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8 abnormal phenomena in concrete construction and treatment measures

2015/8/6 10:49:23 Click:
      I. honeycomb

( One The mixing ratio is not accurate, and the gradation of sand and gravel is not good.

( Two Stirring unevenness;

( Three Template leakage;

( Four Insufficient vibration or vibration.

( Five Once pouring concrete is too thick, the layering is not clear, the concrete is not clear and the quality of vibration can not be grasped.

( Six The height of free fall exceeds the requirement, concrete segregation and gravel pile up.

( Seven Vibrator damage, or temporary power failure caused by vibration.

( Eight When the vibration time is not enough, the bubbles are not excluded.

One Control measures

1. Strictly control the mixture ratio, strictly measure and check regularly.

2. Concrete mixing should be full and uniform.

3. Cutting height exceeds 2m Use string or chute.

4. Layering blanking, layered tamping and preventing leakage.

Check the gap of the formwork and check the slurry leakage at any time during pouring.

Two Processing method

(1) use smaller honeycomb for cleaning and cleaning. One : Two Cement mortar smoothing compaction;

(2) for larger honeycombs, chipping away loose and loose particles, cleaning the supporting formwork, and carefully tamping with fine concrete with high strength grade.

(3) for deeper honeycombs, the grouting pipe and exhaust pipe can be embedded inside, and mortar is put on the surface or cement is poured after concrete is closed.

Two.  

( One The same reason as "honeycomb";

( Two Template cleaning is not clean, or mold removal too early, template adhesion;

( Three The mold coating is not evenly brushed or brushed.

( Four The wood mould is not watered and moistened, and the concrete surface is dehydrated and powdered.

( Five The pouring time is too long, too much ash is hung on the formwork, so the surface layer is not dense.

( Six When the vibration time is not enough, the bubbles are not excluded.

One Control measures

First, the template should be cleaned, and the wood formwork should be wetted before the concrete is poured.

2. Seal up the cracks in the slab and deal with leakage at any time during pouring.

3. Vibration should be fully dense.

Two Processing method

(1) the surface can be treated without painting.

(2) if the surface is not painted, it should be moistened and completely pressed with cement mortar.

Three. Holes  

( One The same reason as "honeycomb";

( Two The steel bar is too dense, the concrete aggregate is too thick, it is not easy to ash down, and it is not easy to vibrate.

( Three There is no exhaust port at the entrance of the tunnel and the bottom of the pit, and there are air bags in the concrete.

One Control measures

(1) use the high strength grade fine aggregate concrete in the dense area of the steel bar, and seriously separate the layer or tamper with it.

2. The reserved holes should be cut off from both sides at the same time and seriously vibrated.

Remove debris from concrete in time.

Two Processing method

Remove loose concrete around the hole, rinse it with high pressure water, and use the high strength grade fine concrete to form the tamping.

Four. Exposed tendons  

( One The same reason as "honeycomb";

( Two The processing of steel skeleton is not allowed.

( Three Lack of protective layer pad;

( Four The steel bar is too dense.

( Five No reinforcing bar positioning measures and steel bar displacement sticking.

One Control measures

1. Before pouring concrete, check the reinforcement and protective layer pad correctly, and the wood formwork should be fully moist.

2. Coarse aggregate should be selected with suitable diameter when the steel bar is dense.

3. Ensure the mix proportion and workability of concrete meet the design requirements.

Two Processing method

1. Surface exposed tendons can be cleaned and smeared on the surface. One : Two Cement mortar;

(2) after the exposed reinforcement is treated well, the high level fine aggregate concrete will be filled and compacted.

Five, rotten roots  

( One The cracks in the root of the template are not blocked tightly, and the slurry is leaky.

( Two The stone free mortar with no mixture of concrete before pouring and the same composition.

( Three Concrete and poor workability, water cement ratio is too large, stone bottom.

( Four The pouring height is too high, the concrete is concentrated in one place, the concrete is segregating or the stone is heap up.

( Five The vibration is not solid.

( Six In mold cleaning is not clean and wet.

One Control measures

(1) all vertical structures are paved with cement mortar mixed with concrete. Mortar is lifted to the scene with hopper, and evenly spun with spade, not directly pumped by vehicle pumps.

(2) strictly layered pouring, the formwork is tight, and the protective layer of steel bar is evenly arranged.

(3) clean up the formwork before closing the mold and strictly control the slump of the concrete so as to prevent segregation.

4. Lifting materials should be dispersed and suspended.

(5) timely watering and curing for concrete. The curing time can not be less than two weeks.

Two Processing method

The grouting process is used to repair the material, and the concrete grouting material is used. The construction process is as follows: old concrete chipping, water washing, saturation, pouring, grouting and grouting.