Since concrete tends to crack as it shrinks, control joints are sometimes cut into the slab within a few hours after the concrete is finished to create a "weakened plane".

Since concrete cracks generally occur at the weakest point (or the point of greatest stress) this cut in weakened plane "tells" the concrete where to crack, and helps to avoid (as much as possible) unsightly random cracking.

These meandering, sometimes linear cracks are generally caused by normal shrinkage (where control joints should have been placed).

If the random crack varies in width or is wider than 1/16", check to determine if the crack could be the result of settlement, or dynamic movement.

If the slab is not level on both sides of a crack, settlement is usually the cause. This is a situation in which no tile should even be considered until the cause of the settlement is discovered and corrected. Once the slab is stabilized, it should be leveled using a sand/cement leveling material before using Torque Lock.

A serious situation where the concrete is at a different elevation on either side of the crack.  As in settlement cracks, this condition must be corrected immediately! Once the slab is stabilized, it should be leveled using a sand/cement leveling material before applying Torque Lock.