix design shall be submitted at least
30 days prior to the paving of trial length and the design shall be based on laboratory trial
mixes using the approved materials and methods as per IS: 10262 (Recommended
Guidelines for Mix Design) or on the basis of any other rational method agreed to by the
Engineer. Guidance in this regard can also be obtained from IS: SP: 23 Handbook on
Concrete Mixes. The target mean strength for the design mix shall be determined as
indicated in Clause 903.5.2. The mix design shall be based on the flexural strength of
concrete.

602.3.2. Cement content: The cement content shall not be less than 350 kg per
cu.m.of concrete. If this minimum cement content is not sufficient to produce in the field,
concrete of the strength specified in the drawings/design, it shall be increased as
necessary without additional compensation under the Contract. The cement content shall,
however, not exceed 425 kg per cu.m.of concrete.

602.3.3. Concrete strength

602.3.3.1. While designing the mix in the laboratory, correlation between flexural
and compressive strengths of concrete shall be established on the basis of at least thirty
tests on samples. However, quality control in the field shall be exercised on the basis of
flexural strength. It may, however, be ensured that the materials and mix proportions
remain substantially unaltered during the daily concrete production. The water content
shall be the minimum required to provide the agreed workability for full compaction of
the concrete to the required density as determined by the trial mixes or other means
approved by the Engineer and the maximum free water cement ratio shall be 0.50.

602.3.3.2. The ratio between the 7 and 28 day strengths shall be established for the
mix to be used in the slab in advance, by testing pairs of beam and cubes at each stage on
at least six batches of trial mix. The average strength of the 7 day cured specimens shall
be divided by the average strength of the 28 day specimens for each batch, and the ratio
‘R’shall be determined. The ratio ‘R’shall be expressed to three decimal places.

If during the construction of the trial length or during normal working, the average
value of any four consecutive 7 day test results falls below the required 7 day strength as
derived from the value of ‘R’, then the cement content of the concrete shall, without extra
payment, be increased by 5 per cent by weight or by an amount agreed by the Engineer.

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The increased cement content shall be maintained at least until the four corresponding 28
day strengths have been assessed for its conformity with the requirements as per Clause
602.3.1. Whenever the cement content is increased, the concrete mix shall be adjusted to
maintain the required workability.

602.3.4. Workability

602.3.4.1. The workability of the concrete at the point of placing shall be adequate
for the concrete to be fully compacted and finished without undue flow. The optimum
workability for the mix to suit the paving plant being used shall be determined by the
Contractor and approved by the Engineer. The control of workability in the field shall be
exercised by the slump test as per IS: 1199.

602.3.4.2. The workability requirement at the Batching Plant and paving site shall
be established by slump tests carried during trial paving. These requirements shall be
established from season to season and also when the lead from Batching plant site to the
paving site changes. The workability shall be established for the type of paving
equipment available. A slump value in the range of 30 + 15 mm is reasonable for paving
works but this may be modified depending upon the site requirement and got approved by
the Engineer. These tests shall be carried out on every truck/dumper at plant site and
paving site initially when the work commences but subsequently the frequency can be
reduced to alternate trucks or as per the instructions of the Engineer.

602.3.5. Design mix

602.3.5.1. The Contractor shall carry out laboratory trials of design mixes with the
materials from the approved sources to be used. Trial mixes shall be made in presence of
the Engineer or his representative and the design mix shall be subject to the approval of
the Engineer. They shall be repeated if necessary until the proportions that will produce a
concrete which complies in all respects with this Specification, and confirms to the
requirement of the design/drawings have been determined.

602.3.5.2. The proportions determined as a result of the laboratory trial mixes may
be adjusted if necessary during the construction of the trial length. Thereafter, neither the
materials nor the mix proportions shall be varied in any way except with the written
approval of the Engineer.

602.3.5.3. Any change in the source of materials or mix proportions proposed by

the Contractor during the course of work shall be assessed by making laboratory trial
mixes and the construction of a further trial length unless approval is given by the
Engineer for minor adjustments like compensation for moisture content in aggregates or
minor fluctuations in the grading of aggregate.

602.4. Sub-base

The cement concrete pavement shall be laid over the sub-base constructed in
accordance with the relevant drawings and Specifications contained in Clause 601. If the
sub-base is found damaged at some places or it has cracks wider than 10 mm, it shall be

12
Concrete Pavement Section 600

repaired with fine cement concrete or bituminous concrete before laying separation layer.
Prior to laying of concrete it shall be ensured that the separation membrane as per Clause
602.5 is placed in position and the same is clean of dirt or other extraneous materials and
free from any damage.

602.5. Separation Membrane

A separation membrane shall be used between the concrete slab and the subbase.
Separation membrane shall be impermeable plastic sheeting 125 microns thick laid flat
without creases. Before placing the separation membrane, the sub-base shall be swept
clean of all the extraneous materials using air compressor. Wherever overlap of plastic
sheets is necessary, the same shall be at least 300 mm and any damaged sheeting shall be
replaced at the Contractor’s expense. The separation membrane may be nailed to the
lower layer with concrete nails.

602.6. Joints

602.6.1. The location and type of joints shall be as shown in the drawing. Joints
shall be constructed depending upon their functional requirement as detailed in the
following paragraphs. The location of the joints shall be transferred accurately at the site
and mechanical saw cutting of joints done as per stipulated dimensions. It should be
ensured that the full required depth of cut is made from edge to edge of the pavement.
Transverse and longitudinal joints in the pavement and sub-base shall be staggered so
that they are not coincident vertically and are at least 1 m and 0.3 m apart respectively.
Sawing of joints shall be carried out with diamond studded blades soon after the concrete
has hardened to take the load of the sawing machine and personnel without damaging the
texture of the pavement. Sawing operation could start as early as 6-8 hours depending
upon the season.

602.6.2. Transverse joints

602.6.2.1. Transverse joints shall be contraction and expansion joints constructed at

the spacing described in the Drawings. Transverse joints shall be straight within the
following tolerances along the intended line of joints which is the straight line transverse
to the longitudinal axis of the carriageway at the position proposed by the Contractor and
agreed to by the Engineer, except at road junctions or roundabouts where the position
shall be as described in the drawings:

(i) Deviations of the filler board in the case of expansion joints from the intended line of the
joint shall not be greater than + 10 mm.

(ii) The best fit straight line through the joint grooves as constructed shall be not more than 25
mm from the intended line of the joint.

(iii) Deviations of the joint groove from the best fit straight line of the joint shall not be greater
than 10 mm.

(iv) Transverse joints on each side of the longitudinal joint shall be in line with each other and
of the same type and width. Transverse joints shall have a sealing groove which shall be
sealed in compliance with Clause 602.11.

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Concrete Pavement Section 600

602.6.2.2. Contraction joints: Contraction joints shall consist of a mechanical

sawn joint groove, 3 to 5 mm wide and 1/4 to 1/3 depth of the slab + 5 mm or as
stipulated in the drawings and dowel bars complying with Clause 602.6.5 and as detailed
in the drawings.

The contraction joints shall be cut as soon as the concrete has undergone initial
hardening and is hard enough to take the load of joint sawing machine without causing
damage to the slab.

