Self-healing behaviors and its effectiveness evaluations of fiber reinforced shape memory polyurethane/SBS modified asphalt mortar

To further understand self-healing behaviors of cracks in fiber reinforced asphalt mortar, shape memory polyurethane/styrene butadiene styrene modified asphalt mortar (PSAM) was first prepared. Then shape memory properties of lignin fiber reinforced PSAM (LFAM) and polyester fiber reinforced PSAM (PFAM) were characterized. The effects of filler-asphalt ratio and fiber type on the multi-cycle self-healing results of LFAM and PFAM were discussed. The self-healing effectivenesses in each crack-healing cycle and whole multi-cycle self-healing process were evaluated. Results indicate that shape memory properties of LFAM and PFAM are lowered as their filler-asphalt ratios are increased. LFAM and PFAM show satisfactory shape memory properties, but PFAM has better shape memory performance than LFAM, and its higher shape recovery force further improves its self-healing effectivenesses. Also, when the filler-asphalt ratio is raised, both creep deflection and creep slope of LFAM and PFAM are decreased, but their creep stiffnesses are increased. The self-healing mostly restores the mechanical properties of LFAM and PFAM. PFAM shows higher low-temperature crack resistance than LFAM. Meanwhile, the creep deflection and creep slope of PFAM are higher than those of LFAM as the filler-asphalt ratio is the same one, while the creep stiffness of PFAM is smaller than that of LFAM. LFAM shows a brittle failure at low temperature, but PFAM shows a flexible failure. Additionally, the self-healing effectiveness of LFAM and PFAM in each crack-healing cycle is decreased as the crack-healing cycle is increased. Finally, PFAM shows a higher self-healing rate than LFAM. The mechanical and self-healing characteristics of PFAM are more stable than those of LFAM. The multi-cycle self-healing test indexes can assess the multi-cycle self-healing effectiveness of LFAM and PFAM.