溧高高速匝道桥低温浇筑混凝土裂缝成因及处理技术研究

Study on Causes and Treatment Technology of Low Temperature Pouring Concrete Cracks of Ligao Expressway Ramp Bridge

混凝土的低温影响质量的最主要的因素无外乎是要确保混凝土在强度增长初期要有良好的养生环境,即适宜的温度和一定的湿度。溧高高速公路枢纽桥梁施工期正处于低温季节,平均温度低于5℃。施工完成半年后在桥梁外观检测时发现箱梁外侧腹板出现较多裂缝,项目改进小组通过分析认为,该裂缝是由于施工浇筑时的温度较低,且无有效的养护保温措施,因此在表面产生了较多的温度微裂缝,随着温度升高,在涨缩效应影响下使裂缝发展成为肉眼可见的裂缝。由于裂缝为非结构性裂缝,对桥梁的使用功能无明显影响,因此采用封闭补强的方法予以加固,目的是阻断内部与外部空气和水蒸气的进入,提高混凝土耐久性。

The main factor affecting the quality of concrete at low temperature is to ensure a good curing environment at the initial stage of strength growth,that is appropriate temperature and certain humidity.The construction period of the hub bridge of Ligao Expressway is in the low temperature season,and the average temperature is lower than 5℃.Half a year after the completion of construction,many cracks were found in the outer web of the box girder during the appearance inspection of the bridge.Through analysis,the project improvement team believes that the cracks are due to the low temperature during construction pouring and no effective maintenance and thermal insulation measures,so there are many temperature micro cracks on the surface.With the increase of temperature,Under the influence of expansion and contraction effect,the crack develops into a visible crack.As the cracks are non structural cracks,which have no obvious impact on the service function of the bridge,the closed reinforcement method is adopted for reinforcement,in order to block the entry of internal and external air and water vapor and improve the durability of concrete.