不同强度等级和尺寸混凝土自由吸水规律研究  

Study on free absorption of concrete with different strength grades and sizes

作　　者：谭聪 李宗利[1] 韩进生 韩金家 杜向琴[1] TAN Cong;LI Zongli;HAN Jinsheng;HAN Jinjia;DU Xiangqin(College of Water Resources and Architectural Engineering,Northwest A&F University,Xianyang 712100,China)

机构地区：[1]西北农林科技大学水利与建筑工程学院

出　　处：《混凝土》2019年第11期34-38,共5页Concrete

基　　金：国家重点研发计划资助项目（2017YFC405101-2）;国家自然科学基金资助项目（51379178）

摘　　要：开展湿度对混凝土力学性能影响的研究有着重要意义,但在试验中如何有效控制湿度是这类试验的关键技术。通过不同强度等级和尺寸的混凝土试件自由吸水过程中含水率随浸泡时间变化的研究,建立含水率预测模型。结果表明,混凝土自由吸水过程分为快速吸水阶段、降速吸水阶段、基本饱和阶段,吸水过程含水率随时间变化规律采用指数函数拟合较符合实际。混凝土强度等级越高,吸水速率越慢,达到饱和状态所需的时间越长,总吸水量越少,吸水系数越小。C20、C30、C40混凝土试件最大含水率分别比C50增加54.9%、48.7%、11.5%,C50混凝土的吸水系数仅为C20的52%。试件尺寸大小对其吸水特性有影响,对于混凝土立方体试件,边长越大,比表面积越小,前期含水率变化越慢,达到饱和状态所用时间越长,但最大含水率高,试验得到的吸水系数越大。It is of great significance to carry out research on the effect of humidity on the mechanical properties of concrete.However,how to effectively control the humidity in the test is a key technique for such tests.Through the study of the change of water content with the soaking time in the process of free water absorption of concrete with different strength grades and sizes,a water content prediction model was established.The results show that the free water absorption of concrete is divided into the rapid water absorption stage,the water absorption stage and the basic saturation stage.The water content of the water absorption process is fitted with the exponential function with the time change law;The higher the strength level of concrete,the slower the water absorption rate,the longer the time to reach the saturation state,the less total water absorption and the smaller the water absorption coefficient.The maximum moisture content of C20,C30 and C40 concrete specimens increased by 54.9%,48.7% and 11.5% respectively than those of C50,and the water absorption coefficient of C50 concrete was only 52% of C20.The size of the specimen has an influence on its water absorption characteristics.For the concrete cube specimen,the larger the side length,the smaller the surface area,the slower the change of the water content in the early stage,the longer the time it takes to reach the saturation state,but the maximum water cut is higher,the greater the water absorption coefficient is.

关 键 词：混凝土 自由吸水 含水率 强度等级 尺寸影响 

分 类 号：TU528.01[建筑科学—建筑技术科学]