SPECIAL SPECIFICATION 5168 Precast Prestressed Concrete Pavement for a Weigh-In-Motion (WIM) System

Transcription

1 2004 Specifications CSJ SPECIAL SPECIFICATION 5168 Precast Prestressed Concrete Pavement for a Weigh-In-Motion (WIM) System 1. Description. Fabricate and construct a precast prestressed concrete pavement for a Weigh- In-Motion (WIM) System. This Item covers fabrication of the precast panels, transportion to the jobsite, remove the existing pavement and place hot mix asphalt leveling course. Install post-tensioning, grout the tendons, underslab grout, and diamond grind the pavement surface. The prestressed pavement system consists of panels pretensioned during fabrication and post-tensioned in place. Panels refer to the individual precast panels. Slab refers to a continuous section of precast panels post-tensioned together between expansion joints. 2. Materials. Provide new materials that comply with the details shown on the plans, the requirements of this Item, and the pertinent requirements of the following Items: Item 360, Concrete Pavement Item 420, Concrete Structures Item 421, Hydraulic Cement Concrete Item 424, Precast Concrete Structures (Fabrication) Item 425, Precast Prestressed Concrete Structural Members Item 426, Prestressing Item 427, Surface Finishes for Concrete Item 440, Reinforcing Steel Item 454, Bridge Expansion Joints Item 585, Ride Quality for Pavement Surfaces Item 618, Conduit Special Specification, Grinding Concrete Pavement DMS-6100, Epoxies and Adhesives 3. Equipment. Provide the necessary equipment for all work including but not limited to fabrication and handling of the precast panels at the fabrication plant; transportation of the precast panels to the jobsite; handling of the panels at the jobsite; removal of the existing pavement; placement of the hot-mix asphalt leveling course; post-tensioning of the precast panels; underslab grouting; post-tensioning tendon grouting; and diamond grinding of the pavement surface. 4. Construction. Construction encompasses fabrication the precast panels at an approved fabrication plant, transportion of the panels to the jobsite, removal of the existing pavement, placement of the leveling course, installation of the panels, post-tensioning, grouting, and diamond grinding

2 A. Panel Fabrication. Fabricate and store precast panels at an approved fabrication plant in accordance with Item 424, Precast Concrete Structures (Fabrication), Item 425, Precast Prestressed Concrete Structural Members, and the requirements given below: 1. Tolerances. Ensure precast panels, regardless of type, meet the tolerances given below in Table 1. Table 1 Tolerances for Precast Panels Length (parallel to long axis of panel) ± 1/4 Width (normal to long axis of panel) ± 1/8 Nominal Thickness ± 1/16 Squareness (difference in measurement from ± 1/8 corner to corner across top surface, measured diagonally) Horizontal Alignment (upon release of stress) ± 1/8 Deviation from straightness of mating edge of panels Vertical Alignment Camber (upon release of ± 1/8 stress) Deviation of ends (horizontal skew) ± 1/8 Deviation of ends (vertical batter) ± 1/8 Keyway Dimensional Tolerance ± 1/16 Position of Strands ± 1/8 Vertical 1 ± 1/4 Horizontal Position of post-tensioning ducts at mating edges ± 1/8 Vertical 1 ± 1/8 Horizontal Straightness of post-tensioning ducts ± 1/4 Vertical 1 ± 1/4 Horizontal ± 1/8 1 Vertical Dowel Alignment (parallel to bottom of panel) Horizontal Dowel Alignment (normal to ± 1/8 expansion joint) Dowel Location (deviation from shop ± 1/4 Vertical 1 drawings) ± 1/4 Horizontal Dowel Embedment (in either side of expansion ± 1 joint) Position of drainage and electrical conduit ± 1/2 Straightness of drainage and electrical conduit ± 1/2 Vertical 1 ± 1/2 Horizontal Position of lifting anchors ± 3 Position of non-prestressed reinforcement ± 1/4 Straightness of expansion joints ± 1/8 Initial width of expansion joints ± 1/8 Dimensions of blockouts/pockets ± 1/8 1. Measured from bottom of panel 2. Concrete Mix. Provide a concrete mix with the strength requirements set forth in the plans. If minimum strength is not specified in the plans, the minimum compressive at release will be 3,500 psi, and 5,000 psi at 28 days. Provide a mix that is workable enough to achieve the required surface finish described below. The Contractor must approve the coarse aggregate to be used by the precast fabricator

