452SLABJACKING OF PORTLAND CEMENT CONCRETE PAVEMENT

268

TABLE I GROUT MIXTURES MIX PROPORTIONS PERCENT BY VOLUME OF DRY INGREDIENTS GROUT TYPE 1 2 3 4 5 6 Fine Sand 30 50 50 Limestone Dust 50 80 30 Fly Ash 80 30 50 30 Cement 20 20 20 20 20 20

Except as specifically outlined in these specifications, the techniques involved in the slab jacking operation shall be the option of the Contractor as long as the desired results are achieved. Hole drilling patterns for pavement jacking shall be determined by the Contractor in the field based on conditions such as the size or length of the pavement area to be raised, the elevation difference, subgrade and drainage conditions, location of joints and cracks, and similar local circumstances. Extra holes may be required during the jacking process to apply additional pressure in a local area. Holes may be washed with water or blown with air to create a small hole from which the grout slurry can then spread. The injection holes shall be drilled through treated base so the base may be lifted with the pavement. Before slab jacking begins at a location, the Engineer will furnish the Contractor with the profile grade to be attained along with a nearby referenced point of elevation. The Contractor shall pump in a pattern and in the amount required to raise the pavement to within 1/4 of an inch {6 mm} of the designated grade.

During the jacking operation, the discharge end of the grouting apparatus shall not extend below the lower surface of the concrete pavement. Continuous pressures up to 200 psi {1.5 Mpa} will be permitted. Pressures to 300 psi {2.0 Mpa} will be allowed only for short periods. If the pavement is bonded to the subgrade, brief bursts of pressure to 600 psi {4.0 Mpa} will be allowed. After slab jacking has been completed in a hole and the discharge pipe removed, the hole shall be plugged immediately with wooden plugs tapered to fit in the hole to retain the pressure of the grout and stop any waste or return flow of the mixture. When slab jacking to the desired elevation has been accomplished, the temporary plugs shall be removed and the hole filled with an approved stiff cement grout or concrete mixture. Unless approved otherwise by the Engineer, slab jacking operations shall cease as early as necessary to permit the grout to harden at least three hours prior to allowing traffic back on the grouted slab before first darkness. Lifting shall be done using sufficiently sized increments and change in injection locations to keep slab stresses to a minimum and to avoid cracking. Slabs which, in the opinion of the Engineer, have been damaged by the Contractor's operation or lack of control such that their repair or replacement is necessitated shall be repaired or removed and replaced at no cost to the Department.

Any part of the pavement raised above the tolerances listed in Subitem 452.03(b)3.a. above shall, if so directed by the Engineer, be brought to grade by grinding. Should the overjacking be greater than 0.1 foot {30 mm}, the Department at its option may require removal and replacement of the pavement without cost to the Department and to its satisfaction with regard to area involved, method and time of replacement, and materials involved.

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 feet {1.5 m} of such crack measured, the Contractor's pay quantity shall be reduced by 0.25 bag of cement. SLABJACKING OF PORTLAND CEMENT CONCRETE PAVEMENT 269

Should the Engineer deem that continued grout injection at any specific location is no longer economically feasible, he may direct the Contractor to cease grout injection at that location. The Contractor will be paid at the unit bid price for the material used up to that point. The Engineer, at his discretion, may delete any location or may add a new location to be raised. Due to unknown conditions and the experimental nature of this type work, variations of any size in the plan quantity will not be considered cause for any increase or decrease in the unit contract bid price.

452.04Surface Requirements

After the slab jacking has been completed at a location, and before cleaning and sealing of cracks, the pavement surface shall be tested with a 15 foot {4.5 m} straightedge placed on the surface parallel to the centerline of the lane at points as directed across the width of the pavement and lapping 1/2 the length of the straightedge progressing longitudinally along the pavement or with an approved rolling straightedge. The Contractor shall furnish the straightedge and personnel to operate it under the direction of the Engineer. Areas showing high spots of more than 1/4 of an inch {6 mm}, but less than 1/2 of an inch {13 mm}, under the 15 foot {4.5 m} straightedge shall be ground down with approved grinding equipment until the high spot is less than 1/4 of an inch {6 mm} high. If the area is more than 1/4 of an inch {6 mm} low or 1/2 of an inch {13 mm} high under the 15 foot {4.5 m} straightedge, the pavement in the affected area shall be repaired to the Engineer's satisfaction without additional compensation; such repair may require removal and replacement of the affected area. Any area so removed shall not be less than 8 feet {2.5 m} in length nor less than the full width of the lane involved. If the area to be removed extends to a point less than 8 feet {2.5 m} from a joint, it shall be extended to the joint.

