PAM和VAE泡沫混凝土微观结构与宏观性能的研究

Study on Microstructure and Macroscopic Properties of PAM and VAE Foamed Concrete

研究了聚灰比为0、0.1%、0.5%、1.0%时,聚丙烯酰胺(PAM)乳液对泡沫混凝土干密度和抗压、抗折强度的影响;以及聚灰比为0、1.0%、3.0%、5.0%时,乙烯-醋酸乙烯(VAE)共聚乳液对泡沫混凝土干密度和抗压、抗折强度的影响。通过显微图像处理并使用Image-Pro Plus软件分析泡沫混凝土截面微观孔结构,探究泡沫混凝土微观孔结构和宏观性能的变化趋势和对应关系,以及PAM和VAE对泡沫混凝土的改性机理。结果表明:随着聚灰比的增加,PAM泡沫混凝土的孔隙率和平均孔径呈先减小后增大的趋势,圆度值呈先增大后减小再显著增大的趋势,导致干密度、抗压强度和抗折强度总体上均有显著的减小趋势,确定较优聚灰比为0.5%。VAE泡沫混凝土的孔隙率和平均孔径则随着聚灰比的增加呈先减后增的趋势,圆度值呈一直增大的趋势,导致干密度和抗折强度均先减小后增大,抗压强度先增大后减小再增大,确定较优聚灰比为1.0%。对比两者发现,不同聚灰比的PAM泡沫混凝土的孔隙率和平均孔径均小于VAE泡沫混凝土,同时两者的干密度变化趋势也有明显差异,前者抗压强度小于后者,而抗折强度的数值和变化趋势与后者相近。

The effects of polyacrylamide(PAM)emulsion on the dry density,compressive strength and flexural strength of foamed concrete were studied when the polymer-cement ratio was 0,0.1%,0.5%and 1.0%,and the effects of ethylenevinyl acetate(VAE)copolymer emulsion on the dry density,compressive strength and flexural strength of foamed concrete were studied when the polymer-cement ratio was 0,1.0%,3.0%and 5.0%.Microscopic image processing and Image-Pro Plus software were used to analyze the microscopic pore structure of foam concrete section,and to explore the changing trend and corresponding relationship between the microscopic pore structure and macroscopic properties of foam concrete,as well as the modification mechanism of PAM and VAE on foam concrete.The results show that with the increase of polymer-cement ratio,the porosity and average pore size of PAM foam concrete decrease first and then increase,and the roundness value increases first,then decreases,and then increases significantly,which leads to a significant decrease in dry density,compressive strength and flexural strength as a whole.The optimal polymer-cement ratio is 0.5%.With the increase of polymer-cement ratio,the porosity and average pore size of VAE foam concrete decrease first and then increase,and the roundness value increases all the time,which leads to the decrease of dry density and flexural strength first and then increase,and the increase of compressive strength first,then decrease and increase again.The optimal polymer-cement ratio is 1.0%.It is found that the porosity and average pore size of PAM foam concrete with different polymer-cement ratios are smaller than those of VAE foam concrete,and the change trend of dry density of PAM foam concrete with different polymer-cement ratios is also significantly different from that of VAE foam concrete,the compressive strength of the former is smaller than that of the latter,while the value and change trend of flexural strength of the former are similar to that of the latter.