A Study Of The Test Methods For Capillary Water A Bsorption Coefficient Of Porous Building Materials

Moisture transfer in porous building materials is a crucial issue for the building environment Moisture-related processes affect the durability and sustainability of building structures.Moisture transport in porous building materials can be classified into the transport of water vapor and liquid water,and the liquid water transport has the dominant effect in building environments with high relative humidity.So it is very important to evaluate the liquid water transfer parameters correctly The capillary absorption coefficient is a key parameter characterizing the water absorption capacity of porous building materials.There are many methods to measure capillary water absorption coefficient,and the partial immersion method is one of the most commonly used methods.However,the existing standards of partial immersion method are different,and there is no clear and consistent standard in the treatment and experimental operation of samples.And the experimental method itself is rough which leads a large error.In order to solve these problems,we choose one homogeneous and stable porous building materials,B03 and B04 grade autoclave aerated concrete(AAC)as the research object,and the test method of capillary water absorption coefficient of porous building materials is studiedIn order to standardize the influence factors such as sample height and data processing in partial immersion test,we processed the same type of sample to different heights.The capillary water absorption coefficient was measured by partial immersion method,and the data results were analyzed.The results show that the experimental height and the selection of data have certain influence on the experimental results.In this paper,it is suggested that in practical operation,the actual height of materials in engineering can be selected as the height of the experimental test sample,and it is not necessary to absorb water to the saturated state of the sample,just take a proper amount of data points in the stable water absorption stage of the sample.And we suggested that the stable absorption stage should last 11h,and for B03 and B04 grade autoclave aerated concrete,the sample height should be more than 100mmIn addition,the sample should be taken out from the water repeatedly and weighed by partial immersion method,which affects the accuracy and reliability of the experiment seriously Therefore,on the basis of the partial immersion method,a new continuous measurement method was proposed,which can avoid the process of taking the samples out from the water.The experimental results show that the continuous measurement method is simple,easy to operate,and shows high repeatability and strong adaptability.