人工冷粘结轻骨料高强混凝土制备及性能

Preparation and properties of artificial cold-bonded lightweight aggregate high-strength concrete

  • 摘要: 以搅拌站混凝土废浆(Concrete slurry waste, CSW)为原料,利用冷粘结造粒技术结合碳化增强工艺,制备了一种性能优异的人工骨料(Artificial aggregate, AA),并发展了轻骨料高强混凝土(Lightweight aggregate high-strength concrete, LAHC),重点研究了AA的物理性能、力学性能和微观结构,以及LAHC的工作性能、力学性能和收缩性能。研究结果表明,以CSW为原料,利用冷粘结技术结合碳化增强工艺生产的AA,具备可行性;球形AA粒度分布主要在4.75~14 mm之间,松散堆积密度介于950~1100 kg/m3之间,1 h吸水率为9.96%~12.89%。单颗颗粒强度变化范围为13.68~15.64 MPa,筒压强度介于8.18~9.17 MPa;加压碳化3 d对于AA单颗颗粒强度和筒压强度提高约14%和12%,湿法碳化10 min提高约9%和8%,吸水率分别下降约23%和14%,湿法碳化表现出更高的效率优势;制备的人工LAHC 28 d抗压强度可达45.2 MPa,抗折强度4.7 MPa,密度1807.6 kg/m3,满足LAHC的要求;球形AA借助滚珠效应自身具备一定减水功能,预湿处理有助于缓解轻骨料混凝土收缩问题,对AA进行24 h的预湿处理,可以将其90 d的收缩率减少10.0%。研究成果为新一代的混凝土材料低碳化、可持续化提供参考。

     

    Abstract: In this study, an artificial aggregate (AA) with excellent performance was prepared from concrete waste slurry (CSW) as raw material using cold-bonding granulation technology combined with a carbonation reinforcement process, and lightweight aggregate high-strength concrete (LAHC) was developed, focusing on the physical properties, mechanical properties, and microstructure of the aggregate, as well as the workability, mechanical properties, and shrinkage properties of the LAHC. The study results demonstrate that using cold bonding technology combined with a carbonation enhancement process to produce AA from CSW as a raw material is feasible. The particle size distribution of the spherical artificial aggregate mainly ranges between 4.75 mm and 14 mm. The aggregates have loose bulk densities of 950-1100 kg/m³, water absorption rates of 9.96%-12.89% at 1 hour, individual pellet strengths of 13.68-15.64 MPa, and cylinder compressive strengths of 8.18-9.17 MPa; pressurized carbonization 3 d for AA individual pellet strength and cylinder compressive strength increase by approximately 14% and 12%, wet carbonization 10 min increases by approximately 9% and 8%, the water absorption rate decreases by approximately 23% and 14%, respectively, wet carbonization shows higher efficiency advantages; prepared artificial LAHC 28 d compressive strength up to 45.2 MPa, flexural strength 4.7 MPa, and the 28 d compressive strength of the prepared artificial LAHC can reach 45.2 MPa, flexural strength 4.7 MPa, density 1807.6 kg/m3, which meets the requirements of LAHC; the spherical AA itself has a certain water-reducing function, and pre-wetting treatment can help to alleviate the problem of shrinkage of the LAHC, and the pre-wetted AA in 24 h can reduce the shrinkage rate of the concrete in 90 d by 10.0%. The research results provide a reference for the new generation of sustainable concrete materials.

     

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