The Portland Cement Concrete Rigid Pavement-PCCP Method Statement shall consist of the following: construction of unreinforced, dowel jointed, plain cement concrete pavement following specifications, quality, and in accordance with the lines, grades, and cross-sections shown on the approved drawings.
Plant and equipment, materials, and labor shall be furnished, and the engineer shall approve all operations associated with the work.
Field of Application
This Method Statement Portland Cement Concrete Rigid Pavement-PCCP is for the construction of a rigid pavement carriageway on the highway.
Schedule of Construction
The detailed program and schedule for the construction of Portland Cement Concrete Rigid Pavement-PCCP will be provided.
Safety and Risk Precaution
Adequate precautions must be taken to ensure the safety, health, and welfare of workers, as well as the prevention of damage to work, materials, and equipment.
To commence the work, the site must first be readied so that the work will not be obstructed or difficult to execute. Clearance of the site of asphaltic ripping materials, stumps, roots, shrubs, vegetation, waste, and other undesirable materials, as well as easy access to the working area for both manpower and equipment.
All public traffic must be diverted to the temporary access carriageway prior to the start of the construction. Depending on the site conditions and approval from the government regulatory office, the traffic diversion may be split into two or more roads.
Surveyor will lay out the pavement before and after the whole or partial excavation of the existing road structure, depending on the site conditions, and to verify that the pavement is in the correct location and grade. The consultant’s surveyor will mark out and inspect the axis and level at each stage of the pavement.
Concrete work in accordance with the contract.
Mild steel bars for tie bars and dowels: These shall meet the project’s specifications and requirements.
Pre-molded joint filler: Joint filler board for expansion joints proposed for use only at some abutting structures like bridges and culverts shall be of 20-25 mm thickness within a tolerance of ± 1.5 mm of firm compressible material and complying with specification.
There must be 25 mm less thickness in the slab than the thickness of the formwork within a tolerance of ± 3 mm and provided to the full width between the side forms. There shall be appropriate lengths, not to be less than one lane wide. Accurately drilled or punched holes for accommodating dowel bars ensure a snug fit on the dowel bars.
Joint sealing compound: The 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, it shall comply with AASHTO M282, and if cold applied, it shall comply with BS 5212 (Part 2).
Storage of materials:
Materials shall be stored according to specifications and as approved by the engineer. Store the materials in an appropriate place to prevent deterioration or contamination by foreign matter and ensure that they are of satisfactory quality and fit for the intended use.
A platform for stockpiling aggregates must be leveled with 15 cm. of water, mixed, and compacted granular sub-base material. There should be a slope and drain for the drainage of rainwater. The storage space should also allow easy inspection, removal, and storage of the materials.
Aggregates of different sizes should be stored in partitioned stack yards. All such materials, even if stored in approved storage areas, must undergo an acceptance test as per specifications prior to use.
Between the concrete slab and sub-base, a separation membrane must be used preferably polyethylene sheets. The separation membrane must be 125 microns thick impermeable, flat-laid plastic sheeting.
The sub-base must be cleaned using an air compressor before the separation membrane can be placed. Anywhere plastic sheets overlap, it must be at least 300mm. The contractors will replace any damaged sheets. The concrete nails may be used to attach the polyethylene membrane to the lower layer.
The drawings shall show exactly where and how to place joints. Joints should be constructed based on the functional requirements which are described in the following:
The location of the joints shall be taken precisely at the site before cutting with the mechanical saw. It is essential to ensure that the necessary cut depth is maintained from edge to edge of the pavement. Stagger the longitudinal and transverse joints in the pavement and sub-base so that they are not vertically overlapping and are at least 1m and 0.3m apart, respectively. It is recommended to saw joints with diamond-studded blades soon after the concrete has hardened so that the sawing-machine and personnel can operate without damaging the pavement texture. According to the season, sawing operations can begin as early as 6 to 8 hours.
A transverse joint should be a contraction joint and an expansion joint at the spacing described in the drawings.
