超轻质混凝土的抗冻性试验方法研究  

Test Method for Freeze-thaw Resistance of Ultra-lightweight Concrete

作　　者：刘迪 王玲 王振地 方俊 LIU Di;WANG Ling;WANG Zhen-di;FANG Jun(State Key Laboratory of Green Building Materials,China Building Materials Academy,Beijing 100024,China)

机构地区：[1]中国建筑材料科学研究总院有限公司绿色建筑材料国家重点实验室,北京100024

出　　处：《混凝土与水泥制品》2022年第6期31-36,共6页China Concrete and Cement Products

基　　金：国家重点研发计划项目(2017YFB0309903);国家自然科学基金面上项目(51972295)

摘　　要：针对现有方法评价超轻质混凝土的抗冻性存在烘干开裂、冻融失效过快等不足,提出了一种改进测试方法,即试件饱水后再沥水,以调节含水率,并采用气冻气融进行冻融循环试验。研究了沥水时间、融化温度和试件尺寸对超轻质混凝土强度损失率和质量损失率的影响。结果表明:控制沥水时间能有效调节试件的含水率;随着沥水时间的延长,试件的冻融质量损失率和强度损失率大体呈下降趋势;降低冻融循环试验时的融化温度能有效解决试件的开裂问题;尺寸较小试件对温度的敏感程度相对较大,尺寸较大的试件冻融破坏严重,不易搬运。并在此研究基础上,提出了适合超轻质混凝土抗冻性试验的改进方法,确定了适宜的沥水时间、融化温度和试件尺寸,分别为6 h、15℃和100 mm×100 mm×100 mm,可为超轻质混凝土的抗冻性测试提供参考。Aimed to solve the deficiencies of the domestic existing msethod for evaluating the freeze-thaw resistance of ultra-lightweight concrete(ULWC),such as cracking caused by drying and deterioration by freeze-thaw cycles too fast,a new method was put forward,in which the moisture content of the ULWC specimen was adjusted by controlling draining time after soaked in water,and then the mode of freezing and thawing cycle in air was used.The effects of test parameters such as draining time of specimen,thawing temperature and specimen size on the strength loss rate and mass loss rate of ULWC were studied.The results show that controlling the draining time can effectively adjust the moisture content of the specimen.Both the freeze-thaw mass loss rate and strength loss rate of the specimens generally show a downward trend with the extension of the draining time.Lowering the melting temperature can effectively solve the problem of cracking of ULWC specimen during the freeze-thaw test.The smaller size of the specimen is relatively more sensitive to temperature,and the larger size of the specimen is severely damaged by freezing and thawing,and is not easy to handle.Based on the research,a new test method suitable for the evaluation of freeze-thaw resistance of ULWC was proposed.The appropriate drain time,thawing temperature and specimen size were determined to be 6 h,15°C and 100 mm×100 mm×100 mm,respectively.The results can provide a reference for the frost resistance test of ULWC.

关 键 词：轻质混凝土 抗冻性 含水率 融化温度 试件尺寸 冻融循环 

分 类 号：TU528.2[建筑科学—建筑技术科学]