412Section 412

412.01 This work consists of constructing a pavement composed of Portland Cement Concrete

on a prepared subgrade or base course per these specifications and in conformity with the lines, grades, thicknesses, and typical cross sections shown on the plans or established. MATERIALS

412.02 Materials shall meet the requirements of the following subsections:

Fine Aggregate 703.01 Coarse Aggregate 703.02 Portland Cement 701.01 Fly Ash 701.02 Water 712.01 Air- Entraining Admixtures 711.02 Joint Sealant with Backer Rod 705.01 Curing Materials 711.01 Reinforcing Steel 709.01 Chemical Admixtures 711.03 Dowel Bars and Tie Bars 709.03 CONSTRUCTION REQUIREMENTS

412.03 Classification . Concrete shall conform to the requirements for Class P concrete as

specified in Section 601. Fast track concrete pavement is accelerated Class P concrete.

412.04 Proportioning. Proportioning shall conform to the requirements of subsection 601.05.

412.05 Batching . Batching shall conform to the requirements of subsection 601.06.

The Contractor shall provide a Process Control Plan (PCP) to minimize voids in the concrete pavement, such as clay balls, mud balls and other deleterious materials. It shall also identify the Contractor’s method for ensuring that the provisions of the PCP are met. This PCP shall be submitted to the Engin eer at the Pre- construction Conference. Paving operations shall not begin until the Engineer has approved the PCP . This PCP shall identify and address issues affecting the quality of aggregates incorporated into the concrete mix including but not limited to:

412.06 Mixing . Mixing shall conform to the requirements of subsection 601.07.

412.07 Equipment . Equipment and tools shall be capable of handling materials,

performing the work, producing a product of specified quality, and shall be approved. The equipment shall be at the job site sufficiently ahead of the start of paving operations to be examined and approved.

412.08 Preparation of Subgrade . After the roadbed has been graded and compacted, the

subgrade shall be trimmed to the correct elevation and slope. For slip form paving, the elevation and slope of the trimmer shall be automatically controlled from outside reference lines established for this purpose. The trimmed subgrade shall extend at least 2 feet beyond each edge of the proposed concrete pavement when forms are used and at least 1 foot outside the track width of finishing, curing, and tining equipment for slip form operations. Any work required beyond the planned roadbed necessary to support the Contractor’s paving equipment or hauling vehicles, will not be paid for separately, but shall be included in the work. The subbase or base course shall be brought to the specified cross section. High areas shall be trimmed to the proper elevation. Low areas in untreated bases may be filled and compacted to a condition similar to that of the surrounding grade or filled with concrete integral with the pavement. Low areas in treated bases shall be filled with concrete integral with the pavement. The finished grade shall be maintained in a smooth and compacted condition until the pavement is placed. Untreated subgrade or base course shall be uniformly moist during concrete placement. If it becomes too dry, the untreated subgrade or base course shall be sprinkled without forming mud or pools of water.

412.09 Limitations of Placing Concrete. Limitations on the placing of concrete shall

conform to subsections 601.12 (b) and (c), and 412.15.

412.10 Placing Concrete . The concrete shall be uniformly deposited on the grade in a

manner that requires as little re- handling as possible. Concrete for areas that contain load transfer devices shall not be dumped directly from the hauling vehicles onto the grade. Concrete shall be placed by an approved placer spreader machine. Concrete shall be deposited as near to expansion and contraction joints as possible withou t disturbing them but shall not be dumped from the discharge bucket or hopper onto a joint assembly unless the dis charge is well centered on the joint assembly. Necessary hand spreading shall be done with Shovels, not rakes. Workers shall not walk -in freshly mixed concrete with footwear coated with earth or foreign substances. All footprints in the fresh concrete shal l be vibrated and finished flush with the adjacent surface. Construction equipment other than standard paving equipment will not be allowed to handle plastic concrete in advance of the paver in the roadway without approval. Where concrete is placed adjacent to a newly constructed lane of pavement with the concrete paving equipment operating on the newly constructed pavement, the concrete shall have attained a minimum compressive strength of 2 ,000 psi before commencing paving. Determination that the concrete has reached 2 ,000 psi shall not relieve the Contractor of the responsibility for protecting the pavement. Any concrete or foreign material that falls on or is worked into the surface of a completed slab shall be removed immediately. 412.11 412-5 Following placement, the concrete shall be struck off to conform to the cross section shown on the plans and to an elevation such that when the concrete is properly consolidated and finished, the surface of the pavement will be at the elevation shown on th e plans or established. The Contractor shall provide a MIT -Scan-2, which is manufactured by MIT GmbH. The Contractor shall ensure the MIT -Scan-2 is calibrated for the specific dowel bar size or load transfer device being placed and is operating within the manufacturer’s tolerances. The Contractor shall also ensure that the operator of the MIT -Scan-2 is fully competent in the use of the device. The Contractor shall supply the serial number of the device to be used on the project.

