纳米SiO_2改性再生骨料混凝土工程应用研究及实体性能监测

Performance of nano-SiO_2 modified recycled aggregate concrete applied in a real project

研究采用纳米SiO2浸渍再生粗骨料的方式对再生骨料混凝进行改性处理,将经纳米改性和未经纳米改性的再生骨料混凝土应用于实际框架结构工程中,并以普通预拌混凝土作对照,采用同配合比的三种混凝土各原位浇筑一根梁,对这三根结构对称、受荷相似的梁开展构件应变监测,同时对同批浇筑的试块进行试验室力学性能测试,进行对比分析,探索纳米SiO2对再生骨料混凝土的改性效果及其应用可行性。分析结果表明未经纳米改性处理的再生骨料混凝土力学性能劣于同配合比的普通预拌混凝土,但经过纳米SiO2改性处理的再生骨料混凝土力学性能明显改善,其强度与变形性能可与普通预拌混凝土相当。研究同时证明,冬季低温施工对于混凝土、尤其是再生骨料混凝土的强度提升及抵抗变形能力发展具有较大的不利影响。

The modification effects ofnano-SiO2 on properties of RAC and the feasibility of applying modified RAC in real projects is discussed in this article.The modified recycled aggregate concrete（MRAC ）by using recycled aggregates（RA）soaked in nano-SiO2 solution before concrete mixing, was applied in a real framework together with non-modified RAC.Meanwhile the commercially produced, natural aggregate concrete （NAC）was set as control.Three beams bearing the same designed loading in the framework were cast with MRAC, RAC and NAC, respectively, and the strain of those beams was monitored regularly and compared with each other.Meanwhile, the compressive strength of the three groups of concrete was also tested in laboratory and analyzed.The results have shown that the mechanical properties of MRAC can be comparable to those of NAC ,while by contrast,the non-modified RAC is inferior to NAC in both strength and deformation resistance.Furthermore, the test results also indicate that low temperature in winter can bring large adverse effects on performance of concrete, especially on that of RAC.