According to the actual site survey, cracks appeared in the newly poured concrete floor of the ground workshop of an enterprise.

     Cause analysis: According to the depth of the crack is a through-slot, the crack extends in the vertical and horizontal direction, mainly due to the regular vertical and horizontal cracking around the column to the wall, the main reason is the ground crack caused by the changes in the building.

     First, the single-sided or multi-sided concrete of the new building is subject to stress, which increases the internal stress of the concrete and causes cracks in the concrete floor. The second is that industrial plants are affected by natural climate, production equipment, and other factors. The buildings will undergo stress changes. The above-ground part of the plant structure will have large thermal expansion and contraction, while the underground part will be less affected by temperature changes. Basically, there is no temperature deformation. The expansion and contraction of the structure is limited, and thermal stress is generated inside the structure, which causes the ground to crack.

Crack treatment plan 1: concrete welding agent repair

1. Base surface treatment: Use a marble cutter or hand wheel cutter to cut and cut the cracks on the two sides of the gap, and expand the cutting width based on the direction of the gap to the original gap by 3-5mm, and control the cutting depth to 2-3mm. For cutting, clean the surface garbage, pine animals, and dirt, and clean with high-pressure water gun to fully wet the base surface.

2. Spray welding agent: spray the welding agent even when there is no clear water on the ground to ensure the bonding strength of the high-strength floor welding agent.

3. Mortar mixing: mix the repairing material and the welding agent in proportion to form a repairing mortar.

4. Plastering treatment: After the sprayed solder on the base surface is not wet (about 20-30 minutes), repair and compact the gap with the prepared repair mortar, and then use a trowel to smooth it out.

5, curing: 4 hours after the completion of light, spray repair on the repaired surface, conditions allow the cover film to prevent water loss, curing requires a minimum of 7 days to keep the surface wet.

Explanation:

This solution is convenient for construction, and can be used to repair and fill cracks. There will be no detachment or secondary cracks on the welding surface, but it cannot compensate for the cracks caused by the original cracks.

Crack treatment scheme two: cutting the concrete around the crack to remove the newly injected concrete

     Since crack cracks are basically regular horizontal or vertical straight cracks, in order to ensure the overall beauty and long-term stability of the ground after the transformation, it is recommended that the concrete around the cracks be chipped out, the concrete be recast and the concrete surface layer treated.

Process flow:

    The original ground is cut and removed → base surface cleaning → brushing the concrete binder together → concrete pouring → vibrating → scraping ruler leveling → manual slurry extraction → NFJ wear-resistant surface layer construction → maintenance

Concrete cutting: In order to ensure the neatness and integrity of the newly poured concrete, firstly mark the cutting route along the two sides of the seam with a straight line. The cutting width should be at least 30 cm. The cutting machine should cut the cracks on both sides in parallel. The concrete on both sides of the crack is neatly removed.
 

Base surface cleaning: Thoroughly clean the planed construction waste, and chisel the foundation, and then clean the base surface and sides with a high-pressure water gun.
 

Painting concrete welding agent: In order to ensure that the concrete is combined with the old ground, paint the welding agent on the interface between the new and old concrete.
 

Concrete pouring: C30 fine stone concrete is poured, and the concrete is compacted with a vibrating rod to prevent the honeycomb surface of the concrete from appearing.
 

Squeegee leveling: Scrape the aluminum alloy ruler. Before scratching, use the ruler to find out the unevenness of the concrete surface, and then use the ruler to scrape the mortar on the concrete surface back and forth for leveling. Interleaving overlaps.
 

Construction of abrasion-resistant surface layer: When the concrete on the base layer is near the initial setting and there are shallow footprints on the concrete surface, wipe the concrete surface with a washboard, and apply the pressure in both the vertical and horizontal directions. Be sure to smooth the base concrete. Raise the base concrete while vibrating.
 

Wear-resistant surface layer construction:
 

Dry-spread NFJ metal anti-static non-fire abrasion resistant aggregate
 

Brand: NFJ
 

Type: NFJ-06M (2-3mm) metal heavy-duty impact resistant material
 

Dosage: 5kg / ㎡
 

color: grey
 

7.1 According to NFJ-06M (2-3mm) metal heavy-duty impact resistance 5Kg / ㎡, spread uniformly in two batches,

7.2 Material preparation: Select the material conveying channel according to the concrete pouring working surface; divide the working surface into areas, calculate the amount of NFJ material on the ground in this area according to the unit area consumption and area, and transport the NFJ material in place at one time, and evenly place it in the distribution channel. Prepare for construction.

7.3 Spread: Wear protective equipment to ensure that the material is sufficient and uniform.

7.4 NFJ-06M spreading material is divided into two parts: firstly grind the initial setting concrete (when it is 60-7% dry) and grind the ground before spreading, and then uniformly spread 3 kg of NFJ metal aggregate (fabric) for the first time. For 60% of the total, use a rubbing plate for compaction and leveling; secondly spread the NFJ metal aggregate (fabric): first use the rubbing plate to lift the pulp when the base material is hardened to a certain stage (about 1 hour), and then spray NFJ 2 kg of metal aggregate fabric, the amount is 40% of the total amount. After the fabric absorbs a certain amount of water, compact it with a rubbing plate again, and then use a cement steel trowel to lighten the large surface and corners.

     Maintenance: The concrete can be watered for 24 hours after the completion of the concrete pouring. Put a suitable amount of water on the plastic film, and the finished floor surface should be kept moist for at least 7 days;