Evaluation of slag characteristics on the reaction kinetics and mechanical properties of Na2CO3 activated slag

This paper evaluates the slag characteristics on the reaction kinetics, reaction products and mechanical properties of sodium carbonate activated slag (SCAS). The results show that, by reducing the slag particle size, the precipitation of strength-giving phase of SCAS can be dramatically accelerated, and the time to reach the reaction peak (TRRP) can be accelerated from 86 h to 23 h and a 3 d-compressive strength of about 34 MPa is achieved. The fresh behaviour of pastes is affected by the initial precipitation of calcium carbonate and the formation of gaylussite is also accelerated when reducing the particle sizes of slags. It is observed that the early strength development of samples is largely controlled by the fineness of slag particles, while the later strength firstly increases with the reduction of slag particles until reaching a turning point and then decreases. Furthermore, the influential factors including the alkali activator dosage and slag characteristics on the reaction kinetics of Na2CO3 activated slag are discussed.