452.05Opening To Traffic

Unless specifically authorized otherwise, no traffic, including construction equipment, will be permitted on the jacked slabs until at least three hours after the grouting has ceased. When Type III cement is used, traffic will be prohibited until initial set occurs. Initial set shall be defined as 800 psi {5.5 MPa} when tested in accordance with AASHTO T 197. Slabs that have been removed shall be replaced the same day they are removed. No traffic, including construction equipment, will be permitted on the replaced slab until at least six hours after the slab has been poured. Traffic shall be placed on grouted slabs before first darkness of the same day that the slabs were grouted; traffic shall be placed on replaced slabs no later than the morning following the day the slabs were replaced.

452.06Method of Measurement

Portland cement pressure grout for slab jacking will be measured for payment by the bag (94 pounds {42 kg}) of Portland cement used in the grout; all other ingredients required in the grout will not be measured for payment. No other work under this Section will be measured for payment; this includes all hole drilling and any slab repair, removal, replacement, or grinding which may become necessary due to the slab jacking operation.

452.07Basis of Payment

Portland cement pressure grout for slab jacking, measured as noted above, will be paid for at the contract unit price bid per bag of cement used in the grout. This price shall be full compensation for furnishing of the grout, including all ingredients for the type mix designated, for mixing, for pumping of the grout, for all holes drilled, for any and all slab repair, removal, replacement, or grinding, and all equipment, tools, labor, and incidentals necessary to complete this item of work.

452-A Portland Cement Pressure Grout for Slab jacking - per bag PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT 270

PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT

453.01Description

The work covered by this Section consists of the stabilization of existing unstable concrete pavement slabs by pressure pumping of a specified grout under the slabs along with the removal and replacement of designated shattered paving slabs or sections of slabs. The word slab in this Section shall mean not only a slab, or a portion of a slab, in a jointed concrete pavement system, but also a portion of a continuously reinforced concrete pavement. Pressure pumping of grout or sub sealing of the pavement slabs is intended to stabilize the slab by filling voids and cavities under the slabs with a grout mixture that will form a hard insoluble mass. Removal and replacement of concrete pavement shall be as directed by the Engineer. Cracking in concrete pavement is defined as follows:  Hairline cracks - Small, tight cracks which in width resemble shrinkage cracks. No corrective repair procedure is required.  Low severity cracks - Wider than hairline cracks with the crack opening clearly visible. The concrete on both sides of the crack is acting with interlock between the cracked pieces limiting movement of the individual pieces.  Medium severity cracks - The concrete on both sides of the crack is acting with partial interlock between the cracked pieces allowing potential or actual small movement of the individual pieces.  High severity cracks - The concrete on both sides of the crack is acting independently allowing unrestricted movement of the individual pieces. If the crack does not have the same severity level along the entire length, the crack will be rated as the highest severity level present. Appropriate repair procedures for the various types of cracked slabs in a jointed pavement are as follows:  Low severity cracking will not require the removal of pavement. These cracks will be routed and sealed under Item 454-A.  Medium severity cracking will require the removal and replacement of at least a portion of the concrete slab. The entire slab is to be removed and replaced if broken into four or more pieces by at least medium severity cracks.  High severity cracking will require the removal and replacement of at least a portion of the concrete slab. The entire slab is to be removed and replaced if it is broken into three or more pieces of high severity cracks. Due to the variations in quantities that can be experienced in this type work, the quantities for the items in this Section cannot be accurately determined before the work is done; therefore, the items in this Section shall be excluded from those items which may have their unit price adjusted as allowed by Subarticle 104.02(a). At any time during the life of the project, should any process or work herein be deemed ineffective or unnecessary by the Engineer, the Engineer may order any and/or all work under this Section stopped, reduced, and/or eliminated. In such case, the Contractor will be paid for all work ordered and performed. No claim will be considered because of elimination or reduction of work under this Section.

453.02Materials

Materials furnished for use shall conform to the appropriate requirements of Division 800, Materials, and the requirements noted in this Article.

