Reason 1: A low sand rate or a low content of fine particles in the sand will result in low water retention of the concrete, high mud content in the sand, and prone to slurry settlement, that is, “grabbing” end”.
Countermeasures: Increase the sand rate and reduce the mud content in the sand to ensure the workability and strength of concrete.
Reason 2: The total amount of cementitious materials is small, and the slurry volume is less than 300L/m3.
Countermeasures: Add fly ash, especially when preparing low-strength high-fluidity concrete. The amount of fly ash should be appropriately increased to improve its water retention. sex.
Reason 3: The stones have poor gradation or are stones of a single particle size.
Countermeasures: Adjust the stone gradation. For stones with a single particle size, the sand rate should be increased.
Reason 4: Large water consumption reduces the cohesion of the concrete mixture.
Countermeasures: Increase the water reduction rate of admixtures or increase the dosage of admixtures to reduce water consumption.
Cause five: The dosage of admixture is too large, and the admixture contains bleeding ingredients.
Countermeasures: Reduce admixtures or add thickening components and air-entraining components to admixtures to improve the cohesion of concrete and prevent bleeding and segregation. .
Reason 6: Due to the long storage time, the clinker part of the cement has been hydrated, resulting in poor water retention of the cement.
Countermeasures: Compound thickening components and early strength components in admixtures.
Reason 7: The use of slag powder or slag Portland cement has poor water retention and is prone to bleeding and segregation.
Countermeasures: Increase the amount of cement or fly ash, reduce the amount of slag powder, or change the cement type.
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