Stiffness, Strength, and Performance of Unbound Aggregate . - ucprc2.3 Comparison of the California and South Africa Aggregate Specifications. ... G3 for processed crushed stone material and G4 to G6 for natural gravels.crushed stone specifications g4,Aggregate - AfrisamConcrete aggregates include a wide range of stone sizes within target gradings .. Aggregate. Base. G1. G2. Subbase. G4. G5. G7. Roadstone. 19mm. 13,2. 9,5.