A comprehensive study for physical and chemical properties of road dust to utilize in concrete mix design, collected from diversified locations of Delhi NCR

Abstract

Rising volume of road dust is a serious concern in global as well as Indian scenario. To find out the possible application, chemical and physical characterizations of road dust of six diversified sites of Delhi, National Capital Region, India were carried out prior to utilize in concrete mix design. The chemical characterizations suggest major and minor components are oxides of silicon, aluminium, iron, sodium, calcium, potassium, sulphur, phosphorous, manganese etc. X-ray diffraction studies depicted major phases of silica, muscovite/ illite, K-Feldspar and albite minerals. Scanning Electron Microscopy studies depicted flacks, fibrous, spherical, irregular, voids and hexagonal morphologies. Further detailed studies of road dust of two sites were carried out in concrete mix design following IS and ASTM test methods to know the effects on compressive strength, flexural strength, water and rapid chloride permeability test after replacing upto 50% of stone sand by road dust. The 7th and 28th days compressive strength test results of two sites concrete showed 16.51%, 8.25% and 4.67%, 2.34 % lesser strength in comparison to control concrete respectively. Similarly, 7th and 28th days flexural strength studies of same sites concrete showed 19.67%, 14.75% and 6.85%, 1.37% lesser strength in comparison to control concrete, respectively. The depth of water penetration test results of two selected sites of concrete showed 13.14% and 10.22% lesser extent of water penetration under 5 bars hydrostatic pressure, when compared to control concrete. The RCPT results of same sites concrete showed 33.47% and 9.48% greater extent of chloride ion permeability, in comparison to control concrete. The results obtained after 7th and 28th days of conventional stone sand concrete and road dust concrete, showed quite comparable results. However, in case of water permeability test the road dust concrete showed lesser extent of water percolation in comparison to conventional concrete, this may be due to presence of more fines in road dust, which may have caused better packing and lesser voids for water to ingress.