Abstract
This study investigates the mechanical properties of asphalt concrete with crumb rubber (CR) as partial replacement of coarse
aggregate for wearing course. The proportions of the coarse aggregate replacement with crumb rubber (CR) were 5 %, 10 %, 15
%, 20 %, and 25 % by weight of the coarse aggregate. The Marshall Hot Mix Asphalt (HMA) design tests method was adopted in
which 15 specimens (3 samples each of the proportion) were prepared for the evaluation of Stability, flow, bulk density, air void
percentage, and void in mineral aggregate. These tests were conducted after a control test to ascertain the optimum bitumen
content (OBC) with 0 % crumb rubber (CR) and 5 %, 5.5 %, 6 %, 6.5 %, and 7 % of bitumen by weight of the asphalt mixture. It
was found that 5.5 % of bitumen content is suitable for the experiment. At the end of the research, it was found that 20 % of crumb
rubber (CR) replaced coarse aggregate in asphalt concrete is suitable for wearing course having satisfied Nigerian General
Specifications for Roads and Bridges (NGSRB, 1990) for criteria of Stability and flow. Hence, the optimum percentage of crumb
rubber (CR) to be used as coarse aggregate in asphalt concrete mix for wearing course is 20 %

Key words: Asphalt concrete, Coarse Aggregate, crumb rubber (CR), Hot Mixed, Optimum Bitumen Content (O.B.C),