GIS-AHP Based Quarry Site Suitability Analysis and Characterization of Crushed Stone Aggregates for Construction use in Jigjiga Town, Eastern Ethiopia

Abstract

Crushed stone aggregates are the main constituent of concrete. The recent development of Portland cement has increased the use of geological material for concrete production. The crushed stone aggregates are produced by quarrying activity. Nevertheless the activity causes major socio-economic and environmental impacts. Therefore appropriate measures should be taken during quarry site selection and operation. The main objective of this study is to select suitable quarry sites and to assess the suitability of crushed stone aggregates for construction in Jigjiga town. The suitable quarry sites were identified by adopting a GIS- AHP approach in which 8 factors were considered for quarry site selection. In the process of suitable quarry site selection, weighted overlay analyses was used in which land use land cover, distance to buildup area, overburden thickness, distance to water bodies, distance to road, relative relief and slope angle of the area were considered to produce the preliminary quarry suitability map. Finally the final quarry site suitability map of the study was generated, using math algebra product of lithology and preliminary quarry site suitability map. The final preliminary quarry site suitability map showed that 28.2% (598.4 Km2 ) of the study area is highly suitable for quarry sites where as 25.6 %( 543.2 Km2 ), of the area is unsuitable. In contrast the suitability of 11.6 % (246.7Km2 ) and 34.6% (735.6Km2 ) is moderate and low respectively. Following the suitable quarry site selection rock aggregates were collected from highly suitable areas for quarry site and physico-mechanical properties such as water absorption, specific gravity, aggregate shape test, crushing value (ACV) Los Angeles abrasion value (LAV), Impact value (AIV), sodium sulphate soundness test and petrographic analyses were conducted to assess the suitability of the aggregates for construction use. Aggregates from quarries 1, 2, 3, 9 and 10 have shown good quality in term of physical, mechanical properties and also stable in term of alkali-silica reactivity