679SLAB STABILIZATION

679.1DESCRIPTION—This work is the filling of voids beneath existing rigid base courses or pavements

as specified in Section 516 and according to the Standard Drawings and at other locations as directed.

679.2MATERIAL—Use either cement, asphalt, or high density polyurethane grout to stabilize the slab.

Use an accelerator if required.

within the shelf life and temperature limitations set by the manufacturer.

work. Include with the submittal: independent laboratory testing showing 1, 3, and 7 -day compressive strengths; flowability; shrinkage and expansion results; and the time of initial set. Proportion the mix as follows:

One part cement (by volume) Three parts supplementary cementitious material (by volume) Admixtures—if required and accepted Water—an amount such that the time of efflux is within 10 seconds to 15 seconds (ASTM C939)

Furnish mix with an expansion of 0% to 10% (ASTM C940), an initial setting time of 1 hour to 6 hours (AASHTO T 131) and bleeds no more than 2.5% of the volume (ASTM C940). A 7-day compressive strength of 700 pounds per square inch minimum is required, based on the average of five test cylinders (PTM No. 521). Submit a new mix design if the source of any material is changed.

manufacturer listed in Bulletin 15. Provide a supplier certification with each shipment as specified in Section

106.03(b)3

within the shelf life and temperature limitations set by the manufacturer.

supplier certification with each shipment as specified in Section 106.03(b)3. Certify that the material conforms to the following requirements:

Density, lbs/cu. ft. ASTM D1622 min. 3.5 Tensile Strength, psi ASTM D1623 min. 60 Compressive Strength, psi ASTM D1621 min. 50 Shear Strength, psi ASTM C273 min. 40 Closed Cell Content % ASTM D6226 min. 85 Water Absorption % ASTM D2842 < 2

within the shelf life and temperature limitations set by the manufacturer.

679.3CONSTRUCTION—

successful experience, are available at the job. Assign a crew supervisor that has at least 5 years ’ experience in work on projects of similar size and character. Submit three references for crew supervisor and injection nozzle-men from people who were responsible for supervision of these projects. Submit written documentation to the Representative at least 10 working days before start of work. Do not perform work if daytime temperatures are below 40F or if the subgrade and/or base course material is frozen.

• Provide details of proposed hole spacing, depth, diameter, drilling methods, and hole injection sequence for the stabilization operations.

• Provide details of method to locate pavement reinforcement before drilling, if applicable.

• Provide a list of the proposed equipment, including supply pumps, valves, mixing equipment, injection guns and other items required to complete the work.

• Provide details of proposed means of establishing and controlling line and grade of stabilized slabs.

• Provide details of methods for control and disposal of waste materials.

• Provide details of the curing period and open to traffic times.

Do not start work until the Representative has reviewed and approved all submittals.

by the Representative, and as follows: Do not perform testing if air temperature is below 40F or exceeds 70F. Do not test during spring thaw conditions or if subgrade is frozen. If the air temperature is not within the air temperature limits to perform deflection testing, then perform visual verification of pumping or poor joint performance before specifying slab stabilization. Perform deflection testing according to ASTM D4695. Provide to the representative the test data and the slabs recommended for stabilization 15 working days before start of work for approval. Repeat this procedure at every transverse joint and crack. Stabilize all joints or cracks that have a loaded slab corner deflection of 0.02 inch or more, and a joint efficiency at 65%* or more if approved by the representative. Patch and stabilize all joints or cracks that have a loaded slab corner deflection of 0.02 inch or more, and a joint efficiency of less than 65% if approved by the representative. Joint efficiency (JE) is defined as follows:

JE = Unloaded Slab Corner Deflection x 100 Loaded Slab Corner Deflection

* Use the highest Loaded Slab Corner Deflection and the lowest joint efficiency at each joint or crack.

Exercise extra precautions in the handling of hot asphalt hose and nozzle. Provide hot asphalt workmen with safety masks, protective gloves, heavy clothing in two or more layers, closely fitted at the ankles, wrists, and neck.

determines that continued material placement at any specified location is no longer economically feasible, or vertical movement is going to occur, the Representative may direct the Contractor to cease pumping at that location.

tolerance, to the correct grade. Grind as specified in Section 514.3, except grind into the high slab.

or improper methods. Stop work until the cause is determined and corrected.

the entire slab at no additional cost to the Department as specified in Section 516.

with a rapid set, non -shrink concrete patching material. Strike patches flush with the surface of the surrounding pavement.

or crack as specified in Section 679.3(a) 2. Regrout slabs that deflect 0.02 inch or more and retest. The Representative may accept any slab that continues to show movement, in excess of that specified, after two properly performed groutings; or direct the removal and replacement, with a full depth concrete patch, as specified in Section 516 and paid for separately.

1.a Grout Plant. Provide a satisfactory positive displacement cement injection pump and a satisfactory mixing machine, capable of operating at a minimum speed of 800 rpm and a maximum speed of 2000 rpm.

