Performance evaluation of HMAC mixes produced with gilsonite modified bitumen for heavily trafficked roads

Abstract

Abstract The structural distresses in the flexible pavements due to exponential increase in traffic volume, heavily loaded vehicles and changes in climatic conditions are decreasing the performance of the pavement and leading to premature failure. These structural distresses lead to increase in maintenance cost, decreases residual life of the pavement and cause delay to the road users due to lane closures. The concept of Perpetual pavements can be adopted as a solution to addresses these issues because of its enhanced design life with minimum traffic-disrupting reconstruction or maintenance. High modulus layer used in the perpetual pavement can be produced with hard grade bitumen. In this study Gilsonite is used as stiffening additive for modifying VG 30 to produce hard grade bitumen. The physical test results of modified bitumen with different percentages, show that 15% (by weight of VG 30) of gilsonite is the optimum percentage to produce hard grade bitumen according to the specifications of EME2 method. The results of resilient modulus and rutting test on High Modulus Asphalt Concrete (HMAC) mixes show that the modulus value is increased by 2.4 times and rut depth is decreased by 4 mm with conventional mixes. A pavement section for a design traffic of 300 msa has been designed for both conventional and HMAC mixes as per IRC:37-2018 guidelines. Based on the analysis, the thickness of DBM layer with Gilsonite modified bitumen has been decreased by 65 mm in comparison with conventional bitumen, because of which investment of money and use of natural resources like mineral aggregates will be saved.