Research on the synergy of micro-nano bubble water and alkali-free liquid accelerator to improve the early strength and hydration rate of cement

Abstract

Alkali-free liquid accelerator additive has been widely used in shotcrete construction in recent years. However, due to their large dosage, high cost, poor adaptability, and insufficient early strength, there are certain difficulties in promotion and use. Because of its unique properties, micro-nano bubble (MNB) water can shorten the setting time of cement and increase the early strength of cement. Therefore, this study uses micro-nano bubble (MNB) water instead of ordinary water to be used in conjunction with an alkali-free liquid accelerator additive to improve the early strength. In this study, the addition of micro-nano bubble water can significantly shorten the initial and final setting time of cement paste, and the addition of micro-nano bubble water after cyclic shear for 8 min can increase the 1-day compressive strength of the cement mortar by 28.7% and the 7-day compressive strength by 22.7%. The late strength has no reduced phenomenon, and the flexural strength is also significantly improved, which effectively solves the problem of low early strength of the alkali-free liquid accelerator additive. It is analyzed and characterized by microscopic characterization methods such as SEM, XRD, hydration temperature test, the micro-nano bubble water used as mixing cement mortar water has a faster hydration process, better compactness, more uniform structure, faster consumption of C3S and C3A than ordinary water, and higher early hydration temperature peak.