【作者】 王文卓；

【导师】 刘艳峰；

【作者基本信息】 西安建筑科技大学 ， 建筑与土木工程， 2021， 硕士

【摘要】 毛细吸水系数是表征多孔建筑材料液态水吸收能力的重要湿参数之一。目前,相关标准对多孔建筑材料毛细吸水系数测试中试件尺寸及测试条件进行统一的规定。但是,不同的多孔建筑材料由于自身孔隙结构存在差异,导致其吸水能力有所区别,毛细吸水系数测定过程中材料对温度的敏感性也不同,因此,获取材料的毛细吸水系数时采用同一测试条件或标准,将对材料毛细吸水系数的准确性产生影响,测试条件的变化对不同性质的多孔建筑材料毛细吸水系数的影响程度不得而知。针对以上问题,本文研究了目前广泛应用的毛细吸水系数测试方法及实验中影响毛细吸水系数的因素,选用了孔隙结构不同的发泡水泥(FC)、加气混凝土(A AC)和珊瑚砂混凝土(SHS)作为研究对象,通过实验,分析试件尺寸(底面积、厚度)、环境温度(5、15、25、35℃)、浸水深度(3、5、8、10 mm)对毛细吸水系数的影响。由于不同多孔建筑材料的吸水过程存在差异,本研究采用不同的模型(正切法、双切线法、固定时间法、霍尔模型、其他模型)对毛细吸水系数测试结果进行处理分析,得到了各种影响因素下不同多孔建材毛细吸水系数的数据处理方法。通过对比分析,获得了样品尺寸、环境温度、浸水深度对多孔建筑材料毛细吸水系数的影响特性。具体得到以下结论:(1)FC、AAC和SHS吸水过程所绘制的吸水曲线的增长特性不同。FC和SHS吸水过程稳定吸水阶段呈非线性增长,AAC吸水过程稳定吸水阶段呈线性增长。(2)不同厚度(3、4、5 cm)下,FC毛细吸水系数的取值受厚度的影响较大。当厚度从3 cm增长至5 cm时,FC、AAC毛细吸水系数增长率分别约为30.2%、4.3%;SHS毛细吸水系数的取值受厚度影响较小,可以忽略。(3)不同底面积(底面积分别为64 cm~2、100 cm~2、144 cm~2、196 cm~2,材料皆为规整的正方形)下,由于FC内部孔隙较大,易开裂吸水,FC毛细吸水系数的取值受底面积的影响较大。当底面积从100 cm~2增长至196 cm~2时,FC毛细吸水系数增长率约为40.5%。当底面积从64cm~2增长至196cm~2时,SHS、AAC毛细吸水系数增长率分别约为8.1%、4.1%。(4)不同环境温度(5、15、25、35℃)下,AAC毛细吸水系数的取值受环境温度的影响较大。当环境温度从5℃增长至35℃时,AAC、FC毛细吸水系数增长率分别约为71.3%、40.6%。随着温度的升高,SHS水化反应速度变快,内部可溶性盐溶解、沉积导致自封闭现象发生提前,导致其毛细吸水系数的取值随温度从5℃增长至35℃的过程中降低了约4.1%。(5)不同浸水深度(3、5、8、10 mm)下,SHS毛细吸水系数的取值受浸水深度影响较大。当浸水深度从3 mm增长至10 mm时,SHS、FC、AAC毛细吸水系数增长率分别约为38.4%、31.8%、9.1%。最后,本文对影响不同多孔建筑材料毛细吸水系数的因素进行权重分析,为不同多孔建筑材料毛细吸水系数的测定提供试件尺寸、环境温度、浸水深度等实验条件及数据处理方法的建议。更多还原

【Abstract】 Capillary water absorption coefficient is one of the important wet parameters to characterize the liquid water absorption capacity of porous building materials.At present,the relevant standards for the capillary water absorption coefficient of porous building materials in the test of specimen size and test conditions are unified provisions.However,different porous building materials due to their pore structure difference,causes the water absorbing capacity,capillary water absorption coefficient measurement in the process of material is also sensitive to temperature is different,therefore,to obtain materials of capillary water absorption coefficient using the same test conditions or standards,will affect the accuracy of the capillary water absorption coefficient of materials,test condition change on different properties of porous building materials the influence degree of the capillary water absorption coefficient is unknown.In view of the above problems,this paper studies the widely used capillary water absorption coefficient test methods and the factors that affect the capillary water absorption coefficient in the experiment.Foamed cement(FC),aerated concrete(AAC)and coral sand concrete with different pore structures are selected(SHS)As the research object,through experiments,analyze the influence of specimen size(bottom area,thickness),ambient temperature(5,15,25,35℃),and immersion depth(3,5,8,10 mm)on the capillary water absorption coefficient.Due to the differences in the water absorption process of different porous building materials,this study uses different models(tangent method,double tangent method,fixed time method,Hall model,other models)to process and analyze the capillary water absorption coefficient test results,and obtain various Data processing method of different porous building materials’capillary water absorption coefficient under influencing factors.Through comparative analysis,the influence characteristics of sample size,ambient temperature,and water immersion depth on the capillary water absorption coefficient of porous building materials are obtained.The specific conclusions are as follows:(1)The growth characteristics of water absorption curves drawn by FC,AAC and SHS during water absorption are different.FC and SHS showed a nonlinear increase in stable water absorption stage,while AAC showed a linear increase in stable water absorption stage.(2)Under different thickness(3,4,5 cm),the capillary water absorption coefficient of FC is greatly affected by the thickness.When the material thickness increases from3cm to 5cm,the growth rates of the capillary water absorption coefficients of FC and AAC are about 30.2%and 4.3%,respectively.The value of SHS capillary water absorption coefficient is less affected by the thickness and can be ignored.(3)Under different bottom areas(the bottom areas are 64 cm~2,100 cm~2,144 cm~2,196 cm~2,and the materials are all regular squares),due to the large internal pores of the FC,it is easy to crack and absorb water.The value of the FC capillary water absorption coefficient is affected by the bottom area.Greater impact.When the bottom area increases from 100 cm~2 to 196 cm~2,the growth rate of FC capillary water absorption coefficient is about 40.5%.When the bottom area increases from 64 cm~2 to 196 cm~2,the growth rates of SHS and AAC capillary water absorption coefficients are about 8.1%and 4.1%,respectively.(4)Under different ambient temperatures(5,15,25,35℃),ambient temperature has a great influence on the capillary water absorption coefficient of AAC.When the ambient temperature increases from 5℃to 35℃,the growth rates of the capillary water absorption coefficients of AAC and FC are about 71.3%and 40.6%,respectively.With the increase of temperature,the hydration reaction rate of SHS is faster,and the self-sealing phenomenon occurs earlier due to the dissolution and deposition of internal soluble salt,which leads to the value of the capillary water absorption coefficient decreased by about 4.1%as the temperature increased from 5℃to 35℃.(5)Under different water immersion depth(3,5,8,10 mm),the water immersion depth had a great influence on the value of SHS capillary water absorption coefficient.When the immersion depth increased from 3 mm to 10 mm,the growth rates of SHS,FC and AAC capillary water absorption coefficients were 38.4%,31.8%and 9.1%,respectively.Finally,the weight analysis of the factors affecting the capillary water absorption coefficient of different porous building materials is carried out to provide suggestions on the experimental conditions and data processing methods for the determination of the capillary water absorption coefficient of different porous building materials,such as specimen size,ambient temperature,immersion depth,etc.更多还原