Contribution to the modeling of hydration and chemical shrinkage of slag-blended cement at early age

This paper presents a contribution to the modeling of the chemical shrinkage of the slag-blended cement paste (binder) at early age. Assuming that the chemical shrinkage is a direct result of hydration, the hydration modeling of slag-blended cement was studied by considering the interaction between the hydrations of blast furnace slag (BFS) and ordinary Portland cement. The reaction of BFS in the presence of calcium hydroxide CH (Portlandite) produced from the hydration of the cement was investigated. The kinetic hydration of cement was developed, and the volume phases in the cementitious material during the hydration process were calculated. The chemical shrinkage, which is the negative volume balance between the reactants and the products formed, is then calculated. In parallel with this numerical modeling, an experimental study was conducted to investigate the effect of slag’s addition (0%, 30%, 50% and 80%) on the heat of hydration and chemical shrinkage at early age (maturation up to 7 days). The proposed hydration model incorporates the effect of following variables; the chemical composition of the binder, the fineness, the water to binder ratio (w/b), the curing time and the temperature.