602.6.2.3. Expansion joints: The expansion joints shall consist of a joint filler
board complying with Clause 602.2.7 and dowel bars complying with Clause 602.6.5 and
as detailed in the drawings. The filler board shall be positioned vertically with the
prefabricated joint assemblies along the line of the joint within the tolerances given in
Clause 602.6.2.1 and at such depth below the surface as will not impede the passage of
the finishing straight edges or oscillating beams of the paving machines. The adjacent
slabs shall be completely separated from each other by providing joint filler board. Space
around the dowel bars, between the sub-base and the filler board shall be packed with a
suitable compressible material to block the flow of cement slurry.

602.6.3. Transverse construction joint: Transverse construction joints shall be

placed whenever concreting is completed after a day’s work or is suspended for more
than 30 minutes. These joints shall be provided at the regular location of contraction
joints using dowel bars. The joint shall be made butt type. At all construction joints, steel
bulk heads shall be used to retain the concrete while the surface is finished. The surface
of the concrete laid subsequently shall conform to the grade and cross sections of the
previously laid pavement. When positioning of bulk head/stop-end is not possible,
concreting to an additional 1 or 2 m length may be carried out to enable the movement of
joint cutting machine so that joint grooves may be formed and the extra 1 or 2 m length is
cut out and removed subsequently after concrete has hardened.

602.6.4. Longitudinal joint

602.6.4.1. The longitudinal joints shall be saw cut as per details of the joints shown
in the drawing. The groove may be cut after the final set of the concrete. Joints should be
sawn to at least 1/3 the depth of the slab + 5 mm as indicated in the drawing.

602.6.4.2. Tie bars shall be provided at the longitudinal joints as per dimensions and
spacing shown in the drawing and in accordance with Clause 602.6.6.

602.6.5. Dowel bars

602.6.5.1. Dowel bars shall be mild steel rounds in accordance with Clause 602.2.6
with details/dimensions as indicated in the drawing and free from oil, dirt, loose rust or
scale. They shall be straight, free of irregularities and burring restricting slippage in the
concrete. The sliding ends shall be sawn or cropped cleanly with no protrusions outside
the normal diameter of the bar. The dowel bar shall be supported on cradles/dowel chairs
in pre-fabricated joint assemblies positioned prior to the construction of the slabs or
mechanically inserted with vibration into the plastic concrete by a method which ensures

14
Concrete Pavement Section 600

correct placement of the bars besides full re-compaction of the concrete around the dowel
bars.

602.6.5.2. Unless shown otherwise on the drawings, dowel bars shall be positioned
at mid depth of the slab within a tolerance of + 20 mm, and centered equally about
intended lines of the joint within a tolerance of + 25 mm. They shall be aligned parallel to
the finished surface of the slab and to the center line of the carriageway and to each other
within tolerances given hereunder, the compliance of which shall be checked as per
Clause 602.10.7.

(i) For bars supported on cradles prior to the laying of the slab:

(a) All bars in a joint shall be within + 3mm per 300 mm length of bar

(b) 2/3rd of the bars shall be within + 2 mm per 300 mm length of bar

(c) No bar shall differ in alignment from an adjoining bar by more than 3 mm per 300
mm length of bar in either the horizontal or vertical plane.

(d) Cradles supporting dowel bar shall not extend across the line of joint i.e. no steel
bar of the cradle assembly shall be continuous across the joint.

(ii) For all bars inserted after laying of the slab:

(a) Twice the tolerance for alignment as indicated in (i) above

602.6.5.3. Dowel bars, supported on cradles in assemblies, when subject to a load of

110 N applied at either end and in either the vertical or horizontal direction (upwards and
downwards and both directions horizontally) shall conform to be within the following
limits:

(i) Two-thirds of the number of bars of any assembly tested shall not deflect more than
2 mm per 300 mm length of bar

(ii) The remainder of the bars in that assembly shall not deflect more than 3 mm per 300 mm
length of bar.

602.6.5.4. The assembly of dowel bars and supporting cradles, including the joint
filler board in the case of expansion joints, shall have the following degree of rigidity
when fixed in position:-

(i) For expansion joints, the deflection of the top edge of the filler board shall be not greater
than 13 mm, when a load of 1.3 kN is applied perpendicular to the vertical face of the
joint filler board and distributed over a length of 600 mm by means of a bar or timber
packing, at mid depth and midway between individual fixings, or 300 mm from either
end of any length of filler board, if a continuous fixing is used. The residual deflection
after removal of the load shall be not more than 3 mm.

(ii) The joint assembly fixings to sub-base shall not fail under the 1.3kN load applied for
testing the rigidity of the assembly but shall fail before the load reaches 2.6 kN.

(iii) The fixings for contraction joint shall not fail under 1.3 kN load and shall fail before the
load reaches 2.6 kN when applied over a length of 600 mm by means of a bar or timber
packing placed as near to the level of the line of fixings as practicable.

15
Concrete Pavement Section 600

(iv) Fixings shall be deemed to fail when there is displacement of the assemblies by more
than 3 mm with any form of fixing, under the test load. The displacement shall be
measured at the nearest part of the assembly to the center of the bar or timber packing.

602.6.5.5. Dowel bars shall be covered by a thin plastic sheath for at least two-
thirds of the length from one end for dowel bars in contraction joints or half the length
plus 50 mm for expansion joints. The sheath shall be tough, durable and of an average
thickness not greater than 1.25 mm. The sheathed bar shall comply with the following
pull-out tests:

(i) Four bars shall be taken at random from stock and without any special preparation
shall be covered by sheaths as required in this Clause. The ends of the dowel bars which
have been sheathed shall be cast centrally into concrete specimens 150 x 150 x 600 mm,
made of the same mix proportions to be used in the pavement, but with a maximum
nominal aggregate size of 20 mm and cured in accordance with IS: 516. At 7 days a
tensile load shall be applied to achieve a movement of the bar of at least 0.25 mm. The
average bond stress to achieve this movement shall not be greater than 0.14 MPa.

602.6.5.6. For expansion joints, a closely fitting cap 100 mm long consisting of
waterproofed cardboard or an approved synthetic material like PVC or GI pipe shall be
placed over the sheathed end of each dowel bar. An expansion space at least equal in
length to the thickness of the joint filler board shall be formed between the end of the cap
and the end of the dowel bar by using compressible sponge. To block the entry of cement
slurry between dowel and cap it may be taped.

602.6.6. Tie bars

602.6.6.1. Tie bars in longitudinal joints shall be deformed steel bars of strength
415 MPa complying with IS: 1786 and in accordance with the requirements given below.
The bars shall be free from oil, dirt, loose rust and scale.

602.6.6.2. Tie bars projecting across the longitudinal joint shall be protected from
corrosion for 75 mm on each side of the joint by a protective coating of bituminous paint
with the approval of the Engineer. The coating shall be dry when the tie bars are used.

602.6.6.3. Tie bars in longitudinal joints shall be made up into rigid assemblies with
adequate supports and fixings to remain firmly in position during the construction of the
slab. Alternatively, tie bars at longitudinal joints may be mechanically or manually
inserted into the plastic concrete from above by vibration using a method which ensures
correct placement of the bars and recompaction of the concrete around the tie bars.

