Effect of aggregate gradation variation on mechanical properties of bitumen concrete.

Abstract

Abstract This India boasts one of the world’s largest road networks, predominantly comprised of macadamized pavement-based highways featuring a thin bituminous layer. Aggregate materials make up over 90% of the hot mixed asphalt (HMA) used in these roadways. Bituminous Asphalt (BA) is commonly used as the top layer to distribute loads and protect weaker foundational surfaces from water damage, meeting strict MORTH classification standards. This study focused on Bituminous Concrete (BC) with grading II. Three aggregate gradation ranges (upper, middle, lower) were employed using the Marshall Method of mix design to evaluate the bituminous mixes. Marshall Stability values were compared among the different gradations. The mixes with median particle size distribution exhibited higher Marshall Stability values than others. Moreover, as particle size decreased, the optimal binding material content increased for each grading standard. Notably, BC II mixes within the middle limit range achieved the highest TSR% (94.70), while upper and lower limits recorded values of 88.11% and 92.78%, respectively. This research demonstrates the importance of aggregate gradation in BC II bituminous mixes for road construction. Median particle size distribution enhances stability, and as granularity decreases, binding material content should be adjusted accordingly. BC II mixes in the middle gradation range exhibited superior resistance to moisture-induced damage, underlining the significance of appropriate grading in road design.