Study on preparation and properties of alkali-free accelerator

Abstract

As one of the main components of shotcrete, accelerator is widely used in housing construction, tunnel engineering and road emergency repair. In this paper, hydrofluoric acid, aluminum sulfate and aluminum hydroxide were used as main raw materials to prepare alkali free accelerator by liquid phase self reaction method. The influence of the amount of hydrofluoric acid, aluminum sulfate and aluminum hydroxide on the coagulation performance and stability of alkali free accelerator was mainly investigated. The test results are as follows: within the experimental range, the influence of aluminum sulfate on the coagulation performance of alkali free accelerator is greater than that of hydrofluoric acid. When the amount of 40% hydrofluoric acid is 100 g ∼ 160g, the amount of aluminum hydroxide is 50 g ∼ 80g, and the amount of aluminum sulfate is 320 g ∼ 400g, the alkali free accelerator products with main indexes of initial setting time ≤ 3 min and final setting time ≤ 6 min can be prepared, which meet the requirements of GB/T 35159-2017"Accelerator for shotcrete". The unit price of the optimized product is ¥1488 which is compared with the main products on the market, This product has good competitiveness.