AfDB has reportedly declined to disburse the first instalment of the loan.
Groupe ADP beat intense competition with several multinationals to clinch the deal.
The runway will nearly double the movement of aircraft from 25 to 45 per hour.
In February, Yapi Merkezi and Mota-Engil Africa were hired for the project.
The signing of the deal will enable the contractor to kick off works by January next year.
The re-introduction of toll stations is, however, likely to face huge legal encounters.
Kenya has recently embarked on projects aimed at opening up the northern corridor.
Bechtel has been picked to build the Mombasa-Nairobi Expressway.
Engineered Material Arresting System is cheaper than the traditional technique.
The project has faced numerous challenges including hiccups in relocating utility lines.