The College of Engineering at the University of Baghdad hosted the public defense of the Master’s student Aya Kamil Asad from the Civil Engineering Department for her thesis titled ” Improving Asphalt Concrete Performance Using Soda Lignin Powder” on Monday, February 17, 2025, in Dr. Khalid Shaker Hall in the Civil Engineering Department, under the supervision of Professor Dr. Amjad Hamad Khalil Albayati.
The main objective of this study was to evaluate the feasibility of using soda lignin powder derived from a plant source as a modifier for asphalt cement to improve the performance of the asphalt concrete mixture. The work includes extraction of soda lignin powder (SLP) from the pinus wood sawdust through an alkaline treatment process. The effectiveness of extracted SLP as an asphalt modifier was examined using three different percentages (2%, 4%, and 6%) by the weight of asphalt cement, through viscosity, penetration, softening point, and ductility tests. Moreover, evaluated the performance of asphalt mixtures for wearing course through Marshall properties, moisture susceptibility using the Indirect Tensile Strength test (ITS), permanent deformation and resilient modulus using uniaxial repeated loading test, and cracking resistance using the Indirect Tensile Cracking test (IDEAL-CT). Asphalt cement test results indicated that incorporating SLP reduced the temperature susceptibility of asphalt by increasing its stiffness and viscosity of the base asphalt increased at each level of SLP. The performance test findings indicated that the asphalt mixtures with 6% SLP showed a higher improvement in Marshall stability with 19.6%, enhanced moisture resistance, with a Tensile Strength Ratio (TSR) of 87%, a 74.1% reduction in accumulated permanent deformation, and a 38.1% increase in the Cracking Tolerance Index (CT index) compared to the control mixture.
Based on the results of this study, some recommendations were proposed for future research, including investigating the effect of using different percentages of SLP in asphalt mixtures in addition to studying the influence of SLP on the aging properties of the asphalt mixture.
After the scientific discussion by the esteemed members of the examination committee, listening to the researcher defense, and evaluating the thesis, the researcher was awarded a Master’s degree in Civil Engineering / Highway and Transportation Engineering.
