紫外线与冻融循环作用下的混凝土耐久性研究

分别制作3种不同水灰比的面板混凝土试件,在紫外线辐射试验的基础上,以未经紫外线辐射的试件作为对照组,对各组经相同时间紫外线辐射后的试件进行冻融循环试验,并每间隔一定的冻融次数测定试件的质量及动弹性模量,根据试验结果,进行拟合分析,建立了考虑紫外线辐射的冻融循环损伤度模型。结果表明:在一定冻融循环次数下,水灰比越小,质量损失率越小,相对动弹模量越高,混凝土的抗冻性越好;相较于未经紫外线照射的对照组,经过紫外线照射的试件在经过一定循环次数的冻融后,其质量损失率更大;紫外线辐射对低强混凝土的质量损失率影响主要是在冻融循环的早期表现出来,而对高强混凝土则是在冻融循环的晚期表现出来;获得的冻融循环损伤度模型能够较好地反映经过紫外线辐射作用的面板混凝土的冻融循环损伤演变规律。

Study on durability of concrete under ultraviolet radiation and freeze-thaw cycles

Three kinds of concrete panel specimens with different water cement ratio were made respectively, on the basis of the ultraviolet radiation test, specimens without uv radiation were used as a control group, and the freeze-thaw cycle test on each specimen irradiated with ultraviolet radiation at the same time for each group . The quality and dynamic modulus of the specimens are measured at regular intervals. According to the results of the test, a freeze-thaw cycle damage degree model considering ultraviolet radiation is established by the fitting analysis. The results showed that under a certain number of freeze-thaw cycles, the smaller the water-cement ratio and the lower the mass loss rate is, the higher the relative dynamic elastic modulus is, the better the frost resistance of the concrete is. Compared to the control group without ultraviolet radiation, the mass loss rate was greater after a certain number of cycles of freezing and thawing . Ultraviolet radiation effect on low strength concrete mass loss is mainly reflected in the early days of the freeze-thaw cycle, and of high strength concrete is expressed in the late stage. The obtained freeze-thaw cycle damage model is a good way to reflect the evolution of the frozen and melt cycle of the concrete with ultraviolet radiation.