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 C.Fly Ash: Fly ash will conform to Section 753. D.Water: Water will conform to Section 790. 392 Page 256E.Jacking Foam: Water blown formulation of high-density polyurethane. The high density, closed cell polyurethane will be hydrophobic and will exhibit the following physical characteristics and properties: The polyurethane foam will be designed for pavement jacking, have a free rise density of 3.0 to 4.2 pounds per cubic foot in accordance with ASTM D1622, and will have a minimum compressive strength of 40 psi in accordance with ASTM D1621. The material will be resistant to oils, gasoline, and most solvents.
392.3CONSTRUCTION REQUIREMENTS
A.General: The Contractor, or subcontractor performing the pavement jacking, will have prior experience with pavement jacking operations and will have personnel on the project with expertise in determining injection hole patterns and jacking sequences. Prior to awarding the contract, the Department may require the Contractor 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 the pavement jacking subcontractor have satisfactorily completed similar work. The Contractor will not start any new location unless the new location can be completed in the same day. If any location is started and cannot be completed prior to the end of the day’s work, the entire area, including adjacent lanes, will be undersealed in accordance with Section 391 before stopping for the day. If PCC pavement foam jacking is specified, foam may be used to underseal adjacent areas. 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. B.Weather and Seasonal Limitations: Pavement jacking will not be performed when the pavement surface temperatures are below 40F, or if the subgrade or base course is frozen. Pavement jacking will not be performed when the subgrade contains an abnormal amount of moisture from recent rainfall, as evidenced by standing water on the pavement or in the joints or cracks. C.Equipment: 1.Grout Plant: When jacking slurry is specified, the grout plant will consist of a positive displacement cement injection pump and a high speed colloidal mixing machine. The colloidal mixing machine will operate between 800 and 2000 RPM, creating a high shearing action and subsequent pressure release to make a homogeneous mixture. 2.Drilling: An air compressor and rock drills or other devices capable of drilling the injection holes through the pavement will be required. 3.Pumping Unit: When Jacking Foam is specified, the Contractor will furnish a truck-mounted pumping unit capable of injecting the high-density polyurethane formulation between the concrete pavement and the subbase and capable of controlling the rate of 392 Page 257rise of the pavement. The pumping unit will be equipped with a metering device to measure the quantity of material pumped. 4.Laser Leveling Unit: The Contractor will furnish a laser leveling unit to ensure that the concrete is raised to an even plane and to the required elevation. D.Drilling Holes: When jacking slurry is specified, a hole pattern for grout injection will be determined by the Engineer in consultation with the Contractor. The Engineer may delete any location or add new locations of pavement to be raised. 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. Holes may be washed to create a small cavity, allowing initial spread of grout. 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. Variations from plans quantity will not be considered cause for renegotiations of the contract unit prices. When jacking foam is specified, a hole pattern for injection will be determined by the Contractor in consultation with the Engineer. The Engineer may delete any location or add new locations of pavement to be raised. Holes will be between 3/8 inch and 5/8 inch in diameter, drilled vertically and round to a depth sufficient to penetrate any stabilized base and in the subgrade material. Holes will be drilled in a manner that prevents breakout at the bottom of the pavement. E.Slurry Pavement Jacking: String lines will be established and blocked up from the pavement high points to monitor movement. 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. The Contractor will pump in a pattern and in the amount required to raise the pavement to within 0.02 foot of the specified grade. Grade tolerances are applicable to both transverse and longitudinal grades. After the pavement has been raised to the desired elevation, all holes will be injected to ensure complete filling of voids. Continuous pressures up to 200 psi will be permitted. Pressures up to 300 psi will be allowed only for short periods. If the pavement is bonded to the subbase, brief pressure rises (10 seconds or less) up to 600 psi will be allowed. 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. Excessive loss of the slurry 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. If the Engineer determines that continued slurry injection at a specific location is no longer feasible due to major voids the Engineer may direct the Contractor to cease slurry injection at that location. 