602.6.6.4. Tie bars shall be positioned to remain within the middle third of the slab
depth as indicated in the drawings and approximately parallel to the surface and
approximately perpendicular to the line of the joint, with the center of each bar on the
intended line of the joints within a tolerance of + 50 mm, and with a minimum cover of
30 mm below the joint groove.

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Concrete Pavement Section 600

602.7. Weather and Seasonal Limitations

602.7.1. Concreting during monsoon months: When concrete is being placed

during monsoon months and when it may be expected to rain, sufficient supply of
tarpaulin or other water proof cloth shall be provided along the line of the work. Any
time when it rains, all freshly laid concrete which had not been covered for curing
purposes shall be adequately protected. Any concrete damaged by rain shall be removed
and replaced. If the damage is limited to texture, it shall be retextured in accordance with
the directives of the Engineer.

602.7.2. Concreting in hot weather: No concreting shall be done when the

concrete temperature is above 30 degree Centigrade. Besides, in adverse conditions like
high temperature, low relative humidity, excessive wind velocity, imminence of rains
etc., if so desired by the Engineer, tents on mobile trusses may be provided over the
freshly laid concrete for a minimum period of 3 hours as directed by the Engineer. The
temperature of the concrete mix on reaching the paving site shall not be more than 300C.
To bring down the temperature, if necessary, chilled water or ice flakes should be made
use of.

No concreting shall be done when the concrete temperature is below 5 degree

Centigrade and the temperature is descending.

602.8. Side Forms, Rails and Guidewires

602.8.1. Side forms and rails: All side forms shall be of mild steel of depth equal
to the thickness of pavement or slightly less to accommodate the surface regularity of the
sub-base. The forms can be placed on series of steel packing plates or shims to take care
of irregularity of sub-base. They shall be sufficiently robust and rigid to support the
weight and pressure caused by a paving equipment. Side forms for use with wheeled
paving machines shall incorporate metal rails firmly fixed at a constant height below the
top of the forms. The forms and rails shall be firmly secured in position by not less than 3
stakes/pins per each 3 m length so as to prevent movement in any direction. Forms and
rails shall be straight within a tolerance of 3 mm in 3 m and when in place shall not settle
in excess of 1.5 mm in 3 m while paving is being done. Forms shall be cleaned and oiled
immediately before each use. The forms shall be bedded on a continuous bed of low
moisture content lean cement mortar or concrete and set to the line and levels shown on
the drawings within tolerances + 10 mm and + 3 mm respectively. The bedding shall not
extend under the slab and there shall be no vertical step between adjacent forms of more
than 3 mm. The forms shall be got inspected from the Engineer for his approval before 12
hours on the day before the construction of the slab and shall not be removed until at least
12 hours afterwards.

602.8.2. At all times sufficient forms shall be used and set to the required alignment
for at least 200 m length of pavement immediately in advance of the paving operations,
or the anticipated length of pavement to be laid within the next 24 hrs whichever is more.

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Concrete Pavement Section 600

602.8.3. Use of guidewires

602.8.3.1. Where slip form paving is proposed, a guidewire shall be provided along
both sides of the slab. Each guidewire shall be at a constant height above and parallel to
the required edges of the slab as described in the contract/drawing within a vertical
tolerance of + 3 mm. Additionally, one of the wires shall be kept at a constant horizontal
distance from the required edge of the pavement as indicated in the contract/drawing
within a lateral tolerance of + 10 mm.

602.8.3.2. The guidewires shall be supported on stakes not more than 8 m apart by
connectors capable of fine horizontal and vertical adjustment. The guidewire shall be
tensioned on the stakes so that a 500 gram weight shall produce a deflection of not more
than 20 mm when suspended at the mid point between any pair of stakes. The ends of the
guidewires shall be anchored to fixing point or winch and not on the stakes.

602.8.3.3. The stakes shall be positioned and the connectors maintained at their
correct height and alignment from 12 hours on the day before concreting takes place until
12 hours after finishing of the concrete. The guidewire shall be erected and tensioned on
the connectors at any section for at least 2 hours before concreting that section.

602.8.3.4. The Contractor shall submit to the Engineer for his approval of line and
level, the stakes and connectors which are ready for use in the length of road to be
constructed by 12 hours on the working day before the day of construction of slab. Any
deficiencies noted by the Engineer shall be rectified by the Contractor who shall then re-
apply for approval of the affected stakes. Work shall not proceed until the Engineer has
given his approval. It shall be ensured that the stakes and guidewires are not affected by
the construction equipment when concreting is in progress.

602.9. Construction

602.9.1. General: A systems approach may be adopted for construction of the

pavement, and the Method Statement for carrying out the work, detailing all the activities
including indication of time-cycle, equipment, personnel etc., shall be got approved from
the Engineer before the commencement of the work. The above shall include the type,
capacity and make of the batching and mixing plant besides the hauling arrangement and
paving equipment. The capacity of paving equipment, batching plant as well as all the
ancillary equipment shall be adequate for a paving rate of at least 300 m in one day.

602.9.2. Batching and mixing: Batching and mixing of the concrete shall be done
at a central batching and mixing plant with automatic controls, located at a suitable place
which takes into account sufficient space for stockpiling of cement, aggregates and
stationary water tanks. This shall be, however, situated at an approved distance, duly
considering the properties of the mix and the transporting arrangements available with the
Contractor.

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Concrete Pavement Section 600

602.9.3. Equipment for proportioning of materials and pouring

602.9.3.1. Proportioning of materials shall be done in the batching plant by weight,

each type of material being weighed separately. The cement from the bulk stock may be
weighed separately from the aggregates and water shall be measured by volume.
Wherever properly graded aggregate of uniform quality cannot be maintained as
envisaged in the mix design, the grading of aggregates shall be controlled by appropriate
blending techniques. The capacity of batching and mixing plant shall be at least 25 per
cent higher than the proposed capacity of the laying/paving equipment.

602.9.3.2. Batching plant and equipment:

(1) General- The batching pant shall include minimum four bins, weighing
hoppers, and scales for the fine aggregate and for each size of coarse
aggregate. If cement is used in bulk, a separate scale for cement shall be
included. The weighing hoppers shall be properly sealed and vented to
preclude dust during operation. Approved safely devices shall be provided
and maintained for the protection of all personnel engaged in plant operation,
inspection and testing. The batch plant shall be equipped with a suitable non-
reset table batch counter which will correctly indicate the number of batches
proportioned.

(2) Bins and hoppers- Bins with minimum number of four adequate separate
compartments shall be provided in the batching plant.

(3) Automatic weighing devices- Batching plant shall be equipped to proportion

aggregates and bulk cement by means of automatic weighing devices using
load cells.

(4) Mixers- Mixers shall be pan type, reversible type or any other mixer capable
of combining the aggregates, cement, and water into a thoroughly mixed and
uniform mass within the specific mixing period, and of discharging the
mixture, without segregation. Each stationary mixer shall be equipped with
an approved timing device which will automatically lock the discharge lever
when the drum has been charged and released it at the end of the mixing
period. The device shall be equipped with a bell or other suitable warning
device adjusted to give a clearly audible signal each time the lock is released.
In case of failure of the timing device, the mixer may be used for the balance
of the day while it is being repaired, provided that each batch is mixed 90
seconds or as per the manufacturer’s recommendation. The mixer shall be
equipped with a suitable non-reset table batch counter which shall correctly
indicate the number of batches mixed.

