EFFECT OF SAND REPLACEMENT BY MILL SCALE ON THE PROPERTIES OF CONCRETE

Abstract

Concrete is the most widely used construction material in the world. This popularity of concrete carries with it an immense environmental cost. Billions of tons of natural materials are mined and processed each year to be used in concrete, which leaves a substantial mark on the environment. Efforts to use suitable recycled materials as substitutes for concrete aggregate are gaining in importance, such as recycled concrete aggregate, post-consumer glass, tires, etc. But one waste material which has not been extensively tested yet is mill scale. Mill scale is a flaky hazardous solid waste formed on the steel’s surface during the steel manufacturing processes. This work aims to evaluate the use of mill scale in Portland cement concrete, as a replacement for natural fine aggregates. Cement mortars with mix proportioning 1:3 were prepared varying the mill scale content of fine aggregate form 0% to 100%, for determination of compressive and tensile strength. The water/cement ratio used was 0.5 for all mix proportions. The compressive strength at different proportions did not give a general trend and two peaks were obtained at 60% replacement and 100% replacement. Maximum tensile strength was observed at 60% replacement of standard sand. A mix design was also done for M35 grade of concrete by the IS method. OPC of 43 grade was selected and sand replacement was done with mill scale varying from 0% to 80% with a suitable water cement ratio of 0.40. The compressive strength was measured after 28 days of completion of curing. Maximum strength was obtained for 40% sand replacement. Moreover, concrete with mill scale has demanded greater water content to maintain the workability.