Early-age strength development of cement pastes made of CEM I, limestone, and calcined clay: the governing role of OPC hydration

The study quantitatively investigates to which extent the hydration of ordinary Portland cement (OPC) contributes to the early-age strength evolution of cement pastes produced with binders containing OPC and limestone (acronym LPC) as well as OPC, limestone, and calcined clay (acronym LC3), respectively.A multiscale strength model for OPC pastes is adapted to binary and ternary mixtures made of CEM I, limestone, and calcined clay.To this end, limestone and calcined clay are introduced as chemically inert spherical inclusion phases which are embedded (next to reactive cement clinker grains) in the hydrate foam matrix.The volume fractions are calculated using Powers' hydration model extended towards consideration of the two additional inert inclusion phases.Elastic phase properties are taken from the literature.The strength predictions for the OPC, LPC, and LC3 pastes are checked against strength values obtained from compressive strength testing during the first week after paste production.The study shows that the OPC hydration plays a governing role when it comes to the early-age strength development of the LPC and LC3 pastes.