EVALUATION OF MECHANICAL PROPERTIES OF ASPHALT MIXTURE CONTAINING STEEL SLAG AND POLYMER MODIFIED BITUMEN

Abstract

Natural aggregates compose 85% to 90% of the typical asphalt mixture. Therefore, natural aggregates play a significant function in the asphalt mixture. However, extracting natural aggregate has negative effects on the environment[1]; also, natural aggregates are not available in some areas. Therefore, to reduce the dependency on natural aggregates, we need to find some viable alternatives that we can use for road construction. Steel slag is waste produces in the steel manufacturing industry. This research explores the viability of incorporating steel slag as a coarse aggregate in bituminous concrete mixes and its impact on various properties. Marshall specimens were prepared using five different mixtures, varying in the percentage of coarse steel slag aggregates (ranging from 0% to 100%) and employing two types of binders (SBS modified binder and VG-10). The optimum bitumen content was determined through these preparations. The mechanical performance of the mixtures was determined through different standard tests (like Marshall properties, Resilient modulus, Indirect tensile strength, cantabro loss, rutting resistance, fatigue test, and moisture resistance test). Steel slag exhibited superior strength and hardness characteristics compared to natural limestone aggregates. Significant findings suggested that replacing natural aggregates with steel slag improved the performance properties of the asphalt mixture. Although the incorporation of steel slag has significantly increased optimum binder content because of steel slag's porous nature, significant improvement in marshal stability has been observed. The incorporation of steel slag improved the rutting and fatigue resistance of the asphalt mixture. Similarly, maximum resilient modulus was observed when 100 % natural coarse aggregates were replaced with steel slag aggregates. Because of steel slag, a rougher texture surface and angular shape improved the interparticle friction between two aggregates, further improves the mechanical properties of asphalt mixtures. Steel slag asphalt mixture with polymer-modified binders performed better than steel slag and VG-10 mixes. According to our findings, a 100% coarse steel slag mixture is the optimum content for the asphalt mix preparation. Aging is a critical factor affecting the long-term performance of asphalt mixtures. As asphalt binder ages, it undergoes oxidative hardening, which can lead to increased stiffness and brittleness, ultimately resulting in a higher susceptibility to cracking and reduced fatigue life. This study also investigates the aging characteristics of asphalt mixtures containing steel slag. Laboratory aging simulations were performed to evaluate the changes in mechanical properties over time. The results indicate that steel slag-containing mixtures exhibit better resistance to aging compared to natural aggregate mixtures, thereby enhancing the durability and lifespan of the pavement.