Assessment of Mine Tailing and Quarry Dust as Joint Concrete Aggregates

Abstract

The consumption of natural resources like sand and stones for concrete production has resulted not only in their scarcity but also in environmental degradation associated with their extraction, and air pollution due to the generated quarry dust as result of the rock crushing. Also, with increase of mining sites in Rwanda, the amount of mine tailings has extremely increased, and their dumping is becoming a big challenge. The purpose of this study was to search for an engineering solution to the above dual problem, analyzing the performance of both mine-tailings and quarry dust as potential replacements for ordinary aggregates in concrete. The methodology consisted of evaluating the properties of the two materials, and then the analysis of strength characteristics for the new concrete manufactured using the two new aggregates. Concrete preparation was done by keeping constant the mine tailings portion as coarse aggregate, while partially replacing river sand by quarry dust at different fractions as 0%, 10%, 30% and 50%. It was established that, comparatively to normal concrete at 28 days, the compressive and tensile strengths of concrete with mine-tailings and river sand increased from 27MPA to 37.5 MPA, and from 1.9 to 3.1 MPA respectively on one hand, and on the other hand the compressive and tensile strengths decreased with partial replacement of river sand by quarry dust from 37.5 to 27.9MPA and from 3.1 to 2.3 MPA at replacements from 0% to 50% respectively. It was concluded that mine tailings and quarry dusty can be used together as concrete new aggregates in replacement of ordinary aggregates, with a due attention to concrete workability and its area of application.