3 3. Pretensioning. Provide pretensioning materials and procedures conforming to Item 424, Precast Concrete Structures (Fabrication) and Item 426, Prestressing. Unless otherwise shown on the plans, use 7-wire low-relaxation pretensioning strand, as given by Item Dowels and Expansion Joints. Submit the expansion joint detail and materials to the Engineer for approval prior to fabrication of the Joint Panels. Provide an expansion joint that will be able to withstand the expansion and compression and traffic loading requirements specified on the plans. Provide dowels for the expansion joints that conform to the requirements of Item 360, Concrete Pavement. Unless otherwise specified on the plans, use dowels that are either stainless steel clad or epoxy coated. Coat the entire length of the dowel with an approved grease, hot applied asphalt cement, or other approved material, as per Item 360. Ensure that dowels remain parallel to the bottom surface of the panel and normal to the expansion joint during casting. Unless otherwise shown on the plans, provide a minimum length of dowel embedded in the Joint Panel on either side of the expansion joint of one-half the length of the dowel minus one-half the specified initial width of the expansion joint. If specified in the plans, provide dowel expansion caps that have been approved prior to use and conform to Item 360, Concrete Pavement. Ensure free movement of the dowel end is as specified on the plans. 5. Finishing. Unless otherwise shown on the plans, apply a carpet drag texture finish to the top surface of the panels (driving surface), as per Item 360, Concrete Pavement. Apply the texture in a timely manner after final screeding so the desired texture depth in achieved without disturbing the underlying concrete or turning over aggregate. Apply the surface texture either parallel or normal to the long axis of the panel, as directed. 6. Placement in Forms. Place concrete in the forms in accordance with Item 424, Precast Concrete Structures. Place concrete in a single lift and distribute in such a manner that embedded items such as reinforcement, ducts, dowels, anchors, and lifting devices are not dislodged by the concrete mass. Properly consolidate the concrete such that honeycombing or segregation does not occur and all spaces around embedded items and around the panel forms are filled. 7. Curing. Cure the precast panels in accordance to Item 424, Precast Concrete Structures (Fabrication). Submit the proposed curing methods and procedures for approval prior to placing concrete. Begin curing immediately following surface finish texturing. Membrane curing, in accordance with Item 360, Concrete Pavement is permitted at the discretion of the Engineer. If membrane curing is used, apply a minimum 2 applications of the curing membrane immediately after surface texture finishing. Remove membrane curing residue from all adjoining surfaces prior to shipment such that the bond between the epoxy and concrete in the joints between panels is not affected

4 Maintain curing for a minimum of 72 hours from the beginning of curing operations on the sides and top surface of the panels. While in the forms, the forms will be considered to provide adequate curing for the edges (vertical faces) of the panels. If any part of the form is removed, apply curing to the exposed surface as described above. Ensure curing for any given panel is not interrupted for more than 4 hours during removal of panels from the forms to the storage area. 8. Removal from Forms and Storage. Ensure no damage occurs to the panels when removed from the forms. Handle and store panels in accordance with Item 425, Precast Prestressed Concrete Structural Members. Ensure damage does not occur to either the panels or blockouts when removing materials forming blockouts from the panel. Store panels so adequate support is provided to prevent cracking or creep-induced deformation (sagging). Stack panels no higher than 5 panels per stack, with adequate support between panels. Store panels so individual panels or stacks of panels are not touching one another. For panels stored for long periods of time (longer than one month), check the panels for creep-induced deformation at least once per month. 9. Unobstructed Ducts and Conduit. After removal from the forms and prior to shipment, check for obstructions in all post-tensioning ducts and embedded conduits. Check the post-tensioning ducts by feeding a post-tensioning strand of the same size or greater as that specified for actual post-tensioning completely through each duct. If the strand does not slide freely through the duct, remedy the cause of the obstruction, at the expense of the Contractor, before the panel is shipped. Check embedded conduit for obstructions in accordance with Item 618, Conduit. 