As a kind of building construction material, concrete plays an increasingly important role in the construction of buildings, and the subsequent problems of concrete cracks have also received close attention from the relevant industries in the society. It is difficult to prevent the occurrence of concrete cracks due to the control and measures in the construction process.
There are three conditions for large cracks in concrete: surface cracks, deep cracks and through cracks. Insufficient structure and bearing capacity and durability of concrete often lead to cracks on the surface of concrete buildings. Because its threat to safety and its impact are very small, we generally do not consider and deal with it. For deep cracks and fissures, we can adopt the control method of chiseling and removing cracks, which can be completed by air picks, drills or manual methods. First, the cracks are chiseled and then concrete is placed on the trapezoidal gouge.
1 Analysis of the causes of concrete cracks in building construction
1.1 Plastic shrinkage cracks in gradually solidified concrete, some water and heat may be evaporated due to the effect of hydration heat, which is an important reason for the rapid shrinkage of concrete volume. Mass concrete is particularly interesting because shrinkage stresses occur when the concrete is subjected to external disturbances during shrinkage. However, as long as the stress exceeds the tensile strength limit of the concrete, cracks will appear on the concrete surface, and cracks are often a quality problem of the concrete. In addition, there are quality problems in the concrete material itself, such as the type of cement, stability factors, the mud content of sand and stone, and the excessively large water-cement ratio. The hazard is a quality related to physical properties. The key factors of concrete durability have been severely affected. Most of these cracks already existed during the construction stage. Although some cracks appeared after the completion of the construction, these were not caused by the long-term use of the construction project, but were quality issues that already existed in the early construction.
The decrease in the tensile strength of concrete is caused by the existence of cracks, and it will also cause many harmful substances to penetrate into the structure inside the concrete, resulting in corrosion of the reinforced materials, and seriously impairing the durability of the overall structure of the concrete.
To be continue…