Pumping concrete requirements for cement
The role of cement in the pumping process The pumping pressure of concrete is transmitted by the liquid phase in it. The liquid phase carries the solid phase to move together to complete the pumping. Cement has two functions. One is the cementing effect, which makes the concrete maintain the state of solid phase surrounded by liquid phase during pumping;
01 Good fluidity
Good fluidity reduces the friction resistance between concrete and the mechanical part of the pump, the conveying pipeline and the inside of the concrete, and has good fluidity.
02 Select high-quality cement varieties
The influence of cement varieties on the pumpability of concrete Cement should have good water retention properties, so that the concrete is not easy to bleed during pumping. Ordinary silicate cement and pozzolana cement have good water retention, while slag cement has poor water retention. If it is used to mix and pump concrete, it is necessary to increase the amount of cement, appropriately increase the sand ratio or add a part of fly ash, and use a lower slump. When fly ash cement is used, the concrete has better fluidity, but the early water bleeding is larger. It is advisable to use a lower slump and pump as continuously as possible. 03 Appropriate cement dosage The amount of cement should be appropriate. If the amount of cement used is insufficient, the pumping volumetric efficiency will decrease, the conveying resistance will increase significantly, and the water retention of this concrete will be very poor, and it will easily bleed, segregate and become blocked. If the amount of cement used is too large, the concrete will become too viscous and the conveying resistance will increase, but the pumping volumetric efficiency will not change much.
