TES analysis for crushed stone aggregate quarry site selection: the case of limestone terrain around Harer-Dire Dawa towns, Eastern Ethiopia

Abstract

The quality of crushed stone aggregates influences the durability and performance of pavement and concrete as they are the dominant component in the mix. Hence, the selection of a suitable quarry site with the quality source material is essential. Since the quarry site suitability assessment involves various factors, it is more economical to follow a stage-wise suitability assessment approach (i.e., preliminary evaluation and then refinement based on field data). The preliminary evaluation was done using readily available data in the office such as lithology, land use–land cover, proximity to built-up areas, distance to watercourses, distance to existing roads, relative relief, and slope angle. The purpose of the present work is to refine the preliminary limestone crushed stone aggregate suitability map (produced in the preceding work) considering the rock mass quality, slope stability, reserve, depth to groundwater table, and overburden thickness. The required data, such as unconfined compressive strength, rock quality designation, and geometrical properties of discontinuity, were collected during a detailed field survey from preliminary highly and moderately suitable sites. Rock mass classification systems, such as rock mass rating (RMR) and slope mass rating (SMR), were used to assess rock mass quality and slope stability, respectively. The weighting scheme approach is then applied and the ratings assigned to each factor (RMR, SMR, reserve, depth to water table, and overburden thickness) summed up to produce a total estimated suitability (TES) map. The map showed that 40.4% of the preliminary suitable sites are unsuitable, 20.3% moderately suitable, 14.7% highly suitable, and 24.7% most suitable.