轻骨料混凝土早龄期湿度扩散试验研究

Experimental study on moisture diffusion of lightweight aggregate concrete at early age

为了研究轻骨料混凝土内部的早龄期湿度变化规律,采用0.35、0.45水灰比,40%、20%的粗骨料体积比,堆积密度为900、500级的轻骨料制成轻骨料混凝土试件,对早龄期轻骨料混凝土开展了一维湿度扩散试验和自干燥试验研究,并采用拟合的方法建立了早龄期轻骨料混凝土一维湿度扩散和自干燥作用数学模型。试验结果显示,水灰比、粗骨料体积比和级别对混凝土内部的湿度扩散规律有明显的影响,水灰比越低、粗骨料体积比越大,粗骨料密度等级越低,轻骨料混凝土内部湿度传输速率越快;自干燥试验显示,水灰比不同的混凝土内部相对湿度降低速率基本相同;数学模型和轻骨料混凝土试验数据计算吻合,可揭示早龄期轻骨料混凝土湿度扩散的规律。

In order to study the law of humidity variation inside the lightweight aggregate concrete(LWAC)at early age,ratios of water to cement of 0.35 and 0.45,aggregate ratios of 40%and 20%,and lightweight aggregates with bulk densities of class 900 and class 500 were used to make LWAC specimens,one-dimensional humidity diffusion test and self-drying test of early age LWAC were carried out,and two mathematical models of LWAC of one-dimensional humidity diffusion and self-drying are established at early age by fitting method.The experimental results show that the water-cement ratio,the volume ratio and grade of coarse aggregate have obvious influence on the moisture diffusion law in concrete,the lower of water-cement ratio,the larger the volume ratio and the lower the density of coarse aggregate are,the faster the moisture transfer rate in LWAC is.The self-drying test shows that the ratio of relative humidity reduction in concrete with different water-cement ratio is basically the same.The mathematical model coincides with the experimental data of all types of LWAC,which can reveal the law of humidity diffusion of LWAC at early age.