Contraction (saw cut), isolation, expansion, and construction joints – when properly detailed, located, installed and protected – reduce cracking and protect concrete from deterioration. The American Concrete Institute recommends joint spacings no more than 12-15 feet apart, depending on slab thickness and shrinkage rate (ACI 360R-10).
When floor joints are not properly introduced, long-term durability issues in the form of spalling under traffic, uneven settlement, delamination, curling, and a reduction in load transfer capacity can occur.
Is there a way to reduce the quantity of joints and still manage the risk of cracking?
For many owners, extended-joint floors reinforced with steel or synthetic fibers are a revolutionary solution to this age-old problem. The fibers create a more homogeneous concrete mixture, discouraging the natural settlement and segregation of ingredients. The evenly-distributed fibers provide improved mechanical bonding and reduced concrete cracking and curling in critical areas.
The benefits are immediate, preventing early-age shrinkage cracking in freshly placed concrete. Both synthetic and steel fibers increase impact and abrasion resistance, with more tensile strength and increased structural integrity over time. These qualities allow for the safe reduction of joints up to 50-80% without increasing the thickness of the slab.
Speculative warehouses are successfully incorporating extended-joint floor construction in speed bays. Speed bays, adjacent to loading areas, are used to move goods in a quick, efficient manner, providing only short-term storage.
They are typically 60 feet from the dock wall to the first interior column. This area endures heavy, repetitive, and often higher-speed traffic.
Extended-joint construction provides versatility in flooring construction, balancing the right joint spacing, dosage levels, and floor thickness to meet your needs and budget.