Performance of modified asphalt binders and mixtures incorporating palm oil fuel ash, garnet waste, and sawdust as additives / Wan Noor Hin Binti Mior Sani,

Faculty of Civil Engineering Technology

Thesis (Doctor of Philosophy in Civil Engineering) -- Universiti Malaysia Pahang Al Sultan Abdullah – 2025

Includes bibliographical references

Given the increasing traffic loads and challenging environmental conditions, significant attention had been devoted to developing high-quality asphalt mixtures with desirable characteristics. Nonetheless, modified asphalt binders demonstrate difficulties in accurately predicting their constant performance when combined with waste elements. Therefore, this study investigated the characteristics and applications of modified asphalt binders and mixtures containing palm oil fuel ash (POFA), garnet waste, and sawdust as additives in asphalt modifiers. The process involved thorough evaluations regarding several aspects: (i) the chemical and physical features of modified asphalt binders and mixtures, (ii) the mechanical properties of modified asphalt mixtures, and (iii) the structure and morphology of these mixtures analysed using response analysis and image processing. Various mixtures comprising asphalt grade 60/70 were combined with different proportions of 0% (0:0:0), 3% (3:3:3), 6% (6:6:6) and 9% (9:9:9) (POFA: garnet waste: sawdust) by weight of the original asphalt. The unprocessed wastes and modified asphalt binders were then analysed regarding chemical and physical characteristics. These analyses were performed using numerous characterisation tools: (i) chemical analysis involved X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and atomic force microscopy (AFM), while (ii) physical analysis involved penetration, softening point, viscosity, dynamic shear rheometer (DSR), and thin film oven test (TFOT) assessments. Other analyses included in this study for the modified asphalt mixtures involved investigating Marshall stability properties, dynamic creep, resilient modulus, and indirect tensile strength. The response surface methodology (RSM) and ImageJ were also employed to examine the structure and morphology of the modified asphalt mixtures. Consequently, the chemical compositions and morphologies of the mixtures were significantly impacted by the correlation between the 6% of modified asphalt binder and mixture (6% POFA, 6% garnet waste, and 6% sawdust). Compared to other aged modified asphalt mixtures, superior stability, excellent creep recovery, and high temperature susceptibility were demonstrated by the 6% modified asphalt mixture. Thus, these outcomes indicated practical evaluation of the sustainability of waste materials as asphalt modifiers and their corresponding impact on the performances of asphalts. The results could encourage highly sustainable, resilient, and environmentally aware approaches to advancing road construction practices.