Transverse joints must be straight within the following tolerances listed below. They should be parallel to the intended line of joint. This shall be the straight path traversing the carriageway at a position suggested by the contractor and approved by the engineer, except at intersections and roundabouts where the position is shown in the drawings.
a. The filler board in expansion joints must not deviate to ± 10 mm from the intended line of the joint.
b. The straight line that passes through the joints should not be more than 25 mm away from the intended joint line.
c. A deviation of 10 mm in the joint groove from the best-fit straight line of the joint is acceptable.
d. On each side of a longitudinal joint, the transverse joint must be in line with each other and of the same type and width. Transverse joints must have a sealing groove, which must conform to specifications.
Contraction joints shall be formed by mechanically sawed grooves that are 3 to 5 mm wide and 1/4 to 1/3 the depth of the slab x 5 mm, as specified and designated in the drawings, as well as dowel bars that comply with the project specifications.
The contraction joints should be cut once the concrete has been hardened. The concrete must be strong enough to withstand the joint sawing machine’s load without causing any damage to the slab.
The expansion joints must include a filler board and dowel bars that comply with specifications and as per detailed drawings. The filler board should be placed vertically with prefabricated joint assemblies along a line of the joint within the tolerances. It must also be at such depth below the surface that it will not hinder the passage of finishing straight edges and oscillating beams from paving machines. A joint filler board shall be used to separate the slabs adjacent. The space between the subbase and filler board, as well as the space around them, shall be filled with a compressible material that will block the flow of cement slurry.
Transverse Construction Joint
When concreting has been completed within a day or is suspended for longer than 30 minutes, transverse construction joints must be used. These joints will be placed at the regular position of contraction joints with dowel bars. The joint must be of the butt type. Steel bulkheads are used for concrete joints. Concrete laid after the previous pavement must conform to its grade and cross-sections. If the placement of the bulkhead/stop-end is impossible, concrete may be poured to an additional length of 1 to 2 m to allow the joint cutting machine to move. The joint grooves can be made and the extra length cut out after concrete has hardened.
According to the joint details in the drawing, the longitudinal joints must be saw cut. After the concrete has been set, the groove can be cut.
It is recommended that the joints are sawn at least 1/5 of the depth of the slab ± 5 mm as shown on the drawing.
At the longitudinal joints, tie bars should be provided as per the dimensions and spacing are shown in the drawing and per project specifications.
Dowel bars must be made of mild steel round with dimensions and details as shown in the drawing. They should also not contain oil, dirt, loose, or scale. They must be straight and free from any irregularities or burring that could cause slippage in concrete. The ends of the sliding bars must be cut or sawn straight with no protrusions beyond the normal size. The dowel bar must be supported by dowel chairs or cradles in a pre-fabricated joint assembly. These joints are either positioned before the construction of slabs or mechanically inserted into concrete with vibration using a method that ensures proper placement and complete recompaction.
Unless otherwise indicated on the drawings, dowel bar positions shall be at the mid-depth of the slab within a tolerance range of ± 20 mm and equally around the intended lines of the joint within a tolerance range of ± 25 mm. The dowel bars must be aligned parallel with the slab’s finished surface and the carriageway’s centerline. They should also be aligned to each other within the tolerances set forth below.
1) Bars supported on cradles before the slab:
a) All bars shall be laid within ± 3 mm per 300mm length of bars
b) 2/3rds of bars must be within ± 2 mm each 300mm lengths of bars
c) No bars should be aligned with an adjacent bar by more than 3 mm per 300mm length of bars in either the horizontal plane or vertical plane
d). Cradles supporting dowel bars shall not extend beyond the joint line. The joint shall not be crossed by any steel bars from the cradle assembly.
2) All bars that are inserted after the slab has been laid must have twice the tolerance as in (1).
When supported on cradles in assemblies and subjected to a load of 110 N applied vertically or horizontally (upwards and downwards, and both horizontally and vertically), dowel bars shall comply with the following.
i) Two-thirds of the bars in any assembly being tested shall not deflect more than 2 mm per 300 mm in length.
ii) The rest of the bars of that assembly must not deflect more than 3 mm for every 300 mm of the bar.
