Characterization of various modified asphalts using force ductility test with “8“ shaped mold and straight mold

•Force ductility tests were carried out using “8” shaped mold and straight mold.•Three failure types (brittle fracture, flow failure, and ductile fracture) were identified and summarized.•Three stages (elastic, yield, and slender neck) were identified in the force–deformation curve.•True stress was introduced to highlight the toughening effect of elastic modified asphalts.•The “8″ shape mold exhibits better discrimination ability and less variability than the straight mold.