Slab curl occurs when the surface of a concrete slab shrinks during the curing process. If the bottom of the slab does not shrink as much, the slab will curl up, causing the edges to no longer be in contact with the underlying ground. Slab curl repair can’t unbend the slabs, but can stabilize them to address the effects.
If in a retail environment, with no heavy loading, slab curl is usually not a problem–you may be able to hear or feel it while pushing a shopping cart around a grocery store, but it doesn’t affect the function of the floor.
In industrial or commercial settings with heavy traffic, such as fork lifts, when equipment drives over areas that are curled up, the concrete rocks. This rocking can cause joint deterioration, premature tire wear, or in severe cases, load losses, damage to inventory and racks, broken guidance wires, or other problems.
Slab Curl Repair Method
You can’t stop slab curl. However, CJGeo can stabilize the slabs using the polyurethane grouting process. CJGeo uses CJGrout-20SDB to stabilize curled slabs. 20SDB is formulated to be very mobile (spreads far through very tight voids) and provides greater bearing capacity than the underlying soils.
Slab Curl Repair Process
CJGrout-20SDB is injected along each side of an affected joint. The injection holes are 5/8″ diameter, and spaced about every two feet, alternating across the joint. The reactors (special pumps that heat and convey the two components of 20SDB) pump material to the placement point using heated hoses, to a placement gun. The placement gun ensures uniform mixing of the two components, and is clamped to mechanical packers inserted in the injection holes.
During injection, multiple rotary lasers monitor the floor elevation. Grout injection stops once the floor moves a few hundredths of an inch. Grout communication to adjacent injection holes is another cutoff criteria.
Patching after the injection work is with rapid setting grout. This is typically a cement-based grout, but in very clean facilities, epoxy is a very durable alternative for hole patching. Because CJGrout-20SDB geotechnical polyurethane cures very quickly, traffic can resume immediately. Full traffic right after grouting allows for the crew to ensure that the slabs have stopped moving.
Diamond grinding or polishing can reprofile floors after grouting is completed.
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