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.
Highlights
Sprayed concrete is widely used in various types of surrounding rock support such as tunnels, subways and mines
The first generation of accelerator was jointly produced by Austria and Switzerland
When the content was 3%, the initial setting time was within 2 minutes, the final setting time was within 5 minutes, and the subsequent strength loss was 30% the above
Summary
Sprayed concrete is widely used in various types of surrounding rock support such as tunnels, subways and mines. The main components are aluminates and carbonates These accelerators are powdery accelerators with high alkali content. The powdery accelerator is mainly used in dry-mix sprayed concrete. Liquid accelerators are mainly used in wet-mix sprayed concrete. Alkali-free liquid accelerators have problems such as poor stability, large amounts, and toxic substances. Existing alkali-free liquid accelerators are generally added in an amount of 8% to 10%, and the amount is too large, which greatly increases the construction cost and is easy to collapse during the spraying process.
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