Research On Red Mud Filler Modification Technology And Its Asphalt Concrete Performance

China is a large country of aluminum industry.The annual discharge of red mud,a large amount of solid industrial waste,is as high as 45 million tons,and the accumulated reserves have reached 119000 tons.The massive accumulation of red mud not only caused a large amount of land occupation and serious environmental pollution,but also severely restricted the healthy development of the aluminum industry.Based on the analysis of the basic properties of the red mud,the research on the sintering method of red mud asphalt mixture through the method of physical and chemical compound modification is of great significance for protecting the environment and saving resources.In this paper,the micro performance test method is used to study the basic physical and chemical properties of sintering red mud and Bayer red mud.Asphalt mortar is prepared by replacing limestone ore powder with red mud,and the macro performance test of asphalt mortar is used to evaluate the red mud asphalt.The rheological and mechanical properties of the mortar are analyzed,and the influencing factors and strength formation mechanism of the red mud asphalt mortar are analyzed.The original red mud suitable for asphalt mixture is selected;different anti-stripping powder and coupling agent pairs are selected.Red mud is modified,and the microscopic performance test method is used to study the microstructure and chemical composition of physically modified red mud and chemically modified red mud;the rheological properties of asphalt mortar and the adhesion performance of asphalt-aggregate interface are analyzed through macro performance tests.And used the interface mechanics analysis method to study the interfacial properties of physically modified red mud and chemically modified red mud,and proposed a red mud modification plan that is conducive to improving the anti-stripping performance of asphalt mortar;prepared according to the proposed red mud modification plan Asphalt mixtures were used,and road performance and durability research were carried out in accordance with the use standards of asphalt pavements.The main research conclusions are as follows:(1)The pore size and specific surface area of the red mud are much larger than that of limestone ore.The sintering method red mud can improve the high temperature rheological properties and elasticity of the asphalt mortar,while the Bayer method red mud can affect the high temperature of the asphalt mortar under high stress levels.The anti-deformation ability has an adverse effect and has little effect on the elasticity of the asphalt mortar.Based on the above results,sintering red mud was selected for the study of limestone ore powder substitution.(2)The physical mixing method was used to modify the red mud,and it was found that adding 10%slaked lime and cement to the red mud can increase the lowtemperature elongation at break of the red mud asphalt mortar,and damage the work under different water conditions.Under the conditions,the adhesion performance of the asphalt mortar-aggregate interface is enhanced,indicating that slaked lime and cement can improve the low-temperature crack resistance and water damage resistance of the red mud asphalt mortar.(3)Four coupling agents were used to modify the surface of the red mud.The study found that the coupling agent introduced Si—O bonds on the surface of the red mud,and 1%KH-550 and KH-560 were used as modifiers.After surface modification of the red mud,the elongation at break of the red mud asphalt mortar at-12℃ is increased,and the residual bond strength of the immersion in water for 14 days can reach about 95%of the initial value,which means that 1%KH-550 and KH-560 as a modifier to modify the surface of red mud can improve the low-temperature crack resistance and water damage resistance of the red mud asphalt mortar.(4)The optimized red mud modification scheme was used to prepare the asphalt mixture,and the performance analysis was carried out.It was found that ordinary red mud can improve the high temperature stability of the asphalt mixture,but it has an adverse effect on the water stability.The modified red mud It can improve the lowtemperature anti-cracking performance,water stability,and long-term durability of the red mud asphalt mixture.According to the performance test results,the final preferred red mud modification scheme is to mix 10%slaked lime and cement in the red mud or use 1%The mixed amounts of KH-550 and KH-560 modify the surface of the red mud,and the modified red mud asphalt mixture meets the requirements for asphalt pavement use.The use of physical mixing and chemical modification methods improves the low temperature performance,water stability and fatigue performance of the red mud asphalt mixture,and has the potential to improve the safety and stability of the asphalt pavement.The research in this article confirms the use of red mud It is feasible as an asphalt mixture filler and has significant economic and environmental benefits.