10. Lifting and Handling. Handle panels so the panels are not damaged during lifting or moving. Use the lifting anchors cast into the panels lifting and moving the panels at the fabrication plant. Ensure that the angle between the top surface of the panel and the lifting line is not be less than 60, when measured from the top surface of the panel to the lifting line. Secure the two halves of each Joint Panel together so the expansion joint remains closed or at a uniform specified width during handling and transportation. Submit a plan for securing the 2 halves of the Joint Panel together for approval prior to fabrication of the Joint Panels. Ensure the fastening technique will not rely upon the dowel bars to resist hinging at the expansion joint. Repair damage caused to Joint Panels as a result of inadequate bracing, including bending of dowel bars, at the expense of the Contractor to the satisfaction of the Engineer. 11. Transportation. Transport panels in such a manner as to not damage the panel during transportation. Properly support panels during transportation such that cracking or deformation (sagging) does not occur. If more than one panel is transported, provide proper support and separation between the individual panels. Panels will be lying horizontally during transportation, unless otherwise approved. 12. Repairs. Repairs of damage caused to the panels during fabrication, lifting and handling, or transportation will be addressed on a case-by-case basis, and in

5 accordance with Item 424, Precast Concrete Structures (Fabrication). Repair damage (within acceptable limits) caused to the top surface (driving surface) or to keyed edges of the panels using an approved repair method at the fabrication plant at the expense of the Contractor. Repetitive damage to panels will be cause for stoppage of fabrication operations until the cause of the damage is remedied. 13. Demonstration of Panel Fit. Initially fabricate only 3 panels and assemble these panels at the fabrication plant to demonstrate the fit of the panels. Assemble the panels over a level surface that will not cause damage to the panels during or after assembly. Post-tensioning is not required for this trial assembly, and epoxy is not required in the joints between panels. Ensure that joints between panels are not more than 1/4-in. wide when assembled. Correct any imperfections that cause problems with fitting the panels prior to proceeding with panel fabrication. Commence panel fabrication following the trial assembly only upon approval. B. Base Preparation. Place the precast panels over a prepared surface as shown on the plans Ensure the surface is free from debris and other materials that may prevent the panels from fully resting on the base. 1. Base Material. Install the precast panels over either the existing base material or a new asphaltic or cementitious material as shown on the plans. Ensure the material has the drainage characteristics required by the Department. 2. Grade Control for Placement. Establish grade control for placement of the base material to ensure long-wavelength roughness is not built into the base. Establish grade control using stringlines, laser guidance, or other comparable methods. Grade control methods must be approved prior commencement of base preparation. 3. Smoothness. Ensure the finished surface of the prepared base will provide full support beneath the panels. Check the smoothness of the finished surface of the base in accordance with Item 585, Ride Quality for Pavement Surfaces using Test Type A. Use a 20 ft. straightedge instead of a 10 ft. straightedge, and ensure that the variation of the surface will be such that a 6 in. diameter circular plate, in. thick cannot be passed beneath the straightedge. Correct areas of the base surface not conforming to this smoothness requirement at the Contractor s expense to the satisfaction of the Engineer. C. Panel Installation on Site. 1. Equipment. Provide all necessary equipment required for panel installation, posttensioning, and grouting on site prior to commencement of panel installation. Ensure that lifting and transporting equipment does not damage the prepared base prior to or during panel installation. Repair damage to the prepared base at the Contractor s expense to the satisfaction of the Engineer. 2. Polyethylene Sheeting. Place polyethylene sheeting between the prepared base and the precast panels as shown on the plans. Use a single layer of polyethylene sheeting with a minimum thickness of 6 mils (0.006 in.), unless otherwise