The mixers shall be cleaned at suitable intervals. The pickup and throw-over
blades in the drum or drums shall be repaired or replaced when they are worn
down 20 mm or more. The Contractor shall (1) have available at the job site a
copy of the manufacturer’s design, showing dimensions and arrangements of
blades in reference to original height and depth, or (2) provide permanent

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Concrete Pavement Section 600

marks on blade to show points of 20 mm wear from new conditions. Drilled

holes of 5 mm diameter near each end and at midpoint of each blade are
recommended. Batching plant shall be calibrated in the beginning and
thereafter at suitable interval not exceeding 1 month.

(5) Control cabin- An air-conditioned centralized control cabin shall be provided

for automatic operation of the equipment.

602.9.3.3. Paving equipment: The concrete shall be placed with an approved fixed
form or slip form paver with independent units designed to (i) spread, (ii) consolidate,
screed and float-finish, (iii) texture and cure the freshly placed concrete in one complete
pass of the machine in such a manner that a minimum of hand finishing will be necessary
and so as to provide a dense and homogeneous pavement in conformity with the plans
and Specifications. The paver shall be equipped with electronic controls to control/sensor
line and grade from either or both sides of the machine.

Vibrators shall operate at a frequency of 8300 to 9600 impulses per minute under
load at a maximum spacing of 60 cm. The variable vibration setting shall be provided in
the machine.

602.9.3.4. Concrete saw: The Contractor shall provide adequate number of

concrete saws with sufficient number of diamond-edge saw blades. The saw machine
shall be either electric or petrol/diesel driven type. A water tank with flexible hoses and
pump shall be made available in this activity on priority basis. The Contractor shall have
at least one standby saw in good working condition. The concreting work shall not
commence if the saws are not in working condition.

602.9.4. Hauling and placing of concrete

602.9.4.1. Freshly mixed concrete from the central batching and mixing plant shall
be transported to the paver site by means of trucks/tippers of sufficient capacity and
approved design in sufficient numbers to ensure a constant supply of concrete. Covers
shall be used for protection of concrete against the weather. The trucks/tippers shall be
capable of maintaining the mixed concrete in a homogeneous state and discharging the
same without segregation and loss of cement slurry. The feeding to the paver is to be
regulated in such a way that the paving is done in an uninterrupted manner with a
uniform speed throughout the days work.

602.9.4.2. Placing of concrete

Concrete mixed in central mixing plant shall be transported to the site without delay
and the concrete which, in the opinion of the Engineer, has been mixed too long before
laying will be rejected and shall be removed from the site. The total time taken from the
addition of the water to the mix, until the completion of the surface finishing and
texturing shall not exceed 120 minutes when concrete temperature is less than 250C and
90 minutes when the concrete temperature is between 250C to 300C. Trucks/tippers
delivering concrete shall not run on plastic sheeting nor shall they run on completed slabs

20
Concrete Pavement Section 600

until after 28 days of placing the concrete. The paver shall be capable of paving the
carriageway as shown in the drawings, in a single pass and lift.

602.9.4.3. Where fixed form pavers are to be used, forms shall be fixed in advance
as per Clause 602.8. of the Specifications. Before any paving is done, the site shall be
shown to the Engineer, in order to verify the arrangement for paving besides placing of
dowels, tie-bars etc., as per the relevant Clause of this Specification. The mixing and
placing of concrete shall progress only at such a rate as to permit proper finishing,
protecting and curing of the pavement.

602.9.4.4. In all cases, the temperature of the concrete shall be measured at the
point of discharge from the delivery vehicle.

602.9.4.5. The addition of water to the surface of the concrete to facilitate the
finishing operations will not be permitted except with the approval of the Engineer when
it shall be applied as a mist by means of approved equipment.

602.9.4.6. If considered necessary by the Engineer, the paving machines shall be

provided with approved covers to protect the surface of the slab under construction from
direct sunlight and rain or hot wind.

602.9.4.7. While the concrete is still plastic, its surface shall be brush textured in
compliance with Clause 602.9.8 and the surface and edges of the slab cured by the
application of a sprayed liquid curing membrane in compliance with Clause 602.9.9.
After the surface texturing, but before the curing compound is applied, the concrete slab
shall be marked with the chainage at every 100 m interval.

602.9.4.8. As soon as the side forms are removed, edges of the slabs shall be
corrected wherever irregularities have occurred by using fine concrete composed of one
part of cement to 3 parts of fine chips and fine aggregate under the supervision of the
Engineer.

602.9.4.9. If the requirement of Clause 902.4. for surface regularity fails to be

achieved on two consecutive working days, then normal working shall cease until the
cause of the excessive irregularity has been identified and remedied.

602.9.5. Construction by fixed form paver

602.9.5.1. The fixed form paving train shall consist of separate powered machines
which spread, compact and finish the concrete in a continuous operation.

602.9.5.2. The concrete shall be discharged without segregation into a hopper

spreader which is equipped with means for controlling its rate of deposition on to the
subbase. The spreader shall be operated to strike off concrete upto a level requiring a
small amount of cutting down by the distributor of the spreader. The distributor of
spreader shall strike off the concrete to the surcharge adequate to ensure that the vibratory
compactor thoroughly compact the layer. If necessary, poker vibrators shall be used
adjacent to the side forms and edges of the previously constructed slab. The vibratory

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Concrete Pavement Section 600

compactor shall be set to strike off the surface slightly high so that it is cut down to the
required level by the oscillating beam. The machine shall be capable of being rapidly
adjusted for changes in average and differential surcharge necessitated by changes in slab
thickness or cross fall. The final finisher shall be able to finish the surface to the required
level and smoothness as specified, care being taken to avoid bringing up of excessive
mortar to the surface by over-working.

602.9.6. Construction by slip form paver

602.9.6.1. The slip form paving train shall consist of power machine which spreads
compacts and finishes the concrete in a continuous operation. The slip form paving
machine shall compact the concrete by internal vibration and shape it between the side
forms with either a conforming plate or by vibrating and oscillating finishing beams. The
concrete shall be deposited without segregation in front of slip form paver across the
whole width and to a height which at all times is in excess of the required surcharge. The
deposited concrete shall be struck off to the necessary average and differential surcharge
by means of the strike off plate or a screw auger device extending across the whole width
of the slab. The equipment for striking-off the concrete shall be capable of being rapidly
adjusted for changes of the average and differential surcharge necessitated by change in
slab thickness or crossfall.

602.9.6.2. The level of the conforming plate and finishing beams shall be controlled
automatically from the guide wires installed as per Clause 602.8 by sensors attached at
the four corners of the slip form paving machine. The alignment of the paver shall be
controlled automatically from the guide wire by at least one set of sensors attached to the
paver. The alignment and level of ancillary machines for finishing, texturing and curing
of the concrete shall be automatically controlled relative to the guide wire or to the
surface and edge of the slab.

602.9.6.3. Slip-form paving machines shall have vibrators of variable output, with a
maximum energy output of not less than 2.5 KW per meter width of slab per 300 mm
depth of slab for a laying speed upto 1.5 m per minute or pro-rata for higher speeds. The
machines shall be of sufficient mass to provide adequate reaction during spreading and
paving operations on the traction units to maintain forward movements during the placing
of concrete in all situations.