A thin plastic sheath covering dowel bars must be at least two-thirds the length of dowel bars in contraction joints. For expansion joints, the sheath should cover half the length plus 50mm. The sheath must be strong, durable, and not exceed 1.25mm in thickness.
A cap measuring 100mm in length and made of waterproofed cardboard, or an approved synthetic material such as PVC or GI pipe, shall be fitted over each dowel bar’s sheathed end for expansion joints. A compressible sponge should be used to create an expansion space between the cap’s end and the dowel bar’s end. Tape can be used to block cement slurry from entering between the cap and dowels.
Side Forms and Rails
Side forms must be made of mild steel at a depth equal to that of pavement, or slightly less to accommodate sub-bases surface regularity. To accommodate irregularities in the subbase, the forms can be placed on a series of steel packing plates. They must be strong enough to withstand the pressure and weight of paving equipment.
Side forms that are used with wheeled pavers must have metal rails fixed at a constant height above the forms. To prevent any movement, the rails and forms must be secured by no less than three stakes/pins for each length of 3 m.
While paving is taking place, forms and rails must be straight within a tolerance limit of 3 mm in each 3 m. Before each use, forms must be cleaned and oiled immediately. The forms must be positioned on a continuous, low-moisture cement mortar or concrete bed and should be set according to the lines and levels indicated on the drawings.
Tolerances of ± 10 mm and ± 3 mm are allowed. The bedding must not extend below the slab, and there should be no vertical steps between adjacent forms that exceed 3 mm. The consultant must inspect the forms and give his approval prior to the slab’s construction. They should not be removed for at least 12 hours after that time.
Always use sufficient forms and align them to at least 200m of pavement before the paving operations or for the expected length of pavement that will be laid in the next 24 hours, whichever comes first.
A guidewire must be installed along the slab’s sides for slip-form paving. The guide wires must be placed at the same height as the slab’s edges and within a vertical tolerance between ± 3mm and ± 3mm.
One of the wires must be maintained at a constant horizontal distance to the pavement’s required edge as specified in the contract/drawing. This tolerance should not exceed ± 10mm.
Guidewires must be supported on stakes no more than 8 m apart using connectors that can finely adjust horizontal and vertically. The guidewire must be tensioned to the stakes such that a 500-gram weight produces a maximum deflection of 20 mm when suspended at the midpoint between stakes. The guide wires’ ends must be attached to the fixing point or winch, not at the stakes.
From the time concrete is finished, the stakes must be placed and the connectors aligned correctly. This should take place between 2 and 12 hours. Before concreting any section, the guidewire must be installed and tensioned on all connectors for at least two hours.
The consultant shall approve the contractor’s line and level, as well as the stakes and connectors. These must be in place by the time the road is constructed.
The consultant/inspector may note any deficiencies and the contractor will rectify them. The inspector must approve all work before it can proceed.
When concreting is underway, it must be made sure that the guide wires and stakes are not damaged by the construction equipment.
Construction-Portland Cement Concrete Rigid Pavement (PCCP) Method Statement
The pavement may be constructed using a system approach. Before the work can begin, the Engineer must approve the Method Statement, which details all activities, including the indication of the time cycle, equipment, personnel, etc.
This shall include details about the type, make, and capacity of the batching and mixed plant as well as the hauling arrangement. For a minimum of 300 m per day, the capacity of batching and paving equipment as well as any ancillary equipment must be sufficient.
Batching and mixing
Batching and mixing concrete at a central plant equipped with automatic controls shall be performed. This plant should be located in a place that allows for adequate space to stockpile cement, aggregates, and stationary water tanks. However, this must be located at an approved distance taking into account the mix’s properties and transport arrangements with the contractor.
Paving and material proportioning equipment
In batching plants, materials should be proportioned by weight, with each material being weighed separately. Bulk cement can be weighed separately from aggregates and water shall be measured by volume.
