Preparation And Performance Optimization Of Mine Shotcrete Materials With Red Mud

In coal mining and other underground projects in China,rock tunnels are generally supported by bolting and shotcrete.The shotcrete material uses mainly cement as the cementing material,which consumes a large amount of cement every year,and the cost of shotcrete is high and expensive.In addition,a large amount of red mud is produced every year in China,which can not be fully utilized.Using industrial waste residue red mud to prepare polymer based shotcrete materials to partially replace cement-based shotcrete materials is of great significance for protecting the ecological environment of mining areas,saving natural resources and turning waste into treasure.In this paper,the characteristics of red mud are comprehensively analyzed by modern test methods such as XRD,TG-DTA and PTIR.According to its characteristics,the red mud is activated by physical activation and chemical activation.Then,according to various activation methods,the change law of the cementitious property of red mud lime slag system with the mixture ratio of red mud with other constituent materials and activator is studied,And the hydration hardening process of red mud lime slag system and the microstructure characteristics of cement hardened body are comprehensively and systematically studied.Finally,the mechanical properties of red mud based cementitious material concrete shotcrete are experimentally studied.In order to achieve the above objectives,systematic theoretical analysis and experimental research are carried out,which are summarized as follows:The research results of the preparation technology of red mud geopolymers show that the sintering method of red mud itself does not have good gelling performance and strength,and chemical activation is the main way of red mud activation.The stimulating effect of lime on red mud is much higher than that of other stimulating agents.Its best ratio is red mud: lime=3:1.The disadvantage is that the later strength will decline significantly.Sodium hydroxide,water glass,calcium sulfate,sodium sulfate other stimulants are combined with lime to stimulate the red mud.Compared with single stimulation,the stimulation effect is more obvious,and not only the flexural strength and compressive strength of each age are improved.And can overcome the shortcomings of the late strength decline of the lime-red mud combination.Slag and fly ash have good complementarity with red mud.The red mud-lime-slag composite material has better mechanical properties,but the flexural and compressive strength of each age is still far less than the strength of PC 32.5 cement.Completely replace cement.Sodium hydroxide,water glass and gypsum all have a certain stimulating effect on the red mud-lime-slag composite material.Among the four activators of sodium hydroxide,water glass,gypsum,and sodium citrate,sodium hydroxide and water glass are The excitation effect is the best,and its strength increases with the increase of the slag content,which can reach the strength level of PO 42.5 cement.The X-ray diffraction analysis,thermogravimetric analysis and infrared spectroscopy analysis of the hardened slurry of the alkali-excited red mud-based cementitious material show that the alkali-excited red mud-based cementitious material is a mineral that is different from the cementitious material of ordinary Portland cement.Polymeric materials are mainly the polymerization reaction of aluminosilicate raw materials,and their synthesis mainly includes four processes of dissolution,hydrolysis,polycondensation and solidification under alkali activation conditions.Using red mud geopolymer instead of cement to carry out spraying material mixing and its performance research,the best mixing ratio of red mud spraying material mixing was determined,and field test of red mud spraying material spraying support was carried out.,Studied the influence of the red mud geopolymer excitation technology and the reasonable proportion of the mixture on the rebound rate,mechanical strength,and the bonding properties of the surrounding rock of the shotcrete.The key problems in the shotcrete construction process were solved,and the material ratio and technology were improved based on the field test results,and the guidance for industrial application was put forward.There are 87 figures,15 tables and 58 references in this thesis.