1 September 1999
5-4. SHINKAGE COMPENSATING CONCRETE. Edge curling and shrinkage cracking can be
reduced through the use of shrinking compensating concrete that is properly reinforced. The
ACI Committee 223 Report, "Standard Practice for the Use of Shrinkage-Compensating
Concrete" recommends that the area of steel reinforcement be greater than or equal to 0.15
percent of the cross-sectional area of the concrete and less than or equal to 0.20 percent, and
that it be located in the upper half of the slab.
5-5. POST-TENSIONED SLABS. Post-tensioning of slabs-on-grade can be useful where it is
desirable to eliminate joints, design the slab-on-grade to resist foundation movements at sites
containing expansive soils, or to provide the slab-on-grade system with the capacity to span
over weak subgrade areas. The Post-Tensioning Institute (PTI) Reports, "Design and
Construction of Slabs-on-Ground," and "Post-Tensioned Commercial and Industrial Floors" can
be used as a basis for design of post-tensioned slabs.
5-6. SPECIAL TESTS AND SPECIAL INSPECTIONS. In addition to the usual concrete
testing, shrinkage testing of concrete mixtures to minimize shrinkage potential, modulus of
rupture testing of concrete mixtures to maximize the ability of the concrete to resist tensile
stress form shrinkage and load induced flexure, should be considered.