Effect of a Carboxylic Acid on Rheological Properties of a High Alumina Cement Mortar

In this work, we studied the effect of carboxylic acid on the rheological properties of a high-alumina cement mortar (CH45) produced by the Algerian firm REFRACTAL. The investigated properties are setting time, water consumption, electrical conductivity, pH, density and the compressive strength. The results show a setting time of about 200 min for the acid free, 180 min with 0.1 % of carboxylic acid and 18 hours with 2 % of this acid. A significant reduction in water consumption was noticed. The water/cement ratio of the acid free-mortar is reduced from 0.24 to 0.16 with 2% acid. The rheological investigations carried out on the mortar-water mixtures with and without carboxylic acid show a Newtonian behavior. The setting of hydrated mortar-water with acid mixtures shows an increase in the apparent density leading to an improvement of the compressive strength.