Research On Sulphoaluminate Cement Foam Filling Material In High-collapse Area

In recent years,there have been many safety accidents caused by coal mining tunnels in China,and the high rise area formed by the top coal fall of the tunnels seriously endangers the underground safety production.At present,domestic and foreign management of high riser area mostly adopts rapid filling method,and the filling materials are mostly organic filling materials such as polyurethane,the shortcomings of organic filling materials such as higher cost and poor flame retardancy limit the development of high riser area filling.If inorganic filling materials can be made to have high and stable foaming performance,they will be more suitable for solving the problem of high bubble area filling.According to the preparation principle of foamed cement,combined with the site construction conditions of high bubble area filling,a rapid foaming filling material suitable for high bubble area filling is developed,using sulfate cement as the cementitious material,hydrogen peroxide as the foaming agent,adding modifiers and stabilizers and other additives,so that it can be quickly foamed and cured at room temperature and pressure to achieve the expected filling effect.In this paper,we first analyzed the characteristics of hydration and hardening of the main raw material sulfur aluminate cement and the decomposition characteristics of the foaming agent hydrogen peroxide,and modified the sulfur aluminate cement according to the decomposition conditions and rate of hydrogen peroxide,and then used the single-factor and multi-factor control variables method to determine the admixture dose of foaming agent,water-cement ratio and foam stabilizer,and the macroscopic properties of the material such as strength,apparent density,foaming time and setting time were determined.The macroscopic properties of the material such as strength,apparent density,foaming time and setting time were measured,and the pore structure characteristics were characterized using SEM and Image-Pro plus(IPP)image processing software.The comprehensive properties such as apparent density of 264kg/m~3and 7d compressive strength of 1.26 MPa were successfully prepared.In addition,in the field construction process of high-crater filling,the downhole high-crater filling equipment system for sulfur-aluminate cement-based foaming filling materials was developed by combining the dual-liquid grouting process and equipment system.This filling system separates and mixes the filling materials and completes the mixing at the outlet,which not only ensures the effect of filling in the high risk area,but also reserves enough operation time for the construction personnel.Finally,the application test of sulfur aluminate cement-based foaming filling material was carried out with the filling of high-crater area of underground roadway,and its properties of expansion performance,compressive strength,apparent density and foaming setting time were tested,and the filling effect was good.