412.11 Test Specimens. The Contractor shall furnish the concrete necessary for casting test

cylinders and performing air and slump tests.

412.12 Finishing . The sequence of operations shall be strike -off and consolidation, floating ,

and final surface finish. Water shall not be added to the surface of the concrete to assist in finishing operations. The surface shall be finished to a uniform texture, true to grade and cross section, and free from porous areas. When the finishing machine, either form, slip form, or hand finishing method, leaves a surface that is not acceptable, the operation shall stop, and corrective action shall be taken. Inability of the finishing machine to provide an acceptable surface finish, after corrective action, will be cause for requ iring replacement of the finishing machine. Wastewater generated from concrete finishing operations shall be contained and disposed of per subsection 107.2 5.

412.13 Joints . Joints shall be constructed of the type, dimensions, and at locations

required by the Contract. When a joint is saw cut more than 3 inches from the designated location, the pavement shall be removed and replaced to the nearest correct joints. When portions of concrete pavement are removed and replaced, the portion removed shall be the full width of the lane and length of the affected slabs. This corrective action shall be at the Contractor’s expense. Immediately after sawing, the sawed joints shall be flushed with water to remove any saw residue, and the saw residue shall be completely removed from the surface of the pavement. This residue shall be removed by approved methods. All equipment other than saws shall be kept off the pavement until the sawing is complete. 412.13 412-7 After the proper curing period, the sawed joint shall be thoroughly cleaned and immediately sealed per subsection 412.18.

412.14 Curing. Immediately after the finishing operations have been completed the entire

surface and exposed sides of the newly placed concrete, shall be sprayed uniformly with a curing compound meeting the requirements of ASTM C309, Type 2. The ASTM C309 Type 2 curing compound shall be volatile organic content (VOC ) compliant. The curing compound shall be applied within 10 minutes after the final finish has been applied. Failure to cover the surface of the concrete within 10 minutes shall be cause for immediate suspension of the paving operations. An initial application of curing compound shall be applied under pressure by mechanical sprayers at the rate of at least 1 gallon per 180 square feet of pavement surface. A second application of curing compound shall be applied within 30 minutes after the initial application. The second application rate shall be at least 1 gallon per 180 square feet of pavement surface. Alternatively, the Contractor may apply the curing compound in one application of at least 1 gallon per 120 square feet. Additional curing compound shall be applied as needed to ensure that 100 percent of the pavement is covered. The spraying equipment shall be fully automated, equipped with a tank agitator, and a wind guard. During application, the compound shall be in a thoroughly mixed condition with the pigment uniformly dispersed throughout the vehicle and the compound shall be stirred continuously by effective mechanical means. Hand spraying of irregular widths or shapes and surfaces exposed by removal of forms will be permitted. Curi ng compounds shall not be applied to the inside faces of joints to be sealed. Should the curing film become damaged from any cause, within 72 hours after concrete placement, except for concrete open to traffic, the damaged portions shall be repaired immediately with additional curing compound, payment for which shall be at the Contractor’s expense. The sides of pavement slabs shall be immediately sprayed with curing compound when the forms are removed.

