RCP: CONCRETE PAVING
RCP: CONCRETE PAVING
1. SCOPE
This specification covers the requirements for the materials, testing, placing, strength, design mix,
formwork, reinforcing and jointing of concrete paving. Together with the curing, tolerances,
finishes and methods of measurement and payment for the finished structure.
2. MATERIALS
2.1 Cement:
2.1.1 Applicable Specification
The cement shall comply with the latest CAS No. A46 Portland Cement.
2.1.2 Storage of Cement
Cement that is stored on site shall be kept under cover that provides proper protection against
moisture and other factors that may promote deterioration.
Storage of cement in bulk in weatherproof silos or similar containers will be permitted provided
that the cement drawn for use is measured by mass and not by volume.
2.2 Water
Water shall be clean and free from injurious amounts of acids, alkalis, organic matter and other
substances that may impair the strength or durability of concrete.
2.3 Aggregates
2.3.1 Applicable Specification
The aggregates shall comply with the latest CAS 233 Aggregates from Natural Sources for
Concrete.
2.3.2 Storage of Aggregate
Aggregates of different nominal sizes shall be stored separately in such a way that segregation is
minimized and contamination with other material is prevented.
2.4 Additives
No additives may be used in the concrete without the Engineers written approval.
2.5 Reinforcement
Reinforcing bars shall comply with the relevant requirements of BS4449 "Hot rolled steel bars for
the reinforcement of concrete for Mild Steel Bars and BS4461 "Cold worked steel bars for
reinforcement of concrete" (but not including C.1.2.(3) definition of nominal size) for Square
Twisted Bars.
Steel fabric shall be made from hard drawn steel wire and shall comply with the latest SABS CKS
158 "Welded wire mesh for concrete reinforcement".
Steel shall be so stacked off the ground as to prevent distortion and shall be protected from
aggressive environments and contamination.
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RCP: CONCRETE PAVING
2.6 Deteriorated Material
Material that has deteriorated, or that has been contaminated or otherwise damaged, shall not be
used in concrete. Such material shall be removed from the Site without delay.
2.7 Samples
The Contractor shall supply in good time to the Engineer for his approval samples of aggregates
(and if so ordered, of the water) that he proposes using for concrete.
For each source of supply the required mass of samples shall be as follows:
i) Fine aggregate - 120 kg
ii) Coarse aggregate - 240 kg total, the proportion of each size to be in accordance with the mix
design proposals
3. PLANT
3.1 Batching Plant
The Contractor shall regularly calibrate and test the batch plant, to ensure that
a) Cement may be batched to an accuracy of within
2% of the mass required
b) Water may be measured to an accuracy of within 2% of the quantity required
c) Aggregate may be batched to an accuracy of within 3% of he mass required
The plant shall at all items be in the control of a competent experienced operator.
3.2 Mixing Plant
The concrete shall be thoroughly mixed in approved mechanical drum -type mixer of minimum
capacity 0,3m3 of loose material. Worn or bent blades or paddles shall be replaced.
The type and capacity of mixing machine shall be such that the rate of output of concrete is
suitable for the rate of concreting.
A minimum mixing time which shall not be less than one and a half minutes, shall be agreed and
used for the entire works. The period of mixing will commence when all the materials are in the
drum, to commencement of discharge.
3.3 Vibrators
Vibrators shall be capable of fully compacting each layer of concrete where compaction by
vibration is specified. At least one standby vibrator shall be available for every three (or smaller
number of) vibrators necessary to maintain the rate of placing.
3.4 Formwork
3.4.1 Design
Formwork shall be so designed and constructed that the concrete can be properly placed and
compacted and that, subject to the tolerances specified, the required shapes, finishes, positions,
levels, and dimensions shown on the drawings are maintained. The formwork and joints shall be
capable of resisting the dead load, including the pressure exerted by the wet concrete, wind forces,
and all other superimposed loads and forces.
3.4.2 Finish
The quality of formwork shall be such that the finished surface of the concrete is as scheduled or
shown on the drawings.
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RCP: CONCRETE PAVING
4. CONSTRUCTION
4.1 Reinforcement
4.1.1 Bending
Bars and bending dimensions shall be as shown on the drawings in accordance with BS4466
"Bending dimensions and scheduling of bars for the reinforcement of concrete."
