Concrete is made from natural materials which expand and contract with changes in moisture and temperature. The overall tendency is for the concrete to contract and this can cause cracking at an early age of the concrete.
We place control joints in the concrete slab which encourages the concrete to crack along these ‘pre-planned cracks’ so when the concrete contracts, it will crack in the control joint instead of randomly across the slab.
Irregular cracks sometimes do appear, but don’t be alarmed, these won’t affect the integrity of the concrete.