Effect of calcium formate/nano C-S-H composite on early hydration and microstructure of the GGBS-cement system under steam curing
The influence of calcium formate (CF)/nano C-S-H (NC) composite on the early strength of the ground granulated blast-furnace slag (GGBS)-cement system under steam curing conditions was investigated, and the mechanism behind was analyzed by means of XRD, FTIR and MIP. Results show that the early strength of the GGBS-cement system can be obviously improved by the incorporation of CF, and the optimum added quantity is 1.5%; the addition of CF can enhance the hydration of cement and GGBS, promote the generation of hydration products and reduce the total pore volume and the most probable aperture of the GGBS-cement system. The addition of CF/NC composite can further improve the compressive strength, and in the range of 1%~4%, the greater the content of NC, the higher the compressive strength, which is related to the density improvement of the system by the nucleation effect and micro-aggregate filling effect of NC.
1. Introduction
Ground granulated blast-furnace slag (GGBS) is the residue formed by impurities such as SiO2 and Al2O3 and lime in the iron making process, which is collected and water quenched to obtain high fineness and high activity powder. When GGBS is applied to cement, the OH- provided by clinker hydration can stimulate the potential activity of GGBS. Compared with Portland cement, GGBS cement has the advantages of lower hydration heat and inhibition of alkali aggregate reaction. After GGBS is incorporated into cement, the microstructure is relatively loose and the strength develops...