6 specified. Ensure there are no folds or creases in the sheeting beneath the panels. Clear the surface of the prepared base of loose debris, which may puncture the polyethylene sheeting, prior to placement of the polyethylene sheeting. Repair tears or punctures in the polyethylene sheeting to the satisfaction of the Engineer prior to placement of the precast panels over the sheeting. Prevent the polyethylene sheeting from becoming pinched in the joints between individual precast panels during panel installation. 3. Temporary Post-Tensioning. Provide temporary post-tensioning as shown on the plans during panel installation. Unless otherwise specified on the plans, apply temporary post-tensioning after placement of no more than 2 adjacent panels. Space temporary post-tensioning tendons no more than 20 ft. apart and no more than 10 ft. from the edge of the panels, as measured across the width of the pavement. Repair any damage to the precast panels caused by temporary posttensioning operations at the Contractor s expense to the satisfaction of the Engineer prior to installation of additional panels. 4. Joint Epoxy. Unless otherwise shown on the plans, apply epoxy to the adjoining surfaces of the precast panels prior to assembly. Use an epoxy material conforming to the requirements of DMS-6100, Epoxy and Adhesives, for a Type I (Precast Concrete Segment Adhesive), Type V or Type VII (Concrete Adhesives) epoxy, proportioned and applied according to the manufacturer s recommendations. Apply epoxy to both faces of adjoining panels, and keep epoxy a minimum of 1/2 in. away from duct openings. Use an epoxy with a set time that will permit final post-tensioning to be completed before the epoxy hardens. Remove any excess epoxy squeezed out of the joint onto the surface of the precast pavement during assembly or post-tensioning before it hardens. 5. Placement Technique. Install panels one at a time, and in such a manner that neither the base material nor the polyethylene sheeting is damaged during installation. Ensure that the angle between the top surface of the panel and the lifting line attached to each lifting anchor is not less than 60, when measured from the horizontal surface of the panel to the lifting line. Aligned in the longitudinal direction (parallel to the roadway centerline) using the centerline of the panels, mark the centerline of each panel on the top surface of the panel at the adjoining edges. Determine the location of the centerline on each panel from the location of the post-tensioning duct openings at the adjoining edges of the panels (not from the ends of the panels). If necessary, pull panels together during placement using approved temporary devices. Repair damage to the panels caused by temporary devices at the Contractor s expense to the satisfaction of the Engineer. Align the centerline of the panels to a line laid out by a surveyor (provided by the Contractor) on the surface of the base prior to placement of the panels. If necessary, use shims in the joints between panels to correct horizontal misalignment of the centerline of the panels. Ensure that the total thickness of shims used in any joint

7 will be no more than 1/8-inch. Repair damage caused to the panels by shims at the Contractor s expense to the satisfaction of the Engineer. 6. Placement Tolerances. Unless otherwise indicated on the plans, place the centerline of all precast panels to within 1/4-in. of the pre-surveyed centerline marked on the surface of the base, and the centerline of adjoining panels to within 1/8-in. of each other at the adjoining edge. For vertical alignment, ensure that the top surface of an individual panel is no more than 3/16-in. higher or lower than the top surface of an adjoining panel at any point along the joint between the panels. Ensure that the width of the gap between adjoining panels at the top surface of the joint is no more than 1/8-in. after completion of temporary post-tensioning. 7. Expansion Joints. Provide an expansion joint seal conforming to the requirements of DMS-6310, Joint Sealants and Fillers, for a Class 6 or Class 7 joint seal, and Item 454, Bridge Expansion Joints. When a Header-Type Expansion Joint is specified on the plans, install the header material at the fabrication plant prior to shipment of the panel, unless approved for installation at the job site. Unless otherwise specified on the plans, install the expansion joint seals following final post-tensioning and prior to opening the pavement to traffic. Adjust the width of the expansion joints after final post-tensioning to that specified on the plans. 