Post Date:10,Nov,2025

The dosage of admixtures is not a fixed value and needs to be adjusted dynamically according to the characteristics of raw materials, project type and environmental conditions.

(1) The influence of cement properties The mineral composition, fineness and gypsum form of cement directly determine the admixture requirements. Cement with a high C3A content (>8%) has a strong adsorption capacity for water reducers and the dosage needs to be increased by 10-20%. For every 50m2/kg increase in cement specific surface area, the water reducer dosage needs to be increased by 0.1-0.2% to cover the larger surface area. For cement with anhydrite (dihydrate gypsum content <50%), the water reducer adsorption rate is slow and the dosage can be reduced by 5-10%, but the mixing time needs to be extended to ensure uniform dispersion.

(2) The influence of mineral admixtures The adsorption characteristics of mineral admixtures such as fly ash and slag powder will change the effective concentration of admixtures. The adsorption capacity of Class I fly ash (water demand ratio ≤ 95%) for water reducers is only 30-40% of that of cement. When replacing 20% ​​of cement, the water reducer dosage can be reduced by 5-10%. When the specific surface area of ​​slag powder is greater than 450m2/kg, the admixture dosage needs to be increased by 5-8% when replacing 40% of cement. When fly ash and slag powder are mixed in a 1:1 ratio (total replacement amount 50%), the water reducer dosage can be reduced by 3-5% compared with the single slag powder system due to the complementary adsorption characteristics of the two. Due to the large specific surface area of silica fume (>15000m2/kg), the water reducer dosage needs to be increased by 0.2-0.3% for every 10% of cement replaced.

(3) Influence of aggregate properties The mud content and particle size distribution of aggregate are important bases for adjusting the dosage. For every 1% increase in the stone dust content (<0.075mm particles) in the sand, the water reducer dosage should be increased by 0.05-0.1%, as the porous structure of the stone dust will absorb the admixture. When the content of needle-shaped and flake aggregate exceeds 15%, the water reducer dosage should be increased by 10-15% to ensure encapsulation. Increasing the maximum particle size of the coarse aggregate from 20mm to 31.5mm reduces the void ratio, and the dosage can be reduced by 5-8%.
The dosage of admixtures is not a fixed value and needs to be adjusted dynamically according to the characteristics of raw materials, project type and environmental conditions.

(1)The influence of cement properties The mineral composition, fineness and gypsum form of cement directly determine the admixture requirements. Cement with a high C3A content (>8%) has a strong adsorption capacity for water reducers and the dosage needs to be increased by 10-20%. For every 50m2/kg increase in cement specific surface area, the water reducer dosage needs to be increased by 0.1-0.2% to cover the larger surface area. For cement with anhydrite (dihydrate gypsum content <50%), the water reducer adsorption rate is slow and the dosage can be reduced by 5-10%, but the mixing time needs to be extended to ensure uniform dispersion.

(2)The influence of mineral admixtures The adsorption characteristics of mineral admixtures such as fly ash and slag powder will change the effective concentration of admixtures. The adsorption capacity of Class I fly ash (water demand ratio ≤ 95%) for water reducers is only 30-40% of that of cement. When replacing 20% ​​of cement, the water reducer dosage can be reduced by 5-10%. When the specific surface area of ​​slag powder is greater than 450m2/kg, the admixture dosage needs to be increased by 5-8% when replacing 40% of cement. When fly ash and slag powder are mixed in a 1:1 ratio (total replacement amount 50%), the water reducer dosage can be reduced by 3-5% compared with the single slag powder system due to the complementary adsorption characteristics of the two. Due to the large specific surface area of silica fume (>15000m2/kg), the water reducer dosage needs to be increased by 0.2-0.3% for every 10% of cement replaced.

(3) Influence of aggregate properties The mud content and particle size distribution of aggregate are important bases for adjusting the dosage. For every 1% increase in the stone dust content (<0.075mm particles) in the sand, the water reducer dosage should be increased by 0.05-0.1%, as the porous structure of the stone dust will absorb the admixture. When the content of needle-shaped and flake aggregate exceeds 15%, the water reducer dosage should be increased by 10-15% to ensure encapsulation. Increasing the maximum particle size of the coarse aggregate from 20mm to 31.5mm reduces the void ratio, and the dosage can be reduced by 5-8%.