The grout used in pressure grouting shall consist of one of the mixtures shown in Table I with the materials complying with the following:  Type I III, IL, IP, or IS Cement – Section 815  Calcium Chloride - Section 805 Type I  Fly Ash - Section 806 modified to waive the Loss on Ignition requirement PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT 271

 Water - Section 807  Admixtures - Section 808 and 809  Limestone Dust - Limestone dust shall be thoroughly dry, free of lumps, meeting the following gradation requirements: Size % Passing by Weight {Mass} No. 30 {600 µm} Sieve 100 No. 100 {150 µm} Sieve 90 - 100 No. 200 {75 µm} Sieve 65 - 100  Fine Sand Fine sand shall comply with the appropriate requirements of Section 802 allowing the use of manufactured sand from limestone, sandstone or granite, or natural silica fine sand meeting the following gradation requirements:

Size % Passing by Weight {Mass} No. 10 {2.00 mm} Sieve 95 - 100 No. 60 {250 µm} Sieve 40 - 90 No. 200 {75 µm} Sieve 0 - 50 Percent Silt 0 - 25 Percent Clay 0 - 12 Percent Organic Material 0 - 3 Sand shall be non-plastic as determined by AASHTO T 89 and T 90.

Concrete for Portland Cement concrete pavement replacement shall meet the requirements of non-chloride accelerator. The use of an accelerator will not be required when the ambient air temperature is above 85 °F {29 °C}.

Adhesives furnished for anchoring tie bars and dowel bars shall meet the requirements of Article

870.04

453.03Construction Requirements

The equipment for pressure grouting of concrete pavement shall be that customarily used in the pressure grouting of earthen embankments or in mud-jacking of concrete pavement consisting of at least the following:

approved diameter holes through the rigid pavement. The equipment shall be operated in such a manner so as to prevent unnecessary damage to the slab.

slab movement during grouting of holes near the pavement edge. Dial gages with at least 1 inch {25 mm} of travel arm and capable of detecting 0.001 of an inch {25 µm} of movement shall be placed within 1 foot {300 mm} of the hole being grouted and 1 foot {300 mm} outside the edge of paving. The dial gage measuring movement within 1 foot {300 mm} of the hole being grouted shall have an arm length of at least 6 feet {1.8 m}. The base of the support for the gage apparatus shall be a minimum of 5 feet {1.5 m} outside the edge of paving during the monitoring of movement and shall be moved along the shoulder during the grouting of holes along the pavement edge. An engineer's level, furnished and operated by the Department, will be used, periodically throughout the day, to supplement the gage PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT 272

apparatus to monitor slab movement. Alternate gage apparatus setups may be used if requested in writing by the Contractor and approved by the Engineer.

various materials composing the grout. When volume is used, the weight per cubic foot {mass per cubic meter} of the materials will be determined and mix proportions adjusted accordingly.

high speed, colloidal type mixer will be required for grout mixes containing only cement and fly ash.

beneath the pavement slab. The pump shall be capable of supplying adequate pressure at the end of the discharge pipe to ensure filling of all voids at the required hole spacing. A gage shall be located on the discharge side of the pump to measure the pumping pressure.

determination of the consistency of the grout. The flow cone shall conform to the dimensions and other requirements of ALDOT-338.

The equipment for removal and replacement of the concrete pavement slabs shall be suitable for the purpose intended and approved by the Engineer. Attention is directed to the operational requirements for removal and replacement in Subarticle (c) below.

Unless approved otherwise by the Engineer in writing, all pressure grouting shall be performed between the dates of April 1 and November 1. Pressure grouting operations may not be started unless the air temperature, in the shade and away from artificial heat, is at least 35 °F {2 °C} and rising. Pressure grouting shall stop if the temperature is 40 °F {4 °C} and falling or when the subgrade contains an abnormal amount of moisture as evidenced by standing water on the pavement or in joints or cracks. To accelerate setting and provide early strength to mixes utilizing Type I, Type IL, Type IP or Type IS cement, calcium chloride shall be used in the proportions tabulated below for respective temperature ranges. Normal traffic flow may be resumed three hours after grouting. Atmospheric Temperature % Calcium Chloride by Weight {Mass} Of Type I, IL, IP or IS Cement 35 – 55 °F {2 - 12 °C} 5 56 – 69 °F {13 - 20 °C} 4 70 – 79 °F {21 - 26 °C} 3 80 – 89 °F {27 - 31 °C} 2 90 °F {32 °C} and above 1 When Type III cement is used, 0-2% calcium chloride may be required as needed to accelerate setting in cold weather. Grouted slabs may be opened to traffic in accordance with Subarticle

