Use of Industrial Silica Sand as a Fine Aggregate in Concrete—An Explorative Study

Industrial silica sand is a by-product obtained from the industries like paint, paper, rubber etc. It has a similar property with river sand and& M sand. This study explores the effect of high content of silica sand as a partial replacement for fine aggregate for concrete making in construction purpose. In this present research four types of silica sand from two different industrial units (coarser silica sand (VC and TC) and finer silica sand (VF and TF)) were used. The physical classification and morphology observation of silica sand through scanning electron microscope (SEM), energy-dispersive X-ray (EDAX), X-ray fluorescence (XRF) is examined. Fresh and hardened concrete properties were performed for the six sand samples, with two grades (M20 and M30) of concrete. No new compositions or phases were identified in silica sand concrete. Both fine and coarse silica sands were finer than river sand and M sand, as evaluated from the physical classification. The workability of silica sand mix at a fresh state improves the concrete performance up to 40%. The mix, which contains 80% coarser silica sand (TC) with 20% river sand, attained the maximum compressive strength of 34.5 Mpa and tensile strength of 3.5 Mpa at 28 days, which was the greatest of all the mixes. The combination of silica sand and river sand or M sand showed the superior impact of the concrete over the discrete concrete. SEM images showed the well-developed hydrated products like calcium silicate hydrate (CSH), calcium hydroxide (CH) and ettringite in all concrete mixes. It was observed from the XRD pattern that all concrete mixes containing silica sand have a high peak of quartz (SiO2), and calcium silicate hydrate (CSH) exhibits the formation of hydration products in the concrete. Similar stretching and bending patterns of silica sand concrete relates the pattern of nominal sand concrete as observed from Fourier-transform infrared spectroscopy (FTIR).

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