Use of clay as a cement replacement in mortar and its chemical activation to reduce the cost and emission of greenhouse gases

The effect of industrially produced quicklime on the strength development and pozzolanic reaction rates of Clay-Cementitious systems was investigated. The compressive strength development of mortars containing Quicklime–Clay–Cement (C–C–L) was studied and presented. New efficiency factors were calculated in order to find out the optimum amount of quicklime to be added. The addition of quicklime increased both the early and later strengths of the cement–clay specimens. Hydration evolution and pozzolanic reaction rates of the Quicklime–Clay–Cement (C–C–L) system were monitored. To know the quantity of hydration products, Non-evaporable water content of the produced pastes was determined. A 3% addition of quicklime was found as optimum dosage both for short and longer curing periods. The increase in the strength could be due to the fact that the lime fully employed the available silica from the clay to form additional cementitious compounds, prevailing pozzolanic calcium silicate hydrate with increase in the amount of quicklime, no accelerating effect was detected due to the diminished proportion of soluble silica in the pore solution.