412.15 Cold Weather Concrete Paving . The Contractor is responsible for the strength and

quality of the concrete placed during cold weather. Before starting paving operations, the Contractor shall be prepared to protect the concrete from freezing. Maturity meters, to monitor and record time and pavement temperature, shall be installed at the t ime of placement when the air temperature is expected to fall below 40 ˚F during the next three days or as requested by the Engineer when the air temperature is expected to fall below 45 ˚F during the ne xt three days. The Contractor shall maintain the temperature of the pavement at or above 40 ˚F until the pavement has attained a compressive strength of at least 2000 psi. The compressive strength of the concrete shall be determined by the use of maturity meters. Maturity meters shall be placed in three locations for each day’s concrete paving operations. One maturity meter shall be placed in the final 15 feet of paving, and the two other maturity meters shall be 412.16 412-12 placed at locations designated by the Engineer. The maturity meter probes shall be located on the outside edge of the slab, at least 1 foot and not more than 2 feet from the edge and at mid depth of the slab. Each maturity meter shall be capable of recording the time and temperature. The maturity meters shall remain in place until the concrete has attained a compressive strength of 2000 psi. The Contractor shall develop maturity relationships for each mix placed during the cold weather conditions described above per CP 69: The development of the maturity relationship is part of the trial mix and shall be submitted to the Engineer before cold weather concrete paving. The Contractor shall provide the maturity meters and all necessary wires and connectors. The Contractor shall be responsible for the placement, protection and maintenance of the maturity meters and wires. Locations where the maturity meters are placed shall be protected in the same manner as the rest of the concrete pavement. The following procedures shall be followed if the temperature of the concrete pavement falls below 32 °F before the concrete reaches 2 ,000 psi:

412.16 Repair of Defective Concrete Pavement . Defective concrete pavement shall be

repaired or replaced at the Contractor’s expense. This corrective work shall be accomplished before joint sealing and final smoothness measurement. Defective concrete pavement replaced after smoothness measurement shall be retested for localized roughness. The Contractor’s corrective work plan shall be approved before performing the work. When necessary, the extent of defects will be determined by the inspection of cores drilled at the Contractor’s expense. Crack depth shall be determined by taking one core at the center of the crack or as approved by the Engineer. The Contractor shall tak e the cores and supply to the Engineer immediately after the coring.

412.17 Surface Smoothness. The roadway surface smoothness shall be tested per

subsection 105.07.

412.18 Sealing joints. Before installation of the backer rod or sealant, the following shall

be completed:

412.19 Construction by Form Method . Straight side forms shall be made of a metal having a

thickness of at least 7/32 inch and shall be furnished in sections at least 10 feet in length. Forms shall have a depth equal to or greater than the specified edge thickness of the concrete, without horizontal joint, and a base width equal to or greater than the depth of the forms. Top surface of the forms shall be set flush with the proposed concrete surface. Flexible or curved forms of proper radius shall be used for curves of 100 feet radius or less . Flexible or curved forms shall be of a design acceptable to the Engineer. Forms shall be provided with adequate devices for secure setting so that when in place they will withstand, without visible spring or settlement, the impact and vibration of the co nsolidating and finishing equipment. Flange braces shall extend outward on the base at least ⅔ the height of the form. Forms with battered top surfaces, and forms that are bent, twisted, or broken shall not be used. Repaired forms shall not be used until inspected and approved. Built -up forms shall not be used except where the total area of the pav ement, of any specified thickness, on the project is less than 2 ,000 square yards. The top face of the form shall not vary from a true plane by more than 1/8 inch in 10 feet, and the vertical leg shall not vary more than 1/4 inch from vertical. The forms s hall contain provisions for locking the ends of abutting form sections together tightly, and for secure setting. Forms for bridge approach slabs or for pavement areas with irregular dimensions shall be made of metal or straight, sound timber. Forms shall be free from warp and of sufficient strength to resist springing out of shape. Forms shall be staked securely to line and grade to the sati sfaction of the Engineer. All mortar and dirt shall be removed from the forms.

412.20 Construction by Slip Form Method . The subgrade shall be completed per

subsection 412.08 and then checked and approved by the Engineer before installation of load transfer units, if required, and placement of concrete. Concrete shall not be placed on a subgrade that has not been approved. If any traffic uses the finished subg rade, the grade shall be checked and corrected immediately before placement of the concrete. The concrete shall be finished with an approved, self -propelled slip form paver capable of spreading, consolidating, screeding, and finishing the freshly placed concrete with one pass of the paver. The paver shall be capable of providing a dense and homogeneous pavement with an even texture and no porous areas, and to the slope and elevation specified. The alignment and elevation of the paver shall be automatically controlled from outside reference lines established to obtain a smooth alignment and profile. For mainline paving of Pavement Smoothness Category I roadways, as defined in Table 105 -14 all slip form paving shall be accomplished by a machine capable of paving at least a 24 feet minimum width as recommended by the equipment manufacturer.

412.21 Determining Pavement Thickness. Pavement thickness will be determined by

cores or magnetic pulse induction (MPI). The Contractor shall select the pavement thickness determination method at the Pre- paving Conference.

