Effect of some admixtures on the setting time and strength evolution of cement pastes at early ages

The purpose of this work is to investigate the effect of using some admixtures such as calcium nitrate, triethanolamine and triisopropanolamine, on the setting and hardening process of cement pastes at 20 degrees C temperature. Tests were performed on specimens from various mixes considering two types of cements. The results obtained indicate that the calcium nitrate used alone acts as a setting accelerator and has relatively little beneficial effect on the long term development of mechanical resistances. Regardless of the cement type used, both alkanolamines used alone performed well as a hardening accelerator at all ages. The combined additions produced at very early age significant and promising results with respect to both setting and hardening acceleration, and to a continuous compressive strength increase with time. (c) 2006 Published by Elsevier Ltd.