硅粉
水合硅酸钙
材料科学
火山灰
胶凝的
火山灰反应
固化(化学)
氢氧化钙
收缩率
极限抗拉强度
复合材料
骨料(复合)
火山灰活动
纳米-
扫描电子显微镜
水泥
化学工程
硅酸盐水泥
工程类
作者
Yunchao Tang,Chao Zheng,Wanhui Feng,Yumei Nong,Cong Li,Jieming Chen
标识
DOI:10.1515/ntrev-2021-0058
摘要
Abstract Recycled aggregate concrete (RAC) is an environmentally friendly material. However, owing to inherent characteristics of the recycled aggregate (RA), it is difficult to promote and apply it in structural engineering. Silica fume (SF) and nano-silica (NS) have different characteristics as additives for RAC. It has been proven that adding SF only enhances the strength of RAC at a later stage, and NS can improve the early strength of RAC owing to its high pozzolanic activity. In this study, to further improve the properties of RAC, two types of additives were combined into RAC, which was named SF-NS-modified RAC (SSRAC). Compression and split tensile tests were conducted to analyze the mechanical properties of SSRAC at different curing ages. The results indicated that the combined addition of NS and SF improved the performance of RAC at early and later curing ages. Scanning electron microscopy and X-ray diffraction analyses were performed to explore the NS and SF mechanism. The results indicated that SF and NS in SSRAC had a good pozzolanic effect and underwent a secondary hydration reaction with calcium hydroxide to increase the production of calcium silicate hydrate, resulting in an increase in the properties of the interface transition zone. Finally, 6% SF and 2 or 3% NS are recommended as supplementary cementitious materials for RAC.
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