The northbound side at Exit 164, reopened about 6 p.m.
The southbound lanes were closed for two hours but reopened around 2:40 p.m. on Monday.
NEW: @OCNCGOV tells @ABC11_WTVD tandem trailer (truck w/two trailers) that exploded this morning on I-85 was carrying resin & paint thinners. Early analysis suggests truck hit debris, sparked fire then caused subsequent blasts. #ABC11 #BreakingNews pic.twitter.com/bSoSieSGU9— Jonah Kaplan (@KaplanABC11) May 4, 2020
Orange County officials told ABC11 that the tractor hauling two trailers was carrying resin, paper and rolls of cloth.
Investigators say the truck hit a mattress which sparked a fire that moved to the truck's first trailer.
Once the highly-explosive resin was consumed by the fire, firefighters moved in to extinguish the rest of the fire, which was still burning the load of paper and cloth.
A camera from the North Carolina Department of Transportation showed the vehicle erupting into flames.
The explosion and resin spill led to evacuations of businesses within 1,000 feet. The closures were a precaution because of the high-density vapors.
Two firefighters from the Efland Fire Department were injured when they took off gear that had resin on it, Hillsborough officials said in a news release.
The truck driver was not injured.
"Secure your loads," deputy Fire Chief Mac Cabe said. "If you lose something on the interstate, it's dangerous."