8. Cover Plate/Edge Drain for Expansion Joints. Provide cover plates or edge drains at both ends of each expansion joint as shown on the plans. Install a cover plate with an edge drain at the low end of the expansion joint and a solid cover plate at the high end of the expansion joint. Install cover plates such that they do not inhibit free movement of the expansion joint. Clean expansion joints of debris prior to installation of cover plates/edge drains. 9. Repairs and Patching. Repair damage caused to the precast panels during any part of the panel installation process at the Contractor s expense to the satisfaction of the Engineer. Repairs of damaged areas will be addressed on a case-by-case basis by the Engineer. Repair damage within acceptable limits caused to the top surface (driving surface) or to keyed edges of the panels using an approved repair method. Repetitive damage to panels will be cause for stoppage of installation operations until the cause of the damage can be remedied. Patch post-tensioning anchor access pockets, lifting anchor recesses, and all other recesses using approved patching materials and methods. 10. Voids Beneath Pavement. Inspect the pavement during panel placement for voids beneath the precast panels. At the discretion of the Engineer, the Contractor will be required to stop panel installation and correct imperfections in the base material causing voids beneath the precast panels. 11. Matching Existing Pavement. Tie the precast panels into the existing pavement as shown on the plans. Raise or lower the surface of the existing pavement as required to match the top surface of the precast pavement such that the existing pavement is no more than 1/8-in. above or below the surface of the precast pavement

8 12. Mid-Slab and End-Slab Anchors. Mid-slab and end-slab anchors will be provided as shown on the plans to tie the precast pavement slab to the existing subbase. The mid-slab and end-slab anchors will prevent movement of the pavement slab at the anchor point over the life of the pavement. D. Post-Tensioning. Provide post-tensioning materials and procedures conforming to Item 426, Prestressing. Use the post-tensioning system shown in the plans, unless a comparable system is approved for use. 1. Materials. Unless otherwise shown on the plans, use low-relaxation strands for post-tensioning, as per Item 426, Prestressing. Use corrugated polypropylene ducts with an inside diameter at least 3/8-in. larger than the nominal diameter of the post-tensioning strand. 2. Strand Insertion. Insert post-tensioning strands into the ducts as shown on the plans. Push or pull the strands through the ducts by hand or using an approved mechanical strand pusher. Prevent separation of the individual wires from the strand during strand insertion. If transverse (normal to the roadway centerline) post-tensioning is specified in the plans, fully insert transverse post-tensioning strands into the ducts prior to stressing of the longitudinal (parallel to the roadway centerline) tendons. 3. Tendon Stressing. Obtain approval of the tendon stressing sequence prior to the start of post-tensioning. Complete stressing will be completed in one stage unless otherwise specified. Stress longitudinal tendons (parallel to the roadway centerline) by starting with a tendon at or near the midpoint of the panels, subsequently alternating between the tendons on either side of the centerline until all tendons have been stressed. For stressing of transverse tendons (normal to roadway centerline), start with the tendons nearest the middle of the slab, subsequently alternating to tendons to either side of the midpoint until all tendons have been stressed. Stress tendons to the magnitude specified in the plans. Measure and record individual tendon elongations during stressing in accordance with Item 426, Prestressing. After completion of post-tensioning, trim the tails of the post-tensioning strands and use an approved grease cap to cover and seal the end of the strand and posttensioning anchor. 4. Faulty Anchors or Tendons. In the event of a faulty post-tensioning anchor or tendon, submit a repair or alternate stressing strategy for approval. E. Tendon Grouting. Unless otherwise shown on the plans, the post-tensioning system will consist of grouted tendons conforming to Item 426, Prestressing. 1. Grout Mixture. Provide grouting materials conforming to Item 426, Prestressing. Use a pre-packaged grout specifically manufactured for prestressed tendon grouting, approved by the Department prior to use. Proportion the grout with water according to the manufacturer s recommendations. Provide water conforming to Item 421, Hydraulic Cement Concrete

