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Effect of early strength agent

Release time:

2022-05-30

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(1) Influence on concrete mixture

　　early strength agentGenerally, it can shorten the setting time of concrete, but when the content of tricalcium aluminate in cement is low or lower than that of gypsum, sulfate will delay the setting time of cement. The early strength agent generally does not increase the air content in the concrete, and the air content of the early strength water reducing agent is determined by the air content of the water reducing agent. For example, with the sugar calcium water reducing agent compound, the gas content will not increase, but with the wood calcium water reducing agent compound, the gas content will increase significantly.

(2) Impact on concrete

　　early strength agentIt can improve its early strength; the improvement of the same early strength agent depends on the amount of early strength agent, ambient temperature, curing conditions, water cement ratio and cement type. The effect on the long-term strength of concrete is inconsistent, with high and low. The early strength agent has a good effect within a reasonable dosage range, but when the dosage is large, it will adversely affect the later strength and durability of concrete. Early strength water reducing agent also has a good effect of early strength, the performance is better than that of early strength agent, can control the late strength change. Triethanolamine can stimulate the early strength of cement. It can accelerate the hydration of tricalcium aluminate, but retard the hydration of tricalcium silicate and dicalcium silicate. If the content is too high, the strength of the concrete will be reduced.

Durability sulfate early strength agent has no effect on rebar corrosion, while chlorideearly strength agentContains a large number of chloride ions, will promote the corrosion of steel. When the amount is large, it will also reduce the chemical resistance, wear resistance, frost resistance, etc. Concrete, reduce the flexural strength of concrete, increase the early shrinkage of concrete, and have little effect on the later stage of concrete. At present, in the new national standard, the use of chloride-containing additives has been prohibited. In order to prevent the effect of chloride salt on the corrosion of steel bars, rust inhibitors and chloride salts are often used in combination.

When using sulfateearly strength agentIt will increase the alkalinity of the concrete liquid phase, so it should be noted that when the aggregate contains active silica, it will promote the reaction between alkali and aggregate, so that the concrete will be destroyed by alkali expansion.

Triethanolamine will increase the shrinkage of concrete. When the content is greater than 0.05%, it will reduce the later strength. The greater the content, the more the reduction.

Due to the role of water reducing agent, early strength water reducing agent can make upearly strength agentDefects, change the pore microstructure of concrete, improve the compactness, so that the concrete frost resistance, anti-mixing, compression, flexural strength, elastic modulus and steel bonding are improved. In the reasonable content range, there is no adverse effect on the corrosion of steel, and the early shrinkage increases slightly, so it is widely used in our country.

A large number of tests show that sulfate series early strength agents can improve the impermeability of concrete.

deformationearly strength agentGenerally, it has little effect on the deformation (dry shrinkage) of concrete.

Key words:

Early strength agent

What is early strength agent? Classification and application analysis of early strength agent

Mechanism of action of early strength agent

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