Study on the structural build-up of cement-ground limestone pastes and its micro-mechanism

Abstract

In this paper, the influences of ground limestone content, fineness and water to binder ratio (W/B) on the structural build-up of cement pastes were studied. The interparticle forces and hydration kinetics were introduced to reveal the micro-mechanism of structural build-up of cement-ground limestone pastes. The results showed that the addition of ground limestone decreased the structural build-up rate of cement pastes and the structural build-up rate declined with increasing the ground limestone content and increased with increasing the ground limestone fineness. The reduction in W/B resulted in the increase of the structural build-up rate. The calculated total interparticle force based on Derjaguin–Landau–Verwey–Overbeek (DLVO) theory (van der Waals force and electrical double layer force) and cohesive force due to ion-ion correlations explained the physical effect in the structural build-up of cement-ground limestone pastes. The nucleation rate constant (KN) and growth rate constant (KG) of the hydration products based on boundary nucleation and growth (BNG) model played an important role in the structural build-up of cement-ground limestone pastes and revealed its mechanism of chemical action. A semi-empirical model of the structural build-up rate and the total interparticle forces, hydration kinetics parameters, etc. was established and verified, whose estimated values were close to the experimental values in general. The model revealed the structural build-up process of cement-ground limestone pastes from both physical and chemical perspectives.