How long does it take for the shrinkage-free grouting material to dismantle the mould?

The non-shrinkage grouting material is made of high-strength materials (such as quartz sand, emery, etc.). ), cement, grouting masterbatch and other media, supplemented by additives with high fluidity, slight expansion and anti-segregation (such as water reducer). Add a certain amount of water to the construction site and mix it evenly before use. Let's take a look at how long it takes for the shrinkage-free grouting material to dismantle the mold.

1. If the non-shrinkage grouting material used for roofing is of early strength type, the formwork can be removed in three days, otherwise it will take at least seven days.

2. When using grouting material to dismantle formwork, it should be noted that the load-bearing side formwork, including the side formwork of beams, columns and walls, can be dismantled as long as the concrete can ensure that its surface and edges and corners are not damaged due to formwork removal; Load-bearing formwork, including the bottom formwork of horizontal structural members such as beams and plates, can only be removed after the strength of test blocks cured under the same conditions as the structure reaches the specified level. In the process of form removal, if it is found that the actual strength of concrete does not meet the requirements and there are quality problems that affect the safety of the structure, the form removal should be suspended. After proper treatment, the actual strength can meet the requirements.

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Knowledge point 1. How long does the non-shrinkage grouting material solidify?

Grouting materials have initial setting time and final setting time after use, and the final setting time of grouting materials after construction varies according to different models. The setting process of grouting material is divided into two stages: initial setting and final setting.

1. The initial setting stage is from adding water to the grouting material until the grouting material loses fluidity, and the initial setting is earlier than 25 minutes.

2. The final setting stage of grouting material is to add water until the slurry loses plasticity, which is the final setting time, and the final setting time is not later than 60 minutes.

3. It should be noted that the replacement water required for cement hydration will leave gaps in the hardened body, which will reduce the strength and durability of grouting materials. Therefore, the water consumption must be strictly controlled and added according to the specifications of the construction instructions. When the water consumption is greater than the required value, excess water will float on the surface of grouting material slurry, thus delaying the setting time.

4. After grouting construction, the final setting cannot be carried out immediately, and the initial setting must be carried out. It will take some time to do it. Therefore, grouting construction must ensure that the grouting material finally reaches a certain compressive strength. Different grouting materials have different final setting time. For early-strength grouting materials, it usually takes one to two days to smear, while for ordinary grouting materials, it takes one to two weeks to solidify.

Knowledge point 2. Advantages of non-shrinkage grouting material

Non-shrinkage grouting material has good self-flow, fast hardening, early strength, high strength, no shrinkage and slight expansion; Non-toxic, harmless, non-aging, pollution-free to water quality and surrounding environment, good self-tightness, rust resistance and other characteristics. It has the advantages of reliable quality, low cost, short construction period and convenient construction and use. It is an ideal choice in the era of installation without pad iron to fundamentally change the stress condition of the No.3 transformer equipment base, so that it can bear all the loads of the equipment evenly, thus meeting the installation requirements of various electromechanical equipment (heavy equipment high-precision grinder).

Knowledge point III. The role of non-shrinkage grouting materials

Main uses of grouting materials: Non-shrinkage grouting materials are mainly used for anchoring anchor bolts, repairing airplane runways, fixing nuclear power equipment, strengthening road and bridge engineering, machine foundation, steel structure and foundation, equipment foundation, planting and burying rebar, reinforcing and transforming concrete structure, treating cracks in old concrete structure, installing electromechanical equipment, track and steel structure, sealing piles in static pressure piling engineering, thickening wall structure and repairing leakage, and various foundations.

Knowledge point four. Construction method of non-shrinkage grouting material

1, mixer, grouting equipment, formwork and maintenance items shall be prepared before grouting construction.

2. For secondary grouting, the horizontal distance between the formwork and the equipment base should be controlled around 100mm; The elevation of the top of the formwork shall be not less than 50 mm on the upper surface of the equipment base.

3, concrete structure reinforcement, formwork support should have enough grouting holes and vent holes, grouting hole diameter is not less than 50mm, spacing is not more than1000 mm.. ..

