Post Date:22,Dec,2025

Which factors in concrete raw materials have a greater impact on the adaptability of admixtures? The main factors are summarized as follows: 1. Cement (1) If the tricalcium aluminate content in cement is high, the concrete mixture will collapse too much over time. Consult with the cement manufacturer to control the tricalcium aluminate content within a reasonable range. (2) When the standard consistency water consumption of cement is too high (greater than 145g water), admixtures are needed to increase the water reduction rate to meet the concrete mixture’s delivery requirements. (3) When the factory temperature of cement is too high (greater than 70℃), the concrete mixture will collapse too much and solidify quickly. During the summer, cement manufacturers should be required to control the factory temperature of cement below 70℃. 2. Fly ash (1) The finer the fly ash, the better the fluidity of the concrete mixture; conversely, the coarser the fineness, the worse the fluidity of the mixture. Finer grade I and II fly ash should be used as admixture. (2) The higher the carbon content of fly ash, that is, the higher the loss on ignition, the greater the amount of admixture required to achieve the same out-of-the-machine effect, because carbon absorbs admixtures. Try to use fly ash with a lower loss on ignition.

(3) The smaller the water requirement ratio of fly ash, the better, so that the amount of admixture can be reduced to achieve the same out-of-the-machine effect; conversely, the amount of admixture needs to be increased.

3. Sand and gravel

(1) When the mud content of sand is too high (greater than 3%), it will absorb some of the admixture, causing the concrete mix to have a low slump when it is out of the machine. The admixture formula must be adjusted to meet the requirements of the material used. Try to use sand with a low mud content. Machine-made sand or partially machine-made sand can also be used.

(2) When the mud content of gravel is too high (greater than 2%), it will absorb some of the admixture, causing the concrete mix to have a low slump when it is out of the machine. The admixture formula must be adjusted to meet the requirements of the material used. Try to use gravel with a low mud content. (3) When the shale content in the stone is too high (greater than 10%), it will absorb some of the admixtures, causing the concrete mix to have a low slump when leaving the machine. This is mainly due to the high water absorption rate of shale (greater than 3%). Stone without shale should be used as coarse aggregate whenever possible.