Dependent on the origin of the aggregates (sea, river or crushed), their shape and
surface characteristics might be rather different; cements and fillers also differ on these
aspects. According to Wadell [1935], sphericity gives an indication of the shape and the
surface characteristics of solids and is defined as the surface area of a sphere having the
same volume as the particle divided by the surface area of the particle (Equation 4.2).