Most owners would like to eliminate or control cracking in any industrial floor slab they build, reduce the number of joints in the slab, and get a superior, long-lasting concrete floor. These desirable results can be achieved through three separate but highly compatible factors: expansive cement, deformed welded wire fabric, and a new program of certified quality control. Using these three components to produce a better floor begins in the planning/design phase of a project and continues, with close attention to detail, to final acceptance by the owner. This article describes how a recently completed industrial floor illustrates how the three factors work together.
Topics include: expansive cement concrete specified; expansion against restraint essential; deformed welded wire fabric for restraint; certified quality control retained; fabric placement procedures; and concrete placement procedures.
The highly visible benefits of crack control and joint reduction require more than just a decision to use shrinkage-compensating concrete. Inattention to necessary design-details and construction procedures can mar those results. Among those details and procedures: construction joints in industrial floors should be doweled or keyed to allow thermal contraction and expansion deformed bars across these joints would cause cracking of nearby slab areas; rectangular column boxouts that form reentrant corners may create stresses that initiate cracking; and, slabs should be cast leaving at least two adjacent sides unrestrained and free to permit the desired initial expansion plan the casting schedule carefully and release the edge forms or stakes as soon as the concrete has been finished.