Where properly graded aggregate of uniform quality cannot be maintained as per mix design, the grading of aggregates will be controlled by appropriate blending techniques. The batching and mixing plant’s capacity should be at least 25 percent greater than that of the paving/laying equipment.
Plants and equipment used in batching
The batching plant must include four bins, weighing hoppers, and scales for fine aggregate and coarse aggregate of each size. There should be a separate scale for cement if it is used in bulk. To prevent dust during operation, weighing hoppers should be adequately sealed and vented.
All personnel engaged in plant operations, inspections, and testing must be protected with approved safety devices. Batch plants must be equipped with a suitable non-resettable batch counter that will accurately display the number of batches proportioned.
Bins and hoppers
Batching plants must be equipped with bins that have a minimum number of four separate compartments.
Automatic weighing devices-
Automated weighing devices utilizing load cells shall be used in the batching plant to proportion aggregates and bulk cement.
Mixers should be panned, reversible, or any other type capable of thoroughly mixing and uniformizing the aggregates, cement, and water within the specific mixing period, discharging the mixture without segregation.
The stationary mixers shall be equipped with an approved timing device that will automatically lock the discharge lever after the drum has been charged and release it at the end of the mixing period. An audible signal shall be given each time the lock is released by a bell or other suitable warning device.
Should the timing device fail, the mixer can continue to be used until it is repaired, provided that each batch is mixed for 90 seconds or as per the manufacturer’s recommendation.
In order to correctly indicate the number of batches mixed, the mixer must be equipped with a non-resettable batch counter.
It is necessary to clean the mixers at regular intervals. Whenever the pickup and throw-over blades of the drum or drums are worn down by 20 mm or more, they shall be repaired or replaced.
Provide permanent markings on the blade to show 20 mm wear points resulting from new conditions, or supply a copy of the manufacturer’s design at the job site, showing dimensions and arrangements of blades.
As recommended, a hole of 5 mm diameter should be drilled near each end and at the midpoint of each blade.
Calibration shall be performed in the beginning, and thereafter at suitable intervals not exceeding 1 month.
The equipment shall be operated automatically by an air-conditioned control cabin.
Placement of the concrete shall be done with an approved fixed form or slip form paver with separate units that is designed to:
(ii) consolidate, screed and float-finish,
(iii) In addition, the freshly placed concrete must be texture and cured in one complete pass of the machine so that a minimum of hand finishing will be required and so that a dense and homogeneous pavement is provided in accordance with the plans and specifications.
In order to control/sensing line and grade the paver, electronic controls must be equipped on either or both sides of the machine.
Vibrators should operate from 8300 to 9600 impulses per minute under load with a maximum spacing of 60 cm. The machine shall include a variable vibration setting.
The Contractor shall provide an adequate number of diamond-edged saw blades for concrete saws. An electric saw machine or a petrol/diesel saw machine shall be used. Water tanks with flexible hoses and pumps should be made available for this activity on a priority basis.
At least one standby saw must be in good working order. Concreting work may not commence unless the saws are in working order.
Concrete hauling and placement
A sufficient number of trucks/tippers of sufficient capacity and approved design shall be used to transport fresh concrete from the batching and mixing plant to the paver site to ensure a constant supply.
A truck/tipper shall be capable of discharging mixed concrete in a homogeneous state and without segregation or loss of cement slurry. In order to maintain a uniform speed throughout the day’s work, the paver must be fed in such a manner that it is uninterrupted throughout the day.
Concrete shall be protected against the weather by covers.
Concrete that has been prepared in a central mixing plant must be quickly transported to the site.
Concrete that has been mixed for too long prior to laying shall be rejected by the consultant/inspector and removed from the site. When the concrete temperature is below 30oC, the total time from adding water to the mix for surface finishing and texturing should not exceed 120 minutes.
It will take 90 minutes if the concrete temperature is between 30oC-35 oC. Concrete trucks/tippers must not pass above the plastic sheeting or slabs that have been cast until after 28 days. The paver must be able to pave the carriageway in one pass and lift.
