How to eliminate concrete hemp surface, how to deal with concrete hemp surface

Workaround:1In strict accordance with the provisions of the "Technical Regulations for the Construction of Commercial Concrete Pumping", the pouring thickness of each layer of commercial concrete should not be greater than 50 cm.

2 .Choose to use a high-quality release agent.

3 .Under the condition of conditions, bamboo and wood formwork pressed by urea-aldehyde resin should be preferentially selected for molding.

4 .Rejuvenation is the elimination of the surface layer of commercial concrete structures.

One of the most effective methods of honeycomb flour. The author once found that the lower part of the surface of 6 commercial concrete bridges in a construction site in Beijing was smooth and clean, the more bubbles went up, the most bubbles in the upper layer, and the same batch of commercial concrete was used for a bridge, or even the same car of commercial concrete, and the upper and lower formwork were the same, and the results showed different states. Check its reason is mainly that the first layer was vibrated unconsciously when the second layer of commercial concrete was vibrate, and the second layer and the first layer were vibrated unconsciously when the third layer was vibrated again, according to this method, the commercial concrete of the lower part of the bridge is equal to many times by vibration, because the appearance is smooth and clean, the more up the relative vibration times gradually decrease, so the whole pier surface layer gradually increases the bubble from bottom to top.

Although it is clearly stipulated in the "Technical Regulations for Commercial Concrete Pumping" that the interval is 20 -30 minutes and then revitalized, it is particularly important to carry out commercial concrete construction in spring and autumn. According to the author has been at the construction site for a long time.

Observation, the actual operation of such units is rare, should cause the construction management personnel to pay great attention.

5 .Use defoamers wisely.

Defoaming includes two meanings, one is "foam suppression", that is, to prevent the generation of bubbles or foam; The second is "bubble breaking", that is, eliminating the gas satiety (or foam) that has been generated. In addition to the special requirements of the foaming system, the defoamer also has strong defoaming power and low dosage; The addition to the foaming system does not affect the basic properties of the system; Chemically stable and oxidation resistant.

Strong; Solubility in foaming solutions.

Good; It has no physiological activity and high safety characteristics. In addition, the use effect has a lot to do with the variety and dosage of the defoamer, and the expected effect will not be achieved if the selection is not appropriate or the dosage is not appropriate.

Causes of concrete hemp noodles:

The air content of concrete is too large, the quality of air-entraining agent is not good, because there is a large difference in the performance of various air-entraining agents, the state presented in concrete is not the same, some air-entraining agents form larger bubbles in concrete, and the surface energy is low, it is easy to form a large bubble of connectivity, and the vibration is unreasonable, and the large bubble can not be completely discharged, and will cause honeycomb surface to the surface of hardened concrete structure.

Improper concrete mixing, concrete is too viscous, and it is difficult to discharge bubbles when vibrating, which is also the reason for the honeycomb surface on the surface of hardened concrete structure.

Concrete workability is poor, resulting in segregation of water. In order to prevent concrete delamination, the concrete does not dare to fully vibrate after entering the mold, and a large number of air bubbles cannot be discharged, which will also lead to the appearance of honeycomb surface on the surface of the hardened concrete structure.

Add some grinding aids, some of which have air entrainment, and the introduced air bubbles are uneven and large, which will also cause honeycomb surface on the surface of hardened concrete structures.

Ways to eliminate concrete hemp surface:

Choose to use high-quality air-entraining agents.

Reduce the viscosity of concrete, appropriately adjust the water-cement ratio, sand ratio, amount of cementing material and the composition of admixtures to improve the viscosity of concrete.

The concrete surface layer formed by bamboo and wood formwork pressed with urealdehyde resin is significantly better than that of iron formwork, and the bamboo and wood formwork pressed by urealdehyde resin should be preferentially used under conditions.

Rejuvenation is also one of the most effective ways to eliminate the honeycomb surface of the concrete structure surface.

Before pouring concrete, the formwork should be watered and fully moistened, and the formwork gaps should be blocked with linoleum paper and putty, and the formwork isolating agent should be selected for a long-term effect, evenly brushed, and should not be missed; The concrete should be evenly vibrated and compacted in layers until the bubbles are removed.