1.b Water Tanker. Supply water from a water truck with adequate capacity and pressure for delivery to the grout machine.

1.c Drill. Provide generator, core drill, and diamond-tip core barrels, or other satisfactory equipment capable of drilling the grout injection holes through the pavement and base material; and equipment in satisfactory condition and operated to produce holes that are smooth, vertical, and do not break out the bottom of the slab.

1.d Vertical Movement Testing. Supply satisfactory equipment to measure slab lift, capable of detecting simultaneously the lift of the pavement edge, or of any two outside slab corners adjacent to a joint and the adjoining shoulder. Use equipment with a capability of making these measurements to within 0.001 inch.

1.e Miscellaneous. Provide necessary hoses, valving, and valve manifolds with positive cutoff and bypass provisions to control pressure and volume, pressure gauges with gauge protectors, expanding

packers or hose for positive seal during grout injection, hole washing tools, drill steel, bits, and any other miscellaneous tools required.

2.a Drilling Holes. Drill grout injection holes in the pattern shown on the Standard Drawings, or as directed. Drill holes not larger than 1 1/2 inches in diameter, vertical and round, and to a depth sufficient to penetrate any stabilized base.

2.b Mixing. Accurately measure the dry materials by mass, if in bulk, or provide them packaged in uniform volume sacks. Batch with water through a meter or scale that totals the day's consumption. Do not hold mixed material in the mixer or injection pump sump for more than one hour after mixing. Dispose of material held for longer times. Make flowability measurements at least two times during each work shift.

2.c Cement Grout Injection. During the filling operation, use a positive means of monitoring lift as specified in Section 679.3(b)1.d. Upward movement of the pavement greater than 0.05 inch will not be allowed. Lower an expanding rubber packer or hose, connected to the discharge from the pump, into the hole. Do not extend the discharge end of the packer or hose below the lower surface of the concrete pavement. Pump each hole until maximum pressure is built up or material is observed flowing from hole to hole. Do not exceed a maximum pressure of 200 poun ds per square inch, unless otherwise directed. Monitor the pressure in the grout line. Protect the gauge from the grout slurry. Allow the water, displaced from the void structure by the grout, to flow out freely. Excessive loss of the grout through the cracks, joints, or from back pressure in the hose or in the shoulder area will not be allowed.

2.d. Opening to Traffic. Do not open to traffic for a minimum of 12 hours after grouting operations have been completed, or according to the contractor’s approved field QC plan, and according to Manufacturer’s recommendations.

1.a Asphalt Transport Tanker. Use a fully insulated asphalt tanker with a removable access hatch, a 2 inch minimum size overflow pipe and suitable strainers at the outlet to the pumps. Heat the asphalt in the tanker to the application temperature and circulate it during the entire heating process. Provide necessary readout equipment for temperature in the cab of the tanker. Provide certification for the accuracy of the method used to measure the amount of asphalt used on the project.

1.b Asphalt Underseal Pump . Use a separate, self -contained reversible pump equipped with quick connectors. Use a pump a 1 1/2-inch minimum size, flexible metal circulating hose with a quick cut off valve for recirculation when the asphalt is not being injected into the voids.

1.c Pressure Water Distributor Trailer. Provide a pressure water distributor trailer with a minimum 50 gallon capacity. The unit may have its own pump system or be compatible with the air system on the transport tanker or as approved by the Representative.

1.d Compressor Unit. Provide compressor units capable of delivering a minimum of 100 cubic feet of air per minute to blow air into the cavities beneath the pavement.

1.e Drill. Provide generator, core drill, and diamond -tip core barrels, or other satisfactory equipment capable of drilling the grout injection holes through the pavement and base material; and equipment in satisfactory condition and operated to produce holes that are smooth, vertical, and do not break out the bottom of the slab.

1.f Asphalt Nozzles . Provide a tapered nozzle, tube , or other mechanical device of sufficient length, approved by the Representative, that can be used to inject the asphalt under the pavement. Use a

nozzle with a three way valve designed to circulate the asphalt back to the distributor tank when pumping operations are not in progress. Provide handles so that the operator can move the nozzle from hole to hole without touching the hot nozzle or hose.

1.g Pavement Plugs. Provide cylindrical plugs of sufficient length and diameter to plug the holes. Taper one end so that the plug can be driven a maximum of 2 inches into the hole.

1.h. Vertical Movement Testing. Supply satisfactory equipment to measure slab lift, capable of detecting simultaneously the lift of the pavement edge, or of any two outside slab corners adjacent to a joint and the adjoining shoulder. Use equipment capable of detecting slab lift to measurements of 0.001 inch.

1.i Miscellaneous . Provide necessary sprinkling cans, picks, shovels, water , and any other miscellaneous tools required to perform the work.

