Crack control of concrete structure of the hottest

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Crack control of residential concrete structure

at present, in the era of quality competition in China's real estate, "residential concrete floor cracks" has become a hot spot of residential quality complaints. Many concrete structures have different degrees and forms of cracks in the process of construction and use, such as surface cracks, oblique cracks and so on. This is a quite common phenomenon and a technical problem that has plagued construction engineering technicians for a long time. Although these cracks have little impact on the use, they often affect the use of buildings due to spiritual effects, architectural decoration effects and aesthetic reasons. This is an urgent technical problem to be solved, and it is necessary to effectively control it in actual construction. To control cracks, we should prevent them in the first place. Next, we will analyze the causes of cracks from the construction operation and discuss the specific prevention measures of concrete cracks in the construction process

cause analysis of cracks the formwork and its support are not firm, resulting in deformation and local settlement, resulting in negative bending moment of the support and transverse cracks

early dismantling or loading before the concrete reaches the final setting time may directly cause the early strength of the concrete floor to be low or no strength, resulting in internal injury or fracture of the floor when bearing bending, compression and tensile stress

excessive troweling and calendering make the fine aggregate of the concrete float to the surface, forming a cement slurry layer with a large amount of water. The contact between calcium hydroxide in the cement slurry and carbon dioxide in the air causes the hydration shrinkage of the surface volume carbon, resulting in the surface cracking of the concrete slab

improper maintenance is most likely to produce temperature difference cracks. During winter construction, the temperature difference is too large when removing the insulation material 335 underground waterproof engineering material, causing cracks. When the sun is exposed, it is not properly protected, and sudden rainfall produces cracks

concrete water cement ratio, improper mix proportion, large silt content in silt and yellow sand, large concrete shrinkage, low tensile strength, easy to produce plastic shrinkage cracks

due to the hydration heat of mass concrete, the temperature difference between the interior and the surface is too large to produce cracks

the position of the main reinforcement is seriously displaced or the protection of the reinforcement is not paid attention to in the construction, which leads to the negative bending moment of the negative reinforcement on the plate surface or the support, and cracks appear in the tensile area (plate surface) of the structure

the concrete is vibrated after initial setting, and the construction joint is improperly left during construction, resulting in cracks

post cast strip construction, etc. you'd better understand these standards in advance. Careless construction, incomplete construction according to the design requirements, incomplete chiseling of loose concrete, and improper concrete mix ratio may cause cracks on the slab surface

these factors will cause large shrinkage of concrete, resulting in cracks or loose cracks, resulting in micro cracks in concrete. The hull is rapidly expanded by light construction technology and modern materials, forming macro cracks

prevention and control of cracks according to the causes of concrete cracks, it is more effective to take appropriate measures to prevent than to remedy afterwards, that is, to take the method of prevention first. To sum up, we can start from the following aspects

the good prospect is that in the design, attention should be paid to those parts that are easy to crack, such as deep foundation and shallow foundation, high and low spans, etc. Weak links caused by differential settlement of foundation or structure should be solved in design

on the premise that the allowable reinforcement ratio of the member section is unchanged and the pouring is convenient, the thinner the reinforcement diameter and the smaller the spacing are, the more beneficial it is to prevent cracking

defects that affect the performance of concrete structures must be studied and dealt with jointly with the design and other relevant units

a good construction scheme has a great relationship with the prevention and control of cracks. The construction scheme should mainly determine a certain amount of pouring, construction joint spacing, location and structure, pouring time, transportation and vibration, etc. The length of one-time pouring is divided by the vertical construction joint, and the best position is at the variable cross-section or the position bearing tensile, shear and bending stresses

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