国家自然科学基金资助项目（52078358）
采用减水剂缓凝剂体系对不合格新拌混凝土的工作性能进行调节，并利用不合格新拌混凝土部分取代同配合比新拌混凝土来制备再生混凝土.通过坍落度和抗压强度测试，分析了不合格新拌混凝土放置时间(90、180、270min)和取代率(10%、20%、30%)对再生混凝土工作性能和力学性能的影响.结果表明：不同放置时间下，再生混凝土30min内的坍落度经时损失均与新拌混凝土标准相近，但60min后的经时损失显著增大；再生混凝土7、28d抗压强度与放置时间和取代率总体呈负相关关系；在不同放置和取代率下，放置时间180min、取代率30%时的再生混凝土7d抗压强度最低，为315MPa；放置时间270min、取代率30%时的再生混凝土28d抗压强度最低，为501MPa.试验表明，初凝前的不合格新拌混凝土可以作为再生混凝土的制备材料.
The water reducer and retarder were adopted to modify the working performance of disqualified fresh concrete, and the modified concrete was mixed into the fresh concrete with a constant mix proportion for recycling. The effect of different placing time(90,180,270min) and replacing rate(10%,20%,30%) were studied by the tests of slump loss through time and compressive strength. According to the results, the slump loss through time of the recycled concrete is similar to the result of fresh concrete within 30minutes but increases rapidly after 60min, the minimum compressive strength of the recycled concrete after 7days was 315MPa with the placing time equal to 180 min and replacing rate equal to 30%, and the minimum compressive strength after 28days is 501MPa with the placing time equal to 270 min and replacing rate equal to 30%. The experiment shows that the disqualified fresh concrete before the initial setting was suitable for the preparation of recycled concrete.
易卓然,肖建庄,薛松涛,韩女,张恒春.不合格新拌混凝土回收利用基本试验研究[J].建筑材料学报,2021,24(3):637-643
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