2.a Drilling Holes. Drill grout injection holes in the pattern shown on the Standard Drawings, or as directed. Drill holes not larger than 1 1/2 inches in diameter, vertical and round, and to a depth sufficient to penetrate any stabilized base.

2.b B lowing Holes . Blow compressed air into the hole, as the drill is being backed out, for approximately 5 to 15 seconds to clear the hole. When water or thin mud is encountered, blow air into the hole until water stops coming through adjacent holes and cracks.

2.c Preparation of Asphalt. Heat the asphalt to a temperature of 380F to 450F before pumping operations begin. Asphalt heated 500F or more will be rejected. Exercise extreme care to ensure that the asphalt does not contact an open flame. Circulate the asphalt before pumping to free and warm up the lines of the circulating hose.

2.d Asphalt Grout Injection. Apply water around the hole before pumping to prevent any seepage from sticking to the pavement. Erect a splash shield, no less than 15 square feet, of an approved dimension and stability, between the nozzle and passing traffic to prevent possible damage or injury from uncontrolled spraying of hot asphalt. Pump asphalt at a pressure of 25 pounds per square inch to 45 pounds per square inch. Control the amount of rise by regulating the rate of injection of the mater ial. Use a positive means of monitoring lift, as specified in Section 679.3(c)1.h. Upward movement of the pavement greater than 0.05 inch is not allowed. If asphalt seeps from joints or cracks before undersealing is complete halt pumping until asphalt has congealed. Resume pumping until the slab lift limit is reached. When the nozzle is removed from the hole, remove any excess material from the area.

2.e Opening to Traffic. Do not open to traffic for a minimum of 30 minutes after grouting operations have been completed or according to the contractor’s approved field QC plan and according to Manufacturer’s recommendations.

1.a Pump Unit . As a minimum, provide a mounted unit capable of injecting the high -density polyurethane material at a controlled rate, underneath the pavement and capable of controlling the rate of rise of the pavement. Equip the pumping unit with a calibrated meter to measure the amount of high density polyurethane materials injected at each location and capable of instantaneous control of the material flow to avoid lifting of the pavement slabs. Equip each pumping unit with a display output device capable of recording the amount of material used. The output display device needs to be ca pable of providing the amount of material used in pounds. Also equip each display output device with a manual reset button. Provide certification of the calibration testing showing that the unit has been calibrated within the last 12 months before the start of the project. Provide pressure and temperature control devices capable of maintaining proper temperature and

proportionate mixing of the polyurethane component materials.

1.b Drill. Provide generator, core drill, and diamond -tip core barrels, or other satisfactory equipment capable of drilling the grout injection holes through the pavement and base material; and equipment in satisfactory condition and operated to produce holes that ar e smooth, vertical, and do not break out the bottom of the slab.

1.c Pavement Plugs. Provide cylindrical plugs of sufficient length and diameter to plug the holes. Taper one end so that the plug can be driven a maximum of 2-inches into the hole.

1.d. Vertical Movement Testing. Supply satisfactory equipment to measure slab lift, capable of detecting simultaneously the lift of the pavement edge, or of any two outside slab corners adjacent to a joint and the adjoining shoulder. Use equipment capable of detecting slab lift to measurements of 0.001 inch.

1.e Miscellaneous. Provide necessary hoses, valving, and valve manifolds with positive cutoff and bypass provisions to control pressure and volume, pressure gauges with gauge protectors, expanding packers or hose for positive seal during injection, hole washing tools, drill steel, bits, and any other miscellaneous tools required.

2.a Drilling Holes. Drill grout injection holes in the pattern shown on the Standard Drawings, or as directed. Drill holes not larger than 5/8 inches in diameter, vertical and round, and to a depth sufficient to penetrate any stabilized base.

2.b Preparation of Polyurethane. Mix components according to manufacturer’s specification.

2.c Polyurethane Grout Injection. Inject the high-density polyurethane material under the slab. Control the amount of rise by regulating the rate of injection of the material. Use a positive means of monitoring lift, as specified in Section 679.3(d)1.d. Upward movement of the pavement greater than 0.05 inch is not allowed. When the nozzle is removed from the hole, remove any excess material from the area. Stop pumping when any vertical movement occurs. The Inspector-in-Charge may direct pumping to cease if no vertical movement occurs.

2.d Opening to Traffic. Do not open to traffic for a minimum of 30 minutes after grouting operations have been completed , or according to the contractor’s approved field QC plan and according to Manufacturer’s recommendations.

679.4MEASUREMENT AND PAYMENT—

The price includes patching of the hole.

The unit price includes an accelerator, if required. For each 5 linear feet of radial cracking, as specified in Section 679.3(a)6, the Department will reduce this pay item by one bag of cement. The Department will not pay for any wasted grout material.

Includes plugs and patching of the hole.

Measured by calibrated flow meter. The Department will not pay for any wasted grout material.

Measured by calibrated flow meter. The Department will not pay for any wasted grout material.