Lime replacement by finely ground clay from the north fluminense region of RJ in mortar for coating walls and ceilings

This work aims to identify the effects of replacing lime to finely ground kaolinitic clay (GC) in mortars for coating walls and ceilings, evaluating the water retention, calorimetry, XRD, mechanical resistance, water absorption and void index, and comparing these properties with a mortar with lime, called reference mortar (RM), and one with the addition of a commercial clay (CC) sold at the local trade. The justificative of this work is due to the fact that clay is empirically incorporated into mortars, as a substitute for lime, in order to improve its workability. However, these replacements modify the properties of the mortars and, therefore, experimental evidence to evaluate the most important properties must be carried out. Through the tests performed, an increase in water consumption in mortars of 36% with CC and 45% with GC was observed, however these results did not influence the properties of water retention. Through the patterns obtained in the XRD test, it was observed that the addition of GC in the mortar consumed the portlandite, meaning that there is a probable pozzolanic reaction in the formation of new C–S–H compounds. These results prove that kaolinitic clay can be added in 1:1:6 mortars, maintaining its most important properties for use as coatings.