Evaluation of fracture performance of Polyvinyl Alcohol fiber reinforced hot mix asphalt

Abstract

• Fracture performance of reinforced HMA was significantly affected by Gradation type, binder grade, and PVA fiber dosage. • Coarse graded reinforced HMA exhibited 25% higher strength than fine graded HMA at 0.3% fiber content. • FE and FI doubled for lower grade asphalt reinforced HMA than control. • Coarse graded HMA showed higher fracture growth rate. • SEM and DIC analyses revealed effective crack bridging and enhanced strain distribution due to fiber reinforcement. Several studies have been conducted over the past two decades to evaluate the fracture and fatigue performance of hot mix asphalt (HMA) reinforced with different fiber types, dosages, and aspect ratio. However, a few studies focused on the impact of aggregate gradation and binder grades on the fracture performance of fiber reinforced mixtures. This study adopted a systematic approach to evaluate the impact of three different coarse and fine aggregate gradations with different nominal maximum sizes using three different binder grades and varying Polyvinyl Alcohol (PVA) fiber content. Semicircular bending beam (SCB) test was performed to evaluate several fracture characteristics of PVA fiber reinforced HMA. Experimental results revealed that binder grades and gradation significantly affect the fracture performance of such mixtures. Total fracture energy, flexibility index, and stiffness of 0.3% PVA reinforced PG 58-22 mixtures were doubled relative to control ones. However, fiber reinforced PG76-22 mixtures exhibited up to 50% improvements. The fracture growth rate reduced by 250% at 0.3% fiber content in coarse graded mixture while cumulative energy per unit crack length increased by 190% in fine graded mixture. Digital Imaging Correlation analyses revealed more twisted and convoluted fracture path and higher strain distribution in lower grade asphalt reinforced mixtures with lower nominal maximum size gradation. Scanning electron microscopy micrographs showed proper fiber coating of asphalt and effective fiber bridging across the cracks indicating enhanced resistance to post-peak deformation under load.