602.9.6.4. If the edges of the slip formed slab slump to the extent that the surface of
the top edge of the slab does not comply with the requirements of Clause 602.14, then
special measures approved by the Engineer shall be taken to support the edges to the
required levels and work shall be stopped until such time as the Contractor can
demonstrate his ability to slip form the edges to the required levels.

602.9.7. Construction by hand-guided method: Areas in which hand-guided

methods of construction become indispensable shall be got approved by the Engineer in
writing in advance. Such work may be permitted only in restricted areas in small lengths.
Work shall be carried out by skilled personnel as per methods approved by the Engineer.
The acceptance criteria regarding level, thickness, surface regularity, texture, finish,

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Concrete Pavement Section 600

strength of concrete and all other quality control measures shall be the same as in the case
of machine laid work.

602.9.8. Surface texture

602.9.8.1. After the final regulation of the slab and before the application of the
curing membrane, the surface of concrete slab shall be brush-textured in a direction at
right angles to the longitudinal axis of the carriageway.

602.9.8.2. The brushed surface texture shall be applied evenly across the slab in one
direction by the use of a wire brush not less than 450 mm wide but longer brushes are
preferred. The brush shall be made of 32 gauge tape wires grouped together in tufts
spaced at 10 mm centers. The tufts shall contain an average of 14 wires and initially be
100 mm long. The brush shall have two rows of tufts. The rows shall be 20 mm apart and
the tufts in one row shall be opposite the center of the gap between tufts in the other row.
The brush shall be replaced when the shortest tufts wears down to 90 mm long.

602.9.8.3. The texture depth shall be determined by the Sand Patch Test as
described in Clause 602.12. This test shall be performed at least once for each day’s
paving and wherever the Engineer considers it necessary at times after construction as
under:

Five individual measurements of the texture depth shall be taken at least 2 m apart
anywhere along a diagonal line across a lane width between points 50 m apart along the
pavement. No measurement shall be taken within 300 mm of the longitudinal edges of a
concrete slab constructed in one pass.

602.9.8.4. Texture depths shall not be less than the minimum required when
measurements are taken as given in Table 600-2 nor greater than a maximum average of
1.25 mm.
TABLE: 600-2. Texture Depth

Required
Number of Texture Depth (mm)
Ti me of Test
Measurements
Specified
Tolerance
Value
1. Between 24 hours and 7 days after the
An average of 5
constn. of the slab or until the slab is 1.00 + 0.25
measurements
first used by vehicles.
2. Not later than 6 weeks before the road An average of 5 + 0.25
1.00
is opened to public traffic. measurements - 0.35

602.9.8.5. After the application of the brushed texture, the surface of the slab shall
have a uniform appearance.

602.9.8.6. Where the texture depth requirements are found to be deficient, the
Contractor shall make good the texture across the full lane width over length directed by
the Engineer, by retexturing the hardened concrete surface in an approved manner.

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Concrete Pavement Section 600

602.9.9. Curing

602.9.9.1. Immediately after the surface texturing, the surface and sides of the slab
shall be cured by the application of approved resin-based aluminized reflective curing
compound which hardens into an impervious film or membrane with the help of a
mechanical sprayer.

Curing compounds shall contain sufficient flake aluminium in finely divided

dispersion to produce a complete coverage of the sprayed surface with a metallic finish.
The compound shall become stable and impervious to evaporation of water from the
surface of the concrete within 60 minutes of application and shall be of approved type.
The curing compounds shall have a water retention efficiency index of 90 per cent in
accordance with BS Specification No. 7542.

602.9.9.2. The curing compound shall not react chemically with the concrete and
the film or membrane shall not crack, peel or disintegrate within three weeks after
application. Immediately prior to use, the curing compound shall be thoroughly agitated
in its containers. The rate of spread shall be in accordance with the manufacturer’s
instructions checked during the construction of the trial length and subsequently
whenever required by the Engineer. The mechanical sprayer shall incorporate an efficient
mechanical device for continuous agitation and mixing of the compound during spraying.

602.9.9.3. In addition to spraying of curing compound, the fresh concrete surface

shall be protected for at least 3 hours by covering the finished concrete pavement with
tents as described in Clause 602.7.2, during adverse weather conditions as directed by the
Engineer. After three hours, the pavement shall be covered by moist hessian and the same
shall then be kept damp for a minimum period of 14 days after which time the hessian
may be removed. The hessian shall be kept continuously moist. All damaged/torn hessian
shall be removed and replaced by new hessian on a regular basis.

602.9.9.4. The Contractor shall be liable at his expense to replace any concrete
damaged as a result of incomplete curing or cracked on a line other than that of a joint.

602.10. Trial Length

602.10.1. The trial length shall be constructed at least one month in advance of the
proposed start of concrete paving work. At least one month prior to the construction of
the trial length, the Contractor shall submit for the Engineer’s approval a detailed method
statement giving description of the proposed materials, plant, equipment and construction
methods. All the major equipments like paving train, batching plant, tippers etc.,
proposed in the construction are to be approved by the Engineer before their
procurement. No trials of new materials, plant, equipment or construction methods, nor
any development of them shall be permitted either during the construction of trial length
or in any subsequent paving work, unless they form part of further, approved trial. These
trial lengths shall be constructed away from the carriageway but with at least a subbase
layer below it.

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Concrete Pavement Section 600

602.10.2. The Contractor shall demonstrate the materials, plant, equipment and
methods of construction that are proposed for concrete paving, by first constructing a trial
length of slab, at least 60 m but not more than 300 m long for mechanised construction
and at least 30 m long for hand guided methods. If the first trial is unsatisfactory, the
Contractor shall have to demonstrate his capability to satisfactorily construct the
pavement in subsequent trials.

602.10.3. The trial length shall be constructed in two parts over a period comprising
at least part of two separate working days, with a minimum of 30 m constructed each day
for mechanised construction and a minimum of 15 m on each day for hand guided
construction. The trial length shall be constructed at a similar rate (speed, around lm/hr)
to that which is proposed for the main work.

602.10.4. Transverse joints and longitudinal joints of each type that are proposed
for dowel-jointed unreinforced concrete slabs in the main work shall be constructed and
assessed in the trial length. If in the trial length the construction of expansion joint and
longitudinal joint is not demonstrated, the first 2 expansion joints and at least the first 150
m of longitudinal construction joint for mechanised paving in the main work, shall be
considered as the trial length for these joints.

602.10.5. The trial length shall comply with the Specification in all respects, with
the following additions and exceptions:

602.10.5.1. Surface levels and regularity

(i) In checking for compliance with Clause 903.5 the levels shall be taken at intervals at the
locations specified in this Clause along any line or lines parallel to the longitudinal center
line of the trial length.

(ii) The maximum number of permitted irregularities of pavement surface shall comply with
the requirements of Clause 902.4. Shorter trial lengths shall be assessed prorata based on
values for a 300 m length.

602.10.5.2. Joints
(iii) Alignment of dowel bars shall be inspected as described in Clause 602.10.7 in any two
consecutive transverse joints. If the position or alignment of the dowel bars at one of
these joints does not comply with Clause 602.6.5, if that joint remains the only one that
does not comply after the next 3 consecutive joints of the same type have been inspected,
then the method of placing dowels shall be deemed to be satisfactory. In order to check
sufficient joints for dowel bar alignment without extending the trial length unduly,
Contractor may, by agreement with the Engineer, construct joints at more frequent joint
intervals than the normal spacing required in the Contract.

