不同容重等级微孔混凝土基本性能及微观结构研究

Research on basic properties and microstructure of microporous concrete with different densities

制备容重等级700~1300 kg/m^(3)的微孔混凝土试件,研究微孔混凝土干湿容重的关系,容重等级与抗压强度、吸水率、软化系数、抗折强度和折压比的关系,以及聚丙烯纤维对微孔混凝土抗压强度和抗折强度的影响。结果表明,微孔混凝土的容重越高,其抗压强度、抗折强度越大,吸水率越低,软化系数越高;1.4%体积掺量的聚丙烯纤维可以显著提高微孔混凝土的抗折强度。通过电镜观察和XRD分析,揭示了微孔混凝土的孔结构、水化产物的微观形貌、膨胀珍珠岩和聚丙烯纤维在胶凝材料中存在的形式及水化产物,从微观结构角度解释容重等级对微孔混凝土基本性能的影响。

The relationship between dry and wet bulk density of microporous concrete specimens with bulk density 33 ranging from 700kg/m to 1300kg/m is studied.The relationship between bulk density grades and compressive strength,water absorption,softening coefficient,flexural strength,and flexural compression ratio is also investigated.In addition,the effect of polypropylene fibers on the compressive and flexural strength of microporous concrete is studied.The results show that the higher bulk density of microporous concrete results in greater compressive and flexural strength,lower water absorption,and higher softening coefficient.The addition of 1.4%volume fraction of polypropylene fibers can significantly improve the flexural strength of microporous concrete.Furthermore,SEM and XRD analysis are conducted to reveal the pore structure of microporous concrete,microstructure of hydration products,and presence of perlite and polypropylene fibers in cementitious material.The influence of bulk density grade on the basic properties of microporous concrete is explained from microstructural perspective.