4. When mixing cement-based grouting materials, water should be added according to the water demand of the products. Mechanical stirring should be used. When mixing, first add 2/3 water and mix for about 3min, then add the rest water and mix evenly, and the mixing place should be near the grouting place.

5, anchor bolt anchorage grouting:

(1) When the anchor bolt is drilled, the wall of the bolt hole is rough, and the hole should be cleaned without floating ash, oil pollution and other impurities. Soak in water for 8 ~ 12h before grouting to remove the accumulated inflammation in the hole.

⑵ Oil stain and rust on the surface of anchor bolts should be removed before grouting.

(3) When the mixed cement-based grouting material is poured into the bolt hole, the position of the bolt can be adjusted as needed. Vibration is strictly prohibited during grouting, but it can be inserted properly, and the bolt can not be adjusted after grouting.

6, equipment foundation secondary grouting:

(1) Before grouting, the equipment floor and concrete foundation surface in contact with grouting materials shall be cleaned, and there shall be no loose gravel, laitance, floating ash, oil pollution and wax. 24 hours before grouting, the surface of foundation concrete should be fully wet, and 65438 0 hours before grouting, the accumulated water should be removed.

(2) During secondary grouting, grouting shall be carried out from one side until it overflows from the other side, and grouting shall not be carried out from two opposite sides at the same time. After grouting begins, it must be carried out continuously and the grouting time should be shortened as much as possible.

(3) When the track foundation or grouting distance is long, it can be constructed in sections according to the actual situation of the project, and the length of each section is no more than 5 meters. If the structure of equipment bottom plate is complex, pressure grouting should be adopted.

(4) It is forbidden to vibrate during grouting. If necessary, a grouting booster can be used. The booster pushes the grouting material from the bottom along the flow direction of the slurry, and it is forbidden to push it from the middle and upper part of the grouting layer.

5] After the grouting of equipment foundation is completed, it is advisable to cut a 45 oblique angle outward along the edge of the bottom plate after the initial setting of grouting material (as shown in the figure). If the edge can't be trimmed, the surface of grouting layer should be polished with spatula after initial setting.

7, concrete structure transformation and reinforcement grouting:

(1) The concrete surface in contact with cement-based grouting materials shall be chiseled flat.

(2) When repairing the structural defects of concrete, the brittle concrete should be removed to expose the steel bars, and the edge of the repaired area should be cut vertically.

(3) Before grouting, all gravel, dust or other sundries shall be removed and the surface of concrete base shall be wetted.

(4) Pour the evenly stirred grouting material into the formwork and knock the formwork properly.

5] When the thickness of grouting layer is greater than 150mm, corresponding measures should be taken to prevent temperature cracks.

8, construction and maintenance measures:

(1) When grouting, the daily average temperature should not be lower than 5℃. After grouting, the exposed part should be sprayed with curing agent or covered with plastic film in time, and covered with wet straw bag to keep it moist. When covered with plastic film, the exposed surface of cement-based grouting material should be covered tightly to keep the condensed water in the plastic film. When the surface of grouting material is inconvenient to water, curing agent can be sprayed.

⑵ Grouting materials shall be kept in a wet state, and the curing time shall be not less than 7d.

(3) When using quick-setting and quick-hardening cement-based grouting materials, the maintenance measures should be implemented according to the product requirements.

(4) In winter construction, when the project has no special requirements for strength growth, after grouting [1], the exposed part shall be covered with plastic film and covered with thermal insulation materials in time. The initial curing temperature should not be lower than 5℃. Do not water when curing at negative temperature.

5] When the difference between the surface temperature of cement-based grouting material and the ambient temperature is greater than 20℃ after formwork removal, thermal insulation materials should be used for covering and curing.

[6] If the ambient temperature is lower than the minimum construction temperature required by cement-based grouting materials or the strength growth needs to be accelerated, artificial heating maintenance can be adopted; Maintenance measures should comply with the current national standard "Code for Winter Construction of Building Engineering" JJ104.