Slab Curling – The Basics

What is Slab Curling?

 

Slab curling is the slight bending (upwards or downwards) of concrete slabs at the edges and corners. The curling causes small voids below the concrete that will cause the slab to rock back and forth when under heavy load. This distortion can cause further damage to the warehouse floor, such as chips, cracks, damages to the nosing between slabs, and can also be hard on the warehouse equipment. At times, slab curling can be significant enough to distinctly hear a “knocking” sound from the slab when traffic moves across the slab.

What Causes Slab Curl?

 

Slab curling is most often related to moisture and temperature differences above and below the concrete slab. For example, if the bottom of the slab is hotter than the top of the slab, then the colder side will contract, causing the concrete to bow upwards. Water leaving the concrete will cause stress on one side of the slab. The curling that occurs is most noticeable near the corners and edges.

The most common type of curl is when the top of the slab dries more than the bottom. This causes an upward curl.  Curling shortly after placement is likely due to poor curing or drying too quickly. Excess bleeding due to water in, and on the surface of the concrete can increase the drying shrinkage compared to the bottom of the slab.

How Slab Curl is Remedied.

 

To remedy this issue, Advanced Construction Services brings the best methods to the table. First, we inject the void area with a structural polyurethane that will stabilize any loose soils underneath by consolidating the loose soils into the foam. Second, the polyurethane expands under the slab to underseal the slab and stabilize it from future movement. After injecting the polyurethane, the construction joints are filled with a polyurea joint filler. This repair is quick, long-lasting, clean, and requires very little down-time for production. Forklift traffic can also resume work immediately after the repair.

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