What is the appearance of concrete under vibration

Vibration leakage will occur during concrete pouring; The surface of the concrete is matte, exposed and honeycomb.

The treatment phenomenon of honeycomb on the surface of concrete surface hemp surface:

1) The surface of the concrete is rough and lacking in slurry, and there are many small pits.

2) The main reinforcement, auxiliary reinforcement or stirrups in the structure are exposed.

3) There are many local slurry stones in the concrete, forming honeycomb-shaped holes.

4) There is a cavity in the concrete structure, there is no concrete locally, and the honeycomb is particularly large.

Treatment: 1) The hemp surface part should be brushed with clean water, and smoothed with cement slurry or cement mortar after being fully wet.

2) Clean the concrete and rust on the exposed steel bars, and then wipe and smooth with cement mortar (1:2 ratio). If the exposed tendons are deeper, they should.

The weak concrete is removed, cleaned up, compacted with a higher level of bean stone concrete, and carefully maintained.

3) The small honeycomb can be rinsed with water first and repaired with 1:2 cement mortar; For large honeycombs, remove loose stones and protruding particles first.

In addition, and cut into a bell mouth, then rinse with clean water and soak, and then use a higher level of bean stone concrete to tamp and carefully maintain.

4) It is necessary to work with the design unit to study and formulate a reinforcement plan, and then deal with it according to the approved plan. In the process of processing the hole in the beam.

When the hole, it should be supported at the bottom of the beam with support, and then the non-dense concrete at the hole is chiseled off, and it should be chiseled into an oblique shape in order to pour the concrete. Use.

Rinse with clean water and keep it moist for 72 hours, then pour it with a higher grade of bean stone concrete. Mix 1/10,000 of the amount of aluminum powder in the bean stone concrete. Strengthen the curing after pouring. Sometimes the concrete is poured only after the formwork is supported because of the large hole.

The hemp surface honeycomb, the surface of the hole is hollow, not real.

In the process of concrete pouring, due to the error of the vibrating operator, the place that is not vibrated is called leakage vibration.

The place that should be vibrated is called leakage vibration because the surface is cement slurry and there is no vibration.

The surface is prone to ash and sand, resulting in a decrease in surface strength and a serious impact on the strength of the entire concrete body. It is recommended to measure accurately according to the concrete mixture.

1. The surface is powdered and easy to sand.

2. The color is darker.

There will be floating ash and sand on the surface. There is also an effect on the setting time, the main problem is the impact on the intensity! Be sure to design the mix according to the standard!

The first person said it very well, there is nothing more to say.

If it exceeds the initial setting time, there is no need to shake, if it is a very important part, only to knock it off and come again, there is no way.

If you want to get by, you can touch the cement slurry after removing the mold to improve the appearance quality of the concrete, but the actual strength is not guaranteed, you had better not do this. Dare to take responsibility, and you will not forget this lesson in the future.

Good luck!

Reason 1: There is water accumulation on the surface of concrete in the early stage of condensation.

Reason 2, the water in the foundation pit has not been eliminated, and this part of the water is flooded to the upper side when the concrete is poured, resulting in surface water.

Reason 3: The concrete water-cement ratio is too large or caused by arbitrary sprinkling of water when pouring concrete.

Reason 4: Soak in water too early (watering or raining).

Concrete surface peeling, if it is the upper surface peeling (ground, pavement, bridge deck, etc.) is generally caused by floating slurry. If it is side peeling, it is likely to be caused by chemical corrosion, such as acid rain, sulfate, etc.

The reasons for the formation of slurry are not complicated. Low-strength concrete (with a large amount of water or high water and cement) and concrete with poor water retention (such as the use of slag cement, slag or cement grinding is not fine enough), after pouring and pounding, there will be water leakage to the upper surface, forming a layer of floating slurry layer on the upper surface of the concrete. Due to the high water content, the floating slurry layer has shrinkage cracks after water evaporation, and the strength is very low, and it is basically not wear-resistant after hardening, which is manifested as peeling.

In the past, the method to prevent peeling was "secondary slurry removal", that is, after the first plastering was completed, the second plastering was carried out after the surface water evaporated, and the water content of the floating slurry layer was reduced at this time, and the floating slurry layer was compacted through the plastering surface.

Now, the methods to prevent the flaking of the slurry from peeling include: 1) improving the water retention of concrete. For example, add mineral admixtures such as silica fume, ultra-fine mineral powder, and ultra-fine metakaolin with high specific surface area materials in concrete, or use polycarboxylic acid superplasticizer with good water retention, or use low water-glue ratio; Wait a minute.

2) Before the initial setting of concrete, a layer of silica fume is sprinkled on the surface of the concrete, and then the surface is plastered under pressure, which can be made into a high-strength and high-wear-resistant concrete surface. Method 2) Now it is more widely used in warehouses and industrial floors that require high wear resistance.

It is used to distinguish the basis of large volume concrete, and the cooling surface area refers to the surface area that can be exposed to dissipate heat.

1. Cover it immediately after watering, and sprinkle it in time to maintain health.

The most effective preventive measure for cracks is to protect the concrete pouring surface when pouring concrete, avoid wind and sun, and cover the surface immediately after the concrete is poured, and sprinkle water in time for health. In addition, adding an appropriate amount of air-entraining agent to concrete can also help to reduce shrinkage cracks.

2. Secondary vibration before initial setting.

When the surface of the formwork is uneven, or the release agent is applied unevenly, the friction of the formwork prevents this settlement, which will produce cracks on the vertical surface of the concrete. This situation is generally easy to occur in the corners of concrete pillars or other narrow and long structures. A second vibration before the initial setting of the concrete is the best way to avoid this defect.

3. Add fly ash and set up cooling water pipes.

When the surface concrete shrinks is hindered, the concrete will be stretched, and once the strain capacity of the concrete is exceeded, cracks will be generated. In order to reduce the shrinkage constraint as much as possible so that the concrete can have sufficient strength to resist the stress caused, it is necessary to effectively control the internal heating rate of the concrete. Adding an appropriate amount of mineral fly ash to the concrete can slow down the release rate of hydration heat; The temperature of the raw materials is controlled, and the cooling pipe is used inside the concrete structure to circulate the water, which can also release the hydration heat energy in time.

4. It is strictly forbidden to mix cement.

The mixing of different brands of cement will also cause cracks in the concrete. Different brands of cement have different fineness, strength, initial and final setting time, stability, chemical composition, etc., and there are also compatibility problems. In concrete construction, it should be strictly forbidden to mix different brands and different grades of cement together.

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