Concrete Prep Guide

This question is answered by understanding the importance of the substrate not sustaining damage that reduces the integrity of the surface that a coating, screed or membrane/ overlay is bonded to.Some mechanical methods impact the surface so hard that micro-cracking of the substrate occurs with the risk that the coating is bonded to chunks of concrete that can pull out. When the coating is removed there are chunks of concrete stuck to the coating or floor covering.
Flame blasting is also likely to cause deep micro-cracking due to the thermal stress.

What Is Laitance?
Laitance is the weak, milky layer of cement and sand fines that rise to the surface especially with over-wet concrete and mixes with bleed water, usually as a result of premature finishing or trowelling.
Why remove Laitance?
The life of a coating on a concrete floor is dependant on proper adhesion to the concrete. If a coating is applied directly to the laitance layer (which is inherently weak), floor traffic from trolleys, forklifts or other machinery will cause dis-bonding of the coating.
By removing the laitance layer, coatings can firmly adhere to the concrete substrate giving longer service life