An extensive laboratory investigation of the use of bio-oil modified bitumen in road construction

• Forensic investigation on binder bleeding in bio-oil modified surface dressings.
• Bio-oils had solubility issues with bitumen; low bonding between binder and stones.
• Modified binders showed high mass loss but kept rheological behavior after aging.
• Fish oil modified bitumen worked a little better than rapeseed oil modified binder.

Several roads in Iceland with bio-oil modified surface dressings exhibited severe distresses such as bleeding, binder drain down, and eventually as surface dressing sticking to tires. Samples from six road sections were evaluated in the laboratory to determine the causes of the failure. Binders with and without bio-oil, rapeseed oil and fish oil, were evaluated through a comprehensive rheological and chemical characterization. Both oils, exhibited solubility issues with the bitumen; consequently, the oils covered the aggregates, preventing bonding between binder and stones. It appears that fish oil worked a little better than rapeseed oil for binder modification.