快硬性建筑垃圾流动化回填材料制备与性能

为了解决城市建筑垃圾再生利用水平低、道路管沟回填施工周期长的问题，将建筑垃圾细料应用于早强型控制性低强度材料（controlled low strength materials，CLSM）中，考察促凝剂掺量、促凝剂类型、水固比与胶集比等因素对CLSM的工作性能、力学性能及抗干缩性能的影响.研究结果表明：促凝剂对CLSM流动度无明显影响，但对泌水率与干缩率有显著削减作用；2种促凝剂的早强特性存在一定差异，其对应的最优掺量分别为40%与20%，4 h强度均为0.7MPa以上；在促凝剂掺量一定时，早期小时强度受胶凝材料总量与实际自由水量的综合影响；增大水固比可提高流动度、泌水率及抗干缩性能，降低力学性能，而增大胶集比可提高流动度与力学性能，降低泌水率与抗干缩性能.

Performance evaluation of recycled asphalt mixtures by construction and demolition waste materials

To solve problems of low recycling level of urban construction and demolition (C&D) waste and long period of backfill construction for road trench, recycled fine aggregate from C&D waste was used in rapid-hardening controlled low strength materials (CLSM). The influence of four factors (including accelerator type, accelerator-to-binder, water-to-solid and binder-to-recycled fine aggregate ratios) on workability, mechanical properties and resistance to dry shrinkage of CLSM was investigated. Results show that the accelerator has no obvious effect on the flowability of CLSM, however, reduces its bleeding rate and dry shrinkage significantly. There is existing certain difference in the early strength characteristics of two types of accelerator. The optimal accelerator-to-binder value for best early strength development is 40% and 20%, respectively, with the 4-hour strength all reaching 0.7 MPa. Additionally, with the accelerator-to-binder ratio fixed, the early hour strength of CLSM is affected by the amount of cementitious materials and the actual content of free water. Increasing the water-to-solid ratio will increase the flowability, bleeding rate and resistance to dry shrinkage of CLSM, and reduce its mechanical properties; while increasing the binder-to-recycled fine aggregate ratio will increase the flowability and mechanical properties, and reduce its bleeding rate and resistance to dry shrinkage.