412.22 Opening to Traffic . The pavement shall not be opened to traffic until the concrete

has achieved a compressive strength of 3 ,000 psi. Concrete compressive strength shall be determined by maturity meters . Before opening the pavement to traffic the roadway shall be cleaned, as approved. Before placement of concrete whose strength will be determined with maturity meters, the Contractor shall provide the Engineer a report of maturity relationships per CP 69. The Contractor shall provide maturity meters and all necessary wires and connectors. The Contractor shall be responsible for the placement and maintenance of the maturity meters and wires. At a minimum a maturity meter will be placed once per day and then once per 5,000 square yards. Placement shall be as directed by the Engineer. For placements with multiple maturity meters, the lowest compressive strength shall determine when the pavement may be opened to traffic. If a maturity meter fails, is tampered with, is destroyed or was not placed, the section of pavement represented by the maturity meter shall remain closed to traffic for a period of 28 days. The Contractor may choose at his own expense to core the section of pavement represented by the maturity meter. Cores will be obtained and tested according to CP 65. Cores will be a minimum of 4 inches in diameter. A minimum of three cores in a two square foot area will be obtained. If the compressive strength of a ny one core differs from the average by more than 10 percent that compressive strength will be deleted and the average strength will be determined using the compressive strength of the remaining two cores. If the compressive strength of more than one core differs from the average by more than 10 percent, the average strength will be determined using all three compressive strengths of the cores. To open the section of pavement, the average compressive strength of the cores shall be a minimum of 3,000 psi. METHOD OF MEASUREMENT

412.23 The quantities of Concrete Pavement, and Place Concrete Pavement to be paid for

under these items will be the number of square yards completed and accepted. The width for measurement will be the width of the pavement shown on the typical cross section of the plans, including additional widening where called for, or as otherwise direct ed by the Engineer in writing. The length will be measured horizontally along the centerline of each roadway or ramp. 412.24 412-21 The quantity of Furnish Concrete Pavement to be paid for under this item will be the number of cubic yards of concrete delivered and accepted. The concrete volume will be based on batch weights of the concrete converted to volumes by use of the conversion factor developed with the specific mix design. Quantities of concrete that are wasted, spilled, or used as a result of excessive thickness shall be deducted from the pay quantity. Excessive thickness shall be considered any thickness in excess of 1/2 inch greater than the specified depth that continues for a length of 200 feet or more. Yield shall be determined per AASHTO T 121. Where concrete is paid for by cubic yard batched, the pay quantities for all concrete produced with a relative yield less than 0.99 shall be corrected per the following formula: Corrected cubic yards = (cubic yards batched) • (relative yield) Reinforcement other than dowels, tie bars, and other joint material will be measured by the pound. BASIS OF PAYMENT

412.24 General. The accepted quantities will be paid for at the contract unit price for each of

the pay items listed below that appear in the bid schedule. Payment will be made under: Pay Item Pay Unit Concrete Pavement ( Inch) Square Yard Place Concrete Pavement Square Yard Furnish Concrete Pavement Cubic Yard The price per square yard of Concrete Pavement shall be full compensation for furnishing and placing all materials, including dowels, tie bars, joint materials, texturing, sawing, finishing, and rumble strips. The price per square yard for Place Concrete Pavement shall include everything included in the pay item, Concrete Pavement, except furnishing concrete. The price per Cubic Yard for Furnish Concrete Pavement shall be full compensation for furnishing the concrete to the project site. Reinforcing steel will be measured and paid for per Section 602. Furnishing, installing, and monitoring vibrators and vibrator monitoring device will not be measured and paid for separately, but shall be included in the work for concrete pavement. Incentive and Disincentive Payments (I/DP) will not be made on interim estimates. I/DP will be made when the concrete pavement or a major phase of the concrete pavement has been completed and all the data for computing the I/DP is available. Furnishing, calibrating and use of maturity meters, wire and other appurtenances including the molding, curing and breaking of cylinders for calibration and placement of calibration slabs will not be measured and paid for separately, but shall be included in the work. All costs associated with developing correlation curves used to evaluate low flexural strength results per the Contract, or as requested by the Engineer, shall be included in the work. This shall include all materials, forms, testing, equipment and labor. 412.25 412-22 (a) Where the pavement thickness is more than Plan Thickness (PT) minus 1.0 inch, I/DP for the element of pavement thickness will be applied to the contract unit price per subsections 105.06 and 412.21. I/DP for other elements will be applied to the contract unit per Section 105. Adjustments in payment because of deviations in air content will be per subsection 601.17 using $100 per cu. yd. for the unit bid price. DESCRIPTION

