Shape/Texture of Aggregate:

Angular aggregate and aggregate with rough surface provides better bond due to more surface area hence gives better strength to concrete. Flaky and elongated particles being weak in strength and also providing the weaker bond, their presence always lead to poor strength of concrete.

Soundness of Aggregate

Weak and porous aggregate containing any undesirable extraneous matter makes the aggregate unsound which in general reduces the strength of concrete particularly, under the moderate or severe exposure conditions like variation in temperature, freezing and thawing condition, alternate wetting and drying condition, etc.