If the surface is whitewashed, it can not be treated, and if the surface is not whitewashed, it should be watered and fully moistened on the hemp surface, and the original concrete mix ratio should be used to remove the stone mortar, and the hemp surface should be smoothed and calendered. Lead rent.

For defect thickness of less than 5mm, the surface layer can be repaired with engineering durability thin-layer repair material, and in the case of more than 5mm, it is necessary to use engineering durability high-strength repair material for repair. Among them, the interface treatment is also required at the junction of the old and new concrete to prevent the occurrence of hazards such as hollowing and surface falling off in the later stage.

Several treatment methods for concrete hemp surface treatment:

1. Strengthen the concrete vibration during pouring.

2. Clean the template in time and oil the template.

3. The formwork is tightly blocked to prevent slurry leakage.

Common Problems with Concrete:

1. The workability of commercial concrete is not good.

2. a broken plate. 3. Other common quality accidents.

Concrete, for short"Concrete (tóng).": refers to the general term of engineering composite materials that cement aggregates into a whole by cementitious materials.

The word concrete usually refers to the use of cement as cementitious material, sand and stone as aggregates; Cement concrete, also known as ordinary concrete, is widely used in civil engineering engineering when it is mixed with water (which can contain admixtures and admixtures) in a certain proportion and is mixed to obtain cement concrete.

Concrete honeycomb, hemp surface, holes.

1. Causes: (1) The joints of the template are not tight, and the slurry leaks at the joints of the plates. (2) The surface of the template is not cleaned or the template is not coated with a release agent.

3) The concrete vibration is not compact, and the leakage vibration causes the honeycomb surface to be not compact. (4) The concrete mixing is uneven, and the workability is not good; When the concrete is put into the mold, the free falling height is too large, resulting in segregation. (5) The concrete mixing time is short, the amount of water added is not accurate, the workability of concrete is poor, and there are places where there are less mortars and more stones after concrete pouring, forming honeycombs.

6) There is no layered pouring of concrete, and improper blanking results in concrete segregation, honeycomb surface, etc.

2. Preventive measures (prior control) :(1) Before pouring concrete, the tightness of the formwork gap should be checked, and the formwork should be cleaned and moistened with water, leaving no stagnant water, and the formwork gap should be expanded tightly. (2) The concrete pouring height is generally not more than 2 meters, and measures should be taken when it exceeds 2 meters, such as blanking with strings.

3) After the concrete is put into the mold, the vibration time must be mastered, generally the vibration time of each point is about 20-30 seconds, so that the concrete will no longer sink significantly, no longer appear bubbles, the concrete surface is slurry and in a horizontal state, and the concrete fills the corners of the formwork to the fullest.

3. Treatment method (post-treatment) :(1) The hemp surface mainly affects the use function and appearance, and should be repaired, and the hemp surface part is moistened and smoothed with cement mortar. (2) If the honeycomb is small, you can wash it with water first, and then use 1:

2 or 2:5 cement mortar repair (3) If the honeycomb is large, the loose stone should be removed first, washed with water to clean and wet, and then tamped with fine stone concrete with a grade of improved grade and strengthened maintenance. (5) If it is a hole, it should be studied by relevant personnel and a reinforcement plan should be formulated for treatment.

Concrete bars.

1. Causes: (1) When the concrete vibrates, the cushion block is displaced or there are too few cushion blocks, and the steel bar is close to the formwork, resulting in exposed ribs after demoulding. (2) The cross-sectional size of the component is small, the steel bar is too dense, and the cement slurry can not fill the steel bar when the big stone is stuck on the steel bar, so that the steel bar is dense and the bar is exposed.

3) When the concrete is vibrating, the vibrating rod hits the steel bar, and the steel bar is vibrated and displaced, resulting in exposed ribs.

2. Preventive measures (prior control) :(1) During the construction of reinforced concrete, the cushion block should be fixed and fixed. At the same time, the thickness of the protective layer is guaranteed.

