How to prevent and deal with common problems such as concrete segregation and surface defects! Shandong anti-segregation agent manufacturer

1. Concrete segregation

Concrete segregation is the cohesion between the components of the concrete mixture Insufficient to resist the sinking of coarse aggregate, the components of the concrete mixture separate from each other, resulting in uneven internal composition and structure. It usually manifests as the separation of coarse aggregate and mortar from each other, for example, dense particles are deposited at the bottom of the mixture, or the coarse aggregate is separated from the mixture as a whole.

2. Pockmarked noodles

Cause analysis:

1) The surface of the template is rough or not cleaned well;

2) The release agent is unevenly applied or partially missed;

3) The formwork joints are not tightly spliced, and slurry leaks from the gaps when pouring concrete;

4 ) Vibration is not dense, and the bubbles in the concrete are not discharged and some of the bubbles stay on the surface of the formwork.

The concrete surface is partially rough due to lack of slurry and has small pits

Prevention and control measures:

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1) Clean the surface of the formwork, and no hard cement or other substances may be stuck on it

2) Pouring Before concrete is placed, the formwork should be moistened with clean water without leaving any accumulated water, and the gaps in the formwork should be tightly spliced

3) The release agent must be applied evenly without any leakage

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4) The concrete must be vibrated and compacted in layers according to the operating procedures to strictly prevent vibration leakage. Each layer of concrete should be vibrated until bubbles are released

3. Honeycomb

Cause analysis:

1) The concrete mix ratio is inaccurate or the aggregate measurement is wrong;

2) The concrete mixing time is short, the mixing is not uniform, the workability of the concrete is poor, and the vibration is Not dense;

3) When pouring concrete, improper cutting or too much loading at one time, and no segmented and layered pouring, resulting in concrete leakage and segregation;

4) The pores of the template are not blocked, or the template support is not firm.

The template Shifting, causing serious grout leakage or wall root rot.

Phenomena: The concrete is partially loose, with less mortar and more stones. There are gaps between the stones, forming honeycomb-shaped holes

4. Holes

Cause analysis:

1) In the steel bar Concrete pouring is not smooth in dense areas or reserved holes and embedded parts

2) Failure to follow the application sequence and construction technology carefully, resulting in leakage vibration

3) Concrete segregation, mortar separation, piles of stones, or severe slurry

4) Concrete There are mud blocks, wood blocks and other debris mixed in

5) The material is not cut according to the regulations, too much material is cut at one time, and the vibration is not in place

Prevention and control measures:

1) In places where it is difficult to cut materials, manual spreading of concrete can be used

2) Correct vibration to prevent leakage of vibration, and strengthen vibration at the corners

3) Prevent the mixing of debris such as earth or wood blocks

4) Choose a reasonable cutting and pouring sequence

5) Strengthen construction technology management and quality inspection

5. Gap interlayer

Cause analysis:

1) Before pouring, the surface of the construction joint was not carefully treated

2) Insufficient tamping

3) Failure to clean up the garbage before pouring

Prevention and control Measures:

1) Before pouring concrete, carefully clean up the garbage and debris in the formwork, and treat the surface of the construction joints

2) During the pouring process, it must be vibrated and compacted; at the same time, prevent wood blocks and other debris from falling into the concrete

3) Winter construction It is necessary to formulate preventive measures for winter construction to prevent interlayering of ice and snow

6. Missing edges and corners

Cause analysis:

1) The wooden formwork was not moistened or not moistened enough before the concrete was poured, or the steel formwork was not coated with release agent or was applied unevenly

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2) Poor concrete maintenance;

3) Premature removal of side non-load-bearing formwork;

4) When removing the formwork, external force or heavy object impact, or poor protection, the edges and corners are knocked off

Phenomena: Concrete partially falls off at right angles to beams, columns, slabs, walls and openings, is irregular, and has defective edges and corners

Prevention and control measures:

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1) The formwork should be fully moistened or evenly coated with release agent before pouring concrete, and should be carefully watered and maintained after pouring concrete

2) When removing the side non-load-bearing formwork, the concrete should have sufficient strength;

3) Do not use excessive force when removing the formwork urgent. Pay attention to protecting the edges and corners; when lifting, it is strictly forbidden to hit the edges and corners of the template;

4) ReinforcementThe plywood increases the stress-bearing area and prevents the concrete from being stepped on.

(3) The side formwork of vertical components can only be removed when the strength of the concrete can ensure that its surface area and edges will not be damaged by removing the formwork. The form removal time is generally controlled to 8 hours in summer and 8 hours in winter. The specific time needs to be adjusted according to the conditions provided by the ready-mixed concrete mixing station.

(4) The stair steps that have been poured with concrete should be covered with 1.8cm thick plywood to prevent damage to their edges and corners.

Construction during rainy season

(1) The mixing station strictly controls the water consumption of concrete. The calculation is The water content of the sand and gravel is taken into account, and the slump is strictly controlled to ensure the strength of the concrete.

(2) It is not advisable to pour concrete in the open air when it rains. Be sure to understand the weather changes before starting work to avoid sudden rains that may affect concrete pouring.

(3) The concrete that has been put into the mold and vibrated must be covered in time to prevent sudden rain and rainwater

(4) If concrete cannot be poured in time after the mold is closed, drainage holes should be reserved in appropriate parts of the formwork to prevent water from accumulating in the mold due to sudden rain

(5) If it suddenly rains when pouring concrete, the work will not stop during light rain. If it rains heavily, a rainproof shed or temporary construction joints can be erected before closing. If the construction continues after the rain, the construction joints must be inspected. Process before pouring.

(6) Windproof fastening measures should be strengthened during construction during rainy periods

(7) All Construction machinery shall take corresponding measures to prevent leakage.

Winter construction

(1) Winter construction uses sand and stone for mixing concrete. Cement should be kept at a positive temperature.

(2) The ready-mixed concrete is mixed by heating water, and the water temperature should not exceed 80 ℃.

(3) The aggregate must be clean and must not contain ice, snow and other frozen structures and minerals that are prone to freeze cracking. The mud content must not exceed the specified value and must not be mixed with When potassium or sodium ion early-strength antifreeze is used, active aggregates must not be mixed in the concrete.

(4) Strictly control the water-cement ratio, which shall not be greater than 0.6. The water consumption per cubic meter of concrete shall be no less than 300kg. The moisture brought by the aggregate and the external All moisture in the agent solution should be deducted from the mixture.

(5) Before mixing concrete, the mixer should be rinsed with hot water.

(6) The temperature of the concrete mixer shall not be lower than 10℃, and the mold entry temperature shall not be lower than 5℃.

(7) Before pouring concrete, the ice, snow, frozen blocks and dirt on the steel bars and formwork should be removed in time.

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