412.25 Cross Stitching . This work consists of cross stitching longitudinal cracks and joints

by directionally drilling holes in concrete pavement, injecting grout, and inserting deformed steel reinforcing bars per these specifications and the details shown on the plans. Cross stitching shall not be used for thin concrete overlays (8 inches or less). MATERIALS

412.26 Materials for cross stitching shall be #6 or #8 deformed steel reinforcing bars, grade

60, epoxy coated, with length as specified on the plans. Epoxy or cementitious grout shall be on the Department’s Approved Products List. The epoxy shall be either an epoxy or polyester resin. The epoxy or cementitious grout shall be submitted to the Engineer for approval at least five working days in advance of the commencement of cross stitching work.

412.27 Placement. Directionally drilled holes shall be 1.000 to 1.125- inch diameter for #6

bars and 1.125 to 1.375- inch diameter for #8 bars and drilled at an angle from the horizontal designated on the plans. Holes shall be started at a distance shown on the plans on a line perpendicular to the crack/ joint and shall extend through the crack/joint. Drilled holes shall be spaced on 20 -inch centers and shall alternate from side to side along the full length of the crack/joint. Holes shall not be drilled within 24 inches of an existing transverse joint. Holes shall not extend through the bottom of the slab. Drilled holes shall be blown free of drill dust, dirt, and moisture with oil and moisture -free compressed air immediately before placing the grout. Holes shall be filled with epoxy/grout by injecting from the bottom of the hole. The Contractor shall insert the tie bar and remove excess epoxy/grout and finish flush with the pavement surface. Pavement may be opened to traffic when the epoxy/grout is dry to the touch .

412.28 Equipment . The drill for boring the cross stitch holes shall be selected to minimize

damage to the concrete surface. The drill shall be capable of low -impact operation in order to minimize spalling damage and prevent bottom breakout of the concrete pavement. The drill shall be skid or frame mounted. Handheld drilling will not be allowed. The first ten holes shall be visually inspected to determine if the bottom of the slab has broken out and measured for length of minimum embedment. Installation of the tie bars and epoxy shall not occur until the Contractor ’s drilling method has been inspected and approved. After the Contractor’s method has been approved, the Contractor may proceed with cross stitching so long as the method and equipment remain the same. 412.29 412-23 Drill bit changes do not require re- inspection. If the Contractor’s method or equipment changes, the first 10 holes made with the new method shall be visually inspected to determine if the bottom of the slab has broken out and measured for length of minimum embedment. BASIS OF PAYMENT

412.29 Cross stitching will be measured for payment by the number of cross stitches placed.

Payment will be made under: Pay Item Pay Unit Cross Stitching Each The accepted quantity of drilled holes, filled with epoxy/grout and reinforcing bars will be paid for at the contract unit price per each hole drilled. Payment for deformed bars, grout, labor , materials, equipment, tools and incidentals necessary for completion of the work will not be measured and paid for separately but shall be included in the work. DESCRIPTION

412.30 Slot Stitching . This work consists of installing tie bars across cracks in concrete

pavement per these specifications and the details shown on the plans. Slot stitching shall not be used for thin concrete overlays (4 inches or less). MATERIALS

412.31 Concrete patching material to be used as backfill shall be a product on the

Department’s Approved Products List. Concrete patching material shall attain an average compressive strength of at least 4,500 psi at 24 hours. Concrete patching material compressive strengths shall be tested according to ASTM C39 or ASTM C109. Concrete patching material shall provide a minimum bond strength of 1,000 psi at 24 hours, as tested by ASTM C882. Concrete patching material shall have a relative durability factor gre ater than 90 as tested by ASTM C666 method A. Concrete patching material shall have a maximum shrinkage of 0.13 percent at four days as tested by ASTM C157. Steel tie bars shall be 18 inches long #6 deformed steel tie bars, grade 60, and epoxy coated. CONSTRUCTION REQUIREMENTS

