ISTANBUL, March 27 (Reuters) - A consortium building a motorway between Gebze and Izmir in western Turkey plans to sign a $600 million loan accord with eight banks for a section of the road in April, consortium leader Nurol Holding&aposs chief financial officer said on Thursday.A consortium of Nurol, Italy&aposs Astaldi AST.MI , Ozaltin Makyol, Yuksel and Gocay Insaat won the 22-year operating rig