4.1.2 Fixing
Steel shall, at the time of the placing of the concrete, be free from loose or powdery rust, scale, oil,
and other coatings that may reduce the bond between steel and surrounding concrete, affect the
durability of the concrete, or initiate corrosion of the reinforcement. If any substance other than
water is used for lubricating the formwork, every precaution shall be taken to avoid contamination
of the reinforcement by such substance.
Reinforcement shall be positioned as shown o the drawings and maintained in those positions
within the tolerances given. It shall be secured against displacement by tying at intersections with
annealed binding wire or if permitted by the Engineer, by welding. Reinforcement shall be
supported in its correct position by means of hangers or saddles, and aligned by means of chairs
and spacers of approved design.
The Engineer will inspect all steel fixing once the reinforcement is completely in position. The
Contractor must obtain the written approval of steel fixing before concrete can be poured in any
part of the Works.
Notwithstanding the approval by the Engineer of any steel fixing, the Contractor shall be solely
responsible for the accuracy and conformity with the Drawings of all steel reinforcement.
4.1.3 Cover
Distance of reinforcing from the forms shall be maintained by means of stays, blocks, ties, hangers
or other approved supports, at the dimension shown on the drawing within the tolerance specified.
The use of pebbles, pieces of broken stone, brick or wooden blocks will not be permitted.
4.1.4 Dowels
These shall consist of plain mild steel bars positioned as shown on the drawings at right angles to
joint. They shall be straight free from burred edges and shall have their sliding ends sawn.
Dowels shall be held in their correct position by a dowel support frame to be left permanently in
place.
The free end of the dowel shall not be welded onto the frame but shall be tied by soft binding wire.
4.2 Formwork
4.2.1 Class of Finish
Formwork will be classified according to the surface condition of the finished concrete and so
scheduled
a) Class F1:- the forms may consist of any
suitable material.
b) Class F2:-the forms shall consist of plywood or similar sheeting or of steel in approved
condition.
c) Class F3:- forms as for F2 surface, but the finished surface shall be washed well with water
followed by application of cement wah and then rubbed in with Carbondium blocks and
within 48 hours of removal of the forms.
d) Class V1
e) Class V2
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4.2.2 Preparation of formwork
Forms shall be erected with joints tight enough to prevent leakage of cement mortar.
Surfaces of forms (regardless of the material of which they are made) that are to be in contact with
fresh (wet) concrete shall be treated with a coat of non-staining mineral oil or other approved
material or, only in the case of timber forms, by thorough wetting of the surfaces with water, so as
to ensure easy release and prevent adhesion of the formwork during stripping.
4.2.3 Re-use of formwork
Before reuse, all formwork shall be reconditioned, and all form surfaces that are to be in contact
with concrete shall be thoroughly cleaned.
4.2.4 Removal of Formwork
Side forms shall remain in place for 24 hours. The concrete and projecting dowels shall not be
damaged in anyway during the removal of the forms.
4.3 Concrete
4.3.1 Quality
The grade of concrete used in each part of the structure shall be as specified on the Drawings. The
concrete shall comply with the characteristic compressive strength at 28 days which is defined as
that value of strength below which 5% of the population of all possible strength measurements are
expected to fall.
The type of aggregates and cement shall not be altered during the currency of the contract without
prior approval.
The flexural strength of the concrete shall be tested in accordance with BS 1881
4.3.2 Consistency
The slump for road paving concrete, when measured in accordance with SABS 862 shall be
between 50 and 30 mm.
4.3.3 Mix Design
The Contractor shall be responsible for the design of the concrete, and for the testing of test cubes
through an approved laboratory, and for the measurement of constituent materials to produce
concrete that complies with the concrete grade and stone size specified. No concrete shall be
placed in the works before the Engineer has approved the Contractors mix design proposals.
4.3.4 Batching
4.3.4.1 Cement
The mass of cement supplied in a standard sack shall be assumed to be 50 kg.
4.3.4.2 Water
Mixing water for each batch shall be measured and allowance made for the moisture content of the
aggregate.
