Comparative study on the engineering properties of crushed coarse aggregates used in jimma town.

Abstract

This experimental study carried out to investigate the quality and suitability of using locally available coarse aggregates in Jimma Town to make a concrete mix. Aggregate samples were collected from five different quarries according to ASTM sampling procedure. The experiments were performed on collected samples of coarse aggregates to evaluate their physical and mechanical properties as per ASTM and BS standards. Concrete compositions made, using the same aggregates were tested for mechanical properties (Engineering property and compressive strength). Concrete mixtures were prepared, tested and compared regarding Compressive strength and Engineering property. These tests were carried out to evaluate the strength properties at 7 th day, 14th day and 28th day. The results of this study showed that the concrete made using Geruke quarry crushed coarse aggregate performed satisfactorily regarding mechanical properties. Moreover, their performance was found to be quite similar to those aggregates commonly available and used in the town of Jimma quarry sites such as Beda Buna, Sheteradion, Kisho, and Buna Board quarry crushed coarse aggregates. The result showed that sheteradion, kisho, and geruke crushed coarse aggregate, were within the acceptable limit of ASTM C-33 standards. Whereas beda buna and buna board crushed coarse aggregates showed insignificant amount (89.1% and 87.49% percent pass through sieve no 25.0mm) or below the standards. The other aggregate quality test for Bulk density, Surface water contents, Specific Gravity, Absorption, Aggregate Impact Value, Aggregate Crushing Value, Abrasion and Impact in the Los Angeles and soundness by Sodium, were noted within the stipulated standard and limits. Properties of the concrete, mostly depend on the characteristics of the aggregates. It was observed that except SCCA and KCCA aggregates, the rest of the aggregates revealed higher compressive strength which is satisfactorily. Therefore, it can be concluded that the strength and durability of concrete are greatly influenced by the quality, strength, and durability of the coarse aggregate used. The result substantiated that variation in the compressive strength of concrete mixes with BBCCA, SCCA, KCCA, BB'CCA, and GCCA, with the values of 33.8 Mpa, 29.6 Mpa, 28.3 Mpa,32.7 Mpa and 34.7 Mpa respectively.