What are the common causes of cracking in concrete? How can it be prevented?

1. After the concrete is formed, the maintenance is improper, the wind and sun are exposed, the surface water is dispersed quickly, the volume shrinkage is large, and the internal humidity changes very little, and the shrinkage is also small, so the surface shrinkage deformation is constrained by the internal concrete, and the tensile stress appears, causing the concrete surface to crack, the lower the relative humidity, the greater the dry shrinkage of the cement slurry, and the easier the dry shrinkage cracks;

2. The water-cement ratio of concrete is too large, and the early maintenance, especially the winter maintenance, does not meet the specifications;

3. After the concrete is vibrated to form a mortar layer with more cement content on the surface;

Improper proportioning and poor maintenance. Reasonable proportion, pay attention to the maintenance time.

If the concrete mixing and transportation time is too long, the water will evaporate too much, causing the concrete to collapse too low and irregular shrinkage cracks appear.

The template job is not standardized.

The stiffness of the formwork is insufficient, and when pouring concrete, the formwork is deformed due to the action of lateral pressure, resulting in cracks consistent with the formwork deformation. During construction, the formwork is removed too early, and the concrete strength is insufficient, which makes the components crack under the action of self-weight or construction load.

The formwork support is not compacted enough or the bracket stiffness is insufficient, and the bracket sinks unevenly after pouring concrete, resulting in cracks in the concrete.

The formwork is not watered enough before pouring, and it is too dry, and after pouring, due to the large water absorption of the formwork, the concrete shrinks and produces plastic shrinkage cracks.

Hello, the common reason for the cracking of concrete is generally that the cement should be cured after pouring, and it should be watered frequently, if it is not watered, the concrete is not well maintained, and the moisturizing effect is too dry, which will affect the cracking of the concrete. After the concrete is poured, it is necessary to maintain the humidity for curing. The solidification of concrete will be better and harder.

The main thing is that the construction technology and maintenance are not standardized, and who will worry about building their own house. Why doesn't the Three Gorges Dam crack. Cracks caused by loads, cracks caused by shrinkage, cracks caused by foundation deformation, cracks caused by steel rust, cracks caused by frost heave, cracks caused by the quality of construction technology, cracks caused by the quality of construction materials.

This place is too small to say, and the civil engineering network has relevant information.

What are the causes and treatment methods of concrete cracks?

1. Dry shrinkage cracks: caused by the rapid evaporation of concrete water, the treatment method is to strengthen its early curing and appropriately extend its curing time; 2. Plastic shrinkage cracks: Concrete has basically no strength or low strength before final setting, and its treatment method is to strictly control the water-cement ratio and reduce the amount of cement and water.

What are the prevention and control measures for cracks?

1. When calculating the mix ratio of concrete, the unit water consumption of concrete should be reduced as much as possible under the condition of ensuring that it has excellent workability.

2. Structural reinforcement should be added to improve crack resistance, and small diameter and small spacing should be selected for reinforcement. The reinforcement ratio of the whole cross-section must be controlled to about the same.

3. Prevent stress concentration caused by structural abrupt changes, and select strengthening measures in weak parts that are prone to stress concentration.

4. Add dark sorghum at the edge position that is easy to crack to improve the reinforcement ratio of this area, so as to improve its ultimate tensile.

5. In the structural design, the climatic disturbance in the construction process should be reasonably considered, and the post-pouring joints should be reasonably arranged, and under normal construction conditions. The spacing between the post-pouring joints is between 20 and 30 meters. The retention period is usually not less than 60 days.

If it is not possible to meet the specific conditions in the construction process, the design can also be temporarily changed according to the specific situation.

6. Strictly control the quality and technical specifications of concrete raw materials, and use low-hydration thermal cement, and the mud content of coarse and fine aggregates should be reduced as much as possible (less than 1 to.

7. Control the water-cement ratio of concrete, reduce the slump of concrete, and fully add plasticizer and superplasticizer.

8. According to the characteristics of the project, the final strength of concrete can be used, which can reduce water consumption, reduce hydration heat and shrinkage.

The cause of concrete cracking: due to the deformation of the formwork and support system, the concrete cracks in the early stage of the increase in compressive strength. Prevention and control methods:

Improve the stability of the formwork support system and avoid deformation. The thickness of the protective layer in the concrete is too small, which causes the protective layer concrete to crack due to retraction. Prevention and control methods:

In the middle of the formwork and the building reinforcement, small cement cushion blocks of the same strength are bundled to ensure the thickness of the concrete protective layer. The application of concrete with a strong water-glue ratio will cause the concrete work to crack due to the release of heat from the internal structure.

