既有裂缝对混凝土热湿物性参数的影响分析

ANALYSIS OF THE INFLUENCE OF EXISTING CRACKS ON THERMAL CONDUCTIVITY AND MOISTURE CONTENT OF CONCRETE

为解决既有裂缝对混凝土热湿物性参数影响的问题,通过3D打印技术制作裂缝模型,以裂缝体积与混凝土试块体积比值作为变量,针对不同裂缝体积占比混凝土的导热系数、吸水系数、水分扩散系数和水蒸气渗透系数展开研究。结果表明:混凝土的导热系数随着含湿量的增大而增大,随着裂缝体积占比的增大而减小,且导热系数对裂缝体积的敏感性逐渐减小。裂缝体积占比0.1%~0.3%的干燥混凝土相较于无裂缝混凝土,导热系数增大比例最小为7.96%,最大为30.9%。拟合得到混凝土吸水系数、水分扩散系数与裂缝体积占比的关系曲线,两者皆随着裂缝体积占比的增大而增大。拟合得到不同裂缝体积占比的混凝土的水蒸气渗透系数与含湿量的变化曲线,曲线的斜率逐渐增大,其随裂缝体积占比的增大而增大,且含湿量越大,水蒸气渗透系数随裂缝体积增大的幅度越大。

In order to overcome the influence of existing cracks on the thermal conductivity and moisture content of concrete,a crack model was made by 3D printing.With the crack volume and concrete test block volume as variables,the study was conducted on the thermal conductivity,water absorption coefficient,water diffusion coefficient and vapor permeability coefficient of concrete with different crack volume ratios.Results showed:The thermal conductivity of concrete increased when the moisture content rose,but decreased when the crack volume ratio increased.In addition,the sensitivity of thermal conductivity to crack volume decreased gradually.Compared with uncracked concrete,the thermal conductivity of dry concrete with a crack volume ratio of 0.1%-0.3%increased by 7.96%to 30.9%.The curves of relationships between the water absorption coefficient and water expansion coefficient of concrete and the crack volume ratio were obtained by fitting.Both the water absorption coefficient and water expansion coefficient increased when the crack volume ratio rose.The curves of changes in the vapor permeability coefficient and moisture content of concrete with different crack volume ratios were obtained by fitting.The curve slope increased gradually.Both the moisture content and vapor permeability coefficient of concrete increased as the crack volume ratio rose.