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

To explore a suitable mold for the force ductility test and propose a new index to better characterize low -temperature properties of modified asphalt, plain asphalt (PG 58-16, PG 52-22), styrene-butadienestyrene (SBS) modified asphalt (4.2 %, 7.5 %), low-density polyethylene (LDPE) modified asphalt (3 %, 8 %) and crumb rubber modified asphalt (20 %) were characterized using the force ductility test with 8 shaped mold and straight mold, respectively. The difference between their failure types and force-deformation curve evolution stages was analyzed. True stress was calculated to highlight the toughening effect of elastic polymer modifiers. Results demonstrate that three failure types (brittle fracture, flow failure, and ductile fracture) and three deformation stages (elastic, yield, and slender neck stage) can be observed and summarized for the force ductility test. The ductile failure and slender neck deformation stage is only observed for elastic-modified asphalts, which highlights the elastic polymer's toughening effect. 8 shaped mold appears to be a better choice than straight mold due to its better discrimination ability and less variability. The calculated true fracture stress has a very strong correlation (R2 > 0.95) with deformation energy, which shows a good discrimination between modified asphalts.

Automated summary

This study explores a suitable mold for the force ductility test and proposes a new index to better characterize low-temperature properties of modified asphalt. By analyzing the difference in failure types and force-deformation curve evolution stages, three failure types and three deformation stages are observed and summarized for the force ductility test. The results show that elastic polymer modifiers have a toughening effect. The 8-shaped mold is better for distinguishing different modified asphalts compared to the straight mold. The calculated true fracture stress has a strong correlation with deformation energy, providing good discrimination between modified asphalts.