Activation effects and micro quantitative characterization of high-volume ground granulated blast furnace slag in cement-based composites

Abstract To increase the early strength and usefulness of ground granulated blast furnace slag (GGBFS) in cement-based composites, five different chemical reagents were added to a blend of cement with 80% GGBFS at low curing times. The orthogonal design and methods of range and variance analysis were used to determine the optimal dosage and ratio of activators. The activation mechanism was ascertained by using the full-spectrum fitting of X-ray diffraction and microscopic analysis of 29Si NMR. The prediction model of hydration products was given in GGBFS-cement system activated and the micromechanical properties of main hydration products C-A-S-H gel were simulated by the simulation of molecular dynamics. The results show that combined activators are better than an individual activators. The optimum combination is Ca(OH)2 + CaSO4 (CA) with a dosage of 3% for GGBFS mass and ratio of 3:1. The activation index with CA increase by 32.5% compared with control groups (CG) at 7d, respectively. The relative bridge oxygen characterized the degree of network structure polymerization decreases by 45% when CA is added compared with CG after a curing time of 14d. The C-A-S-H gels increase the bonding energy between the silicon chains and the calcium layer and the tensile strength.