What factors contribute to the loss of slump during the pumping of shotcrete?

The loss of slump during the pumping of shotcrete can be influenced by a variety of factors, and the correct answer acknowledges that multiple conditions play a role.

The type of pump used is significant because different pumps can apply varying pressures and flow rates, which can affect the fluidity and workability of the shotcrete mixture. Some pumps might cause more friction or require higher pressure to transport the material, leading to a reduction in slump.

The length of the delivery line also contributes to slump loss. A longer line can increase the friction between the shotcrete and the inner walls of the hose, leading to a drop in pressure and an increase in viscosity as the material moves through this extended distance. This means that the material is subjected to greater resistance, which can reduce its workability.

The initial level of air content in the shotcrete mixture is crucial as well. Air content affects the density and flow of the material. A higher air content can enhance workability, while too low of air content may lead to a stiffer mix, and thus, greater slump loss during pumping.

By recognizing that all these factors interplay in the behavior of shotcrete, it becomes clear why the combined influence of the type of pump, the length of the line, and the