Evaluation of suitability of coarse aggregates for concrete in mekelle area, Ethiopia

Abstract

Aggregates constitute the bulk of the total volume of concrete and hence influence the strength of concrete to great extent. It is essential that aggregates used in construction purposes are strong and durable. Construction aggregate is crushed rock material used in concrete which make up most of engineering works. The main objective of this research was to assess the quality of coarse aggregates and evaluate their suitability for concrete of the limestone rock material sources in Mekelle area, northern Ethiopia. As there was no previous studies on the quality of aggregates in Mekelle this research was designed to better understand the properties and qualities of aggregates used in the project area. The study involved assessment of the different sources of rocks for concrete aggregates, collecting representative samples and laboratory analysis. The study mainly focused on 20-30km radius from Mekelle city and 10 representative quarry sites were analyzed. The properties used to assess the suitability of rocks as aggregate materials include tests like: Los Angeles Abrasion (LAA), Aggregate crushed value (ACV), sieve analysis, flakiness index, moisture content, unit weight, specific gravity and water absorption. Results of the analysis show that the ACV of aggregate varies between 5.9% and 19.7%, the LAA value ranges from 24.94% to 33.62%, the water absorption ranges from 0.34% to 0.76%, and the moisture content falls below one percent. All the test result shows that the aggregate fulfill the ASTM standard requirement except moisture content is below the minimum ASTM requirement. This research has given a better understanding of the quality and suitability of rock material used for concrete in Mekelle area, Ethiopia.