With the continuous increase in the amount of concrete expansive agent, poor application and failure of use have occurred from time to time, and quality accidents causing leakage and cracking of concrete structures are also commonplace. As a result, some people have expressed doubts about the compensatory shrinkage of concrete expansive agents. Some people even refused to use the project. The following small series introduces the expansion agent usage method and expansion agent type.
Expansion agent use method
1. Scientifically and reasonably select the amount of expansion agent, and the expansion agent must be adapted to the concrete mixing station. The purpose of fitting is mainly to determine the reasonable amount and method of incorporation according to the design expansion rate index. The method of incorporation is usually two methods of blending and partially replacing mineral admixtures.
2. It is reasonable to control the temperature of concrete pouring into the mold in the range of 30±5°C.
3, to strengthen concrete vibrators, more dense than ordinary concrete vibrators.
4. Scientific and reasonable maintenance methods. Strengthen conservation 7 days before pouring. Every day between 10:00 am and 4:00 pm, it should be sprinkled with water no less than 5 times. Every day after the 8-14th day, it should be once every morning and afternoon. It is not advisable to carry out watering maintenance at night and it is not advisable to carry out excessive maintenance in the winter. The strict combination of temperature monitoring for conservation is very important, keeping in mind the principle of temperature control for “heating at the warming stage and warming at the cooling stageâ€.
5. It is not appropriate to use concrete with excessive mud content to produce concrete, and it is not appropriate to load the concrete prematurely.
Expansion agent type
1. Calcium sulphoaluminate
Among these types of swelling agents are: alumite swelling agents (the main components are alum and anhydrite or dihydrate gypsum); CSA swelling agents (the main component is anhydrous calcium sulfoaluminate); U-type swelling agents (main components are Anhydrous calcium sulfoaluminate, alum, gypsum, etc.
2, calcium oxide expansion agent
There are various preparation methods for such expansion agents, such as calcined lime at a certain temperature, adding appropriate amounts of gypsum and water-quenched slag, and mixing lime and stearic acid; burning limestone, clay and gypsum at a certain temperature. The mature material is ground and then mixed with finely ground gypsum calcined at a certain temperature.
3, metal expansion agent
Commonly used iron filings are formulated with iron powder mixed with an appropriate amount of oxidant (such as perchromate, permanganate, etc.).
Expansion agent effect
1. Underground buildings: such as subways, underground parking lots, underground warehouses, tunnels, mines, civil defense projects, foundation pits, etc., mixing stations, etc.
2, pools, swimming pools, water towers, storage tanks, large containers, granaries, oil tanks, caves and other warehouses
3, high-strength highway pavement, bridge concrete surface, culverts, etc.
4. Prefabricated components, anchorage of frame structure joints, pipe joints, grouting material of post-prefabricated prefabricated components, backfilling of post-seam joints, magmatic grouting materials
5. Cement products: self-stressing, prestressing and prestressed concrete pipes, slabs, columns, beam columns, waterproof roof panels, etc.
Editor's summary: The use of expansive agents and the types of expansive agents are introduced here. Hopefully everyone will be helpful. If you want to know more related information, you can pay attention to this website information.
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