废弃混凝土作为再生粗骨料对新拌混凝土性能的影响

Influence of Waste Concrete as Recycled Coarse Aggregate on Performance of Fresh Concrete

废弃混凝土资源化再利用是绿色循环经济的重要方法,目前主要通过将其破碎制成再生粗骨料进行循环利用。主要研究了再生粗骨料的掺量、最大粒径、不同级配形式、间断级配再生粗骨料的掺量等因素对混凝土性能的影响。结果表明:再生粗骨料的掺量越大,最大粒径越小,则混凝土的坍落度和抗压强度越小;掺入间断级配再生粗骨料的混凝土的坍落度和强度大于掺入连续级配再生粗骨料的混凝土;间断级配再生粗骨料的掺量对混凝土的性能影响与连续级配再生粗骨料的影响一致。与未掺加再生粗骨料的混凝土的强度增长率相比,掺加再生粗骨料的混凝土的强度增长较大。为了解释上述宏观性能变化,通过激光拉曼光谱法研究了废弃混凝土中未水化水泥的水化等对强度发展的影响。

Recycling of waste concrete is an important method of green recycling economy.At present,it is mainly recycled by crushing into recycled coarse aggregate.The influences of the content of recyced coarse aggregate,the maximum particle size,different grading forms,and the content of discontinuous grading recycled coarse aggregate on the performance of concrete were mainly studied.The results show that with the increase of the content of recycled coarse aggregate and the decrease of the maximum particle size,the slump and compressive strength of concrete decrease.The slump and strength of fresh concrete with discontinuous grading recycled coarse aggregate are greater than that with continuous grading recycled coarse aggregate.The influence of the content of recycled coarse aggregate with discontinuous grading on the performance of concrete is consistent with that of recycled coarse aggregate with continuous gradation.Compared with the strength growth rate of concrete without recyled coarse aggregate,the strength of concrete with recycled coarse aggregate grows greatly.In order to explain the above changes in macro properties,the influence of the hydration of the non-hydrated cement in the waste concrete on the strength development was studied by using the laser Raman spectroscopy.