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4.3.5 Mixing
4.3.5.1 Site Mixing
Mixing of materials shall be conducted by an experienced operator, and in an approved sequence.
Before any concrete is mixed the inner surface of the mixer shall be cleaned and wetted with a 1:2
cement sand slurry.
4.3.5.2 Ready mix concrete
The use of ready mixed concrete shall be subject to the approval of the Engineer. If ready mixed
concrete is used then placing of concrete shall be completed within one and a half hours after the
introduction of mixing water to the cement and aggregate.
4.3.6 Placing
4.3.6.1 Unless otherwise directed, concrete shall not be placed unless the Engineer or his representative is
present, and has previously examined and approved in writing the positioning, fixing and
condition of reinforcement and the cleanliness alignment dimensions and suitability of the
containing surfaces.
4.3.6.2 Surfaces receiving concrete shall be sprayed with water and drained before placing starts.
4.3.6.3 Placing of concrete shall be complete within 30 minutes of discharge from the mixer.
4.3.6.4 The concrete shall be deposited in the forms and placed as near as possible to its final position and
spread uniformly.
4.3.6.5 Placing of concrete under water will be permitted only under exceptional circumstances when it is,
in the opinion of the Engineer, not practicable to dewater before placing. No concrete shall be
placed in flowing water.
4.3.6.6 For the construction of concrete paving, slabs are to be cast in alternate bays.
4.3.7 Compaction
The concrete shall be fully compacted by approved means during and immediately after placing.
It shall be thoroughly worked against the formwork and around reinforcement and other embedded
items without displacing them.
Compaction shall be carried out with mechanical vibrators and by experienced operators only.
Over-vibration resulting in segregation, surface laitance or leakage shall not be permitted.
4.3.8 Finishing
The surface of the concrete shall be brought up smooth and true to a plane, uniform surface with
suitable screed boards.
It shall then be finished with wood-floats to the tolerances specified.
Finished concrete shall have a neat, smooth, even, and uniform finish free from any
honeycombing. If the finish of any formed or floated concrete surface is, in the opinion of the
Engineer, unsatisfactory and does not conform to that specified, the Contractor will be required, at
his own expense, to rub down such surface while it is still green, or, alternatively, to grind it down
with carborundum or other suitable material when it has hardened or to take other approved
remedial measures to give the specified finish.
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4.3.9 Curing and Protection
4.3.9.1 Curing
After the concrete has initially set and finishing is complete (6-10 hours) the concrete shall be kept
moist and warm by one or more of the following methods
a) Ponding the exposed surfaces by means of water;
b) covering the concrete with sand, or mats made of a moisture-retaining material, and
keeping the covering continuously wet;
c) continuously spraying the exposed surfaces with water;
d) covering the concrete with waterproof or plastics sheeting firmly anchored at the edges;
e) the use of an approved curing compound applied in accordance with the
manufacturer's instructions.
Whatever method of curing is adopted, its application shall not cause staining,
contamination, or marring of the surface of the concrete. Curing shall continue
for a minimum of 7 (seven) days
4.3.9.2 Protection
No heavy vehicular traffic shall be allowed on the new concrete for a period of 28 days after it has
been formed. Light vehicles may use the pavement after a period of 14 days.
4.3.10 Adverse weather Conditions
Concrete shall not be placed during periods of rainfall, unless fresh concrete is protected from the
rainfall.
Concrete shall not be placed when the air temperature is at or below 8 degrees C or when in the
opinion of the Engineer it is likely to drop below 2 degrees C within 24 hours.
When the air temperature is 30 degrees C or higher the Contractor shall protect the concrete
ingredients and works being poured to insure that the temperature of concrete being placed is not
higher than 30 degrees C.
4.3.11 Defects
The concrete shall be homogeneous and free from honeycombing, interstices, and planes of
weakness. If, after the removal of the forms, the concrete shows any defect, the Contractor shall
immediately report such defect to the Engineer, and he shall not carry out any patching or remedial
work until authorised to do so by the Engineer.
After thorough inspection and investigation of the quality and strength of the defective work and
after due consideration of the possible consequences of such defect, the engineer will either
specify the extent and method of repair or order the demolition and reconstruction of the whole of
the defective work to the extent that he considers necessary.
