Crushed sand in concrete – Effect of particle shape in different fractions and filler properties on rheology

Studies of sand particle characteristics (shape, voids content, filler particle size distribution) and rheology of concrete (slump-flow, yield stress and plastic viscosity) show that the 0.125/2 mm particle shape and ≤0.125 mm filler properties are the most important factors for concrete workability when the sand grading 0/8 mm is kept constant. By normalizing the maximum variation of rheology (slump-flow value in mm) obtained in mixes where different size fractions are exchanged, the fraction ≤ 0.125 mm was found to have around 6–8 times larger effect on rheology per unit volume % exchanged, compared to the coarser sand fractions: ≤0.125 mm = 35.2 mm/%; 0.125/2 mm = 4.9 mm/%; 2/5 mm = 6.0 mm/% and 5/8 mm = 3.8 mm/%.