Composite structural material and aggregate therefor

A composite structural material in the form of concrete for making a concrete structure comprising:

• an aggregate;
• and
• a cementitious binder having a Portland cement, a slag cement or a fly ash to combine with the aggregate to form the concrete,
• the aggregate being a particulate material where each particle includes at least three radial legs extending into three dimensions outwardly from a central hub to form three dimensional aggregate particles,
• the at least three radial legs having a diameter, at a location closest to the central hub, which is less than the diameter or width of the central hub,
• the central hub having a spherical shape, a cylindrical shape, or a cuboid shape and having exposed surface portions located between the at least three radial legs, which exposed surface portions include a surface contour,
• whereby the composite structural material includes an amount of aggregate of 2.0% to 7.5% v/v.