2) When the steel bar is denser, it is necessary to choose appropriate stones, so as not to get stuck in the steel bar too large, and when it is difficult to pour ordinary concrete, fine stone concrete can be used. (3) It is strictly forbidden to vibrate the steel bar when the concrete is vibrated to prevent the deformation and displacement of the steel bar.

3. Treatment method (post-treatment): clean up the concrete and rust on the exposed steel bar, then rinse and moisten with water, and smooth it with 1:2 or cement mortar; If the exposed reinforcement is deep, all the weak concrete should be chiseled off, washed clean and wetted, and then compacted with fine stone concrete with a higher grade grade, and the maintenance should be strengthened.

(1) The hemp surface part should be brushed with water, and smoothed with cement slurry or cement mortar after being fully wetted; Control the strength of mold removal, and it is not easy to remove the mold early.

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, the weak concrete should be removed, cleaned up, tamped 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, the loose stones and protruding particles are first removed, and cut into a bell mouth, then rinsed with clean water and soaked thoroughly, and then tamped with a higher level of bean stone concrete, and carefully maintained.

4) It is necessary to study and formulate a reinforcement plan with the design unit, and then deal with it according to the approved plan. When dealing with the holes in the beam, the bottom of the beam should be supported 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 concrete. Rinse with clean water and keep it moist for 72 hours, and 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.

There are many reasons for the honeycomb surface of concrete, the main reason is that the vibration is not sufficient, and it may also be that the concrete collapse degree is too large, and the concrete produces segregation. It can be repaired with high-strength mortar.

1. Strengthen the concrete vibration during pouring.

2. Clean the template in time and oil the template.

3. The formwork is tightly blocked to prevent slurry leakage.

The hemp surface of concrete should be treated in time, and the steps are as follows:

1. Strengthen the concrete vibration during pouring.

2. Clean the template in time and oil the template.

3. The formwork is tightly blocked to prevent slurry leakage.

The reasons for the appearance of hemp surface in concrete are: 1, the water-cement ratio is too large, 2, the steel bar is too dense and the concrete is not easy to pour, 3, the height of the component is too high, and the concrete is segregated when watering, 4, the vibration is not enough, etc.

Concrete is one of the most important civil engineering materials in contemporary times, with high compressive strength, good durability and a wide range of strength grades. In the construction of houses, the quality of concrete works is particularly important. The appearance of matte surfaces on the concrete surface is a common problem in the construction process.

Next, I will introduce you how to correctly construct to prevent the appearance of hemp surface on the concrete surface and the treatment method of the matte surface.

First, the main reason for the appearance of hemp noodles.

1.In the case that the concrete formwork is not watered and moistened or not wet enough, the moisture of the concrete on the surface of the component will also be absorbed, so that the concrete will lose too much water, so there is a situation of hemp surface.

2.If the concrete surface is not cleaned up, when the mold is removed, it will cause the concrete surface to be sticked.

3.When building the formwork, if the splicing and splicing joints are not strict, it will lead to local slurry leakage, and the most bridged finger will eventually lead to the occurrence of hemp surface.

4.When carrying out concrete construction, if we do not vibrate properly, the air bubbles inside the concrete will not be discharged, so they will stop on the surface of the formwork, and eventually form pitting.

5.When the formwork separator is painted, if the painting is uneven during construction, it will lead to local missing brushing or failure, so that the concrete surface is bonded with the formwork, resulting in the situation of hemp surface.

Second, the correct construction steps.

1.The surface of the formwork should be cleaned up, and the formwork should be fully watered and moistened before pouring concrete.

2.For the gaps of the template, it is necessary to use linoleum paper or putty powder to plug tightly, and a long-term separator can be selected, which needs to be evenly brushed and not missed.

3.The concrete is evenly vibrated in layers until the air bubbles inside are discharged.

Third, the treatment method of the appearance of hemp surface.

1.The surface is not stuccoed.

You can water the place where the hemp surface appears to moisten, and use the original ratio of concrete mortar to remove the stones inside and apply the hemp surface evenly. Nuclear fission.

2.The surface is stuccoed.

This is the easiest situation, because then we don't need to treat it, and we can paint it directly on the surface of the matte surface.