If fixed-form pavers will be used, the forms must be fixed in accordance with Specifications. The engineer must inspect the site before any paving can be done. This is to confirm the layout of the paving and to place tie-bars and dowels as required by this specification. Mixing and placing concrete must be done at a speed that allows proper finishing, protection, and curing.
In all cases, the temperature in concrete must be measured at the point where it is discharged from the delivery truck.
Water addition to concrete surfaces to aid in finishing operations is not permitted without the Engineer’s approval. It shall only be allowed if it is applied as a mist using approved equipment.
Engineers may require that paving machines be fitted with approved covers to protect the slab surface from direct sunlight, rain, or hot wind.
Brush the surface of the slab and apply the curing compound while the concrete is still plastic. The concrete slab must be marked at 100 m intervals with the chainage after the surface texturing but before the curing compounds are applied.
After the side forms have been removed, the edges of the slabs will be repaired if there are any irregularities. This can be done by using fine concrete consisting of 1 part cement to 3 parts fine chips and fine aggregate.
Construction with a fixed-form paver
The fixed-form paving trains will be composed of separate powered machines that spread, compact, and finish concrete in continuous operation.
The concrete shall be poured into a hopper spreader without segregation. This spreader is equipped with controls for the concrete’s rate of deposition onto the sub-base. The spreader must be used to strike off concrete to a level that does not require any cutting by the distributor. The concrete shall be spread by the distributor to the appropriate surcharge to ensure that the vibratory compressor compacts the layer.
Poker vibrators may be used in conjunction with the edges and side forms of the slab if necessary. The vibratory compactor should be used to strike the surface slightly higher so that the oscillating beam can cut it down to the required level. The machine must be able to adjust quickly for changes in the average or differential surcharge due to changes in slab thickness, cross fall, or other factors. The final finisher should be able to finish the surface to the specified level and smoothness. However, it is important to not add mortar to the surface through overworking.
Slip form paver construction
The power machine that compacts, finishes, and spreads the concrete will comprise the slip-form paving train. The slip-paving machine will compact concrete using internal vibrations and shape it between side forms using either a conforming plate, vibrating and oscillating finishing beams, or a conforming plate.
The concrete must be laid in front of a slip form paver, without segregation, across its entire width and up to a height that is not greater than the applicable surcharge. The concrete must be struck off according to the required average and differential surcharge using a strike plate or a screw-auger device that extends across the entire slab’s width.
The equipment used to strike-off concrete must be able to adjust quickly for any changes in slab thickness or cross falls.
The guide wires with sensors attached to the four comers on the slip form paver machine will control the level of the finishing beams and conforming plates. At least one set of sensors must be attached to the paver to control the alignment of the paver. An automatic control system shall determine the position and level of any ancillary equipment for finishing, texturing, curing concrete relative to the guidewire or the slab’s edge.
For slip-form paving machines, vibrators with variable output shall be used. They must produce a maximum of 2.5 KW per meter of slab width and 300 mm of slab depth. This will allow for a speed of 1.5 m/minute or pro-rata for faster speeds.
During concrete placing, the machines must possess sufficient mass to maintain forward movement in all conditions while performing spreading and paving operations on the traction units.
If the edges of the slip formed slab slump to the extent that the top edge of the slab does not meet the requirements, special measures will be taken by the Engineer to support the edges, and work should be stopped until the contractor can demonstrate that he can slip from the edges to the required levels.
Methodology of hand-guided construction: Areas in which hand-guided construction methods become indispensable shall be approved by the Engineer in advance in writing. However, such work may be permitted only in restricted areas and for short distances.
The work shall be performed by qualified personnel according to the engineering methods approved by him.
In addition, all other quality control measures such as level, thickness, surface regularity, texture, finish, the strength of concrete, etc. must be the same as they are with machine laid work.
Prior to the application of the curing membrane, the concrete slab shall be brush-textured in a direction perpendicular to the longitudinal axis of the carriageway.
