Abstract:

In order to simplify the recycling process of demolished concrete,the authors and their team have proposed the concept of the regeneration structural members containing the demolished concrete with a significantly larger size than those of conventional recycled aggregates. In the proposed structural members,the recycling of the demolished
concrete is promoted from an aggregate level of not more than 40 mm to a distinctly larger size level of 50 ～ 300mm for the demolished concrete blocks ( DCBs) or of more than 500mm in the length direction for the demolished concrete segments ( DCSs) . This paper presents a brief review of the studies conducted by the authors and their team on the proposed structural members in recent years,and introduces preliminary engineering applications of these members to real-life structures. Moreover,the research and development orientation of the proposed structural members is pointed out. The results of the studies and applications indicate that ( 1) the method of recycling demolished concrete through the proposed members not only simplifies the tedious production process of the recycled aggregates but also reduces the corresponding secondary energy consumption,so the method is more economical than that of using the recycled aggregates; ( 2) the fundamental properties and seismic performance of the proposed members are close to or slightly inferior to those of the counterpart members made only from cast-in-situ concrete; ( 3) based on the concept of the combined strength of the new and old concrete used in the proposed members,the formulas specified in current design codes for members made only from cast-in-situ concrete can be applied to the proposed members directly or after a slight modification; and ( 4) applying the proposed structural members,especially the thin-walled steel-concrete composite members containing large-size demolished concrete,to practical engineering is feasible and dependable,so it is an effective approach to the demolished concrete recycling.

Key words: demolished concrete, recycling use, regeneration structural member, mechanical properties, engineering application