再生蒸压加气混凝土的性能及水化机理研究

Study on performance and hydration mechanism of recycled autoclaved aerated concrete

将废混凝土粉作为硅质材料掺入蒸压加气混凝土中,研究了废混凝土粉的掺量(40%~70%)、蒸压压力(0.9~1.7 MPa)和蒸压时间(4、6、8 h)对蒸压加气混凝土性能的影响,并通过XRD和SEM分析了其水化机理。结果表明:当废混凝土粉掺量为50%、蒸压压力为1.1 MPa、蒸压时间为8 h时,制备的再生蒸压加气混凝土的抗压强度和干密度分别达到7.5 MPa和647 kg/m3,满足相关标准中的A5.0、B06级别要求;蒸压养护促进了蒸压加气混凝土中的硅质材料和钙质材料反应,生成了大量的片状托贝莫来石、半结晶CSH(Ⅰ)、CSH凝胶和少量水化石榴石、硬石膏等水化产物,从而提高了蒸压加气混凝土的强度,降低了其干密度。

The effect of the content of waste concrete powder(40%~70%),autoclaved pressure(0.9~1.7 MPa),and autoclaved time(4,6,8 h)on the performance of autoclaved aerated concrete was studied by adding waste concrete powder as the siliceous material.The hydration mechanism was analyzed by XRD and SEM.The results show that when the content of waste concrete powder is 50%,the autoclave pressure is 1.1 MPa,and the autoclave time is 8 h,the compressive strength and dry density of the prepared recycled autoclaved aerated concrete can reach 7.5 MPa and 647 kg/m3,respectively,meeting the requirements of A5.0 and B06 in relevant standards.Autoclave curing promotes the reaction of siliceous materials and calcareous materials in autoclaved aerated concrete,and generates a large number of flaky tobermorite,semi crystalline CSH(Ⅰ),CSH gel,and a small amount of hydrated garnet,anhydrite and other hydration products,thus improving the strength of autoclaved aerated concrete and reducing its dry density.