9 Use grout ports that are compatible with the tendon ducts, providing a water-tight seal between the duct and port. Use grout ports with a minimum inside diameter of 1/2-in. Ensure that grout ports do not protrude from the finished surface of the precast panels as per Item 426, Prestressing, and are located as shown on the plans. Unless otherwise specified, locate grout ports at the extreme ends of each tendon, and not more than 50 ft. apart between the ends. 2. Grouting Equipment. Provide grouting equipment conforming to the requirements of Item 426, Prestressing, consisting of at least the following: Equipment for accurately measuring and proportioning by volume or weight the various materials composing the grout, A colloidal mixer, capable of operating in a range from 800 rpm to 2,000 rpm and thoroughly mixing the various components of the grout in an approved manner, A positive action pump capable of forcing grout into the post-tensioning ducts. The injection pump will be capable of continuous pumping at rates as low as 1-1/2 gal. per minute, A discharge line equipped with a positive cut-off valve at the nozzle end, and a bypass return line for recirculating the grout back into a holding tank or mixer unless otherwise approved, and A stop watch and flow cone conforming to the dimensions and other requirements of Test Method Tex-437-A, Method of Test for Flow of Grout Mixtures (Flow-Cone Method). 3. Grouting Procedures. Conduct grouting in accordance with Item 426, Prestresing. Submit a grouting plan for approval at least 4 weeks before starting grouting operations, in accordance with Item 426. Complete grouting within 7 days after stressing of the post-tensioning tendons. Do not begin grouting until all central stressing pockets and anchor access pockets have been patched. Check the grout fluidity, bleed, and strength in accordance with Item 426. Ensure efflux time for fluidity is between 11 seconds and 30 seconds after mixing, but no more or less than recommended by the manufacturer. Adjust the fluidity of the grout to achieve the necessary flow requirements to achieve fully grouted tendons. If excessive bleeding of the grout is observed, adjust the grout mixture as directed by the Engineer. Collect samples for grout compressive strength determination at least once per day during grouting operations. Cast a minimum of three strength cubes during each sampling. Test the compressive strength of the cubes in accordance with test method Tex-442-A, and ensure that the average compressive strength of 3 cubes is a minimum of 5,000 psi at 28 days. Pump grout into the lowest end of the tendon at the end port. Ensure that grouting pressure does not exceed the bursting pressure of the duct and port connection or 145 psi, whichever is less. If grout does not flow from the nearest intermediate port after the maximum grouting pressure has been reached, pump grout into intermediate ports as needed

10 Produce a diagram of grout flow to demonstrate full grouting of the tendons. 4. Grouting Problems. If grout is observed leaking into an expansion joint, from the end of a joint between panels, from beneath the slab, or out of an adjacent duct, discontinue grouting and pump grout into the nearest intermediate port. Flush grout that flows into an expansion joint immediately. Remove any grout that hardens in an expansion joint at the Contractor s expense. 5. Cleanup. Upon completion of grouting, fill recesses in the surface of the panels at the grout ports with an approved mortar and finish to the satisfaction of the Engineer, as per Item 426, Prestressing. Immediately flush grout that flows onto the finished surface of the pavement during the grouting operation. Remove residual grout which hardens on the pavement surface using an approved technique to the satisfaction of the Engineer at the expense of the Contractor. F. Underslab Grouting. Perform underslab grouting to fill voids beneath the precast panels that may be present after placing the panels over the prepared base. Utilize the grout channels and ports shown in the plans for underslab grouting. 1. Grouting Materials. Furnish materials for a grout mixture consisting of Type I, II or III Portland cement, a fluidifier, fly ash and water. Provide a fluidifier as a cement dispersing agent possessing such characteristics that will inhibit early stiffening of the pumpable mortar, tend to hold the solid constituents of the fluid mortar in suspension and prevent completely all setting shrinkage of the grout. Water will conform to Item 421, "Hydraulic Cement Concrete". Use Class C fly ash, meeting the requirements of DMS Select the fly ash to be used from a list of approved sources maintained by the Materials and Pavement Section, Construction Division. 