391 Page 250391 UNDERSEALING
391.1DESCRIPTION
This work consists of filling existing voids under PCC pavement by drilling injection holes and pumping a cement/fly ash grout under the pavement slab.
391.2MATERIALS
A.Design Mix: The design mix for grout will conform to the following proportions by absolute volume: 1 Part Portland cement 3 Parts fly ash Water to achieve the specified fluidity Fluidity of the grout when measured by a flow cone in accordance with ASTM C939 will have a time of efflux between 9 and 15 seconds. The Contractor will submit for approval materials proposed for use. The submittal will include mill certification for cement, physical and chemical analysis for fly ash, and tests of the grout slurry by a Department approved testing laboratory. Tests will show one-, three-, and seven-day strengths, flow cone times, shrinkage and expansion observed, and time of initial set. The seven-day strength will be at least 600 psi as measured in accordance with ASTM C942. As an alternate, standard 6 inch diameter by 12 inch high water tight concrete cylinder molds may be used to determine seven day strength. When the cylinder molds are used, the strength will be 700 psi minimum. Compressive strength results that do not meet the minimum requirement will be evaluated by the Department’s Concrete Engineer to determine if the grout is structurally adequate. If the Contractor disputes the accuracy of the results of the compressive strength testing, the Contractor must submit a written proposal for how the in place strength will be evaluated to the Department’s Concrete Engineer within 5 calendar days of the Department notifying the Contractor of the deviation. The proposal must be successfully reviewed by the Department’s Concrete Engineer before the Contractor may proceed with any in place strength evaluation. Alternate design mixes for the grout may be submitted to the Engineer for approval. B.Portland Cement: Type I or Type II cement is required. The cement will meet the requirements of C.Fly Ash: Fly ash will conform to Section 753. D.Water: Water will conform to Section 790.
391.3CONSTRUCTION REQUIREMENTS
A.General: The Contractor, or subcontractor performing the undersealing, will have prior experience with undersealing operations and will have personnel on the project with expertise in undersealing. Prior to awarding the contract, the Department may require the 391 Page 251Contractor to substantiate previous experience with this type of work. The Contractor, upon Department request, will be required to submit a list of at least three projects on which the Contractor or undersealing subcontractor has satisfactorily completed similar work. Deflection testing of the joints will be performed as required by the Engineer. Testing may be performed either before and or after the undersealing operation. The Contractor will take the necessary precautions to avoid slurry or foam from entering areas such as pipes, culverts, voids behind abutments, and other such areas that may hinder the functionality of the roadway. If foam or slurry enters these areas, it will be removed to the satisfaction of the Engineer at no additional expense to the Department. Jacking foam will not be used for undersealing except as allowed as per Section 392.3 A. B.Deflection Testing: The Contractor will furnish either a deflection measuring device that can apply at least 8000 pounds of force (either vibrating or falling weight), or a loaded vehicle having a single axle that can be loaded to 18 kips evenly distributed between the two sides to test joints and cracks. 1.If a deflection measuring device is used, the loading plate will be placed as close as possible to the slab corner. Load transfer will be measured with sensors that are placed adjacent to the joint or crack on the loaded and unloaded side. 2.If a loaded vehicle is used as a measuring device, a gauge mount will be positioned with one gauge referenced to the corner of each slab on both sides of the joint near the shoulder edge perpendicular to the pavement joint. The gauges should then be zeroed with no load on the slab on either side of the joint. A loaded truck will then be moved into position with the center of the 18 kip axle 1 foot behind the joint and the outside test wheel 1 foot from the pavement edge, both gauges will be read. The loaded truck will be moved across the joint to a position 1 foot past the joint and both gauges read again. Deflection testing will be performed when the slabs are not experiencing curl or joint closure. This normally takes place between midnight and 10:00 a.m. The Engineer may stop testing earlier if there is evidence of slab lockup due to thermal expansion of the slabs. The Engineer may allow the testing to continue after the hour specified, providing the slabs are not interlocked or under compression. Upon completion of preliminary deflection testing of joints, the Engineer will determine the deflection range that warrants undersealing. C.Weather and Seasonal Limitations: Grout undersealing will not be performed when the pavement surface temperature is below 40F, or if the subgrade or base course is frozen. D.Equipment: 1.Grout Plant: The grout plant will consist of a positive displacement cement injection pump and a high-speed colloidal mixing machine. The colloidal mixing machine will 391 Page 252operate between 800 and 2000 RPM, creating a high shearing action and subsequent pressure release to make a homogeneous mixture The injection pump will have pressure capability from 250 to 300 psi when pumping a grout slurry mixed to a 12 second flow cone time. The pump will be capable of continuous pumping at rates as low as 1.5 gallons per minute or have the system modified by adding a recirculation hose and valve at the discharge of the pump. 2.Drilling: An air compressor and rock drills or other devices capable of drilling the injection holes through the pavement will be required. The equipment will be operated in such a manner that holes are vertical and not out of round. Holes will be drilled in a manner that prevents breakout at the bottom of the pavement. The downward force of the drill will not exceed 200 pounds. E.Drilling Holes: A hole pattern for grout injection will be determined by the Engineer in consultation with the Contractor. Variations from plans quantity will not be considered cause for renegotiation of the contract unit prices. Holes will be between 1.5 and 2 inches in diameter drilled vertically and round to a depth sufficient to penetrate any stabilized base and into the subgrade material. Subgrade penetration will not exceed 3 inches. Holes may be washed to create a small cavity, allowing initial spread of grout. F.Subsealing: During subsealing operations, the upward movement of the pavement will not exceed 0.125 inches, unless otherwise allowed by the Engineer. The Contractor will supply equipment to measure slab deflection and lift. This equipment will be capable of detecting simultaneously the movement of the