The mixtures used in pressure grouting shall consist of the proportions tabulated in Table I. The consistency may be varied by the addition of water and/or other additives. The quantity by weight {mass} of equivalent 100% pure calcium chloride to be included in the mixture shall be in accordance with Item 1 above. The calcium chloride, when required, shall be thoroughly premixed in the approximate quantity of mixing water required for a predetermined batch size before combining with the other ingredients. The consistency of the grout shall be determined in accordance with ALDOT-338. The quantity of mixing water used shall be that which will produce a grout of such consistency that the time of efflux from the flow cone will be a minimum of 14 seconds and a maximum of 22 seconds for undersealing. After the initial introduction of a sufficient amount of water into the mixture to obtain the necessary consistency, no additional water shall be added. The grout shall be used within 90 minutes after introduction of water into the mixture. Dry ingredients may be added to a mixed batch only in the amounts necessary to bring a too thin mixture to the required consistency. In this case the added dry ingredients shall be in the PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT 273

specified ratio. Grout which fails to meet the flow requirements specified above, shall not be used in grouting operations. A grout mixture shall be selected by the Contractor from the mixtures shown in Table I below. The Engineer reserves the right to specify a different mixture if the one chosen by the Contractor fails to produce the desired results. TABLE I GROUT MIXTURES Mix Proportions, Percent by Volume of Dry Ingredients Grout Type 1 2 3 4 5 6 Fine Sand 30 50 50 Limestone Dust 50 80 30 Fly Ash 80 30 50 30 Cement 20 20 20 20 20 20

Selected slabs designated by the Department for pressure grouting shall be drilled as indicated on the plans or designated by the Engineer. For holes nearest the edges of the slab, the joints, or a major crack, a maximum of 3 inches {75 mm} from the precise marked location is considered to be reasonable. For other holes, a maximum 6 inch {150 mm} tolerance is considered to be reasonable. Should it become necessary or desirable to drill holes at locations other than those shown on the plans, such holes shall be drilled only as approved by the Engineer. In no instance shall holes be drilled in the wheel paths of a lane. The drills shall be rotated to avoid cracking the pavement and to provide satisfactory holes of the proper diameter for effective operations in pressure grouting. When drilling holes, the drills shall be held as nearly perpendicular to the pavement surface as possible. Holes which cannot be satisfactorily used in pressure grouting shall be filled with grout and not measured for pay; new holes shall be drilled. After the holes are drilled, and just prior to pressure grouting, a high pressure air pipe may be required to clean the hole, if deemed necessary by the Engineer, to facilitate introduction of the grout. After the holes are cleaned, the discharge hose on the pressure grout pump shall be connected to the hole in a manner that will provide adequate seal to maintain pressure past the connection. The discharge end of the pipe shall not extend below the lower surface of the concrete pavement. To fill all voids, pumping of grout will be required in holes designated by the Engineer. The maximum pressure allowed during the grouting operation will be 200 psi {1.5 Mpa}. A gage shall be located on the discharge side of the pump to measure the pumping pressure. Normally, indication that grout is flowing out of an adjacent hole or joint or the edge of the slab is sufficient evidence that all cavities or voids are filled within the range of the hole being grouted and pumping in such hole shall cease. Additional evidence that grouting should cease is a rapid rise of the slab, or indications of a rise of the adjacent shoulder. A minimal lifting of the slab will be allowed but not to exceed 0.05 of an inch {1 mm} per grouting pass. Care shall be taken not to crack slabs by differential lifting. Any slab or portion of slab or shoulder which is raised more than 0.05 of an inch {1 mm} each grouting will require corrective action, without payment, by the Contractor. Such corrective action shall consist of grinding or other methods approved by the Engineer. After grouting has been completed in a drill hole, the discharge pipe shall be withdrawn and latent grout removed. The hole shall not be plugged unless authorized otherwise by the Construction Engineer. Patching of the hole shall begin after the grout has taken an initial set. The grout shall be removed to a minimum depth of 4 inches {100 mm} below the pavement surface. A low slump concrete mix consisting of 1-part Type I, Type IL, Type IP, Type IS or Type III cement and 2-parts No. 100 concrete sand by volume shall then be placed in the hole, rodded and leveled with the pavement surface. Filled holes that later shrink below the finished surface, ravel out, or otherwise become damaged before project completion shall be repaired. Corrective measures shall be taken in case stooling occurs by making proper adjustment in the stiffness of the grout being used. In case stooling does occur, additional holes shall be provided as directed and a more fluid grout shall be pumped through these new holes to fill the voids between the stools. At least 24 hours, but no later than 5 days, after a slab has been grouted, it shall be tested for movement between the hours of 3:00 a.m. and 7:00 a.m. On cool, cloudy days, this time frame PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT 274