412.32 Slot Formation . Slots shall be made from multiple saw cuts made with a diamond

impregnated saw blade to a depth as shown on the plans. Slots shall be approximately perpendicular to the general trend of the crack. Slots shall be 1.75 to 2.25 inches wide. Lightweight jackhammers weighing less than 35 pounds or hand tools shall be use d to remove the “fins” formed by sawing. The length of the slot shall allow the tie bar to be placed at the mid-depth of the slab with a 1 -inch space between the ends of the tie bar and the ends of the slot. Deviations from this method require a method statement detailing the means and methods for how the Contractor will perform the work. The Contractor shall demonstrate slot stitching work for approval using the proposed equipment and procedures. The first five slots shall be visually inspected for bottom of the slab breakouts and minimum dimensions. Installation of tie bars and concrete patching 412.33 412-24 material shall not occur until the Contractor’s method has been inspected and approved. After the Contractor’s method has been approved, the Contractor shall proceed with slot stitching as long as the method and equipment remain the same. Saw blade chang es do not require re- inspection. If the Contractor’s method or equipment changes, the first five slots of the new method shall be visually inspected for bottom of the slab breakouts and measured for minimum dimensions. Tie bars shall be provided at locat ions and spacing as detailed on the plans. Damages to the concrete pavement caused by the Contractor’s operations shall be repaired at the Contractor’s expense. Slots shall be sand blasted or water blasted to remove saw slurry and blow n clean with high pressure oil -free air to remove sand, water, and dust. Tie bars shall be placed on support chairs to rest horizontal at the mid -depth of the slab. Concrete patching material mixing, placement, placement during cold temperatures, consolidation, and curing shall be per the manufacturer’s recommendations. A mix may be extended with aggregate per the manufacturer’s recommendations up to 90 percent of the manufacturer’s maximum extension. The maximum aggregate size shall be 3/8 inch for the extending aggregate. Patching material shall be placed and consolidated in the slot. Patching material shall fill the space under and around the bar. Tie bars shall not be dislodged or moved out of position. The surface of the concrete patching material shall be level with the adjacent pavement.

412.33 Opening to Traffic. The pavement shall not be opened to traffic until all tie bars

have been installed at a joint and the concrete has obtained a minimum compressive strength of 3,000 psi. Pavement shall be cleaned before opening to traffic. METHOD OF MEASUREMENT

412.34 Method of Measurement. Slot stitching will be measured for each completed and

accepted tie bar complete in place. BASIS OF PAYMENT

412.35 The accepted quantities will be paid for at the contract unit price for the pay

item listed below. Payment will be made under: Pay Item Pay Unit Slot Stitching Each The work performed and materials furnished per this item will be paid for at the unit price bid. This price is full compensation for furnishing all materials, tools, labor, equipment and incidentals necessary to complete the work. Payment will not be made for extra work required to repair damage to the adjacent pavement that occurs during slot stitching. 412.36 412-25 DESCRIPTION

412.36 Dowel Bar Retrofit. This work consists of placing epoxy coated smooth dowel bars in

transverse joints as identified on the plans. This shall be done by cutting slots into the existing concrete pavement, installing dowel bars, and filling the slots at locations as shown on the plans. The surface shall be finished as approved by the Engineer. All work, including the concrete pavement slot preparation, inserting dowel bars, filling the slot with backfill material, and finishing the surface shall be performed per these specifica tions and the details shown on the plans. MATERIALS

412.37 Materials for dowel bars shall meet the requirements in subsection 709.03. Dowels

shall be equipped with tight fitting, non- metallic end caps to allow 1/4- inch bar movement. Concrete patching material to be used as backfill shall be a product on the CDOT Approved Products List. Concrete patching material shall attain an average compressive strength of at least 4,500 psi at 24 hours. Concrete patching material compressive strengths shall be tested according to ASTM C39 or ASTM C109. Concrete patching material shall provide a minimum bond strength of 1,000 psi at 24 hours , as tested by ASTM C882. Concrete patching material shall have a relative durability factor greater than 90 as tested by ASTM C666 method A. Concrete patching material shall have a maximum shrinkage of 0.13 percent at four days as tested by ASTM C157. The proposed material shall be submitted to the Engineer for approval at least five days in advance of the start of dowel bar placement. Installation of dowel bars shall not begin until approval has been received in writing from the Engineer. CONSTRUCTION REQUIREMENTS

