283 SECTION 512 CONCRETE SLAB STABILIZATION
512.1 -DESCRIPTION : This item of work shall consist of drilling holes in Portland cement concrete pavement as directed, pumping a portland cement/fly ash grout through the holes to fill voids under the pavement, and filling the drilled holes with mortar.
512.2 -MATERIALS : Materials shall meet the requirements of the following Sections:
MATERIAL SECTION OR SUBSECTION Accelerating Admixtures 707.13, 707.14 Curing Compound 707.9 Fine Aggregate 702.1 Fly Ash 707.4.1 Portland Cement 701.1, 701.3 Water -Reducing Admixtures 707.3
512.3 -PROPORTIONING : 512.3.1 -Mix Design Requirements: The subsealing grout mix shall be as follows: 94 pounds of portland cement (minimum) 210 pounds of fly ash Water -reducing admixture dosed at the Manufacturer’s recommended dosage rate for the cementitious material content listed above Water to achieve required fluidity
If ambient temperatures are below 55°F, an accelerating admixture shall be used. Prior to the start of construction, the Contractor shall design and submit to the Engineer for approval the prop ortions of materials, including admixtures, to be used which will result in a workable subsealing grout mixture having the desired properties. Submittals shall include tests of the grout by an approved laboratory showing 1 -day, 3 -day, and 7 -day compressiv e strengths and flow cone efflux time. An approved laboratory is defined as a laboratory which is regularly inspected by the Cement and Concrete Reference Laboratory. The 7 -day strength shall not be less than 400 psi as measured by ASTM C109. The subsealing grout efflux time shall be measured by ASTM C939 (Flow Cone Method) and shall be between 16 and 25 seconds.
512.4 -EQUIPMENT : The grout plant shall consist of a positive displacement cement injection pump and mixing equipment that is capable of providing a thoroughly mixed and homogenous mixture. Rock drills or other devices capable of drilling the grout injection holes throug h the pavement and base material will be permitted. The rock drill shall not be heavier than 60 pounds, and the downfeed pressure whether by hand or mechanical means shall not damage the bottom portion of the slab. The Contractor shall supply equipment c apable of detecting the lift of the pavement near the hole being grouted. These devices shall make lift measurements from a stable reference point and shall be of a design satisfactory to the Engineer.
284 The Contractor shall also furnish all necessary ho ses, valves, valve manifolds, positive cut - off, bypass provisions, pressure gauges with gauge protectors, expanding packers or hose for positive seal, and any other equipment necessary to control pressure and volume during grout injection.
512.5 -CONSTRUCTION METHODS : 512.5.1 -Drilling Holes: The hole pattern for joints or transverse cracks shall require one hole in the approach panel or slab 1.5 feet from the fissure and six (6) feet from the centerline, and two holes in the slab on the panel on the opposite side of the fissure. This side of the fissure shall be noted as the leave panel. Of these two leave panel holes, one hole shall be three ( 3) feet from the fissure and three ( 3) feet from the pavement edge, and the other hole shall be three ( 3) feet from the fissure and three ( 3) feet from the centerline. When full depth repairs were made under previous contracts, the hole pattern for grouting shall be two approach panel holes and two leave panel holes, 1.5 feet from the full depth repair and three ( 3) feet from the pavement edge and centerline, respectively. Full depth repairs made under this contract shall not be grouted. Grout holes shall not be larger than 2.5 inches in diameter. Holes shall be drilled to a depth sufficient to penetrate through any stabilized base, but they shall not penetrate into a granular subbase more than one ( 1) to two ( 2) inches. Holes may be washed or blown out, if necessary, to obtain thorough distributio n of the injected grout.
512.5.2 -Subsealing: The Contractor shall grout one hole at a time using an expanding rubber packer or hose on the nozzle connected to the discharge of the grout pump. When grout appears at any longitudinal or transverse crack or adjacent holes, or when the lift monitoring device indicates slab movement of 3/16 inch, grouting shall be stopped. Immediately, after the nozzle is removed, the grout hole shall be temporarily sealed with a round tapered plug construc ted from wood or another suitable material as approved by the Engineer. The plug shall remain in place until the grout in the hole is not disturbed by adjacent grouting. Pavement which has been raised in excess of ¼ inch shall be deemed unacceptable. No payment for any subsealing material at the subject location shall be made when this tolerance is exceeded. Grout holes shall be filled full -depth and flush with the surface of the pavement with a stiff mortar consisting of one part portland cement to th ree parts of fine aggregate. The surface shall be troweled and painted with curing compound. Grout subsealing shall not be performed when ambient temperatures are below 40 °F. In addition, subsealing operations shall not be performed if the subgrade or base course material is frozen. Mixed grout held in the mixer or injection pump for more than one hour after mixing shall not be used. In the event the Engineer determines that continued grout injection at any specific location is no longer practical, he may direct the Contractor to cease grout injection at that location.
