The main advantage of crushed stone is that,Crushed stone grains have different shapes depending on their flakiness. Their surface is coarse, therefore they have good cohesion with cement-and-sand mix in the concrete production process. there for it uses in roofs.
Cohesion property:The force of attraction that holds molecules
of a given substance together. It is strongest in solids, less strong in liquids,
and least strong in gases.
Thus crush stone binds with cement and sand and provide high strength to roofs and buildings which provide strength to buildings.