Abstract Improving and reusing recycled aggregate concrete (RAC) is an ideal approach to develop sustainability in the construction industry. In this article, a newly proposed physical compression casting method was used in combination with a treatment of nano-silica (NS) particles to enhance the properties of RAC. Although using NS contributed to accelerating hydration, promoting pozzolanic reaction, and increasing calcium-silicate hydrate gel, the enhancement in strength and reduction in porosity was found to be limited. Thus, the compression casting method was used to compensate for the weaknesses. The effects of compression casting, NS, and their combinations on the properties of RAC were investigated. At the macro-level, the stress–strain responses were evaluated by examining the compressive strength, peak strain, and modulus of elasticity. At the micro-level, the porosity and pore distribution along the interface transition zones (ITZs) were investigated using mercury intrusion porosimetry analysis and scanning electronic microscope imaging technology. Compared with normal RAC, the compressive strength achieved by using NS particles, compression casting, and their combination were increased by 37, 88 and 143%, respectively. The compression casting or combination of compression casting and NS particles treatment can effectively reduce the total porosity of the mortar and pore ratio along the ITZs.

中文翻译：

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通过压铸和纳米二氧化硅改进再生骨料混凝土

摘要 改进和再利用再生骨料混凝土（RAC）是发展建筑行业可持续发展的理想途径。在本文中，一种新提出的物理压缩铸造方法与纳米二氧化硅 (NS) 颗粒的处理相结合，以增强 RAC 的性能。尽管使用 NS 有助于加速水化、促进火山灰反应和增加硅酸钙水合物凝胶，但发现强度的提高和孔隙率的降低是有限的。因此，压铸法被用来弥补弱点。研究了压铸、NS 及其组合对 RAC 性能的影响。在宏观层面，通过检查抗压强度、峰值应变、和弹性模量。在微观层面，采用压汞法分析和扫描电子显微镜成像技术研究了界面过渡带（ITZs）的孔隙率和孔隙分布。与普通 RAC 相比，使用 NS 颗粒、压铸及其组合实现的抗压强度分别提高了 37%、88% 和 143%。压铸或压铸与NS颗粒处理相结合可有效降低砂浆的总孔隙率和沿ITZ的孔隙率。通过使用 NS 颗粒、压缩铸造及其组合实现的抗压强度分别提高了 37%、88% 和 143%。压铸或压铸与NS颗粒处理相结合可有效降低砂浆的总孔隙率和沿ITZ的孔隙率。通过使用 NS 颗粒、压缩铸造及其组合实现的抗压强度分别提高了 37%、88% 和 143%。压铸或压铸与NS颗粒处理相结合可有效降低砂浆的总孔隙率和沿ITZ的孔隙率。