Study on workability of plastic fresh concrete with machine-made sand

As many differences of machine-made sand from natural sand in particle shape, surface characteristics and particle size distribution (i.e. grading), especially in larger content of stone powder, it is important to realize what influences should be considered of machine-made sand on workability of fresh concrete. This paper firstly reviews the formerly experimental results of workability of plastic fresh concrete affected by fineness modulus and grading of sand, sand ratio, content of stone powder and water to cement ratio. After that, the new experimental results are introduced and analyzed, in which the effects of the content of stone powder in machine-made sand, the water to cement ratio and the content of water reducer were considered. It is concluded that the influence of the content of stone powder on the workability of plastic fresh concrete is inherent in the changes of density, void ratio and water absorption of machine-made sand. The optimum content of stone powder in machine-made sand is 9% in this study of concretes in strength grades of C30, C40 and C50. The reasonable content of water-reducer has not obvious influence on the workability of plastic fresh concrete.