2. Grouting Equipment. Provide grouting equipment similar to that used for tendon grouting. The equipment will consist of at least the following: Equipment for accurately measuring and proportioning by volume or weight the various materials composing the grout, A colloidal mixer, capable of operating in a range from 800 rpm to 2,000 rpm and thoroughly mixing the various components of the grout in an approved manner, A positive action pump capable of forcing grout through grout holes in the slab and into voids and cavities beneath the pavement slab. The injection pump will be capable of continuous pumping at rates as low as 1-1/2 gal. per minute, A discharge line equipped with a positive cut-off valve at the nozzle end, and a bypass return line for recirculating the grout back into a holding tank or mixer unless otherwise approved, and A stop watch and flow cone conforming to the dimensions and other requirements of Test Method Tex-437-A, Method of Test for Flow of Grout Mixtures (Flow-Cone Method)

11 3. Proportioning Grout Mixture. Provide a grout mixture, herein referred to as Grout Slurry, consisting of proportions of Portland cement, fly ash, fluidifier and water. Furnish the Engineer the proposed mix design meeting the following requirements: The grout slurry will remain fluid and not exhibit a resistance to flow for a minimum of one hour, The time of efflux from the flow cone will be between 10 and 20 seconds. The flow test will be performed in accordance with Test Method Tex-437-A, Method of Test for Flow of Grout Mixtures (Flow-Cone Method), The grout slurry will achieve initial set in less than 4 hours. The grout slurry will not be allowed to carry traffic until which time it has set to the satisfaction of the Engineer; or until which set time, as determined with Test Method Tex-302- D, Time of Setting of Hydraulic Cement by Gillmore Needles, has been reached, and The 7 day compressive strength of the grout slurry will not be less than 200 psi. The compressive strength will be determined in accordance with Test Method Tex-307-D, Compressive Strength of Hydraulic Cement Mortars. 4. Procedures. Conduct underslab grouting after stressing of the post-tensioning tendons, but not more than 7 days after placement of the precast panels. The Engineer may require grouting to be completed prior to opening the pavement to traffic if voids observed during panel placement are deemed to be detrimental to pavement performance under traffic loading. Complete underslab grouting prior to tendon grouting only if underslab grouting will not interfere with tendon grouting. Backfill or seal slab edges to prevent grout leakage from beneath the slab during underslab grouting. Seal the bottom of all expansion joints prior to underslab grouting to prevent grout leakage into the joints. Use a sealant material which will be compressible such that it will not inhibit free movement of the expansion joints. Use minimal pressure to force the grout beneath the pavement slab. Under no circumstances should underslab grouting cause the pavement slab to lift. Pump grout into the port at the lowest end of each grout channel in each panel. Pump grout until it flows out of the nearest grout port along the same grout channel, or until the line pressure on the grout pump reaches 5 psi. Grouting pressure of 5 psi may be exceeded if the Contractor can demonstrate that slab lift is not occurring at higher pressures. If grout does not flow from the nearest intermediate port after the maximum grouting pressure has been reached, pump grout into the nearest port until grouting is completed to the satisfaction of the Engineer. Check the fluidity of the grout at the beginning of each grouting operation and after each time the grout pump is flushed. Measure grout fluidity in accordance with test method Tex-437-A, Test for Flow of Grout Mixtures (Flow Cone Method). Adjust fluidity to achieve the necessary flow requirements to achieve full undersealing. If excessive bleeding of the grout is observed, the Engineer may require the Contractor to adjust the grout mixture. 5. Grouting Problems. If grout is observed leaking into an expansion joint, from beneath the slab, or out of an adjacent port, discontinue grouting from the current