The cost of all such investigation, repair, and remedial work and of any demolition and
reconstruction of defective work shall be borne by the Contractor and all repair, remedial, and
reconstruction work shall be executed to the satisfaction of the Engineer.
4.3.12 Joints
4.3.12.1 General
The joint spacing shall be as shown on the drawings.
There are 4 types of joints
a) Standard Construction/contraction joint with key
b) Longitudinal Construction joint with key and tie bars
c) Expansion joint against a fixed structure
d) Concrete/Asphalt pavement transition joint
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4.3.12.2 Materials
The liquid sealants shall comprise a 2 part polyurethane sealant PU and PPU and shall comply
with the manufacturers specifications.
4.3.11.3 Standard Construction/Contraction Joints
The concrete pavement shall be constructed in a series of alternate bays. Keyed construction joints
formed in side shutters, shall be as detailed on the drawings or as directed by the Engineer.
All laitance and loose particles shall be removed and the surfaces of the construction joint shall be
well cleaned with wire brushes, and thoroughly wetted before casting the adjacent bay.
4.3.12.4 Longitudinal Construction joint
Longitudinal construction joints shall be provided where shown on the drawings. Tie bars shall
have the size and spacing indicated on the drawings.
When concreting has been suspended due to breakdown or other causes a Longitudinal
construction joint shall be installed, but only within the middle third of the bay.
4.3.12.5 Sawing of Joints
Sawing of joints in the pavement shall be carried out by experienced personnel. Excessive spilling
of the concrete will not be allowed, and the contractor shall use the type of blade and equipment
best suited to the hardness of the concrete being sawn.
4.3.12.6 Sealing of Joints
Immediately after sawing, the joints shall be washed out with a jet of water, and sealed with the
specified polyurethane sealant according to the manufacturers directions.
4.3.12.7 Junction of Concrete pavement with flexible pavements
The transition of flexible pavements shall be as shown on the drawings.
5. TOLERANCES
5.1 The tolerances for the unformed surface of the carriageway shall be:
a) Departure from designated grade +10-30mm per 8m
b) Deviation from a 2m template 5mm
5.2 The tolerance for setting up the forms shall be +-5mm in the vertical plane.
5.3 Side forms top face shall not vary from a true plane by more than 5 mm in 3 m.
5.4 The thickness of the concrete slab may not vary from the dimensions indicated on the drawings by
more than +20mm or -5mm.
6. TESTS
6.1 Facilities
For the purposes of taking samples and carrying out tests, the Engineer shall have free access to
the Works, and the Contractor shall render any assistance necessary. If so required, the Contractor
shall provide storage and protection for such samples on the Site.
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6.2 General Certificates
The Contractor shall provide manufacturer's test certificates if called upon to do so by the Engineer
within 14 days of request.
6.3 Rate of Concrete sampling and testing
Rate A Rate B Rate C
At initial stages of To check 7 day : Min. rate once quality
contract 28 day relationship control standard is
established
2 cubes per 10m³ 2 cubes per 20m³ 1 cube per 20m³
Test 7 and 28 days Test 7 and 28 days Test 7 days
i) The minimum number of cubes to be taken for any one pour will be four, irrespective of
the volume of concrete poured. One cube will be tested at both 3 and 7 days and two
will be tested at 28 days.
ii) Concrete cubes will be made, cured, stored, transported and tested in compression in
accordance with the appropriate test methods given in BS 1881. Curing temperatures for
concrete cubes will be appropriate to tropical conditions.
iii) The samples of concrete will be taken at intervals during the concrete pour so that they
represent the entire body of concrete.
iv) Flexural strength testing shall be carried out in accordance with BS1881 at the same rate
testing as for compressive strength testing. This is to continue until the Engineer is
satisfied that sufficient consistency of results occur between compressive and flexural
testing.
v) Concrete sampling and testing will be carried out by an independent authority approved
by the Engineer.
6.4 Acceptance Criteria
Acceptance of the characteristic strength of the concrete will be given if both the conditions of
6.4.1 and 6.4.2 are met.
6.4.1 The average strength determined from any group of four consecutive test results exceeds the
specified characteristic strength by 3 MPa.
6.4.2 The strength determined from any test result is not less than the specified characteristic strength
minus 3MPa.
