The potential use of the cinder (scoria) as a base course material when blended with fine crushed rock (The case of Adama Area)

Abstract

In recent years, the highway and construction industries have consumed an enormous amount of conventional aggregate every year. The increasing demand for conventional aggregate causes an increase in the cost of construction. In such instances, using of locally available materials plays a significant role in the cost and time saving of road construction projects. Hence, this research was initiated with the motivation of upgrading and utilizing the cinder gravel, which is one of the abundantly available low-cost materials in the main rift valley of Ethiopia. Besides, in some regional parts of Ethiopia, there is a scarcity of good base course materials. Using these materials everywhere incurs transportation cost and is time consuming. Therefore, this study has been carried out in order to investigate the performance of mechanically blended natural cinder gravels to be used as a road base course material and to provide an alternative material for road construction. An attempt has been made in this study to evaluate the potential use of cinder gravel as a base course material when blended with fine crushed rock aggregate. To achieve the objectives of the research, mechanical stabilization and laboratory tests have been carried out at different percentages of cinder gravel by (0%, 15%, 20%, 25%, and 30%) of fine crushed rock weights. The laboratory test results for cinder gravel indicated Los Angeles abrasion value (LAA), specific gravity (SG), aggregate crushing value (ACV), and aggregate impact value (AIV). Plastic Index, Water Absorption, and California Bearing Ratio (CBR) of 42.7, 2.4, 45.7%, 32.4%, non-plastic, 8.83%, and 65.54%, respectively. These test results failed the ERA standard specification for some tests, and they showed marginal quality values for the standard specification for GB2 and GB3 base course materials. Thus, mechanical stabilization was done to improve the mechanical and physical properties of cinder gravel. Blending of 75% cinder gravel with 25% CFA results in LAA, SG, ACV, AIV, Plastic Index, Water Absorption, and CBR of 35.7%, 2.7, 28.1%, 27.98%, non-plastic, 1.16%, and 125%, respectively. At this proportion, the gradation is also observed to fit with the required ERA standard specification of GB2 and GB3 materials. Therefore, it can be concluded that the use of cinder gravel up to 75% by weight is recommended for the road base course layer in places where the materials are abundantly available