冻融环境下泡沫混凝土的单轴压缩特性

Uniaxial Compression Characteristics of Foamed Concrete under Freeze-Thaw Environment

为了解冻融环境下泡沫混凝土的单轴压缩特性,分别对4种密度(500、600、800和1 000 kg/m3)的泡沫混凝土进行了变加载速率(10~100 N/s)的试验研究,并基于X-CT重构了冻融环境下泡沫混凝土的孔隙结构模型。在此基础上,研究了单轴压缩过程荷载-位移曲线的特征及其影响因素,并借助回归分析和灰关联理论分析了泡沫混凝土密度、冻融循环次数及加载速率与抗压强度的关联程度。结果表明:冻融循环后泡沫混凝土单轴压缩过程荷载-位移曲线的切线模量大幅减小,非线性特征加强;冻融循环后试件孔隙率增大,孔径分布离散化程度加强。冻融环境下泡沫混凝土抗压强度与密度等级之间始终保持指数关系,相关系数均在0.9以上;泡沫混凝土密度等级与抗压强度联系最为紧密,其次是冻融循环次数和加载速率,灰关联度均在0.65以上。

In order to study the uniaxial compression characteristics of foamed concrete under freeze-thaw environment,foamed concrete with four kinds of densities(500,600,800 and 1000 kg/m3)were studied with different loading rates(10~100 N/s).Moreover,the pore structure model of foamed concrete under freeze-thaw environment were illustrated by using X-CT.The characteristics and influencing factors of load-displacement curves in the uniaxial compression process were studied,and the relational degrees among the density,freeze-thaw cycles,loading rate and compressive strength of foamed concrete were analyzed utilizing the regression analysis and grey relational theory.The results show that the tangent modulus of load-displacement curve of foamed concrete is reduced greatly and the nonlinear characteristics are enhanced in the uniaxial compression process after freeze-thaw cycles.Besides,the porosity of specimen increases after freeze-thaw cycles,and the discretization of pore size distribution increases.There remains an exponential relationship between compressive strength and density grade of foamed concrete under freeze-thaw environment,and the correlation coefficients are all above 0.9.According to the grey relational theory,the density grade of foamed concrete is more related to the compressive strength than freeze-thaw cycles and loading rate,and the grey relational degrees are all above 0.65.