Study On Performance Of Low-strength Flowable Backfill Materials Made Of Construction Waste

In view of serious increasing city construction waste pollution to environmentand national strategy to advocate sustainable development of building materials, anew kind of backfill material-low-strength flowable backfill material made ofconstruction waste was proposed in this paper, with construction waste recycling finematerial as the main raw material, mixed with cement, admixtures and water. Thismaterial has the characteristics of self-compacting, low-strength, and its adjustedstrength. The main raw-material-construction waste recycling fine material also hassignificant environmental and economic benefit.To deepen the standardized application of construction waste recycling finematerial, a classification method of the material was determined through experimentaldiscussion of its quality. At the same time, a mixture ratio design method oflow-strength flowable backfill material made of construction waste with water-solidratio and cement-sand ratio as design parameters was also put forward.According to the proposed mixture ratio design method, corresponding indoorexperiment was carried out to study the basic mechanical property of low-strengthflowable backfill material made of construction waste, mainly including thecompressive strength test, CBR and stress-strain test. The influence of variousfactors on strength was emphatically analyzed, and the result show that the strengthincreases with age growth, and a strength prediction model with water-solid ratio andcement-sand ratio as main parameters was put forward. In addition to this, preliminarystudy on the mechanism of the stress-strain was done, and the typical model of stress-strain curve was also put forward.Finally, the endurance test of low-strength flowable backfill material made ofconstruction with different mixture ratio was carried out, including the wetting-dryingresistance test and freezing-thawing resistance test. The experimental results showthat the wetting-drying circulation could improve the compressive strength, and itsability to resist the freezing-thawing circulation increased along with the enhancementof strength.