Experimental Research On Recycled Concrete Fine Aggregate-red Mud Composite Filling Material

With the accelerating pace of modernization,the demolition of old buildings has brought about a large amount of solid waste;at the same time,due to the doubled demand for aluminum metal materials,a large amount of solid waste will be generated in the production process:Red mud.These solid wastes are violating the environment on which mankind depends.In order to be able to absorb solid waste,a new type of filling material is proposed.This not only provides an effective solution for the resource utilization of construction solid waste,but also can effectively reduce the cost of underground coal filling.Based on the above concept,this paper studies the overall performance of recycled concrete fine aggregate-red mud composite filling material.First,the uniaxial compressive strength test of different proportions was carried out,and the optimal proportion of filling paste and the main factors affecting its uniaxial compressive strength were analyzed and determined.At the same time,the uniaxial compressive strength and age were obtained.Through microscopic analysis of the mechanism of its strength growth,the resistivity of the filling paste test block varies with the proportion of different ages,and the resistivity of the filling paste test block varies with age under different proportions.The relationship between the compressive strength and the resistivity under different proportions,and the uniaxial compressive strength,resistivity and temperature change rules of the filled paste test block were fitted,and the compressive strength and the resistivity under different proportions were established.The fitting equations of resistivity and temperature are used to draw experimental conclusions.In the durability research,thermal stability,acid corrosion resistance,and impermeability tests were carried out.Indoor tests were used to simulate the temperature,immersion solution,and water pressure in the mine to comprehensively evaluate the durability of the filling material.It provides data support and theoretical guidance for the feasibility of the filling material.And put forward the suitable service environment of the filling material,which provides a reference for the material selection of the actual filling project.The research results of this article are as follows:（1）The optimal ratio of the recycled concrete fine aggregate-red mud composite filling material is obtained,and the main factors affecting the uniaxial compressive strength of the filling paste test block are obtained through analysis,and the uniaxial compressive strength varies with age,The change rule of the ratio and the change rule of uniaxial compressive strength,age,etc.and resistivity;by analyzing the mixed fitting equation of age and resistivity under different ratios,the formula can be obtained,which can be used to fit Formula to characterize the relationship between age and resistivity,that is,ρ=-60.45×e^（（-t/2.91））+63.83;by analyzing the fitting equation of compressive strength and resistivity under different ratios,the relationship between compressive strength and resistivity can be characterized by the fitting formula,that is,q_u=0.040ρ-0.170.（2）The thermal stability of the concrete solid waste aggregate-red mud composite filling material is relatively poor,and the material’s high temperature resistance is poor,but its compressive strength tends to be stable at a later stage under high temperature,so the concrete solid waste aggregate-The filling paste prepared from the red mud composite material is more suitable for service under the mine with relatively high temperature field in the coal mine;By analyzing the fitting equation of the uniaxial compressive strength and temperature of the cube under different ratios,a mixed fitting equation can be obtained,which can be used to characterize the relationship between compressive strength and resistivity,that is,q_u=-0.012T+3.420.（3）The acid-resistant erosion performance of the concrete solid waste aggregate-red mud composite filling material is relatively good,especially for single SO₄^2-factor erosion,but its compressive strength tends to be stable in the later stage at high temperature,so the concrete solid waste The filling paste prepared by the aggregate-red mud composite material is suitable for service in underground mines containing acidic wastewater or alkaline in underground coal mines in northern China.（4）The impermeability mark of the filling paste is P6,the impermeability grade is relatively weak,and the permeability is good.（5）Experimental studies have shown that the paste suitable for the preparation of concrete solid waste aggregate-red mud composite filling material is more suitable for coal mines in the north of our country（the underground water environment is more acidic and alkaline）and deep mines with higher underground temperatures.