392 Page 258Upon completion of jacking and prior to the injection slurry 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 slurry 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. F.Foam Pavement Jacking: The high-density polyurethane formulation is to be injected under the slab. The amount of rise will be controlled using the pumping unit and by regulating the rate of injection. The Contractor will inject in a pattern and in the amount required to raise the pavement to within 0.02 foot of the specified grade. Grade tolerances are applicable to both transverse and longitudinal grades. A tight string line or laser level will be used to monitor and verify elevations. After the pavement has been raised to the desired elevation, all holes will be injected to ensure complete filling of voids. Excessive loss through cracks, joints, other drilled holes, from back pressure in the hose, in the shoulder area, or as a result of cleaning lines will not be paid for. The Contractor will provide a scale for weighing the waste material. If the Engineer determines continued foam injection at a specific location is no longer feasible due to major voids, the Engineer may direct the Contractor to cease foam injection at the location. Upon completion of the jacking, the upper 2 inches of the drilled holes will be filled with a fast setting sand/cement mixture or other patch material approved by the Engineer. The foam material will be removed from the injection hole appropriately to ensure a good bond between the fast setting sand/cement mixture and the in place concrete. G.Radial Cracks: The slab will not be raised more than 1/4 inch while pumping in any one hole at any one time. Cracks emanating radially from the injection holes will be presumed to have been caused by improper injection techniques by the Contractor. For each 5 feet of crack measured, the pay quantity will be reduced by 1 cubic foot of grout or 10 pounds of polyurethane foam material. H.Transverse Cracks: If cracks develop between adjacent injection holes, the Contractor will repair the cracks by a satisfactory method approved by the Engineer. I.Pavement Raised above Tolerances: Pavement raised above specified tolerances will be brought to grade by grinding. If over jacking is greater than 0.10 foot, satisfactory removal and replacement will be required, at no cost to the Department.
392.4METHOD OF MEASUREMENT
PCC pavement jacking slurry will be measured to the nearest cubic foot. Portland cement will be the only material measured for payment. One bag of cement (94 pounds) will equal 1 cubic foot of PCC pavement jacking slurry. PCC pavement jacking foam will be measured to the nearest pound. 392 Page 259392.5 BASIS OF PAYMENT PCC pavement jacking slurry will be paid for at the contract unit price per cubic foot. Payment will be full compensation for all materials, including fly ash, water, labor, equipment, tools, and incidentals required. PCC pavement jacking foam will be paid for at the contract unit price per pound. Payment will be full compensation for all materials, including high-density polyurethane foam, labor, equipment, tools, and incidentals required. 393 Page 260393 CRACKING AND SEATING OF PCC PAVEMENT
393.1DESCRIPTION
The work consists of cracking and seating concrete pavement prior to placing an asphalt concrete leveling course.
393.2MATERIALS (Not Specified)
393.3CONSTRUCTION REQUIREMENTS
A.General: Cracking and seating will proceed continuously, during normal work hours, until the set of lanes under construction is completed. The pavement will be seated on the same working day that it is cracked. The asphalt concrete leveling course will be placed within 72 hours after the pavement has been cracked and seated. PCC pavement crossovers will be cracked with the same pattern used for the driving lanes. Work will be performed during daylight hours. Prior to cracking the concrete pavement, existing asphalt concrete overlays will be removed. B.Equipment: 1.Pavement Breaker : Pavement cracking will be accomplished with a spade or guillotine type breaker mounted on a vehicle capable of controlled forward and transverse movement. The breaker will be capable of fracturing the pavement to the full depth, while maintaining the fractured face interlock of the aggregate. 2.Roller: A pneumatic roller with a minimum loaded weight of 35 ton will be used to seat the cracked pavement. C.Cracking Locations: Pavement cracking will be performed transverse to centerline at 2 foot intervals ± 6 inches. Breakers will not be operated closer than 2 feet from an existing transverse joint. Cracking will be full pavement depth without loss of interlock. D.Test Section: Before routine cracking operations commence, the Contractor will demonstrate on a 200 foot test section on the project that the cracking and seating procedure is satisfactory to the Engineer. When inspecting the cores for cracking, it may be necessary to wet the core to verify cracking. The Contractor will core or saw samples of sufficient size to establish adequacy of cracking. A minimum of four samples will be required in the test section and one sample per lane mile for routine operations. If subsequent samples indicate that the established cracking procedure is not producing acceptable results, additional test sections may be required to re-establish an acceptable cracking and seating procedure. E.Seating: The cracked pavement will be seated by a minimum of two passes with the pneumatic roller. If two roller passes have not provided a firm seating of the cracked