Qingdao crack repairTell you what is the cause of temperature cracks
For concrete bridge cracks weQingdao crack repairThe editor tells you that it can be divided into five categories: load cracks, temperature cracks, shrinkage cracks, settlement cracks, and corrosion cracks. Let's take a look at temperature cracks.Concrete has the characteristics of thermal expansion and cold shrinkage. When the external environment or the internal temperature of the structure changes, the concrete will deform. If the deformation is constrained, the structure will be stressed. When the stress exceeds the ultimate tensile stress of concrete, temperature cracks will occur. In some long-span bridges, the temperature stress can reach or even exceed the live load stress. The editor of Guizhou Steel Bar tells everyone that the main factor that causes temperature cracks is temperature difference
(1) Annual temperature difference. The temperature changes slowly throughout the year. The impact on the bridge structure is mainly the longitudinal expansion and contraction of the bridge, which is generally coordinated by structural measures such as bridge deck expansion joints, support displacement or the installation of flexible piers. However, when the displacement of the structure is restricted, temperature cracks will occur, such as statically indeterminate arch bridges and rigid frame bridges, which are easy to occur.
(2) Sunshine temperature difference. The temperature of the bridge deck, main girder or pier side exposed to the sun is significantly higher than other parts, and the temperature gradient is non-linear. Due to self-constraint, local tensile stress is relatively large and cracks appear.
(3) Calm down suddenly. Sudden rainstorms, cold air intrusion, sunsets, etc. will cause the temperature of the outer surface of the structure to drop sharply, but the internal temperature changes relatively slowly, resulting in temperature gradients and cracks.
(4) Heat of hydration. The editor of Guizhou Steel Bar tells everyone that during the construction process, after the mass concrete (thickness greater than 2.0m) is poured, the internal temperature is very high due to the heat of hydration of the cement, and the temperature difference between the inside and the outside is too large, resulting in cracks on the surface.
(5) Improper construction measures during steam curing or winter construction, the concrete is suddenly cold and hot, the temperature inside and outside is uneven, and it is easy to crack.