6.4.3 Where test results, upon statistical analysis reveal a standard deviation above 5,5 MPa, the
Engineer may order the Contractor to submit his proposals for improving the mix design and other
factors influencing the control of the concrete production before proceeding with any further
concreting.
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6.5 Failure
Should the concrete not meet the above acceptance criteria the Engineer may adopt one or more of
the following procedures:
a) An assessment of the stress level in the structure concerned in relation to the test result
obtained
b) Non-destructive insitu testing (i.e. calborated impact hammers).
c) The testing of drilled cores
d) The full scale load tests under conditions agreed between the Engineer and the
Contractor
6.6 Replacement or Strengthening of Concrete
Where failure of the concrete has occurred, the Contractor as instructed by the Engineer shall at his
own cost replace or strengthen by approved means each section that failed or contains failed
concrete as relevant.
6.7 Cost of Tests
The cost of all tests required by the Engineer shall be borne by the Owner, either as may be
specifically measured in the Bills of Quantities or as allowed for as an extra to the contract, except
that the costs of the following tests plus incidental expenses related to such tests shall be borne by
the Contractor and shall be deemed to have been allowed for in the rates.
a) Preliminary tests required in terms of Clause 2,0
b) Mix Design Tests (Clause 7.1.3)
c) Such tests (including load tests) as may, in the opinion of the Engineer, be made
necessary by failure on the part of the Contractor to meet the requirements of this
specification and any tests which fail to meet the requirements of this spec.
7. MEASUREMENT AND PAYMENT
7.1 Measurement
7.1.1 Formwork
Formwork, will be measured as the net area of the face of the concrete to be supported during the
deposition of concrete. No deduction will be made for fillets and splays.
Separate items will be scheduled for each class of finish required on the formed concrete and for
the different angles of inclination of the formwork.
The unit rate shall cover the cost of all parts of formwork in contact with the concrete (including
forming fillets or splays up to 20 mm x 20mm) and the necessary bearers, struts, and other
supports plus the labour and plant necessary to erect and strike such formwork.
7.1.2 Reinforcement
Steel for normal reinforced concrete will be measured by mass of all bars, including supporting
steel detailed on the reinforcing schedules. The mass will be computed from the nominal bar size
and the nominal mass per unit length. No allowance will be made for cutting, waste, spacer
devices (materials other than steel bars) or binding wire.
Welded mesh will be measured by area as shown on the drawings, no allowance being made for
cutting, waste, laps, or deductions for end cover. The areas measured will be those of the concrete
floor or slab reinforced by means of mesh.
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Welded mesh will be scheduled separately for each type and mass per square metre of mesh. The
unit rates for steel bars of nominal size 25 mm shall cover the cost of supply, cutting, bending,
placing in position, and fixing of the reinforcing and supporting steel scheduled, and the provision
of all spacer devices and binding wire, as well as the cost of tests.
The unit rate for welded mesh shall cover the supply, cutting, and placing of mesh, and the cost of
all waste due to laps.
7.1.3 Concrete
Concrete will be measured net, to the dimensions shown on the drawings or to the dimensions cast,
whichever is the smaller. Concrete will be measured by volume calculated from the mean
thickness as cast.
Separate items will be scheduled for each type or grade of concrete.
The unit rates shall cover the cost of the design of the mix, the provision of concrete, mixing,
testing, placing, compacting, the forming of stop-ends, and unforseen construction joints, striking-
off or levelling as applicable, and curing and repairing where necessary.
7.2 Payment
7.2.1 Formwork (the class and position of formwork to be stated) ................................................ M2
(If the depth of formwork is stated) .................. M
7.2.2 Reinforcement
7.2.2.1 Steel bars (type of steel to be stated) ................ t
7.2.2.2 High Tensile Welded Mesh (grade to be stated) .......... M2
7.2.3 Concrete Slab (grade of concrete be stated) ........... M3
7.2.4 Surface Finishes (class of finish to be stated) ........ M2
7.2.5 Joints ................................................. M
Separate items to be scheduled for contraction and expansion joints of different types and sizes.
The unit rate shall cover the cost of all materials and labour for the construction of each joint as
specified or shown on the drawings.
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