Investigation of warm mix asphalt with cashew nut shell liquid: a sustainable green mix

Warm mix asphalt (WMA) is the most significant advancement in asphalt technology to create a sustainable environment for pavement construction by reducing harmful gaseous pollutants to the atmosphere. It is essential to propose a green warm mix additive from a renewable and biodegradable source and evaluate its performance in comparison with conventional hot mix asphalt. Present research focuses the effectiveness of cashew nut shell liquid (CNSL), a sustainable organic warm mix additive, having excellent antioxidant and antistripping properties. In this study, CNSL (2% of the bitumen’s weight) was added to both VG-30 bitumen and natural rubber modified bitumen (NRMB) and mixed with aggregates to produce warm mix asphalt (WMA) and rubberized warm mix asphalt (RWMA), respectively. To assess the effectiveness of CNSL, resistance to rutting, moisture susceptibility and fatigue strength of WMA (VG-30 bitumen + 2% CNSL + aggregates) and RWMA (NRMB + 2%CNSL + aggregates) were evaluated and compared with conventional hot mix asphalt (HMA-VG-30 bitumen + aggregates) and rubberized hot mix asphalt (RHMA–NRMB + aggregates). The potential benefits of CNSL help to perform as an effective additive of WMA and to overcome major drawbacks of WMA such as stripping. WMA and RWMA samples could reduce the rut depth by 42.4% and 9.5% and exhibit an increment of 18.07%, 13.5%, respectively, in TSR value compared to HMA and RHMA samples. WMA and RWMA samples could withstand, respectively, 12.36% and 9.04% more cycles to failure than HMA and RHMA at 20% stress level. Statistical analysis using R programming authenticated experimental investigations.