450Pressure Grouting Portland Cement Concrete Pavement

Cement Concrete Pavement

450.1General Description

This work includes pumping a slurry type grout mixture through holes drilled in the pavement into voids underneath the slabs to stabilize and underseal Portland cement concrete pavement. Use a grout mixture that can form a hard and durable mass to fill voids under the pavement. Regrout unstable slabs after initial undersealing and stabilizing as directed by the Engineer. 450.1.01 Definitions Initial set: 200 psi (1380 kPa) with a 0.25 in.² (161 mm²) probe according to AASHTO T 197 (Proctor Needle Test). 450.1.02 Related References

GDT 84 AASHTO T 197 (Proctor Needle Test) 450.1.03 Submittals General Provisions 101 through 150.

450.2Materials

Ensure that fine aggregate meets the requirements of Subsection 801.2.02, except mortar-making properties are not required.

The Bid Item designates the required undersealing grout mixture types. The mixture contains the proportions listed in the Table of Grout Mixtures below. Use enough mixing water with the dry ingredients to produce a grout consistency that makes the efflux time from the flow cone at least 14 seconds and no more than 20 seconds. Use GDT 84 to determine the grout consistency. Add cement, cement and limestone dust, cement and fly ash, or cement and fine aggregate in the proper proportions to a mixed batch to produce the required consistency. 592 592 592 592 592 592 592

Table of Grout Mixtures Mix Proportions, Percent by Weight of Dry Materials Grout Types Dry materials 1 2 3 4 5 Cement (min.) 25 25 25 25 25 Limestone dust — 25 75 50 — Fly ash 25 — — 25 75 Fine aggregate 50 50 — — — Ensure that materials meet the requirements of these Specifications: Material Section Portland Cement Types I or III Section 830 Mineral Filler (Limestone Dust) Section 883 Calcium Chloride, Type I Section 884** Fly Ash, Type F Section 831 Water Section 880 Fine Aggregate Size No. 20 Subsection 801.2.02 Agricultural Lime Subsection 882.2.02* *Agricultural lime used for undersealing shall have at least 95% passing the No. 30 (600 µm) sieve and 30% passing the No. 200 (75 µm) sieve. **The Laboratory may approve other commercially available accelerators that may be substituted for calcium chloride. 450.2.01 Delivery, Storage, and Handling General Provisions 101 through 150.

450.3Construction Requirements

450.3.01 Personnel Provide personnel to control the lifting on every slab that is undersealed. Furnish a truck driver and sufficient workers to assist operating static load measuring gauges on the slab stabilization testing equipment. 593 593 593 593 593 593 593

450.3.02 Equipment

The batching equipment includes weight hoppers and scales for each dry material or calibrated volumetric batch hoppers. Calibrate volumetric batch hoppers in increments equivalent to one 94 lb. (42.6 kg) bag of cement. Use aggregate scales accurate to ± 1 percent and cement scales accurate to plus or minus 0.5 percent. Equip conveyor belts with windproof covers if the belts convey the dry materials into the mixer.

For mix types one through four, use a watertight, batch-type mixer or high-speed colloidal mixer capable of blending the materials into a homogenous mixture. Use a high-speed colloidal mixer for mix type five.

Use grout pumping equipment with a positive displacement plunger or piston-type pump or a screw-type worm pump.

• Pressure gauge at the pump capable of measuring from 0 to 200 psi (0 to 1380 kPa) • Positive cut-off valve at the nozzle end • Bypass return line for recirculating the grout back into a holding tank or mixer

of leaks.

Provide the following drilling equipment: • Air compressors—Provide air compressors with enough capacity to operate pneumatic hammers or drills. • Pneumatic or hydraulic drills—Provide pneumatic or hydraulic drills equipped with bits that will cut 1.5 in. (38 mm) or other approved diameter holes through the concrete pavement. Operate the equipment so as to prevent damage to the pavement being drilled. Do not create excessive down pressure to force the bit through the concrete rapidly. The Engineer must approve the drilling procedure.

Furnish a two-axle truck with dual rear wheels. Load the rear axle to 18 kips (8000 kg) evenly distributed between the two sides.

Ensure that equipment used to measure the slab lift can simultaneously detect movement of the two outside slab corners adjacent to a joint and the adjoining shoulder. Ensure that the equipment can make these measurements to 0.001 in (0.025 mm). 450.3.03 Preparation General Provisions 101 through 150. 450.3.04 Fabrication General Provisions 101 through 150. 594 594 594 594 594 594 594

450.3.05 Construction

Begin pressure grouting operations when the air temperature in the shade and away from artificial heat is at least 35 ºF (2 ºC) and rising. Stop pressure grouting if the temperature is 40 ºF (4 ºC) and falling or when the subgrade contains an abnormal amount of moisture.

Slab testing is performed to detect all slabs having a deflection greater than 0.030 in. (0.76 mm). Perform testing between 3:00 AM and 9:00 AM, unless otherwise directed by the Engineer. In hot weather, test between 3:00 AM and 7:00 AM if directed by the Engineer. Stop testing if slabs are beginning to “lock-up.”

Preliminary testing is not required on slabs that require grouting but have been previously tested and marked by the Department.

If the Department has not performed preliminary testing, use static methods to test each transverse joint and crack on the Project or within designated Project areas. Do not test, however, transverse cracks in slabs that are to be replaced entirely. Test the joints and cracks as follows:

the load to the nearest 0.001 in. (0.025 mm).

personnel to place and assist in operating the gauges.

near the pavement edge. Zero in the gauges with no load on the slab on either side of the joint.

the joint and the outside test wheel approximately 1 ft. (300 mm) from the pavement edge.

