多因素作用下免蒸压加气混凝土性能研究及模型预测

Performance research and model prediction of non-autoclaved aerated concrete under multiple factors

为解决加气混凝土养护条件复杂的弊端,采用一种免蒸压的方式制备大掺量粉煤灰加气混凝土.通过控制水胶比、配合比及养护天数测试免蒸压加气混凝土的抗压强度、劈裂抗拉强度、干密度和含水率四项性能指标,结合电镜扫描分析免蒸压加气混凝土的微观结构,并采用偏相关分析和回归分析建立预测模型.结果表明:当粉煤灰掺量为67%,水泥:石灰为1∶2,水胶比为0.51时,85℃蒸汽养护6d后再自然环境下养护5d可得到干密度716kg/m^(3),抗压强度6.75MPa的免蒸压加气混凝土,与蒸压加气混凝土相比,可达A5.0级标准;通过电镜扫描观察到免蒸压加气混凝土水化产物密集,多为结晶良好的C-S-H凝胶、钙矾石,并伴有针状及叶片状托贝莫来石晶体;同时,建立的线性回归模型误差控制在5%,R^(2)分别为0.934、0.866、0.828、0.795,精度较高,拟合程度好,表明所建立回归模型可以对免蒸压加气混凝土进行性能预测.

In order to solve the problem of complex curing conditions of aerated concrete,a method of non-autoclaving is adopted to prepare aerated concrete with high fly ash content.The compressive strength,splitting tensile strength,dry density and water content of non-autoclaved aerated concrete are tested by controlling water to cementitious material ratio,mix proportion and curing days.The microstructure of non-autoclaved aerated concrete is analyzed by scanning electron microscope,and the prediction model is established by partial correlation analysis and regression analysis.The results show that when the fly ash content is 67%,the ratio of cement to lime is 1:2,and water to cementitious material ratio is 0.51,the non-autoclaved aerated concrete with dry density of 716kg/m and compressive strength of 6.75MPa can be obtained after steam curing at 85℃for 6 days and then curing in natural environment for 5 days.Compared to autoclaved aerated concrete,it achieves the A5.0 standard.By scanning electron microscope,the hydration products of non-autoclaved aerated concrete are dense,mostly well-crystallised Calcium Silicate Hydrate and ettringite,with needle-like and blade-like tobe mullite crystals.Meanwhile,the error of the established linear regression model is controlled at 5%and R?are 0.934,0.866,0.828 and 0.795,respectively,with high accuracy and good fit,indicating that the established regression model can predict the performance of non-autoclaved aerated concrete.