where [d.sub.a] is the size of aggregate, [d.sub.max] is the maximum size of aggregate
, [F.sub.p]([d.sub.a]) represents the ratio of aggregates by weight passing through a sieve of characteristic size equal to [d.sub.a], and n is the exponent of Talbot's equation.
Bazant and Oh  based on their experimental results, suggested to use a minimum beam width of three times maximum aggregate size (da) used in testing, as the width of fracture process zone of the concrete is three times maximum size of aggregate
. As the specimen size has been proposed to be characterized by the aggregate size, therefore, the aim of this paper is to investigate the effect of specimen sizes in the fracture parameters of concrete.
Enter batch percentage: % Compressive strength at 28 days: MPa Slump: Maximum mm Minimum mm Nominal maximum size of aggregate: mm Water-cement ratio: Concrete type Air content: % Permeability: Freeze-thaw: Unit weight of aggregates: F.A.
b) Nominal maximum size of aggregates: Computed according to the following restrictions: