When concrete slabs on grade curl, the curling sometimes has little effect on floor performance. If the total curl is less than 1/4 inch or curling occurs primarily in low-traffic areas or under storage racks, the owner can often live with it, provided that cracking isn't excessive. There are occasions, however, when curling isn't tolerable and repairs are needed.
Will using a thin sand layer under floor slabs reduce subgrade or subbase support, causing cracking and poor joint performance, especially under repeated loadings such as forklift traffic? To gather data to help answer this question, The Aberdeen Group performed California Bearing Ratio tests on three soil samples with varying dry densities.