(iv) If there are deficiencies in the first expansion joint that is constructed as a trial, the next
expansion joint shall be a trial joint. Should this also be deficient, further trial expansion
joints shall be made as part of the trial length which shall not form part of the permanent
works, unless agreed by the Engineer.

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Concrete Pavement Section 600

602.10.5.3. Density
(v) Density shall be assessed as described in Clause 602.3.3. from at least 3 cores drilled
from each part of the trial length.

602.10.5.4. Position of tie bars

(vi) Compliance with Clause 602.6.6. for the position and alignment of tie bars shall be
checked by drilling additional cores from the slab unless they can be determined from
cores taken for density.

602.10.6. Approval and acceptance

602.10.6.1. Approval of the materials, plant, equipment and construction methods

shall be given a trial length complies with the Specification. The Contractor shall not
proceed with normal working until the trial length has been approved and any earlier
defective trial lengths have been removed, unless that can be remedied to the satisfaction
of the Engineer. If the Engineer does not notify the Contractor of any deficiencies in any
trial length within 10 days after the completion of that trial length, the Contractor may
assume that the trial length, and the materials, plant, equipment and construction methods
are acceptable.

602.10.6.2. When approval has been given, the materials, plant, equipment and
construction methods shall not thereafter be changed, except for normal adjustments and
maintenance of plant, without the approval of the Engineer. Any changes in materials,
plant, equipment, and construction methods shall entitle the Engineer to require the
Contractor to lay a further trial length as described in this Clause to demonstrate that the
changes will not adversely affect the permanent works.

602.10.6.3. Trial lengths which do not comply with the Specification, with the
exception of areas which are deficient only in surface texture and which can be remedied
in accordance with Clause 602.9.8.6 shall be removed immediately upon notification of
deficiencies by the Engineer and the Contractor shall construct a further trial length.

602.10.7. Inspection of dowel bars

602.10.7.1. Compliance with Clause 602.6.5. for the position and alignment of
dowel bars at construction and expansion joints shall be checked by measurements
relative to the side forms or guide wires.

602.10.7.2. When the slab has been constructed, the position and alignment of
dowel bars and any filler board shall be measured after carefully exposing them in the
plastic concrete across the whole width of the slab. When the joint is an expansion joint,
the top of the filler board shall first be exposed sufficiently in the plastic concrete to
permit measurement of any lateral or vertical displacement of the board. During the
course of normal working, these measurements shall be carried out in the pavement
section at the end of day’s work by extending slab length by 2 m. After sawing the
transverse joint groove, the extended 2 m slab shall be removed carefully soon after
concrete has set to expose dowels over half the length. These dowels can be tested for
tolerances.

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Concrete Pavement Section 600

602.10.7.3. If the position and alignment of the bars in a single joint in the slab is
unsatisfactory then the next two joints shall be inspected. If only one joint of the three is
defective, the rate of checking shall be increased to one joint per day until the Engineer is
satisfied that compliance is being achieved. In the event of non-compliance in two or
more successive joints, the Contractor shall revert to the construction of fresh trial lengths
and make any necessary alteration to concrete mix, paving plant or methods until dowel
bar position and alignment are satisfactory.

602.10.7.4. After the dowel bars have been examined, the remainder of the concrete
shall be removed over a width of 500 mm on each side of the line of the joint and
reinstated to the satisfaction of the Engineer. The dowels shall be inserted on both sides
of the 1 m wide slab by drilling holes and grouting with epoxy mortar. Plastic sheath as
per Clause 602.6.5.5 shall be provided on dowels on one of the joints. The joint groove
shall be widened and sealed as per Clause 602.11.

602.11. Preparation and Sealing of Joint Grooves

602.11.1. General

All transverse joints in surface slabs shall be sealed using sealants described in
Clause 602.2.8. Joints shall not be sealed before 14 days after construction.

602.11.2. Preparation of joint grooves for sealing

602.11.2.1. Joint grooves usually are not constructed to provide the minimum width
specified in the drawings when saw cut joints are adopted. They shall be widened
subsequently by sawing before sealing. Depth/width gauges shall be used to control the
dimension of the groove.

602.11.2.2. If rough arrises develop when grooves are made, they shall be ground to
provide a chamfer approximately 5 mm wide. If the groove is at an angle up to 10 degree
from the perpendicular to the surface, the overhanging edge of the sealing groove shall be
sawn or ground perpendicular. If spalling occurs or the angle of the former is greater than
10 degrees, the joint sealing groove shall be sawn wider and perpendicular to the surface
to encompass the defects up to a maximum width, including any chamfer, of 35 mm for
transverse joints and 20 mm for longitudinal joints. If the spalling cannot be so
eliminated then the arrises shall be repaired by an approved thin bonded arris repair using
cementitious materials.

602.11.2.3. All grooves shall be cleaned of any dirt or loose material by air blasting
with filtered, oil-free compressed air. If need arises the Engineer may instruct cleaning by
pressurised water jets. Depending upon the requirement of the sealant manufacturer, the
sides of the grooves may have to be sand blasted to increase the bondage between sealant
and concrete.

602.11.2.4. The groove shall be cleaned and dried at the time of priming and
sealing.

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Concrete Pavement Section 600

602.11.2.5. Before sealing the temporary seal provided for blocking the ingress of
dirt, soil etc., shall be removed. A highly compressible heat resistant paper-backed
debonding strip as per drawing shall be inserted in the groove to serve the purpose of
breaking the bond between sealant and the bottom of the groove and to plug the joint
groove so that the sealant may not leak through the cracks. The width of debonding strip
shall be more than the joint groove width so that it is held tightly in the groove. In the
case of longitudinal joints, heat resistant tapes may be inserted to block the leakage
through bottom of the joint.

602.11.3. Sealing with sealants

602.11.3.1. When sealants are applied, an appropriate primer shall also be used if
recommended by the manufacturer and it shall be applied in accordance with their
recommendation. The sealant shall be applied within the minimum and maximum drying
times of the primer recommended by the manufacturer. Priming and sealing with applied
sealants shall not be carried out when the naturally occurring temperature in the joint
groove to be sealed is below 70 C.

602.11.3.2. If hot applied sealant is used it shall be heated and applied from a
thermostatically controlled, indirectly heated preferably with oil jacketed melter and
pourer having recirculating pump and extruder. For large road projects, sealant shall be
applied with extruder having flexible hose and nozzle. The sealant shall not be heated to a
temperature higher than the safe heating temperature and not for a period longer than the
safe heating period, as specified by the manufacturer. The dispenser shall be cleaned out
at the end of each day in accordance with the manufacturer’s recommendations and
reheated material shall not be used.

602.11.3.3. Cold applied sealants with chemical formulation like polysulphide may
be used. These shall be mixed and applied within the time limit specified by the
manufacturer. If primers are recommended they shall be applied neatly with an
appropriate brush. The Movement Accommodation Factor (MAF) shall be more than 10
per cent.