512.5.3 -Testing: The Contractor shall determine the grout efflux time in accordance with ASTM C939. The Contractor shall furnish the flow cone for this test. The Contractor shall perform a minimum of three tests per day, in the presence of the Engineer. More tests shall be performed if deemed necessary by the Engineer. The subsealing grout efflux time shall be between 16 and 25 seconds. Adjustments to the grout mixture will be made during the subsealing operation to meet flow requirements.
285 512.6 -OPENING TO TRAFFIC : No traffic will be permitted on the grouted slabs for at least 3 hours after grouting, unless otherwise approved by the Engineer.
512.7 -METHOD OF MEASUREMENT : The quantity of work performed for concrete slab stabilization shall be measured by the number of holes drilled and filled with grout. This work shall include drilling and filling holes with gr out; full compensation for furnishing all labor, materials, tools, equipment and incidentals; and, for doing all work involved in grout subsealing of existing concrete pavement, in place, complete and accepted. The quantity of grout for subsealing of con crete slabs shall be measured by the number of tons of portland cement used in the work, complete in -place and accepted.
512.8 -BASIS OF PAYMENT : The quantities, determined as provided above, wi ll be paid for at the contract unit bid price for all of the items listed below. The price and payment shall be full compensation for furnishing and placing all the materials and doing the work herein prescribed in an acceptable manner including all labor , tools, equipment, supplies, and incidentals necessary to complete the work.
512.9 -PAY ITEMS: ITEM DESCRIPTION UNIT 512001 -* Holes Drilled For Concrete Slab Stabilization Each 512002 -* Grout Used For Subsealing Of Slabs Tons
* Sequence number
286 SECTION 513 CONCRETE PAVEMENT CROSS STITCHING
513.1 -DESCRIPTION : Concrete pavement cross stitching consists of drilling holes and anchoring deformed reinforcing bars diagonally across longitudinal cracks.
513.2 -MATERIALS : Materials shall meet the requirements of the followingS ubsections of Division 700 :
MATERIAL SUBSECTION Deformed Steel Reinforcing Bars 709.1
513.2.1 -Material Requirements: Deformed Steel Reinforcing Bars shall be Grade 60. Anchoring Material and Dispensing Equipment - Use a pourable, two component, 100% solids structural epoxy which is approved by the Engineer. It shall be dispensed either from:
ii. Thro ugh a static nozzle that homogeneously mixes the material without any hand mixing first.
513.3 -EQUIPMENT AND TOOLS : 513.3.1 -Drills: Use a hydraulic drill with tungsten carbide bits. Control the forward and reverse travel of the drills by mechanically applied pressure. Mount the drill on a suitable piece of equipment such that it is quickly transported and positioned. Rest and reference the drill rig frame on and to the paveme nt surface such that the drilled holes are cylindrical and repeatable in terms of position and alignment on the surface being drilled. Hand -held drills are not permitted.
513.4 -CONSTRUCTION METHODS : 513.4.1 -Drilling Holes: Drill the end holes in a slab eighteen ( 18) – twenty ( 20) inches from the transverse joints. Drill interior slab holes at a maximum of twelve ( 12) inch spacing . Drill such that the:
ii. Hole centerlines are perpendicular to the crack at each location being drilled. iii. Adjacent holes are drilled in opposite directions across the crack. iv. Longitudinal centers of drilled holes are at the crack.
written recommendations. Those recommendations shall be submitted to the Engineer prior to the start of construction. vi. Hole bottoms are no more than one ( 1) inch from the slab bottom.
Repair cracks t hat result from drilling with a full depth repair as approved by the Engineer.
513.4.2 -Cleaning Holes: Clean the drilled holes in accordance with the anchoring material Manufacturer’s written recommendations. Those recommendations shall be submitted to the Engineer prior to the start of construction. As a minimum, clean holes with oil -free and moisture -free compressed air. The Engineer will check the compressed air stream purity with