How can I prevent water segregation in concrete?

First of all, the concrete itself should have good water retention to prevent serious water leakage from causing the water-cement ratio of the concrete surface layer to be too large. Starting from the selection of mix ratio and composition materials, it is necessary to pay attention to the control of the water-cement ratio should not be too large, the admixture should not be too mixed, and the coagulation time should be appropriate. Sand and stone aggregates should meet the national quality requirements, especially the particle content below the sand.

The setting time of cement is not easy to be too long, the specific surface area should not be too small, and the particle gradation should not be too concentrated; Secondly, the construction process should prevent excessive vibration from causing serious segregation and water leakage of concrete; Again, after construction, it is necessary to pay attention to timely maintenance, not only to prevent the concrete surface from being washed by rain before hardening, but also to prevent the moisture in the concrete from being lost before the surface layer establishes strength, especially the concrete mixed with fly ash or slag, due to its low early strength, the surface layer does not have enough hydration products to block the large capillary pores of the surface layer, if you do not pay attention to the early full wet curing, the water dispersion loss of the concrete surface layer is faster and more, and the surface cement can not be fully hydrated, It will also lead to low strength of the surface concrete and loose structure. Usually, when the concrete is close to the final setting, the concrete should be plastered (or pressed) for the second time to make the concrete surface structure more dense.

When mixing concrete, add waterproofing agent and early strength agent.

Increase viscosity Add related additives to communicate me.

<> is very important to solve the way of concrete water leakage, and the most suitable method is used to solve the most practical problem, and the treatment of every detail is very critical. Zhongda Consulting has introduced the old way to solve the water leakage of concrete and introduce it to you.

According to the principle of concrete water leakage and the mechanism of various factors affecting water leakage, the main methods to solve concrete water leakage are as follows.

In terms of concrete mix ratio, the amount of cementitious material should be appropriately increased, the sand rate of concrete should be appropriately improved, and the appropriate amount of concrete air entrainment should be made under the premise of not meeting other properties. On the premise of ensuring construction performance, minimize unit water consumption.

In terms of raw materials, fine cementitious materials and high-quality air-entraining agents are selected.

In terms of superplasticizers, use superplasticizers with less water secretion. If the mix ratio is fixed, under the condition of meeting the standards and use requirements, select the appropriate amount of water reducing agent to avoid water leakage caused by too high water reduction rate.

In terms of construction, the concrete vibration time should be strictly controlled to avoid over-vibration. In addition, for the performance control of freshly mixed concrete, appropriate control points are selected to make the control conducive to reducing the water leakage of concrete. If the maximum gas content is to be controlled, the control point can be selected at the inlet to minimize the impact of air content loss on water leakage during concrete conveying.

First, the cause of water leakage from concrete.

1. The influence of rubber on the water leakage of concrete.

As the most important cementitious material in concrete, cement's setting time, fineness, specific surface area and mineral composition will affect the water leakage performance of concrete. The longer the cement in the concrete sets, the easier it is for the concrete to leak water; The finer the fineness of the cement, the less likely the concrete is to leak water. The C3A content in cement is low and easy to leak water.

2. The influence of aggregate on the water leakage of concrete.

When the aggregate contains more mud, it will delay the hydration of cement and the condensation of concrete, thereby aggravating the water leakage of concrete. The larger the fineness modulus of the sand, the coarser the sand, the easier it is to cause water leakage from the concrete; The fewer fine particles and the more coarse particles, the easier it is for the concrete to leak water.

3. The influence of mineral admixtures on the water leakage of concrete.

The mineral admixture has a small fine particle content and a large coarse particle content, which is easy to cause water leakage of concrete.

4. The effect of admixtures on water leakage of concrete.

The dosage of concrete superplasticizer is too large, the water reduction rate is too high, and the water consumption of unilateral concrete is reduced, which is easy to cause serious segregation of concrete and water leakage; The excessive amount of retarding components and plastic-preserving components in the admixture is also easy to cause segregation of concrete; The compatibility between the superplasticizer and cement is not good, and it will also cause a large amount of water leakage on the surface of the concrete.

5. The influence of mix ratio on water leakage of concrete.

The larger the water-cement ratio of concrete, the longer the cement solidification and hardening time, and the easier it is for concrete to leak water; Too much admixture in concrete, or too much retarding component, will cause serious water leakage in fresh concrete.

6. The influence of construction on the water leakage of concrete.

During the transportation of concrete, the longer the mixing time, the easier it is to leak water. The higher the concrete pouring height, the more water evacuation. Excessive vibration of concrete will lead to segregation and water leakage of concrete; The transportation distance of concrete is long, the mixing time is long, and it is easy to produce water leakage.

Second, the treatment method.

1. Mix ratio.

Appropriately increase the amount of cementitious materials, increase the sand rate, control the water consumption of the mix ratio, select superplasticizers with good compatibility with cementitious materials, appropriately increase the amount of air-entraining agents, and strictly control the dosage.

2. Construction technology.

The concrete vibration time should be strictly controlled to avoid over-vibration; When the vertical blanking drop of concrete exceeds 2 meters, string blanking is adopted; When there is water leakage in the pouring silo surface, it must be eliminated in time by vacuum water absorption and other methods.

There are a variety of factors that cause water leakage in concrete:

First, the characteristics of the cement itself are determined;

Second, the segregation caused by overvibration accumulates a large amount of water on the surface of the concrete;

Third, the slump is too large and it is easy to produce a large amount of water on the surface of the concrete;

Fourth, the reason for the superplasticizer, the superplasticizer and cement are insoluble, and can also produce a large amount of water on the surface of the concrete;

Fifth, the transportation distance is too long or the concrete is transported by agricultural tractors, and sometimes a large amount of water accumulates on the surface of the concrete;

Sixth, the vertical drop of concrete cutting is too large, resulting in segregation, and it is easy to accumulate a large amount of water on the surface of concrete.

Control and prevention measures, how to control it so that it does not produce water, and implement different methods for the above points:

First, it is to fundamentally solve the problem of cement leakage, which must be solved when manufacturers produce cement;

Second, the control time when vibrating the concrete, generally after vibrating the concrete surface is not bubbled;

Third, the slump is controlled according to the design;

Fourth, the superplasticizer should be solubilized when it is mixed to avoid the occurrence of superplasticizer;

Fifth, when the transportation distance is slightly longer, concrete mixer trucks are generally used for transportation, and agricultural transport vehicles are avoided for transportation;

Sixth, when the vertical blanking drop of concrete exceeds 2 meters, string drum blanking is adopted, so that the impact effect of concrete and contact surface is buffered, so as to avoid concrete segregation and water leakage.

1. When the fineness of cement is large, it is easy to leak water, the C3A content in cement is low and easy to leak, and the water consumption of cement standard consistency is small and easy to leak, 2. The amount of cement is small and easy to leak, 3. The concrete of low-grade cement is easier to leak water than that of high-grade cement (with the same amount) 4. The concrete with large unit water consumption is easy to leak water and segregated.

5. Concrete with low strength grade is easy to leak water.

6. Concrete with poor water retention, thickening and air entrainment of concrete admixtures is prone to water secretion.