Investigation on Performances and Functions of Asphalt Mixtures Modified with Super Absorbent Polymer

Abstract: As cities grow and the climate changes, our roads are increasingly exposed to water damage, leading to cracks, potholes, and costly repairs. Traditional approaches tend to be expensive and short-term oriented. In response, engineers are exploring new materials to make roads more durable and long-lasting. One such innovative material is Super Absorbent Polymer (SAP), which shows promise in improving the quality of asphalt pavements by addressing water damage directly. This study delves into the potential of SAP for enhancing asphalt materials, focusing on its capacity to mitigate water migration and infiltration. When SAP encounters water, it swells, forming a viscous hydrogel that potentially seals cracks in the material, thereby preventing water penetration. This unique characteristic suggests SAP's suitability for repairing cracks in asphalt pavements and improving resistance to hydrodynamic damage. The research comprises a series of experiments assessing the impact of SAP on the mechanical properties and functionality of asphalt mastics and mixtures. Initially, SAP's basic properties are examined. Rheological tests are then conducted to explore the physical and mechanical effects of substituting mineral powder with SAP (at volumes of 10%, 20%, 30%, and 40%) in asphalt mastics. Subsequent evaluations, including the Marshall stability test, immersion Marshall stability test, freeze-thaw splitting strength test, Cantabro test, and permeability test, focus on water stability and infiltration resistance of SAP-enhanced asphalt mixtures. Findings indicate that SAP can partially replace mineral powder in asphalt mixtures, improving mechanical properties when substituting less than 10% of the mineral powder. Beyond this threshold, however, the high-temperature performance and fatigue life of the asphalt mastics diminish. The formation of amorphous hydrogels by SAP upon water absorption negatively impacts the water stability of asphalt mixtures as SAP content increases. Nonetheless, permeability tests show that SAP hydrogels effectively block seepage paths, enhancing the mixtures' resistance to water migration and infiltration and reducing permeability coefficients by up to 55%. The study concludes that incorporating an optimal amount of SAP into asphalt mixtures can confer desirable temperature and water stability. Also, SAP's distribution around microfractures or microcracks effectively obstructs rainwater penetration, enhancing the pavement structure's resistance to hydrodynamic forces.