may be extended if approved by the Engineer. The test rolling equipment shall be rubber-tired and of sufficient weight {mass} to give a 20,000 pounds {90 kN} single axle load with a minimum of 10,000 pounds {45 kN} per side (a properly loaded dump truck may be used). Each slab shall be tested by making one or more passes over it with the test roller. The rolling shall be slow enough to allow an observer to measure the movement and mark the slab if regrouting is needed. If the slab moves 0.03 of an inch {0.8 mm} or more during the test rolling, new holes shall be drilled and the slab regrouted. All slabs which have been regrouted shall be retested as outlined above for the initial testing. After two returns for regrouting, should the slab fail the test rolling, the Engineer will make the decision to leave the slab as is, continue regrouting, or remove and replace the slab. Payment will be made under the appropriate pay items for the additional drill holes and grout used in the regrouting operation. The cost of test rolling shall be absorbed in other items of work. The construction methods outlined above may be modified by the Engineer as field conditions indicate. Pressure grouting operations shall cease at least three hours before sundown, except that on cloudy days pressure grouting operations shall cease earlier as necessary to permit grout to harden at least three hours prior to allowing traffic back on the grouted slab before first darkness. First darkness shall be defined as that time of day the average traveling public vehicle would first begin to use its headlights.

The extent of removal shall be as shown on the plans or directed by the Engineer. The slab section designated for removal shall be sawed as shown on the plans. The Contractor shall not oversaw the slab within 2 feet {600 mm} of another oversaw or within 2 feet {600 mm} of any type of joint. Transverse cuts for removal and the placing of new steel tie bars shall be performed as shown by plan details. The sections of pavement to be removed may be removed in any manner approved by the Engineer which does not damage the underlying base layer, adjacent concrete slabs, or the joint steel. Any damage to the underlying base or adjacent slabs shall be repaired to the satisfaction of the Engineer. Joint steel shall be cleaned and reconditioned to provide the same load transfer and/or tie as in the original pavement design. Any damaged or destroyed steel, which in the opinion of the Engineer would not function properly, shall be replaced in kind and retied to the old pavement by drilling an appropriate size hole of the proper depth and anchoring the new bar with an approved adhesive material. This replacement also includes steel damaged or destroyed previous to the removal operation. All tie bars and dowel bars tied to the old pavement shall be anchored into place with an approved adhesive material in such a manner as to meet a 7200 pound {32 kN}, minimum, pull-out requirement. The Department will perform the pull-out tests in accordance with ALDOT-366. The Contractor shall supply the equipment necessary to perform the pull-out test. Slabs shall be removed and replaced during the same day. Preparation for removal, including sawing the slab into smaller pieces, may be done the day prior to removal, but traffic shall be maintained on the slab the night before removal.

After completion of removal operation, the joint steel and/or reinforcing steel shall be reconditioned or replaced (reconditioned means the cleaning and straightening of the steel bars and the cleaning, painting, greasing, replacement, etc. of the dowels), new tie bars placed as detailed by the plans, and the base cleaned and repaired as directed, and then the slab shall be poured. The Contractor shall provide gang drills or templates that will provide the proper alignment for holes drilled for dowels or tie bars. The size of the drilled hole shall be 1/8 of an inch {3 mm} greater in diameter than the diameter of the dowel or tie bar being installed therein. The drill used shall not cause any spalling of the existing concrete around the face of the drill hole. The Contractor shall provide a device that will place the adhesive in the back of the drilled hole first and then proceed toward the front. After the dowels or tie bars are anchored in place, the Contractor shall allow time for the adhesive to set and then allow sufficient time for any required pull-out tests to be performed prior to pouring the replacement slab. The concrete paving slab shall be poured in accordance with the provisions of Section 450 except that Structural Portland Cement Concrete meeting the requirements of Section 501 for a