Potential of Crushed Waste Calcined-Clay Brick as a Partial Replacement for Portland Cement

This paper evaluates the potential of crushed waste calcined clay brick as cement replacement material. The crushed waste was characterized physically, chemically and mineralogically through fineness test, density, chemical composition and X-ray analysis and the consumption of calcium hydroxide determined using differential thermal analysis. The influence of the partial replacement of portland cement by calcined clay on the strength development was evaluated until the age of 365 days. The percentage of cement replacement, by weight, ranged from 20 to 42% whereas the water/cement ranged from 0.37 to 0.45. The carbon dioxide emissions associated with portland cement production were determined as well as the emissions that can be avoided replacing portland cement by the calcined-clay brick. The results show that the crushed waste presented a good pozzolanic activity and that the compressive strength of the blended mortars was higher than that observed for the control mixture for all levels of cement replacement. The reductions in carbon dioxide emissions can be achieved if pozzolanic materials such as calcined-clay brick is adequately used as cement replacement.