602.11.3.4. The sealant applied at contraction phase of the slabs would result in
bulging of the sealant over and above the slab. Therefore, the Contractor in consultation
with the Engineer shall establish the right temperature and time for applying the sealant.
Thermometer shall be hung on a pole in the site for facilitating control during the sealing
operation.

602.11.3.5. Sealant shall be applied, slightly to a lower level than the slab with a
tolerance of 5 + 2 mm.

602.11.3.6. During sealing operation, it shall be seen that no air bubbles are
introduced in the sealant either by vapours or by the sealing process.

602.11.4. Testing of applied sealants: Manufacturer’s certificate shall be produced

by the Contractor for establishing that the sealant is not more than six months old and
stating that the sealant complies with the relevant standard as in Clause 602.2.8. The

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samples shall meet the requirement of AASHTO M 282 for hot applied sealant or BS
5212: (Part-2) for cold applied sealant.

602.12. Measurement of Texture Depth – Sand Patch Method

602.12.1. The following apparatus shall be used:

(i) A cylindrical container of 25 ml internal capacity

(ii) A flat wooden disc 64 mm diameter with a hard rubber disc, 1.5 mm thick, stuck to one
face, the reverse face being provided with a handle

(iii) Dry natural sand with a rounded particle shape passing a 300 micron IS sieve and
retained on a 150 micron IS sieve.

602.12.2. Method: The surface to be measured shall be dried, any extraneous

mortar and loose material removed and the surface swept clean using a wire brush both at
right angles and parallel to the carriageway. The cylindrical container shall be filled with
the sand, tapping the base 3 times on the surface to ensure compaction, and striking off
the sand level with the top of the cylinder. The sand shall be poured into a heap on the
surface to be treated. The sand shall be spread over the surface, working the disc with its
face kept flat in a circular motion so that the sand is spread into a circular patch with the
surface depressions filled with sand to the level of peaks.

602.12.3. The diameter of the patch shall be measured to the nearest 5 mm. The
texture depth of concrete surface shall be calculated from 31000/(DxD) mm where D is
the diameter of the patch in mm.

602.13. Opening to Traffic

No vehicular traffic shall be allowed to run on the finished surface of a concrete

pavement within a period of 28 days of its construction and until the joints are
permanently sealed. The road may be opened to regular traffic after completion of the
curing period of 28 days and after sealing of joints is completed including the
construction of shoulder, with the written permission of the Engineer.

602.14. Tolerances for Surface Regularity, Level, Thickness and Strength

The tolerances for surface regularity, level, thickness and strength shall conform to
the requirements given in Clause 903.5. Control of quality of materials and works shall
be exercised by the Engineer in accordance with Section 900.

602.15. Measurements for Payment

602.15.1. Cement Concrete pavement shall be measured as a finished work in

square metres with specified thickness. The volume to be paid for will be calculated on
the basis of thickness and plans shown on the project drawings and adjusted for the
deficiency in thickness. No additional payment shall be made for extra thickness of the

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slab. The full payment will be made to this item after 28 days strength of the concrete is
found to be satisfactory.

The unit for measurement for concrete pavement shall be the cubic metre of
concrete placed, based on the net plan areas for the specified thickness shown on the
Drawings or directed by the Engineer. The rate shall include all provisions of this
Specification and shall include the provision of all materials including polythene film,
concrete, stock piling, mixing, transport, placing, compacting, finishing, curing together
with all formwork, and including testing and submission of test certificates and records.
No deduction shall be made in measurement for openings provided that the area of each
is less than 0.5 sq. m. The unit rate as entered in the Bill of Quantities shall also include
the full costs of contraction, expansion, construction, and longitudinal joints. It shall also
include joint filler, keys, caulking rod, debonding strip, sealant primer, joint sealant,
dowel bar and tie rod.

602.15.2. Pavement thickness

All precautions and care shall be taken to construct pavement having uniform
thickness as called for on the plans.

Thickness of the cement concrete pavement shall be calculated on the basis of level
data of the cement concrete pavement and the underlying sub-base taken on a grid of 5 m
x 3.5 m or 6.25 m x 3.5 m, the former measurement being in longitudinal direction.

A day’s work is considered as a ‘lot’ for calculating the average thickness of the
slab. In calculating the average thickness, individual measurements which are in excess
of the specified thickness by more than 10 mm shall be considered as the specified
thickness plus 10 mm.

Individual areas deficient by more than 25 mm shall be verified by the Engineer by

ordering core cutting and if in his opinion the deficient areas warrant removal, they shall
be removed and replaced with concrete of the thickness shown on the plans.

When the average thickness for the lot is deficient by the extent shown in Table
600-3, the Contract unit price will be adjusted as per this Table.

TABLE 600-3. PAYMENT ADJUSTMENT FOR DEFICIENCY IN THICKNESS

Deficiency in the average Per cent of Contract unit

thickness of day’s work price payable
Up to 5 mm 100
6 – 10 mm 87
11 – 15 mm 81
16 – 20 mm 75
21 – 25 mm 70

In the stretch where deficiency of average thickness is more than 25 mm, the
section whose thickness is deficient by 26 mm or more is identified with the help of

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Concrete Pavement Section 600

cores. Such slabs shall be removed and reconstructed at the cost of the Contractor. During
such rectification work, care shall be taken to replace full slab and to the full depth.

602.16. Rate

The Contract unit rate for the construction of the cement concrete shall be payment
in full for carrying out the operations required for the different items of the work as per
these Specifications including full compensation for all labour, tools, plant, equipments,
testing and incidentals to complete the work as per Specifications, providing all materials
to be incorporated in the work including all royalties, fees, storage, rents where necessary
and all leads and lifts.

603. ROLLED CEMENT CONCRETE BASE

603.1. Scope

603.1.1. The work shall consist of construction of rolled concrete base course for
cement concrete pavement in accordance with the requirements of these Specifications
and in conformity with the lines, grades and cross sections shown on the drawings or as
directed by the Engineer. The work shall include furnishing of all plant and equipment,
material and labour and performing all operations in connection with the work, as
approved by the Engineer.

603.1.2. The design parameters of rolled cement concrete base course viz., width,
thickness, grade of concrete, details of joints, if any, etc. shall be as stipulated in the
contract drawings.

603.2. Materials

603.2.1. Source of materials: The Contractor shall indicate to the Engineer the
source of all materials to be used in the lean concrete work with relevant test data
sufficiently in advance and the approval of the Engineer for the same shall be obtained at
least 60 days before the scheduled commencement of the work. If the Contractor later
proposes to obtain the materials from a different source, he shall notify the Engineer for
his approval at least 60 days before such materials are to be used.

603.2.2. Cement: Any of the following types of cement may be used with prior
approval of the Engineer.

(i) Ordinary Portland Cement IS : 269, 8112 or 12269

(ii) Portland Slag Cement IS : 455

(iii) Portland Pozzolana Cement IS : 1489

If the subgrade is found to consist of soluble sulphates in a concentration more than

0.5 per cent, cement used shall be sulphate resistance and shall conform to IS : 12230.
Cement to be used may preferably be obtained in bulk form. It shall be stored in

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Concrete Pavement Section 600

accordance with stipulations contained in Clause 1014 and shall be subjected to

acceptance test prior to its immediate use.

