Minimum values of ductility specified by ISI for various grades are as follows. Source of paving bitumen and penetration grade Min ductility value (cms) Assam Petroleum A2Z. =5 A35 =10 A45 =12 A65, A90 and A200. =15 Bitumen from sources other than Assam Petroleum S35 =50 S45, S65 and S90 =75