A wire brush not less than 450 mm wide or longer is preferred for brushing the surface evenly across the slab in one direction. The brush shall be made from 32-gauge tape wires grouped in tufts spaced at 10 mm intervals. An average of 14 wires should be present in the tufts, and initially, they should be 100 mm long. There shall be two rows of tufts on the brush. The rows must be 20 mm apart, and the tufts in one row should be opposite the center of the gap between tufts in the other row. Replace the brush when the shortest tuft wears down to 90 mm.
Sand Patch Tests are used to determine texture depth. Every day’s paving must be tested at least once and whenever the Engineer deems it necessary after construction as follows:
At least five measurements of texture depth must be taken along a diagonal line between points 50 m apart along the pavement spaced at least 2 meters apart.
A concrete slab constructed in one pass shall not be measured within 300 mm of the longitudinal edge.
The depth of the surface should not be less than the minimum required when measurements are taken as shown in Table 1 nor greater than a maximum average depth of 1.25 mm.
|Time of Test||Number of|
Texture Depth (mm) -Specified Value
|During the first 24 hours or 7 days following the construction of the slab, or until the first vehicles are driven on it||Five measurements averaged||1.00||± 0.25|
|No later than six weeks prior to the opening of the road to traffic.||Five measurements averaged||1.00||+0.25|
A uniform appearance shall be achieved after the application of the brushed texture to the slab. To meet the texture depth requirements, the Contractor shall retexture the hardened concrete surface in a manner approved by the Engineer, across the full lane width and length.
As soon as the slab surface and its sides have been texturized, they should be coated with an approved resin-based, aluminized reflective curing compound, which hardens into an impervious film or membrane.
Curing compounds should contain sufficient flake aluminum in a finely divided dispersion to completely cover the sprayed surface. Within 60 minutes of application, the compound should become stable and impervious to the evaporation of water from the concrete surface. It must also be of an approved type.
According to BS Specification No. 7542, the curing compounds must have a water retention efficiency index of 90 percent.
After application of the curing compound, the film or membrane should not crack, peel, or disintegrate within three weeks. It is necessary to thoroughly agitate the curing compound in its containers prior to use.
When using the trial length, the rate of spread shall be in accordance with the manufacturer’s instructions, checked during construction, and subsequently as needed by the Engineer. During spraying, a mechanical sprayer shall incorporate an efficient mechanical device for continuous agitation and mixing of the compound.
In addition to spraying the curing compound on the fresh concrete surface, the finished concrete pavement should be covered with tents during adverse weather conditions, as directed by the Engineer. The pavement shall then be covered with moist hessian and kept damp for a minimum period of 14 days after which time the hessian may be removed. Hessian must be kept continuously moist. On a regular basis, all damaged/torn hessian must be removed and replaced with a new hessian.
It shall be the contractor’s responsibility to replace any concrete damaged due to incomplete curing or cracked on a line other than joint lines.
The trial length must be constructed at a minimum of one month ahead of the planned start date for the concrete paperwork. A minimum of one month before the start of construction on the trial length the contractor must submit to the Engineer’s approval, a complete procedure statement that describes the construction materials, equipment, equipment as well as construction procedures.
All major equipment such as the batching plant, paving train and tippers, etc. which are planned for the construction process must be cleared by the Engineer prior to the purchase.
Trials of new materials plant, equipment, or construction techniques, or any other development thereof, will be allowed in the course of construction of the trial lengths or during any subsequent paving work except when they are part of further trials that have been approved.
Trial lengths must be built away from the carriageway with the sub-base layer underneath.
The contractor shall present the materials such as plant, equipment, and construction techniques that are planned for concrete paving by first creating a trial slab that is at least 60 m in length but not more than 300 meters long for mechanized construction and at least 30 meters long for hand-guided techniques. If the initial trial proves unsatisfactory, the contractor shall prove his ability to construct the pavement in a satisfactory manner during subsequent trials.
The length of the trial must consist of two sections in a time frame that comprises at least a portion of two consecutive working days with the minimum of 30m constructed every day for mechanized construction, and at least 15 meters per day for hand-guided construction. The trial length should be built at a similar speed (speed approximately 1m/hr) similar to the one being planned for the main project.
