Retarding cement hydration by increasing temperature

Abstract

Specific polymer structures at particular dosages have been identified to be able to delay cement hydration as temperature increases. The aim of the present work is to understand the underlying mechanisms involved behind this unexpected phenomenon. In particular, hydration kinetics of chemically admixed cement pastes at different temperatures have been related to the mineralogical changes in pastes, chemical composition of the pore solution and rheological properties. Results have demonstrated a dramatic increase in the low- concentration elements (Si, Al, Mg and Fe) in the pore solution of admixed samples hydrated at room temperature. At this temperature, nano-particles (polymer aggregates involving complexes and/or organo aluminates) have been detected. In contrast, nano-particles are not present at higher temperatures, when the delay of hydration is observed. This could lead to a higher amount of free polymer in the pore solution leading to a greater delay of silicates hydration.