412.38 Slots for dowel bars shall be cut perpendicular to the transverse joint as shown on the

plans by using a slot cutting machine or walk -behind saw. Slots shall be of adequate length and width to accommodate the dowel bar, as shown on the plans or as directed. The concrete in the slot shall be removed by using a lightweight jackhammer weighing a maximum of 30 pounds, or hand tools, to half slab depth. All damage to the concrete slab outside of the slot shall be repaired or replaced at the Contractor’s expense. Slots shall be placed at locations shown on the plans. Slots shall be removed of all debris and cleaned before placement of dowel bars by sandblasting or other procedure so that clean aggregate is exposed. Before placement of backfill material, each dowel bar shall be equipped with a 1/4- to 3/8- inch-thick foam core board to provide a tight seal at the joint. Dowels shall be placed on chairs so that the bar is sitting a minimum of 1/2 inch above the bottom of slot and perpendicular to the transverse joint. The chairs shall be epoxy -coated steel or plastic rigid enough to hold the dowel in place during grout placement. The existing transverse joints shall be sealed with an approved joint sealant along the bottom and sides of the slot to prevent backfill material from infiltrating the joint. The joint sealant material shall be on the CDOT Approved Products list and shall be approved by the Engineer before use. Backfill material to be placed shall be mixed according to the manufacturer’s recommendations. Once in the slot, the material shall be vibrated thoroughly so that the entire bar is encased with the consolidated material. The slot shall be slightly overfill ed, and the area shall be diamond ground once the material has cured to provide a smooth pavement surface. 412.39 412-26 After grinding, transverse joints shall be sawed and sealed per subsection 412.18.

412.39 Opening to Traffic. The pavement shall not be opened to traffic until all dowel

bars have been installed at a joint and the concrete has obtained a minimum compressive strength of 3,000 psi. Pavement shall be cleaned before opening to traffic. METHOD OF MEASUREMENT

412.40 Dowel bar retrofit in concrete pavement will be measured as the actual number of

dowel bars placed and accepted. BASIS OF PAYMENT

412.41 The accepted quantities will be paid for at the contract unit price for the pay item

listed below. Payment will be made under: Pay Item Pay Unit Concrete Pavement Dowel Bar Retrofit Each The accepted quantity of dowel bar slots cut, filled with accepted patching material, and dowel bars will be paid for at the contract unit price per each bar installed. Payment for cutting slots, support chairs, joint sealant, patching, and all labor, mate rials, equipment, tools and incidentals necessary for completion of the work will not be measured and paid for separately but shall be included in the work. Payment will not be made for extra work required to repair damage to the adjacent pavement that occurs during dowel bar retrofitting. 420.01 420-1 SECTION 420 GEOSYNTHETICS DESCRIPTION

420.01 This work consists of furnishing and installing geotextiles and geomembranes for

paving, impervious lining, erosion control, drainage, separators and landscape weed barrier. MATERIALS

420.02 Geotextiles and geomembranes shall meet the applicable requirements of subsections

712.07 and 712.08 for the use intended. Geotextiles for erosion control for drainage or for

separators may be Class 1, Class 2, or Class 3, conforming to subsection 712.08, if the class is not specified on the plans. Asphalt cement binder for the paving geotextile shall be the same grade as the asphalt cement used for Item 403. Paving geotextile shall be a minimum Class 3, conforming to subsection 712.08. CONSTRUCTION REQUIREMENTS

420.03 Areas where the geosynthetic is to be placed shall have a uniform slope, be

reasonably smooth, free from mounds and windrows, and free of any debris or projections that could damage the material. Riprap or cobbles placed on the geosynthetic shall not be dropped from a free fall greater than 3 feet. The cushion layer or initial layer of riprap may require careful placement without free fall to avoid geosynthetic damage. Geosynthetics damaged or displaced before or d uring placement of overlying layers shall be replaced or repaired per the requirements of this section and to the satisfaction of the Engineer, at the Contractor’s expense.

420.04 Paving. The areas to be treated shall be as designated on the plans. The pavement

surface shall be broomed clean immediately before beginning the crack reduction geotextile treatment using a self -propelled power broom. The asphalt cement binder shall be applied to the pavement surface at the rate of approximately 0.25 gallon per square yard. The exact application rate shall be as recommended by the geotextile manufacturer, and at a temperature of 300 to 350 °F . Paving geotextile shall be applied, per the manufacturer’s recommendations, immediately after the application of asphalt cement binder. Construction equipment, including dump trucks, shall not make sudden stops or starts or sharp turning movements on the geotextile. Dump trucks shall not park on the geotextile before dumping into the asphalt paver. Traffic shall be kept off all newly placed binder and geotextile material until the asphalt surface has been placed. The minimum temperature of the hot mix asphalt at the time compaction begins shall be 250 ° F.