Gladstone Airport Runway , Qld – Foamed Bitumen

In June 2010, SPA undertook part service foamed bitumen stabilisation works as part of the $45M redevelopment works at Gladstone Airport to improve existing infrastructure and increase serviceability levels for future growth.

The section of works SPA undertook involved correcting the vertical alignment of the existing runway at a width of 35m between chainages 1920m to 2090m with increase in pavement depth up to 750mm on existing levels. Original designs comprised asphalt courses to achieve this however discussion from SPA engineers encouraged the use of a more economical solution encompassing layers of foamed bitumen (3% C170 bitumen and 1.5% Hydrated lime), combined with a manufactured Type 2.1 gravel. The gravel was mixed and then loaded into trucks to be placed, compacted and trimmed as per conventional granular construction.

Due to the limited occupancy hours overnight for construction, and the need to maintain serviceability of the runway during the daylight hours, it was agreed that foamed bitumen mixing work activities would be undertaken on a pad offline to reduce the number of plant required on the runway and hence minimise risks associated with construction.

Construction was completed over the allotted 6 night duration and all quality targets were achieved as planned. The foamed bitumen pavement was subject to aircraft taxiing loading including point loads up to 9 tonne screwing on the surface with no significant damage.