pavement edge or any two outside slab corners adjacent to a joint and the adjoining shoulder. The equipment will have the capacity of accurately measuring to 0.001 inches. Measurement devices to detect slab movement with respect to a stable reference point will be subject to approval before use. Pavement that has been raised in excess of this amount may be subject to removal and replacement, or grinding to the correct grade, as determined by the Engineer. An expanding rubber packer or other approved device connected to the discharge from the plant will be lowered into the hole. The discharge end of the packer or hose will not extend below the lower surface of the concrete pavement. Each hole will be pumped until maximum pressure is built up or material is observed flowing from hole to hole. Maximum pressure will be 60 psi. A short surge up to 150 psi will be allowed when starting to pump the hole. The pressure will be monitored by a gauge in the grout line that is protected from the grout slurry. Mixed material will not be held in the mixer or injection sump pump for more than one hour after mixing. Any material held longer than one hour will be wasted and will not be paid for. Additional water will not be added after initial mixing of the grout. Water displaced from the void structure by the grout will be allowed to flow out freely. Excessive loss of the grout through cracks, joints, other drilled holes, or from back pressure in the hose or in the shoulder area will not be tolerated and will not be paid for. 391 Page 253If the Engineer determines that continued grout injection at a specific location is no longer feasible due to major voids the Engineer may direct the Contractor to cease grout injection at that location. Upon completion of undersealing and prior to the injection grout drying on the sides of the drill holes, the drill holes will be filled with a fast setting sand/cement mixture or other patch material approved by the Engineer. If the injection grout has dried on the sides of the drill holes, the sides of the drill holes will be sand blasted and blown out prior to filling the holes with fast setting sand/cement mixture. G.Radial Cracks: Cracks emanating radially from the grout injection holes will be presumed to have been caused by improper injection techniques by the Contractor. For each 5 linear feet of crack measured, the pay quantity will be reduced by 1 cubic foot of grout. As an alternative, the Engineer may require replacement of the damaged panel or a portion of the damaged panel, at the Contractor's expense. H.Transverse Cracks: If cracks develop between adjacent grout injection holes, the Contractor will repair the cracks by a satisfactory method approved by the Engineer. As an alternative, the Engineer may require replacement of the entire panel or a portion of a damaged panel at the Contractor's expense.
391.4METHOD OF MEASUREMENT
A.PCC Drill Holes: The holes accepted will be measured per each. The holes drilled after the deflection testing will not be included for payment. B.PCC Pavement Undersealing: Pavement undersealing will be measured to the nearest cubic foot. Portland cement will be the only material measured for payment. One bag of cement (94 pounds) of PCC pavement undersealing (3½ bags of cement will of PCC pavement undersealing). C.Deflection Testing: The test locations will be measured per each. Testing before and after undersealing at the same joint will be measured as separate locations. If the deflection testing after undersealing is in excess of 0.010 inches further undersealing will be required. Should the testing, after the undersealing is performed, indicate a need for further undersealing at that joint, all additional testing at that joint will be at no additional cost to the Department.
391.5BASIS OF PAYMENT
A.PCC Drill Holes: The holes drilled will be paid for at the contract unit price per each. Payment will be full compensation for all materials, equipment, tools, and incidentals required to drill, plug, and seal the holes after the undersealing is completed. B.PCC Pavement Undersealing: Pavement undersealing will be paid for at the contract unit price per cubic foot. Payment will be full compensation for all materials, including fly ash and water, labor, equipment, tools, and incidentals required. 391 Page 254C.Deflection Testing: Testing will be paid for at the contract unit price per each test location. Payment will be full compensation for all materials, equipment, tools, and incidentals required. 392 Page 255392 PAVEMENT JACKING
392.1DESCRIPTION
This work consists of hydraulic pressure jacking PCC pavement to correct the pavement profile. Jacking is accomplished by drilling injection holes and pumping a cement/fly ash slurry or liquid polyurethane
392.2MATERIALS
A.Jacking Slurry Design Mix: The design mix for grout will conform to the following proportions by absolute volume: 1 Part Portland cement 3 Parts fly ash Water to achieve the specified fluidity Fluidity of the grout when measured by a flow cone in accordance with ASTM C939 will have a time of efflux between 16 and 36 seconds. During initial injection at each hole an efflux time between 9 and 15 seconds will be permitted. The use of material with an efflux time between 9 and 15 seconds will be discontinued prior to movement of the pavement. The Contractor will be required to perform this test prior to placing any material. The Contractor will submit for approval, materials proposed for use. The submittal will include mill certification for cement, physical and chemical analysis for fly ash, and tests of the grout slurry by a Department approved testing laboratory. Tests will show one, three, and seven day strengths, flow cone times, shrinkage, and expansion observed, and time of initial set. The seven day strength will be at least 600 psi as measured in accordance with ASTM C942. As an alternate, standard 6 inch diameter by 12 inch high water tight concrete cylinder molds may be used to determine seven day strength. When the cylinder molds are used, the strength will be 700 psi. minimum. Compressive strength results that do not meet the minimum requirement will be evaluated by the Department’s Concrete Engineer to determine if the grout is structurally adequate. If the Contractor disputes the accuracy of the results of the compressive strength testing, the Contractor must submit a written proposal for how the in place strength will be evaluated to the Department’s Concrete Engineer within 5 calendar days of the Department notifying the Contractor of the deviation. The proposal must be successfully reviewed by the Department’s Concrete Engineer before the Contractor may proceed with any in place strength evaluation. Alternate jacking slurry design mixes may be submitted to the Engineer for approval. B.Portland Cement: Type I or Type II cement is required. The cement will meet the requirements of Section 750. C.Fly Ash: Fly ash will conform to Section 753. D.Water: Water will conform to Section 790.