材料期刊网

混凝土在服役环境中的温度响应直接影响其水化进程,而且影响到水分、离子传输与钢筋锈蚀.相对湿度为45%、65%、80%非饱和以及饱和混凝土在5 ℃,45 ℃,65 ℃和85 ℃下进行升温与降温试验,测试混凝土的温湿度演变,并测试非饱和混凝土导热系数.试验结果表明:混凝土湿度越小,其热响应时间越长,相比于饱和混凝土,相对湿度45%混凝土升温、降温过程的热响应时间延长6~7倍和7~8倍.相对湿度45%~65%混凝土与热源接触初期,需经过30~50 min才能传递到10 mm深度.距离热源越近的位置,混凝土的热响应速度越快,升温、降温过程中所需的时间越少.混凝土升降温过程导致混凝土内部相对湿度先增加后保持稳定,温度传输与湿度扩散存在交互效应.随着混凝土内部相对湿度增加,混凝土养护龄期增加,其导热系数增大,热量传递速度逐渐加快.

Temperature responses of concrete in service environment affect the hydration process, water/ions transportation and rebar corrosion in concrete.The temperature and RH (relative humidity) evolution of saturated concrete and Non-saturated concrete with RH=45%, 65% and 80% rising and cooling process at 5 ℃, 45 ℃, 65 ℃ and 85 ℃ temperature were studied.And the thermal conductive coefficient of non-saturated concrete was also tested.The results of the experiment prove that temperature response time of concrete was increased with decreasing RH.Compared with response time of saturated concrete in rising and cooling process, the time of concrete with RH=45% prolonged 6-7 and 7-8 times, respectively.And the time of thermal flow to 10 mm depth of concrete with RH=45%-65% would be 30-50 min.The temperature response time of concrete would be shortened with decreasing distance to thermal source when concrete subjected to rinsing and cooling process.The inner RH of concrete increased firstly, and then trended toward steady in the temperature rising and cooling process.The interaction effects between thermal conduction and RH transportation was observed in this experiment.Additionally, the thermal conductive coefficient of concrete increased with increasing RH in concrete, and extending curing age.