冻融条件下水工混凝土渗透性演化试验研究

寒冷地区的混凝土面板堆石坝在经历长期冻融作用后,其面板渗透性逐渐增大,从而影响大坝安全稳定。为此,通过解决冻融作用下混凝土表面不平整等问题,利用Autoclam渗透性测试仪测试了不同水胶比、掺粉煤灰以及引气剂下混凝土渗透性随冻融次数的变化规律。结果表明,不同水胶比混凝土的渗透系数随冻融次数的增加均呈指数增长趋势,水胶比较小的混凝土其渗透系数增长的最缓慢;高冻融循环次数后,同时掺粉煤灰和引气剂对增强混凝土的抗渗性效果最明显。此外,还探究了冻融条件下混凝土渗透性与其抗压强度之间的相关性。

Experimental Study on Permeability Evolution of Hydraulic Concrete under Freeze-thaw Conditions

After a long period of freezing and thawing,the permeability of concrete face rock-fill dam in cold area increases gradually,which affects the safety and stability of dam.In order to solve the problem of unevenness of concrete surface under freeze-thaw action,the law of concrete permeability changing with freeze-thaw times under different water-binder ratio,fly ash and air entraining agent is tested by Autoclam permeability tester.The results show that,(a)the permeability coefficient of concrete with different water-binder ratio increases exponentially with the increase of freeze-thaw cycles,and that of concrete with smaller water-binder ratio increases most slowly;and(b)after a high number of freeze-thaw cycles,the anti-permeability effect of concrete with fly ash and air entraining agent is most obvious.In addition,the correlation between concrete permeability and compressive strength under freeze-thaw conditions is also explored.