Because the cobblestones with a single particle size has a larger porosity than those with a continuous particle size at the condition of same maximum particle size of the cobblestones, the large porosity should be filled with mortar. And the aggregate surface area of per cubic meter concrete at the same condition is also different. Using single particle size cobble stones has a larger surface size than continuous particle size cobblestones, at the same time, it also needs to add more cement. What’s more, the flow-ability of concrete made of continuous particle size cobblestones is much better so as to be good for pumping. Hence, we should prefer to use the cobblestones with the continuous particle size in pump concrete.