The most common mode of joint deterioration is the wearing of the arris (feather edge). This can be caused by a joint which has opened too wide, or has arrises which aren’t aligned vertically, being trafficked by MHE. It is found often in free-movement joints as these have the potential to open quite wide.
This wearing can be much reduced by the installation of a relatively hard joint sealant. Also, the use of joint armour helps to reduce the chance of the joint wearing in this way.
Sealant installation (or replacement) can fill in small areas of damage, but larger or more significant wear/ damage should be repaired using a resinous mortar and the cut-back and fill method.