Among the shrinkage types of concrete, plastic shrinkage and dry shrinkage are the main causes of volume deion of concrete. When cement contacts with water, the crack of concrete bridge is a common technical problem, and the crack of concrete bridge is a common technical problem. The sub-micro research is carried out through modern concrete strength theory. Rich engineering practice experience.
The results show that cracks in concrete structures are inevitable and the use of fine cracks is harmless. In the design and calculation theory of concrete bridges, cracks are allowed, but the width of cracks can not be controlled too wide. There is another way to repair and strengthen cracks in concrete bridges. After finding out the real cause of the crack, the correct and reasonable repair materials and methods are adopted.
Strengthen the bridge components, improve the structural performance, improve the bearing capacity of the bridge, extend the service life of the bridge, and adapt to the requirements of modern transportation. It can be seen that design cracks, poor construction quality, poor supervision quality and other factors may lead to cracks in concrete bridges. Therefore, design, construction and supervision in strict accordance with the relevant national standards and technical standards are the premise and foundation to ensure the safety and durability of structures.
In the process of operation and management, it is also very important to further strengthen inspection and management, and to find and deal with problems in time. Cracks caused by corrosion of steel bars. Due to the poor quality of concrete or insufficient thickness of protective layer, the protective layer of concrete is carbonized by carbon dioxide to the steel surface, which reduces the alkalinity of concrete around steel bars. Or because of the intervention of chloride ion, the chloride ion content around the reinforcing bar is high, which leads to the rupture of the oxide film on the surface of the reinforcing bar and the invasion and solidification of iron ion in the reinforcing bar. Oxygen in the soil reacts with water and rusts.