Effect of Wet-Ground Silica Fume on High-Strength Steam-Cured Cement Concrete.

In order to improve the dispersion state of silica fume (SF) in cement concrete, accelerate the hydration rate of high-strength steam-cured cement concrete, and reduce production costs. In this paper, SF was made into a wet-ground silica fume (WSF) suspension solution through a wet grinding process and was applied to high-strength steam-cured concrete to replace the SF so as to improve the difficult dispersion of the inner SF and enhance the compressive strength of concrete. The physical and chemical properties of WSF were studied by XRD, SEM, and ZETA potential, and its effects on the mechanical properties, hydration development, and microstructure of cement concrete were studied using XRD, SEM, TG, BET, and NMR. The results show that SF mixed with water is transformed into a kind of suspension solution by wet grinding. After adding WSF, the compressive strength of concrete at 1 d increases when the substitution of WSF increases. Compared with SF-0, the 1 d compressive strength of SF-1 and SF-2 increased by 9.2% and 12.9%. When the WSF substitution was greater than 50%, the compressive strength of concrete did not improve significantly; the 1 d compressive strength of SF-3 and SF-4 is 14.3% and 15.4% higher than SF-0. With the increase in WSF substitution, the porosity of concrete at 1 d decreases, and the structure becomes denser. XRD, TG, and NMR analyses show that WSF can promote the hydration development of cement to form a C-S-H gel. As the amount of WSF substitution increases, its effect on the cement hydration reaction increases first and then tends to be flat.