Shallow investigation into the causes of reinforced concrete building cracks
The causes of reinforced concrete building cracking and water seepage can be classified into three categories: temperature cracks caused by excessive temperature difference;Deformation crack caused by excessive load;Deformation crack caused by shrinkage of concrete.
1. Temperature cracks. Temperature cracks are generally caused by changes in atmospheric temperature, high ambient temperature or hydration heat generated by mass concrete construction.According to relevant studies, when the temperature difference between the inside and outside of concrete is 10℃, the shrinkage value is 0.01%. If the temperature difference between the inside and outside of concrete is 20℃ ~ 30℃, the shrinkage value is 0.02% ~ 0.03%, and the ultimate tensile value of concrete is only 0.01% ~ 0.02%, so when it is greater than the ultimate tensile value of concrete, concrete will crack.
2. Load crack, load crack is the crack caused by the excessive deformation of the building under the action of load.It usually appears in the tension area, shear area or vibration of the component.The main causes are unreasonable structure design, wrong construction method, insufficient bearing capacity and uneven settlement of foundation.
3. Shrinkage cracks, shrinkage cracks are generally caused by material defects.Research shows that the cement after adding water into the cement hardening, absolute volume decreases, and wool stoma seam water overflow capillary pressure, makes concrete capillary contraction, resulting the dry shrinkage of the cement mortar value of 0.1% ~ 0.2%, the drying shrinkage of concrete value of 0.04% ~ 0.06%, and the ultimate tensile strain of concrete value is only 0.01% ~ 0.02%, so when the value of are greater than the ultimate tensile strain of concrete, concrete crack.
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