Research on application of high performance alkali-free liquid accelerator in shotcrete support

Abstract

At present, sprayed concrete has problems such as low strength, large rebound amount, and high dust concentration. Developed a new type of alkali-free liquid accelerator, which can effectively improve the performance of shotcrete. The alkali-free liquid accelerator is mainly composed of aluminum sulfate, active aluminum hydroxide, alcohol amine, amide, and stabilizer. Through laboratory tests and field tests, when the alkali-free liquid accelerator admixture is 5% to 7%, the initial setting time is within 5 minutes, and the final setting time is within 10 minutes. The strength of shotcrete reaches 12.8MPa in one day, and the compressive strength ratio of 28d is more than 95.3%, and the rebound amount is within 10%. Compared with ordinary alkali-free liquid accelerator and alkaline liquid accelerator, the strength of sprayed concrete mixed with the alkali-free liquid accelerator is greatly improved, which is more conducive to the support of the sprayed layer, reduced rebound and dust, effectively improve the construction environment and increase construction efficiency.

Preparation and hydration mechanism of aluminum formate/aluminum sulfate based alkali-free composite accelerator for sprayed concrete

“…AFt plays two roles-as an early reinforcement material or a late deterioration material [34]. This aluminum-sulfate-based quick setting agent has the characteristics of an unstable setting time and poor cement adaptability [35][36][37]. Therefore, to reduce the influence of aluminumsulfate-based liquid accelerators on the concrete durability, the development of low-sulfur alkali-free liquid accelerators may be an excellent alternative [38].…”