Why does refractory need to add coarse firstly and then add fine aggregate?
Binding agent can wrap particles and improve binding effect.
Oh, adding coarse aggregate first is to select good material to make aggregate, and the rest cna be made into fine aggregate. Because if it contains impurities, once being sintered, the appearance will be affected, but fine aggregate does not have this impact.
Adding coarse aggregate is to assure its good combination with fine aggregate. This is just the experience. You don't have to ask.
