452.01 Description.
SLABJACKING OF PORTLAND CEMENT CONCRETE PAVEMEN T
452.01 Description.
The work covered by this Section consists of the raising and leveling of concrete pavements that have settled by the injection of grout under the pavement using hydraulic pressure to raise the pa vement to its designated grade. 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 o rder 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.
452.02 Materials.
a.General . Materials furnished for use shall conform to the appropriate requirements of Division 800, Materials, and the requirements noted in this Article.
b.Grout . The grout used in slabjacking shall consist of one of the mixtures shown in Table I with the materials complying with the following: Type I or III Cement - Article 815.01 and 815.03 Calcium Chloride - Section 805 Type I Fly Ash - Section 806 Modified to waive the Loss on Ignition requirement Water - Section 807 Admixtures - Sections 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 re quirements: 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.
452.03 Construction Requirements.
a.Equipment . The equipment for slabjacking of concrete pavement shall be that customarily used in the slabjacking of concrete pavement consisting of at least the following:
a.Air Compressors of sufficient capacity for operating pneumatic hammers.
b.A discharge pipe with an adequate securing device.
452.03 Construction Requir ements.
c.Pneumatic hammers equipped with drills that will cut 1.5 inch {38 mm} diameter or other 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.
d.A 15 foot {4.5 m} (min.) straightedge and such other equipment as may be necessary to insure that the jacked slabs meet the alignment and s urface requirements.
e.Blow pipe to enlarge void area.
f.Equipment for accurately measuring and proportioning by volume or weight {mass} the various materials composing the grout. When volume is used, the weight per cubic foot {mass per cubic meter} of t he materials will be determined and mix proportions adjusted accordingly.
g.A batch type mixer, capable of thoroughly mixing the various components of the grout. A high speed, colloidal type mixer will be required for grout mixes containing only cement an d fly ash.
h.A positive action pump capable of forcing grout through a drilled hole into voids and cavities beneath the pavement slab. The pump shall be capable of supplying adequate pressure at the end of the discharge pipe to insure 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.
i.A flow cone with all necessary components so that the Engineer may make an accurate field determination of the consistency of the g rout. The flow cone shall conform to the dimensions and other requirements of U.S. Army Corps of Engineers' Test Method No. CRD -C79-58.
b.Jacking of Pavement Slabs .
1.Weather Limitations. Unless approved otherwise by the Engineer in writing, all slabjacking shall be performed between the dates of April 1 and November 1. Slabjacking operations may not be started unless the air temperature, in the shade and away from artificial heat, is at le ast 35 °F {2 °C} and rising. Slabjacking 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 cement, calcium chloride shall be used in the proportions tabulated below for respective temperature ranges. Atmospheric Temperature % Calcium Chloride by Weight {Mass} Of Type I 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.
2.Preparation of Grout Mixture. The mixtures used in slabjacking 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 calc ium chloride to be included in the mixture shall be in accordance with Item 1 above. The calcium chloride, when required, shall be thoroughly pre -mixed in the approximate quantity of mixing water required for a pre -determined batch size before combining with the other ingredients. The consistency of the grout shall be determined by the U.S. Army Corps of Engineers' Test Method No. CRD -C79-58. The quantity of mixing water used shall be that which will produce a grout of such consistency that the time of effl ux from the flow cone will be a minimum of eighteen seconds and a maximum of twenty -five seconds for slabjacking. 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 one and one -half hours 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 specified ratio. Grout which fails to meet the flow requirements specified above shall not be used in jacking operations. A grout mixture shall be selected by the Contractor from the mixtures shown in Table I belo w. The Engineer reserves the right to specify a different mixture if the one chosen by the Contractor fails to produce the desired results.
452.03 Construction Requirements.
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
3.Construction.
a.General. Except as specifically outlined in these specifications, the techniques involved in the slabjacking 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 bas e so the base may be lifted with the pavement. Before slabjacking 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.
b.Jacking. 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 slabj acking 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 slabjacking 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, slabjacking operations shall cease as early as necess ary 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 Departm ent.
c.Overjacking. 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.
d.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 feet {1.5 m} of such crack measured, the Contractor's pay quantity shall be reduced by 0.25 bag of cement.
452.07 Basis of Payment.
e.Unanti cipated and Changed Conditions. 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.
452.04 Surface Requirements.
After the slabjacking has been completed at a location, and before cleaning and sealing of cracks, the pavement surface shal l 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}, und er 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.
452.05 Opening 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 8 00 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.
452.06 Meth od of Measurement.
Portland cement pressure grout for slabjacking 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 slabjacking operation.
452.07 Basis of Payment.
a.Unit Price Coverage . Portland cement pressure grout for slabjacking, 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 m ix 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.
b.Payment will be made u nder Item No .: 452-A Portland Cement Pressure Grout for Slabjacking - per bag
453.01 Description.
SECTION 453 PRESSURE GROUTING AND REPAIR OF PORTLAND CEMENT CONCRETE PAVEMENT
453.01 Description.
The work covered by this Secti on 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 S ection 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 subsealing 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 mov ement 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 quantiti es 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 adju sted 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.
453.02 Materials.
a.General . Materials furnished for use shall confo rm to the appropriate requirements of Division 800, Materials, and the requirements noted in this Article.
b.Grout . 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 or III Cement - Articles 815.01 and 815.03 Calcium Chloride - Section 805 Type I Fly Ash - Section 806 modified to waive the Loss on Ignition requirement
Source: Alabama Standard Specifications for Highway Construction, 2022 Edition. Pages 269–272 of 934.