The method of concrete crack repair: filling method to solve building cracks: apply repair raw materials to immediately fill building cracks, the construction process is simple, and the cost is low.

Building reinforcement method to solve building cracks: mainly for the gaps caused by the overload of the bearing capacity of engineering buildings, the gaps caused by fire accidents, etc. The grouting method solves building cracks, and this method has a wide range of applications, from small cracks to large cracks, and the effect is obvious.

Concrete has the characteristics of thermal expansion and contraction, when the environmental factors or the environmental temperature of the internal structure changes, the concrete will produce deformation, if the deformation is subject to tube constraints, that is, in-situ stress will be generated in the structure, and when the local stress exceeds the compressive strength of the concrete, it will cause temperature cracks. The most important difference between temperature cracks is that the gap will expand or close together with the change of air temperature. The key factors that cause temperature change include annual temperature difference, sunshine, sudden temperature reduction, water-glue ratio, steam curing or unreasonable winter construction measures.

The compressive strength of the base layer and its stability are related to the strength and reliability of the overall surface layer. The secondary supplementary layer caused by the loose coefficient of the bottom layer (or the design elevation of the bottom layer) is not tight, because the secondary supplementary layer and the bottom layer of the next layer cannot be connected with the gap, and it is thin and small, so it is very easy to loosen, thereby causing the ground to be destroyed. The strength of the foundation is uneven, the subgrade filler is doped or compacted is not very good, resulting in uneven settlement, poor flatness of the bottom layer, resulting in uneven thickness of the concrete surface layer, large discreteness, and ground stress under the action of driving load and ambient temperature expansion and contraction stress.

When the local stress exceeds the ultimate strength, gaps will appear in the thickness gaps.

Cracks caused by sudden temperature changes, cracks caused by changes in load support force caused by external forces, and cracks caused by shrinkage can be closed with epoxy cement on the crack surface or coated with cement mortar on the surface of the crack.

There are many reasons for concrete cracking, whether it is a problem with the concrete ratio or a climatic factor, which needs to be repaired quickly.

Most of them are caused by problems in the proportion, and it is necessary to choose the right material to solve it again, so that it can be better repaired.

If there is a cracking problem in concrete, there are still many reasons for it. Today, I will give you a specific introduction to several major causes of cracking, and what are the good ways to repair and recover cracking?

1. Five major causes of concrete cracking.

If the concrete always cracks, it is basically caused by the following reasons.

1. The first reason is that in the process of construction, the proportion of cement lime is incorrect, and some staff may add water privately in order to facilitate construction in the construction process, thereby improving the fluidity of concrete, but increasing the proportion of water and ash, resulting in irregular cracks when hardening in the later stage.

2. The second reason is that the concrete is in the process of mixing and transporting, the time is too long, resulting in the evaporation of water is relatively fast, and when it comes to on-site construction, the strength of the concrete does not meet the requirements, and cracks will occur.

3. The third reason is that in the process of construction, the construction speed is relatively fast, the pouring is more frequent, and the fluidity will be relatively low, resulting in insufficient concrete settlement, and in the process of pouring in the later stage, especially at the joints, cracks are most likely to appear.

4. The fourth reason is that the maintenance is unreasonable, there is no watering in the later stage, and regular wetting is carried out, so that the surface dries relatively quickly, and once the cement loses water, it will shrink sharply. If the strength is reduced, cracking will occur in the later stage.

5. The fifth reason is also related to the environment. For example, if the air is relatively dry, the temperature is relatively high, and the wind blows, the evaporation rate of the surface of the water concrete will be accelerated, and cracking will occur in the later stage. Especially in summer or winter construction, it is most likely to appear that there are cracks in the temperature difference of seepage and rise.

Second, how to solve the problem of concrete cracking.

If the cracked gap is relatively small, we can pour repair materials into the crack, and we can pour a kind of crack sealing paste, which has very good viscosity, and can also effectively prevent the invasion of water vapor and avoid damage to the concrete structure again.

Summary: There are many reasons for concrete cracking, which are nothing more than the above five reasons, so it also shows that in the early stage of construction, including the construction process, the later maintenance needs to be in accordance with certain specifications to avoid the problem of concrete cracking and cracking.