Read the forward gauge.

the plans. Perform additional tests as follows: 1) Drill one hole in the corner of the slab where the movement was measured. 2) Drill the holes the same diameter as the undersealing holes and place the holes 18 in. (450 mm) from the transverse and shoulder joint. 3) Fill the test holes with water and observe. 4) If the Engineer believes the pavement system readily drains the water poured into the test hole, pressure grout the slab. Based on the results of testing, deflection measurements, and water drainage observations, the Engineer will determine which slabs require undersealing.

according to Subsection 450.3.05.B.2, Testing.

plans, as directed. Slabs will be accepted that continue to show movement greater than specified after two properly performed groutings. 595 595 595 595 595 595 595

The Plans show the location of holes to be drilled in each type of slab for undersealing. However, whenever possible, use the holes from previous undersealing work by redrilling. To begin drilling:

from previous undersealing work as possible. The Engineer may alter the hole pattern. Only the actual number of holes drilled will be considered for payment for the initial undersealing.

provide positive seal for the pumping nozzle.

concrete unless the Engineer approves an alternate depth. The Engineer shall designate the number, depth, and location of holes for undersealing attempts after the initial attempt.

according to Section 609 and Section 452.

After drilling the holes, and immediately before pumping the underseal grout, insert a pipe with enough air pressure in each hole to remove debris and to provide a passage for the grout, if necessary.

Properly position the lift measuring device before pumping grout under a slab. Fill the voids under a slab as follows:

grouting during late night and early morning hours if the slabs cannot be stabilized with daytime grouting.

slabs, or substantial rising of the adjacent shoulders.

flowing out of an adjacent hole or joint or the edge of the slab is sufficient evidence that the voids and cavities are filled, and pumping should cease. Additional evidence is that the slab rises rapidly, or the adjacent shoulder begins to rise.

the Engineer. NOTE: Do not crack the slabs by differential lifting.

underneath the slab.

Ensure that the nozzle end does not extend below the bottom of the concrete.

begins to lift excessively.

operations. 596596596596596596596

grout that flows into the edge drain system.

Use the following procedure or an alternate approved by the Engineer to monitor grout flow into the edge

drain system:

shoulder or pavement interface.

flow into the edge drain system.

operation at the Contractor’s expense according to Section 609 and Section 452.

Before permitting traffic on the section, remove grout deposits on the pavement or shoulders and clean the

surface. Remove debris, bags, spillage, etc., from the Right-of-Way each day.

Remove the grout from the holes and fill the holes with a stiff sand-cement mixture or an approved quick setting

patching material.

Repair filled holes that ravel out or become damaged. Also, repair unsatisfactorily filled holes from previous

undersealing work at the Contractor’s expense, as directed by the Engineer.

After pumping the grout under the designated slab and permitting traffic over the slabs for at least 12 hours, test

the slabs for stability.

Conduct these tests by static loading as in Subsection 450.3.05.B.2.h and Subsection 450.3.05.B.2.i. Based on

the test results and criteria on the plans, the slabs will be accepted or designated for further undersealing as

directed by the Engineer.

Do not permit traffic on the grouted slabs until the grout has taken an initial set (normally 4 to 6 hours).

Schedule the operations so that the grout has initially set, and the work area is cleared before traffic is allowed on

the grouted slabs.

450.3.06 Quality Acceptance

General Provisions 101 through 150.

450.3.07 Contractor Warranty and Maintenance

General Provisions 101 through 150.

450.4Measurement

Portland cement incorporated into the pressure grout slurry is measured by the 94 lb. (42.6 kg) bag.

On an initial undersealing attempt, holes drilled through the existing concrete slabs at the locations and to the

depths shown on the Plans or directed by the Engineer are measured per each.

If holes drilled for the first stabilizing attempt are used for the second stabilizing attempt, holes are not paid for

again by the Department. If new holes are drilled, they are measured per each. 597597597597597597597

Preliminary testing described in Subsection 450.3.05.B.2.h and Subsection 450.3.05.B.2.i. is measured by the

linear mile (linear kilometer), horizontal measure for each lane of each roadway tested, when required. Bridges are

not included in the measurement.

Stability testing in Subsection 450.3.05.H is measured by the joint.

450.4.01 Limits

General Provisions 101 through 150.

450.5Payment

Holes will be paid for at the Contract Unit Price per each. Payment is full compensation for drilling and sealing

the hole.

If holes drilled for the first stabilizing attempt are used for the second stabilizing attempt, the Department does

not pay for the holes again.

Portland cement pressure grout slurry will be paid for at the Contract Unit Price bid per 94 lb. (42.6 kg) bag of

cement or fraction thereof. Payment is full compensation for furnishing materials to be incorporated into the grout

slurry, hauling, mixing, pumping, and cleaning to stabilize the slabs.

Preliminary testing when shown on the Plans and in the Proposal as a payment Item will be paid for at the

Contract Price bid per linear mile (kilometer), horizontal measure. Bridges will be excluded from the linear mile

Static testing of slabs performed according to Subsection 450.3.05.B.2.h and Subsection 450.3.05.B.2.i. will be

paid for each time the joint is tested. Payment is full compensation for furnishing the load test truck, driver, and

personnel necessary to assist in the testing.

No separate payment will be made for this work. Include the cost in the bid submitted for Portland cement

pressure grout slurry. The precautions used will require prior approval of the Engineer.

Payment will be made under:

Item No. 450 Holes Per each

Item No. 450 Portland cement pressure grout slurry (grout type___, ___, or___) Per bag 94 lb. (42.6 kg)

Item No. 450 Preliminary testing Per linear mile (kilometer )

Item No. 450 Stability testing Per joint

450.5.01 Adjustments

General Provisions 101 through 150.. 598 598 598 598 598 598 598