建筑垃圾再生骨料性能强化研究进展

为解决再生骨料存在的界面过渡区弱、吸水率高以及微裂纹等问题,对再生骨料的回收工艺、性能强化方法以及再生混凝土的拌合工艺进行了详细阐述,介绍了再生骨料生产时各阶段的回收流程,对比了再生骨料与天然骨料的性能差异。依照性能差异的来源,将性能强化方法分为附着砂浆去除和附着砂浆加固两类,并对各自强化方法的原理、优缺点和应用性进行了分析。最后,介绍了传统拌合工艺(NMA)和改进的拌合工艺(TSMA_S、TSMA_SC),并阐述其工艺原理和差异性。结果表明:现阶段的回收工艺主要以破碎和筛洗为主,极易使再生骨料出现微裂纹,同时骨料表面黏附旧砂浆层; 在附着砂浆去除技术中,预浸泡法和自清洗法工艺简单、经济成本低,但强化效果一般; 机械研磨、加热研磨强化效果有所提升,但能耗较大; 酸处理与热化学处理强化效果好,但需对酸浓度进行严格把控,同时污染严重; 在附着砂浆加固技术中,火山灰浆液浸泡工艺简单、材料易得,但会降低其施工和易性; 聚合物乳液浸泡可以改善施工和易性,但工艺设备复杂,难以推广; 微生物矿化和碳酸化作用能够有效填充附着砂浆的微裂纹和孔隙,应用前景巨大,但目前仍缺乏系统研究,存在不确定性; 裹覆水泥浆层需要耗费大量水泥,其强化效果和水泥浆流动性密切相关; 水玻璃溶液浸泡会降低耐久性,需对其浓度加以控制。

Research Progress on Performance Enhancement of Recycled Aggregate from Construction Waste

In order to solve the problems of the weak interface transition zone, high water absorption and microcrack of recycled aggregate, the recycling process of recycled aggregate, the performance strengthening method and the mixing approach of recycled concrete were expounded in detail. The recycling process in each stage of recycled aggregate production was introduced, and the performance difference between recycled aggregate and natural aggregate was pointed out. According to the source of this performance difference, the performance strengthening methods were divided into two categories: removal of attached mortar and reinforcement of attached mortar. The principle, advantages, disadvantages and applicability of the strengthening methods were analyzed. Finally, the normal mixing approach(NMA)and the improved mixing approach(TSMA_S, TSMA_SC)were introduced. Meanwhile, the principles and differences of them were expounded. The results show that the current recycling process mainly focuses on crushing and screening, which is easy to cause microcracks and old mortar layer adhesion. In the attached mortar removal technology, the pre-soaking in water and the autogenous cleaning process are simple and economical, but the strengthening effect is general. The strengthening effect of mechanical grinding and heating grinding has been improved, but the energy consumption is large. Acid treatment and thermo-chemical treatment are effective, but the acid concentration needs to be strictly controlled and the pollution is serious. In the attached mortar reinforcement technology, the pozzolanic slurry immersion process is simple and the materials are easy to obtain, but it will reduce workability. Emulsion polymer immersion can improve the workability, but it is hard to promote due to the complex process and equipment. Microbial mineralization and carbonation can effectively fill the microcracks and pores of attached mortar, which has great application prospects. However, there are uncertainty and lack of systematic research. Cement slurry coating needs a large amount of the cement and its strengthening effect is closely related to liquidity of the cement slurry. Immersion in sodium silicate solution will reduce the durability, and its concentration needs to be controlled.