桥梁墩台混凝土施工防裂技术

Crack-preventing Technology for Concrete Construction of Abutments of Bridges

如何防止温度裂缝,是大体积混凝土结构施工中的一个重大课题。结合达成扩能改造工程铁路双线桥梁实体墩台施工实践,分析了该桥先期施工中桥墩混凝土表面出现裂缝的原因:除温度裂缝外,还由于施工工艺不当,造成混凝土离析,收缩率不同导致干缩裂缝的出现。介绍了改变混凝土原材料、调整混凝土配合比、改进施工工艺及对混凝土浇灌时进行温度控制和养生过程中采取防护保温等措施,取得了良好效果,可为类似工程施工提供借鉴。

How to prevent temperature-caused cracks from emerging in concrete is always a serious problem in the construction of massive concrete structures. With the construction of the solid abutments of the bridges of the Da-Cheng capability-enhancing project of the double line of the Dazhou-Chengdu Railway as a practical example, the causes of the surface.fissures in concrete of the bridge during the early phase of the construction are analyzed in the paper. It is found that the fissures result from the improper application of construction processes besides temperature changes, which leads to the crumbling of concrete, and different contracting rates also lead to the emergence of contracting cracks. To solve the problem, effective technical measures, such as changing the composition of the raw materials, adjusting the mix ratios of concrete, improving construction technology, adjusting the temperature while pouring concrete and taking protective and warm-keeping measures during the maintenance stage, are suggested in the paper. The success obtained may well serve as a useful reference for other similar projects.