◆a low sand rate or a low content of fine particles in the sand will result in low water retention of concrete. a high mud content in the sand will easily cause slurry settlement, that is, "grabbing the bottom."
◆the total amount of cementitious materials is small, and the slurry volume is less than 300l/m3;
◆the stone gradation is poor, or the stones are of a single particle size;
◆large water consumption makes the viscosity of the concrete mixture low;
◆the amount of admixture is too large, or the admixture has low viscosity and poor water retention;
◆use slag or slag cement itself has poor water retention and is prone to bleeding and segregation.
</p
