负温混凝土内部结构发展的无损监测

Nondestructive monitoring for development of internal structure of concrete at subzero temperature

为实现寒冷地区冬季施工中混凝土内部结构发展的无损监测,研究两种坍落度、两种防冻剂的混凝土在标准养护条件、恒负温养护条件及自然变负温养护下动弹性模量随龄期的变化规律.结果表明:标准养护条件下,高掺量防冻盐类的掺入给混凝土内部结构带来一定的损伤.在负温阶段,异常高的混凝土动弹性模量值是由混凝土内部含冰量所决定的.通过转入正温一定时间内动弹性模量的衰减值可以判断混凝土在负温阶段受冻损伤程度.转入正温条件下混凝土的动弹性模量的发展规律与混凝土强度发展规律是一致的.因此,这一无损检测方法可以应用于冬季施工中.

In order to realize the nondestructive monitoring for the development of internal structure of concrete in winter construction, the variation of dynamic elastic modulus of concretes with ages was investigated, which were cured under standard conditions, at constant negative temperature and at outdoor varying negative temperature. The results show that the high dosage of anti - freezing salts results in certain internal structure damage of concrete under standard curing conditions. In the negative temperature stage, the extraordinarily high value of dynamic elastic modulus of concrete is attributed to ice content in concrete. After moving the concrete cured at subzero temperature into a standard curing room for a certain period, the attenuation of dynamic elastic modulus can be applied to the determination of damage degree of concrete during subzero temperature curing stage, and the development rule of dynamic elastic modulus of concrete accords with that of compressive strength of concrete. Therefore, this non - destructive testing method can be applied to concrete construction in winter.