Pervious concrete reactive barrier containing nano-silica for nitrate removal from contaminated water

Abstract

In this research, the effectiveness of using pervious concrete as a reactive barrier to decrease the concentration of nitrates in polluted water was investigated. Parameters of concrete mix design including water to cement ratio (W/C), aggregate to cement ratio (A/C), the amount of nano-silica (NS), and fine aggregates (FA) were studied based on Taguchi method. Properties of concrete such as compressive strength, density, permeability, and porosity, as well as pH measurement and the column method were carried out to assess the nitrate removal capacity of pervious concrete. Also, SEM-EDX, XRD, and FTIR were used to analyze the results. It was found that the optimum mix design in terms of nitrate removal corresponded to the mix with W/C = 0.26, A/C = 5, NS = 6%, and FA = 20%. Based on the results, it can be said that adding NS (up to 6%) and FA (up to 20%) to pervious concrete had the best influence on nitrate removal and compressive strength. Addition of NS increased the nitrate removal capacity due to increase in surface positive charges and provision of new surface functional groups.

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