Most slabs-on-ground are unreinforced or nominally reinforced for crack-width control. When positioned in the upper or top portion of the slab thickness, steel reinforcement limits the widths of random cracks that may occur because of concrete shrinkage and temperature restraints, subbase settlement, applied loads or other issues.
This type of reinforcement is commonly called shrinkage and temperature reinforcement.
Shrinkage and temperature reinforcement is different than structural reinforcement. Structural reinforcement is typically placed in the bottom portion of the slab thickness to increase the slab’s load capacity. Most structural slabs-on-ground have both top and bottom layers of reinforcement for controlling crack-widths and increasing load capacities. Because of constructability issues and costs associated with two layers of reinforcement, structural slabs-on-ground are not as common as nonstructural slabs.
While there are several reinforcing options for nonstructural slabs-on-ground, this article focuses on steel reinforcing bars and welded wire reinforcement for crack width control.