EXPLORING THE POTENTIAL OF RED ASH AND MARBLE CHIPS AS ALTERNATIVES IN BASE COURSE MATERIAL VIA BLENDING WITH CRUSHED STONE AGGREGATE

Abstract

Despite its abundance, red ash has compaction issues owing to its lightweight, rough circular surface, and high porosity. The usage of conventional base course materials across the country incurs shipping expenses and takes time, slowing down projects because they are only widely available in limited areas across the country. In this study, non-probably sampling approach was used to examine the potential for employing red ash and marble chips as an alternative base course material by mixing them with crushed stone aggregate (CSA). In order to accomplish the goal of this study, an experimental test was conducted via trial and error, focusing on the mechanical stabilization of red ash and marble chips. Their physical characteristics were subsequently assessed through laboratory testing. In the laboratory, nine (9) samples of red ash and marble chips blended with CSA in varying percentages (0, 5, 10, 15, 20, 25, and 30 percent) were examined. The laboratory test results showed that 100% red ash and marble chips gave; CBR, SG, AIV, ACV, LAA, FI, EI, water absorption, and soundness: 55.4%, 2.38%, 18.20%, 26.34%, 19.69%, 5.59%, 12.09%, 2.5% and 13.80 and 83.6%, 2.63%, 19.70%, 26.41%, 19.75%, 23.2%, 16.9%, 1.24% and 12.22 respectively. Several of these test results align with the Ethiopian Road Authority (ERA) standard specifications; however, the findings from the CBR, water absorption, and soundness tests do not. Thus, mechanical stabilization was employed to improve the samples' physical characteristics. Experimental results are obtained by mixing 20% red ash, 20% marble chips, and 60% CSA. The values for CBR, SG, AIV, ACV, LAA, FI, EI, water absorption, and soundness are 102.5%, 2.55, 14.23%, 19.84%, 7.92%, 18.61%, 20.77%, 0.83%, and 7.38, respectively. The CBR, water absorption, and soundness characteristics all meet the necessary ERA standard specifications for crushed weathered rock (GB2) and natural coarsely graded granular materials (GB3) at this particular proportion. Hence, it is recommended to incorporate red ash up to 20% and marble chips up to 20% by weight, alongside 60% CSA, for constructing road base courses, particularly when these materials are reasonably accessible from construction sites and are widely available in the area.