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Sand is an inert element essential in the composition of concrete; its use ensures granular continuity between the cement and gravel for better cohesion of concrete. This paper presents the results of a study that investigated the influence of sand quality on the properties of fresh and hardened SCC (self-compacting concrete). The dune sands are very fine materials characterized by a high intergranular porosity, high surface area and low fineness modulus; on the other hand crushed (manufactured) sand has a high rate into thin and irregular shapes which influence the workability of concrete. The amount of dune sand varies from (0%, 50% to 100%) by weight of fine aggregates. The results show that the rheological properties favour the use of dune sands; however the mechanical properties support the use of crushed sand.

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The use of waste and by-products has been for many decades for the manufacturing of building materials such as concrete and mortars. That responds simultaneously to reasons of economy of natural resources in aggregates (C&D waste) and the possibility of recovering industrial waste additions as replacement in composites. The present study focuses on the use of plastic waste fibers embedded in the cement matrix of self-compacting concrete SCC to improve its properties, either rheological mainly, the stability at fresh state or mechanical responses such as compressive and tensile strengths at hard state. This incorporation of plastic fiber reinforcement on the structure matrix could result an alternative SCC composite as a ductile material with enhanced properties. In this context, the self-compacting composites by adding a variable percentage of plastic fibers at 0.5, 1, 1.5% is formulated. Hence, the effect of plastic fibers waste on the rheological and mechanical properties of SCC is assessed. The obtained results in the present study let us to conclude the beneficial effect of such inclusion of plastic fibers on this new confected SCC fiber composition with acceptable rheological, physical and mechanical properties compared to those of a normal SCC concrete.

Siliceous sand (dune sand) was partially replaced by slag sand (SS) at different proportions (0, 5, 10, 15, 20 and 25%). Using two types of fine aggregates, dune sand (DS) and slag sand (SS), grading, compressive and flexural strengths are measured on mortar. Physical and chemical characteristics of dune sand (DS), slag sand (SS) and cement were determined in this study. The results obtained indicate that the mechanical strength of mortar made with binary sand (DS/SS) depends of the nature and particle size distribution of sand studied.