What can excessive joint spacing lead to in a concrete slab?

Excessive joint spacing in a concrete slab can lead to an increased risk of random cracking, which occurs when the slab is subject to various stresses that exceed its tensile strength. The primary purpose of control joints is to create predetermined weak points where cracks may occur, thereby directing the cracks in a controlled manner. When joints are spaced too far apart, the likelihood of cracks developing in uncontrolled locations increases.

Concrete is prone to shrinkage as it cures, and without adequate joint spacing to accommodate this movement, the internal stresses can lead to random cracking throughout the slab. Proper joint placement and spacing help to mitigate these stresses and control where cracks will form, preserving the aesthetic and structural integrity of the concrete surface.

In contrast, improved structural integrity and reduced moisture retention are not direct effects of joint spacing. Additionally, while plastic shrinkage can occur in concrete with inadequate jointing, it is not the primary concern associated with excessive joint spacing in hardened slabs.