Effect of carbonate and silicate on the microstructural properties of the MgO-activated slag binder

Abstract

MgO-based cementitious materials are an important direction of green, low-carbon and sustainable cementitious materials. This paper investigates the hydration characteristics of MgO-activated slag binder under the influence of carbonate and silicate. The results show that the combination of silica fume and Na₂CO₃ is more effective in obtaining lower pore structure and refining microstructure than using silica fume or Na₂CO₃ alone. The pore volume (<1000 nm) of the MgO-activated slag binder curing for 28d is reduced by nearly 80 % compared with 3d The addition of the small amount of SF reduces the content of bulk crystalline hydrotalcite and the content of bound and interlayer water in the gelling phase and promotes the generation of M-S-H gel phase. Controlling the type and content of multiple carbonates and silicate gel phases in preparing MgO-aluminosilicates binder can achieve better results in reducing the pore volume, refining the pore structure, and increasing the compressive strength.