再生混合混凝土及其组合构件的研究现状

STATE-OF-THE-ART OF RECYCLED MIXED CONCRETE(RMC) AND COMPOSITE STRUCTURAL MEMBERS MADE OF RMC

大尺度废旧混凝土块体(特征尺寸约50 mm^400 mm)与新混凝土的混合物,称为再生混合混凝土。相比传统再生骨料混凝土,再生混合混凝土具有如下优势:1)废旧混凝土的破碎能耗降低40%~60%;2)水泥用量节省约30%。再生混合混凝土与型钢组合而成的构件,称为再生混合混凝土组合构件,包括梁、柱、板、墙以及相应的连接节点等不同构件形式。该文简要总结了笔者所在课题组近年来在再生混合混凝土及其组合构件方面的研究成果,对其施工工艺进行了初步探讨,指出了此类材料及构件进一步发展的方向。研究表明:1)再生混合混凝土存在双尺寸效应,低强度废旧混凝土块体与高强度新混凝土混合可以大大拓展前者的应用范围;2)再生混合混凝土组合构件的基本力学性能、抗震性能、耐火性能和徐变性能总体上与常规组合构件基本相当;3)施工工艺的改进提升是再生混合混凝土大规模工程应用的关键。

A mixture of fresh concrete（FC） and demolished concrete blocks（DCBs） with a distinctly larger size of about 50 mm～400 mm is called recycled mixed concrete（RMC）. In comparison with traditional recycled aggregate concrete, RMC has the following advantages： 1） the energy consumption associated with crushing of waste concrete is reduced by 40%～60%; and 2） cement consumption is reduced by about 30%. Structural members composed of RMC and steel sections include beams, columns, slabs, walls and connections. This paper presents a simple review of the studies conducted by the authors and their group on RMC and the aforementioned composite members in recent years, discusses the construction technologies of the composite members, and suggests the development orientations of RMC and the composite members. From the current studies, it can be concluded that： 1） there are double size effects in RMC and the scope of application of DCBs with lower strength may be remarkably expanded by mixing them with high-strength FC; 2） the fundamental mechanical performance, seismic properties, fire resistance, and creep behaviors of the composite members cast with RMC are generally similar to those of the counterpart members cast with FC alone; and 3） improving the construction technologies in situ is the key to large-scale practical application of RMC.