Transverse and longitudinal joints of every type that are designed for unreinforced concrete slabs dowel-jointed in the main work must be built and evaluated during an initial trial duration. If during the trial length, the construction of an expansion joint or longitudinal joint is not shown the initial 2 expansion joints and, at a minimum, the first 150m of the longitudinal construction joint, for mechanized paving during the main work area, should be taken into consideration as the trial length of the joints.
The length of the trial shall be in line with the specification in all respects, with additional and supplementary requirements:
Levels of the surface and their regularity
i)Levels are taken at intervals between the points mentioned in this clause across any of the lines and lines parallel to the centerline that runs along the length of the trial.
ii.) the maximum amount of allowed irregularities of the pavement’s surface must comply with the standards. The shorter lengths of the trial are evaluated pro-rata on the basis of numbers for a 300m length.
i. Dowel bar alignment should be checked at any time in any two consecutive transverse joints. If the alignment or position of dowel bars at one of these joints fails to conform to the specifications, and this joint is the only one not conforming after the subsequent 3 joints of the identical kind have been examined, then the procedure of placing dowels will be considered satisfactory. To ensure that there are enough joints to ensure alignment of dowel bars without exaggerating the length of the trial or causing unnecessary inconvenience, the contractor can, in arrangement with Engineer build joints with greater intervals between joints that are greater than the standard spacing specified in the contract.
ii. If there is a defect in the initial expansion joint, which is built to test then the next joint will be one that is a trial joint. If this is also deficient additional trial expansion joints are constructed as pans for the duration of the trial. These will not be being part of the permanent work unless the engineer has agreed to it.
The position of tie bars the alignment and positioning of tie bars must be verified by drilling additional holes in the slab unless they are able to be determined by cores that have been taken to determine density.
Acceptance and approval
The approval of the materials plants, equipment, and construction methods will be granted when a trial length is in compliance with the specifications. The contractor will not commence normal work up to the time the duration of the trial is approved and any previous inadequate trial lengths were eliminated and if they are able to be rectified at the pleasure of the engineer. If the engineer fails to inform the contractor of any defects during any length of trial within seven days after the end of the trial, the contractor is entitled to assume that the trial duration as well as the materials, plant equipment, and construction techniques employed are suitable.
After approval has been granted that the plant, materials equipment, and construction techniques will not be altered in the future other than for adjustments that are normal and maintenance of plants, with the permission of the engineer. Any modifications in the materials and equipment, plant or materials, or construction methods will permit the Engineer to demand the contractor to lay a new trial length, as specified in this clause to show that the changes won’t negatively impact the ongoing works.
The Engineer shall immediately remove any trial length which does not comply with the specification, except for areas that are only deficient in surface texture and which can be remedied in accordance with the specifications, and the contractor shall construct a new trial length.
Checking the dowel bars
Measurements relative to side forms or guide wires are required to verify the position and alignment of dowel bars at construction and expansion joints.
After the slab has been constructed, the position and alignment of dowel bars and any filler boards must be measured after they have been carefully exposed in the plastic concrete across its width.
The top of the filler board should first be sufficiently exposed in the plastic concrete so that any vertical or lateral displacement of the board can be measured.
This measurement shall be carried out in the pavement section at the end of each day’s work by extending the slab length by 2 m.
After sawing the transverse joint groove, the extended slab should be removed carefully and dowels should be exposed over half the length.
Tolerances can be tested on these dowels
If a single joint in the slab has an unsatisfactory position and alignment of the bars, then the following two joints should be examined. When only one joint is defective of the three, the rate of checking shall be increased to one joint per day until the Engineer is satisfied that compliance has been achieved. A contractor who fails to comply in two or more successive joints shall build fresh trial lengths and make any necessary adjustments to the concrete mix, paving plant, or methods until the dowel bar position and alignment are satisfactory.
The remainder of the concrete should be removed over a width of 500 mm along the line of the joint and reinserted to the satisfaction of the engineer after the dowel bars have been examined. On both sides of the 1 m wide slab, dowels should be inserted through holes and grouted with epoxy mortar. A plastic sheath shall be attached to one of the joints. The groove of the joint shall be widened and sealed.
