How does concrete pumping agent work?

Pumping concrete has gradually become a commonly used type in concrete construction. It is more and more widely used in industry. It has the characteristics of fast construction speed, good quality, labor saving and convenient construction. It is widely used. General structural concrete for housing construction, road concrete, mass concrete, high-rise buildings and other projects are all the main reasons.

It is required to have good fluidity, and the aggregate particle size is generally not larger than a quarter of the pipe diameter. It is necessary to add a pumping agent to prevent the concrete mixture from segregating and clogging in the pumping pipeline, and to use Admixtures such as water-reducing agents, plasticizers, air-entraining agents and thickeners that can allow the concrete mixture to pass smoothly under pump pressure can be used as pumping agents. Adding an appropriate amount of mixed materials (such as fly ash, etc.) can prevent the mixture from layering, bleeding and clogging of delivery pipes during concrete construction.

Water reducing agent can reduce the free water content in plastic concrete, thereby achieving the purpose of reducing the amount of cement and reducing costs; pumping agents are often used in high-rise multi-layer and long-distance commercial concrete transportation, which can enhance the plasticity of concrete. , Pumpability, some compound pumping agents also contain water reducing agents.

The working principle of pumping agent in concrete: also called concrete pumping agent. It is an admixture that improves the pumping performance of concrete and has excellent water-reducing and enhancing effects and retarding and plastic-retaining properties. The commonly used dosage of this product is 1.5-2.0% of the cement dosage. It can be mixed into concrete together with mixing water. If the post-infiltration method is used, the effect will be more significant, and it is compatible with other admixtures of the same type. However, for cement that uses anhydrite and fluorogypsum as the setting agent, a concrete adaptability test must be conducted, and it can only be used when it is adapted.

The main properties of concrete pumping agents:

1 , The slump loss over time is small, and it can meet the long-distance transportation of commercial concrete.

2. Stable chemical properties, good safety performance, non-toxic, odorless and non-flammable. No crystallization in winter.

3. The water reduction and enhancement effect is good. The water reduction rate is above 22%, and pumpable concrete below C80 can be prepared.

4. Good durability. This product has low alkali content, basically does not contain CLˉ salt, and the shrinkage of concrete is small.

5. Good constructability. This product has an obvious retarding effect, greatly reducing the early hydration heat of concrete. Its initial setting time is delayed to about 10 hours. It can also be adjusted appropriately according to customer needs. It has no bleeding, no segregation, and good water retention properties. The 2h loss is small and has a certain air content, which improves the flexural performance of concrete, greatly improves the elastic modulus and waterproof and impermeability functions of concrete.

Admixtures that can improve the pumping performance of concrete mixtures are called pumping agents. The so-called pumping performance means that the concrete mixture can pass through the transportation pipeline smoothly, without clogging, without segregation, and with good viscoplasticity. The pumping agent is composed of water reducing agent, retardant, air entraining agent, etc.

Characteristics of pumping agent:

Pumping agent is a fluidizing agent (a kind of polymer). It can greatly improve the fluidity of the mixture and can also make fresh concrete Maintain its fluidity for 60~180min, and the remaining slump shall not be less than the original 55%. In addition, it is not a retarder and should not have retardation properties. The retarding time should not exceed +120min (unless there are special requirements) . Add the liquid pumping agent into the mixer together with water and extend the mixing time.

Scope of application

Suitable for various concretes that require pumping technology. Retarding pumping agent Used for large-volume concrete, high-rise buildings, slip form construction, underwater cast-in-place piles, etc. Pumping agents containing antifreeze components are suitable for concrete construction in winter.

Pumping concrete mix design regulations:

The total amount of cementitious materials should not be less than 300kg/m3, the sand rate should be 35%-45%; the water-cement ratio should not be greater than 0.6

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