Such a result is unqualified. The main reason for this phenomenon is that the inner wall of the ductile die is not well bonded, and the biggest possibility is that the inner wall surface is polluted. If it is polluted, it may be that the asphalt sample has been separated from the inner wall of the ductility die at the initial stage of the test, so that the end of the asphalt sample will shrink continuously with the elongation at 5℃. When it reaches about 30cm, the end of the asphalt sample will be pulled out of the ductility die because of excessive shrinkage. This often happens with SBS modified asphalt.

The solution is to clean the inner wall of the ductile mold carefully.

The approximate range of 5℃ asphalt ductility: ordinary asphalt (5 ~10 cm); SBS modified asphalt (20 ~ 60 cm); SBR modified asphalt (usually greater than 100cm)