The function of fine stone concrete pump on cement in the pumping process: The pumping pressure of concrete is transmitted by the liquid phase substance in it. The liquid phase material carries the solid phase material and moves together to complete the pumping. There are two aspects of the role of cement. One is the cementation effect, which enables the concrete to maintain the state of solid phase material surrounded by liquid phase material during pumping; reduces the frictional resistance between the concrete and the mechanical part of the pump, the transportation pipeline and the concrete. Has good fluidity.
The effect of cement types on the pumpability of concrete Cement should have good water retention properties, making it difficult for concrete to leak water during pumping. Ordinary portland cement and pozzolan cement have better water retention, while slag cement has poor water retention. If it is used to mix pumping concrete, it is necessary to increase the amount of cement, appropriately increase the sand rate or add a part of fly ash. Low slump.
The amount of cement should be appropriate. If the amount of cement is insufficient, the pumping volumetric efficiency is reduced, and the conveying resistance is significantly increased. Moreover, the concrete has poor water retention, and is liable to bleeding, segregation, and clogging. Large, but little change in pumping volume efficiency. Compared with the gravel aggregate with the same particle size and gradation, the cement content of crushed concrete is larger.
For fine aggregate, artificial crushed sand uses more cement than natural sand. The smaller the pipe diameter and the longer the pipe, the higher the fluidity, lubricity and water retention of the concrete, so the amount of cement should be increased. If the aggregate gradation is appropriate, the larger the aggregate particle size, the less the amount of cement: but when the aggregate particle size exceeds 30 mm, the oversize aggregate will destroy the continuity of the concrete, and it is difficult for the cement slurry to fully contain the aggregate Therefore, the amount of cement cannot be reduced. If pumping lightweight aggregate concrete, the amount of cement should be increased appropriately.