603.2.3. Aggregates:

603.2.3.1. Aggregates for lean concrete shall be natural material complying with IS:
383. The aggregates shall not be alkali reactive. The limits of deleterious materials shall
not exceed the requirements set out in IS: 383. In case the Engineer considers that the
aggregates are not free from dirt, the same may be washed and drained for at least 72
hours before batching as directed by the Engineer.

603.2.3.2. Coarse aggregate : Coarse aggregates shall consist of clean, hard,

strong, dense, non-porous and durable pieces of crushed stone or crushed gravel and shall
be devoid of pieces of disintegrated stone, soft, flaky, elongated, very angular or splintery
pieces. The maximum size of the coarse aggregate shall be 25 mm. The coarse aggregate
shall comply with the Clause 602.2.4.2.

603.2.3.3. Fine aggregate : The fine aggregate shall consist of clean natural sand
or crushed stone sand or a combination of the two and shall conform to IS: 383. Fine
aggregate shall be free from soft particles, clay, shale, loam, cemented particles, mica,
organic and other foreign matter. The fine aggregate shall comply with the Clause
602.2.4.3.

603.2.3.4. The coarse and fine aggregates may be obtained in either of the following
manner:-
(i) In separate nominal sizes of coarse and fine aggregates and mixed together intimately
before use.

(ii) Separately as 25 mm nominal single size, 12.5 mm nominal size graded aggregate and
fine aggregate of crushed stone dust or sand or a combination of these two.

The material after blending shall conform to the grading as indicated in Table 600-4
below:

TABLE 600-4. AGGREGATE GRADATION FOR DRY LEAN CONCRETE

Percentage Passing the

Sieve Designation
sieve by weight
37.5 mm 100
19.0 mm 80 – 100
9.5 mm 55 – 80
4.75 mm 35 – 60
600 micron 10 – 35
75 micron 0 –8

603.2.4. Water: Water used for mixing and curing of concrete shall be clean and
free from injurious amount of oil, salt, acid, vegetable matter or other substances harmful
to the finished concrete. It shall meet the requirements stipulated in IS: 456.

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603.2.5. Storage of materials: All materials shall be stored in accordance with the
provisions of Clause 1014 of these Specifications, and other relevant IS Specifications.
All efforts must be made to store the materials in proper places so as to prevent their
deterioration or contamination by foreign matter and to ensure their satisfactory quality
and fitness for the work. The storage place must also permit easy inspection, removal and
storage of materials. All such materials even though stored in approved godowns must be
subjected to acceptance test immediately prior to their use. The requirement of storage
yard specified in Clause 602.2.9 shall be applicable.

603.3. Proportioning of Materials for the Mix

603.3.1. The mix shall be proportioned with a maximum aggregate: cement ratio of
15:1. After the approval of all the materials to be used in the concrete, the Contractor
shall submit the mix design based on weighed proportion of all ingredients for the
approval of the Engineer. The mix design shall be submitted at least 30 days prior to the
paving of trial length and design shall be done based on the laboratory trials using
approved materials and methods. The water content shall be adjusted to the optimum as
per Clause 603.3.2. for facilitating compaction by rolling. The target mean strength for
the design mix as well as acceptance Specification of concrete shall be in accordance
with Clause 903.5.2. The mix design shall be based on the flexural strength of concrete.

603.3.2. Moisture content: The right amount of water for the rolled concrete in the
main work shall be decided for ensuring full compaction under rolling and shall be
assessed at the time of rolling the trial length. Too much water will cause the concrete to
be picked up on the wheels of the roller and too little will lead to inadequate compaction,
a low in-situ strength and an open texture surface. The optimum water content shall be
determined in accordance with Clause 603.7. and demonstrated by rolling during trial
length construction; and the optimum moisture content and degree of compaction shall be
got approved by the Engineer. While laying, in the main work, the rolled concrete shall
have a moisture content between the optimum and optimum + 2 per cent, keeping in view
the effectiveness of compaction achieved and to compensate for evaporation losses.

603.3.3. Cement content: The minimum cement content in the rolled concrete shall
not be less than 150 kg/cu.m. of concrete. If this minimum cement content is not
sufficient to produce concrete of the specified strength, it shall be increased as necessary
without additional compensation under the Contract.

603.3.4. Concrete strength: The flexural strength as specified shall be the

governing criteria for approval of the mix. While designing the mix in the laboratory,
correlation between flexural and compressive strengths of concrete shall be established
on the basis of tests on samples for use at a later date to verify the in situ flexural strength
of rolled concrete through testing of cores.

At least a batch of two beam and cube specimens, one each for 3 day and 7 day
strength testing shall be cast for every 100 cum or part thereof of concrete placed during
construction. On each day’s work not less than four beams and four cubes shall be made.

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A ratio between the 3 and 7 day strengths shall be established for the mix to be
used. This will help in assessing the fall in strength, if any in advance so that corrective
action can be taken for the future work.

603.4. Subgrade

The subgrade shall conform to the grades and cross sections shown on the drawings
and shall be uniformly compacted to the design strength in accordance with these
Specifications and the Specification stipulated in the Contract. The rolled concrete base
shall not be laid on a subgrade softened by rain after its final preparation; any surface
trenches, soft spots etc., must be properly back-filled and compacted to avoid any weak
or soft spot. As far as possible, the construction traffic shall be avoided on the prepared
subgrade. A day before placing of the sub-base, the subgrade surface shall be given a fine
spray of water and rolled with one or two passes of a smooth wheeled roller after a lapse
of 2-3 hours in order to stabilise the loose surface. If the Engineer feels it necessary,
another fine spray of water may be applied just before placing the base course.

603.5. Construction

Clause 601.5 shall apply.

603.6. Trial Mix

Using the specified cement content and proportioned aggregates, the Contractor
shall make trial mixes at water contents ranging from 5 per cent to 7 per cent by weight
of dry materials at 0.5 per cent intervals using an aggregate / cement ratio of not greater
than 15.0. Optimum moisture and density shall be established by preparing cubes with
varying moisture contents. The compaction of mould shall be done in three layers as
explained in Clause 903.5.2.1. The optimum moisture content determined normally gives
an indication about the moisture content which after minor adjustment may provide
satisfactory mix which could be rolled.

603.7. Trial Length

Clause 601.7 shall apply.

603.8. Traffic

No heavy commercials vehicles like trucks and buses shall be permitted on the
rolled concrete base after its construction. Light vehicles may be, however, allowed after
7 days of its construction with prior approval of the Engineer.

603.9. Tolerances for Surface Regularity, Level, Thickness and Strength

The tolerances for surface regularity, level, thickness and strength shall conform to
the requirements given in Clause 903.5. Control of quality of materials and works shall
be exercised by the Engineer in accordance with Section 900.

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Concrete Pavement Section 600

603.10. Measurement for Payment

The unit of measurement for concrete and rolled concrete pavement shall be the
cubic metre of concrete placed, based on the net plan areas for the specified thickness
shown on the drawings as directed by the Engineer.

603.11. Rate

The Contract unit rate payable for rolled cement concrete for base course shall be
payment in full for carrying out the required operations including full compensation for
all labour, materials and equipment, mixing, transport, placing, compacting, finishing,
curing, testing and incidentals to complete the work as per Specifications, all royalties,
fees, storage and rents where necessary and all leads and lifts.

_____________

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