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一、引言水下浇筑混凝土的方法一般有导管法、压浆法、柔性管法、倾注法、开底容器法和袋装迭置法等。无论采用何种方法,都存在水泥被冲走和细骨料与粗骨料分离的可能性,使新浇混凝土强度降低,与基层粘结不牢。有资料介绍:用导管法施工时,其表层混凝土强度损失可达50%,在间歇施工时,常因此要清除掉15～45cm厚的表层水下混凝土,或对某些结构每边至少富裕15cm低质量保护层。但是,水下直接浇筑混凝土可省去施工围堰、基础防渗和基坑排水工程,在寒冷和炎热季节,水环境对混凝土硬化具有较适宜的条件。在无法建筑围堰的情况下,水下混凝土甚至是形成水中混凝土建筑物的唯一方法。因此,如何取得高质量而又经济的水下混凝土一直成为人们研究的课题。
I. Introduction Underwater pouring concrete methods are generally catheter method, grouting method, flexible tube method, pouring method, open bottom container method and bagging Diego law. No matter what method is used, there is a possibility that the cement is washed away and the fine aggregate is separated from the coarse aggregate, so that the strength of the fresh concrete is reduced and the bond with the grassroots is not strong. There is information on: the construction of the catheter method, the concrete surface layer loss of up to 50% strength, intermittent construction, often therefore have to clear 15 ~ 45cm thick surface submerged concrete, or on some sides of at least 15cm Low quality protective layer. However, the direct pouring of concrete underwater can save the construction cofferdam, foundation seepage prevention and foundation pit drainage project. In cold and hot season, the water environment has more suitable conditions for the concrete to be hardened. In the absence of cofferdams, underwater concrete is even the only way to create concrete structures in water. Therefore, how to obtain high quality and economical underwater concrete has been the subject of research.