Joint groove preparation and sealing
Sealants must be used to seal all transverse joints in surface slabs. Sealants should not be applied 14 days after construction.
Joint groove preparation for sealing
Generally, when saw cut joints are used, the grooves are not constructed to provide the minimum width specified in the drawings. After sealing, they should be widened by sawing. To control the groove’s dimension, depth/width gauges must be used.
When grooves are made, rough arrises should be ground to create a chamfer approximately 5 mm in width. The overhanging edge of the sealing groove shall be sawn or ground perpendicular if the groove is at an angle of up to 10 degrees from perpendicular to the surface. It is required to saw the joint sealing groove wider and perpendicular to the surface to encompass defects up to a maximum width of 35 mm for transverse joints and 20 mm for longitudinal joints when spalling occurs or the angle of the former exceeds 10 degrees. If the spalling cannot be completely removed, then the arrises should be repaired by a thin bonded arris repair using cementitious materials.
All grooves should be blasted with filtered, oil-free compressed air to remove any dirt or loose material. When necessary, the Engineer may order cleaning by pressurized water jets. Depending on the sealant manufacturer, the sides of the grooves may need to be sandblasted to increase bonding between sealant and concrete.
When priming and sealing, the groove should be cleaned and dried.
It is necessary to remove the temporary seal provided for blocking dirt, soil, etc., before sealing. In the groove, a highly compressible, heat-resistant paper-backed debonding strip shall be inserted to serve the purpose of breaking the bond between the sealant and the groove bottom and to plug the joint groove so that the sealant does not leak through cracks. Debonding strips must be wider than joint grooves so they will fit snugly into the grooves. To prevent leakage through longitudinal joints, heat-resistant tapes can be inserted.
In addition to sealants, a primer should also be used if recommended by the manufacturer, and it should be applied as directed. The sealant should be applied within the manufacturer’s recommended minimum and maximum drying times. When the naturally occurring temperature in the joint groove to be sealed is below 10° C, priming and sealing with applied sealants should not be performed.
If the hot-applied sealant is used, it should be heated and applied from a thermostatically controlled, indirectly heated melter and pourer with recirculating pump and extruder. The sealant should be applied with an extruder with a flexible hose and nozzle for large road projects.
Sealants should not be heated to a temperature higher than the safe heating temperature or for a period longer than the safe heating period, as specified by the manufacturer. The dispenser should be cleaned every day in accordance with the manufacturer’s recommendations, and reheated material should not be used.
Sealants with chemical formulations such as polysulphide can be used as cold-applied sealants. These must be mixed and applied within the manufacturer’s time limit. Primers should be applied neatly with an appropriate brush if they are recommended. Movement Accommodation Factor (MAF) shall be greater than 10%.
Sealants applied during the contraction phase of the slabs would cause the sealant to bulge over and above the slab. Accordingly, the Contractor, in consultation with the Engineer, should determine the correct temperature and time for sealing. In order to facilitate control during sealing, a thermometer should be hung on a pole at the site.
Apply the sealant slightly lower than the slab with a tolerance of 5 ± 2 mm.
During sealing, it is important that no air bubbles are introduced into the sealant, either by vapors or by the sealing process itself.
Tests of applied sealants: A manufacturer’s certificate certifying that the sealant is not older than six months and that it meets the applicable standards must be provided by the contractor. For hot-applied sealant, the samples must meet the requirements of AASHTO M 282 or BS 5212: (Part-2) for cold-applied sealant.
Concrete pavements shall not be used for vehicular traffic for 28 days after construction and until the joints have been permanently sealed. Upon completion of the curing period of 28 days and the completion of joint sealing and construction of the shoulder, the road may be opened to regular traffic with the written permission of the engineer.
Surface Regularity, Level, Thickness, and Strength
Tolerances for surface regularity, level, thickness, and strength must conform to the requirements and specifications. The Engineer is responsible for ensuring the quality of materials and work.