Effect of granite dust on mechanical and some durability properties of manufactured sand concrete

The fabrication process of manufactured sands produces plenty of dust, which not only occupies the land and pollutes the environment but also causes dam breaks and collapses. To make full use of it, such granite dust was herein mixed into manufactured sand concrete as supplementary cementitious materials to replace fly ash in different proportions. The mechanical and some durability properties of these concretes were studied. The results showed an improvement in the workability of the manufactured sand concrete by introducing granite dust. The early strengths of manufactured sand concrete decreased with the fly ash replacement, but the compressive strengths, bending strengths and elastic modulus increased in the later stage when the replacement ratio was 20%. Compared with pure cement concrete, the 56 days chloride penetration resistance of the modified concretes was enhanced remarkably. Although the electric flux increased with the increasing granite dust dosage, it was always located at the low permeability level. The dynamic elastic modulus only had a slightly decrease after 350 freezing and thawing cycles when the granite dust dosage was within 20%, but it obviously dropped down when that dosage reached 30%. The drying shrinkage of the modified concrete was also inhibited within 14 days, compared with the pure cement concrete. (C) 2016 Elsevier Ltd. All rights reserved.