Why Does Grout Crack?

Improper Mixture

• Grout is made up out of a variety of polymer additives along with color pigments and concrete. A very delicate balance is required when mixing the grout for use, with a specific amount of water as well as mixing method required. Slaking, or allowing the grout to rest for 10 to15 minutes after initially mixing it, allows the water time to completely soak through the additives. Mixing the grout with too much water or immediately spreading it can lead to eventual cracks.

Installation Voids

• Voids are usually caused by two things. First is improperly mixing the grout. Grout is meant to be mixed by hand or with a slow RPM drill. Whipping it too fast can lead to air bubbles in the mixture, which then pop after the grout begins to settle into the joint. The second is when grout is not properly forced into all of the spaces in between the tiles and underneath their edges, leading to voids that ruin the structural integrity of the grout and eventually lead to cracks.

Excessive Washing

• Cement hydration is one of the principle parts of the curing process. Curing actually begins as soon as the grout is spread into the joints. When washing the grout and cleaning the residue from the face of the tile immediately after grouting during the installation process it is vital to ensure that too much water is not used, as excessive water during the curing process can lead to grout eventually crumbling within the joint due to too much water ruining the delicate balance of additives, concrete, sand and other ingredients.

Excessive Movement

• Excessive movement can lead to grout cracking. Movement can be caused by seasonal swelling and shrinking, or it can be caused by heavy foot traffic. Movement can also occur due to natural disasters, such as earthquakes, or even things such as vibrations from passing trains, subways or traffic. While latex and other polymers are included in grout to help combat cracking due to movement, excessive movement can still lead to grout cracking.