建筑废土制备可控低强度材料的试验研究

Experimental Research on Preparation of Controllable Low-strength Materials from Construction Wasteland

为综合利用建筑废土,以废土替代砂石骨料,制备一种高流动度、低泌水率的新型回填材料——可控低强度材料(controlled low strength materials,CLSM)。通过流动度、泌水率、湿密度、无侧限抗压强度试验探讨了水胶比、水泥掺量、废土取代量等因素对CLSM物理、力学性能的影响,结合能谱分析(energy spectrum analysis,EDS)、扫描电子显微镜(scanning electron microscope,SEM)进一步揭示了强度影响机理。结果表明:水胶比主要控制CLSM流动度的大小,随着废土掺量的增加,满足材料流动的水胶比不断增大,废土添加极大地减少了材料的泌水率;胶凝材料中水泥掺量影响着CLSM强度的发展;通过微观分析、计算得出土基CLSM强度的形成主要源于水泥的水化反应、团粒化作用以及黏土颗粒的黏结。研究结果为利用废土制备CLSM提供了一种研究思路,制备出优良工作性能的CLSM服务于将来的工程沟槽回填。

In order to comprehensively utilize construction wasteland and replace sand and gravel aggregates,a new type of backfill material(controlled low strength materials,CLSM)with high fluidity and low bleeding rate is prepared.Through the fluidity,bleeding rate,wet density and unconfined compressive strength test,the effects of water-binder ratio,cement content and wasteland content replacement on the physical and mechanical properties of CLSM were discussed.Combined with energy spectrum analysis(EDS)and scanning electron microscope(SEM),the mechanism of strength influence was further revealed.The results show that:the water-binder ratio mainly controls the fluidity of CLSM.With the increase of the wasteland content,the water-binder ratio that meets the flowability of the material continues to increase,and the addition of wasteland greatly reduces the bleeding rate of the material.The amount of cement in the material affects the development of CLSM strength.Through microscopic analysis and calculation,it is concluded that the formation of soil-based CLSM strength is mainly due to the hydration reaction,agglomeration of cement and the bonding of clay particles.The results provide a research idea for the preparation of CLSM using construction wasteland,and prepares CLSM with excellent working performance for future engineering trench backfill.