Evaluation of HMA and WMA RAP mixture using hydrogenated castor oil flakes

In this study, reclaimed asphalt pavement (RAP) used in different percentages in hot mix asphalt (HMA) and warm mix asphalt (WMA) were tested for moisture, fracture and rutting resistance adding hydrogenated castor oil flakes (HCOF) as rejuvenating agent. Volumetric and Marshall parameters were evaluated for both types of mixtures. Addition of 5% of HCOF by weight of binder content in RAP found to restore properties of aged binder. WMA mix was made by adding 0.1% Zycotherm by weight of optimum binder content. Moisture, rutting and fracture damage performance were assessed utilizing indirect tensile strength, wheel tracking and semi-circular bending tests. The mix's tensile strength ratio increased by 2.3% in the HMA with RAP (HMA-R) mix compared to the WMA with RAP (WMA-R) mix at 10% RAP content. HMA mixes provide better resistance to rutting compared to WMA. However, 40% of RAP content HMA-R and WMA-R using HCOF rejuvenator shows greater rutting performance compared to other RAP mix. HMA-R mix fracture resistance increased by 18.14% compared to WMA-R mix when RAP content increases to 40%. Regression analyses were carried out to validate the strain energy found from fracture damage analysis of both HMA-R and WMA-R with R 2 value more than 0.9. HMA-R protected moisture and fracture damage better than WMA-R. The rejuvenating efficiency of HCOF was further validated using Fourier transform infrared and microscopic analysis. • Hydrogenated castor oil flakes (HCOF) used as a rejuvenator in bituminous mixes with reclaimed asphalt pavement (RAP). • The moisture and fracture damage performance of HMA and WMA mixes were evaluated adding 50% RAP and 5% HCOF by RAP bitumen weight. • HMA-R mix exhibited superior moisture, fracture and rutting damage protection compared to the WMA-R mix. • The resistance to fracture damage of the HMA-R mix increased compared to the WMA-R mix as RAP content rises. • Fourier transform infrared analysis and microscopic test also confirm the efficacy of HCOF as a rejuvenating agent.