12 port and pump grout into the nearest intermediate port. Flush grout that flows into an expansion joint immediately. Remove any grout that sets up in an expansion joint at the Contractor s expense. 6. Cleanup. Upon completion of grouting, fill recesses in the surface of the panels at the grout ports with an approved mortar and finish to the satisfaction of the Engineer, as per Item 426, Prestressing. Immediately flush grout that flows onto the finished surface of the pavement during the grouting operation. Remove residual grout which hardens on the pavement surface using an approved technique to the satisfaction of the Engineer at the expense of the Contractor. G. Finished Surface. Ensure a finished pavement surface that meets the smoothness requirements for the WIM system given below prior to installation of the WIM system. 1. Diamond Grinding. Diamond grind the entire area of the pavement surface after completion of post-tensioning, prior to installation of the WIM System, in accordance with the requirements of Special Specification, Grinding Concrete Pavement, and Item 360, Concrete Pavement. In addition to grinding the new precast pavement, diamond grind the existing pavement 25 ft. in advance of and 25 ft. following the new pavement. Ensure that no more than 1/2 in. of concrete is removed from the surface of the pavement within 10 ft. of the WIM loop detectors and WIM frame blockouts during diamond grinding. Perform grinding with abrasive grinding equipment, designed specifically for grinding pavement surfaces to close tolerances, utilizing diamond cutting blades with a minimum cutting width of 36 in. Ensure grinding equipment will accurately establish slope elevations and profile grade controls. Ensure ground surfaces are not smooth or polished. Pick up residue from grinding operation by means of a vacuum attachment to the grinding machine that will prevent it from flowing across the pavement and from being left on the surface of the pavement. Submit a plan for removal of the grinding residue for approval prior to the beginning of grinding operations, as per Special Specification, Grinding Concrete Pavement. 2. Temporary Patch for WIM Blockouts. Temporarily patch the blockouts for the WIM scale frames (in the WIM Panels ) prior to diamond grinding. Unless otherwise shown in the plans, use a cementitious material for the temporary patch that will adequately support the diamond grinding equipment without deformation and will be suitable for diamond grinding. Install the temporary patch at the fabrication plant prior to shipment of the WIM Panels. Finish the patch so the surface of the patch is flush with the surface of the surrounding precast panel. Use a plastic liner or similar bond-breaking material to line the blockouts to prevent the patch material from bonding to the hardened concrete. Provide reinforcement as needed to keep the patch intact when removed. Cast lifting devices into the patch to allow removal of the patch on site. Recess lifting devices a minimum of 1/2 in. so as not to interfere with the diamond grinding equipment. Remove the temporary patch only after completion of diamond grinding, and ensure damage does not

13 occur to the pavement surface when removed. Repair any damage to the surface of the pavement to the satisfaction of the Engineer at the Contractor s expense. 3. Ride Quality. Ensure a finished ride quality after diamond grinding that meets the smoothness requirements given in Special Specification, Grinding Concrete Pavement, using a 20 ft. straightedge for measurement. The surface ride quality measurement will be conducted by the Contractor. H. Installation of WIM Scales. Upon achieving the smoothness requirements given above, install the WIM scales in accordance with Special Specification, Install Weighin-Motion (WIM) Equipment. During installation of the WIM system, ensure the finished surface of the precast pavement is not damaged. Also ensure protection of the integrity of the prestressed system. Repair damage sustained to the finished surface, post-tensioning tendons, or pretensioning strands at the expense of the Contractor to the satisfaction of the Engineer. 5. Measurement. This Item will be measured by the square yard of surface area of completed pavement. Completed pavement is pavement in place, post-tensioned, grouted, and diamond ground to the requirements given in this Special Specification. 6. Payment. The work performed and materials furnished in accordance with this Item and measured as provided under Measurement will be paid for at the unit price bid for Precast Concrete Pavement. This price will be full compensation for furnishing equipment, labor, materials, tools, and incidentals. Grinding Concrete Pavement will not be paid for directly and will be subsidiary to the pertinent bid items