Preparation And Long-Term Performance Study Of Regenerated Flow Mixture

In traditional compaction backfill projects,subsidence diseases caused by limited construction space and insufficient backfill compaction are not uncommon,and flow backfilling technology can solve this problem.At present,there are two main technical routes for material fluidization in China,one is the fluidization of soil,that is,solidified soil technology;The second is the fluidization of road inorganic stabilizers,both of which have different degrees of disadvantages.At present,there is a relative lack of research on liquid mixed materials in China,and even less research on the preparation of liquid mixed materials from waste materials such as redundant soil.In this study,the mixing ratio of cement-based fluid mixture that meets the requirements was studied through working performance,mechanical properties,durability and mechanism analysis by taking redundant soil as the main raw material,supplemented by the adjustment grading of brick-concrete fine aggregate,cement,fly ash and quicklime as the cementing components,and controlling the compressive strength of the fluidized mixture.The influence of alkali slag,slag and fly ash on the properties of the mixture was studied in the form of an isoenthalpy diagram to replace the traditional cement,and the mixing ratio of non-cement-based fluid mixture that met the requirements was studied.The research shows that:In the orthogonal experiment,the influencing factors of compressive strength,fluidity and water secretion rate of cement-based regenerated fluidic mixture were as follows: total cementitious material content> ratio of fly ash to cement> ratio of quicklime to fly ash > sand ratio.The results of range and variance analysis showed that the incorporation of brick-concrete aggregate played a certain role,but it was not significant.In the preparation of non-cement-based fluidic mixture,slag is the most important factor affecting the compressive strength of the specimen,when the content of alkali slag is lower than 20% of the total content of cementitious material,it is difficult to disintegrate and hydrate the cementitious material;Under the same amount of cementitious material,the specimens with larger slag content have high early strength,and the strength growth rate is slightly lower than that of specimens with higher fly ash content.In the range of alkaline residue 15%⁶0%,slag 20%⁸5%,fly ash 0⁶0%,the total amount of rubber materials of 20%,10% and 8% are greater than 1MPa in 28 d.In the durability performance experiment,the strength of the mixture specimen with cement content less than 5% and the non-cementitious mixture specimen with cementitious material content of 8% decreased under the dry and wet cycle,especially the dry cycle.Under the same strength,the frost resistance of non-cement-based fluidic mixture mixed with slag and alkali slag is greater than that of cementitious mixture,and the strength of specimens with compressive strength of 1.5⁴MPa is 0.35¹.6MPa after12 freeze-thaw cycles.The shrinkage value of cement-based fluid mixture between3²8d was greater than that of non-cementitious mixture,and it slowly increased with the increase of age.The shrinkage value of non-cementitious mixture develops rapidly before 14 days and tends to be flat after 14 days.Through XRD,IR and SEM analysis,it was found that the cement-based mixture formed C-S-H gel after hydration,which formed a skeleton,and the active micronized Ca²⁺ in the redundant soil and brick mixed fine aggregate intensified the ion exchange,and the Ca（OH）₂ generated by hydration reacted with fly ash and fine powder particles to improve the strength in the later stage.The slag was depolymerized in the alkaline environment,C-S-H,C-A-S-H and AFt were intertwined to form a skeleton,and the free Cl^-in the alkali slag penetrated the hydration layer on the surface of the mineral admixture,which intensified the reaction.Part of Ca（OH）₂ reacts with Al₂O₃ to form calcium aluminate,and CaCl₂ to form calcium oxychloride to fill pores,and the other part Ca（OH）₂ acts as a "crystal nucleus" to accelerate the hydration process.