Inspire : Inspire Winter 2016
63 TECHNICAL ARTICLES CASE STUDY: GALLIPOLI GROVE In 2011, Boral Asphalt crews contracted to Bardavcol placed WMA as a trial at Gallipoli Grove as part of the $812 million South Road Superway Project in Adelaide. The objective was to assess the performance of Boral’s batch plant foaming unit in producing WarmPave asphalt, and to study the performance of the mix under local conditions. The project supplied and paved 3000 tonnes of WarmPave asphalt to upgrade local roads, to provide alternate access during construction of the Superway. Green field pavement was constructed to provide access for 18,000 vehicles per day for two years. FOAMING TECHNOLOGY A Green Pac foaming unit was installed at Boral’s Gepps Cross plant, allowing for WMA production. The unit injects a small amount of atomised water into the hot bitumen before mixing with heated aggregates, reducing the viscosity of the binder and allowing coating at 135°C. OUTCOMES One concern was that the new technology could increase the chance of rutting and moisture damage early in service life due to heavy traffic loading or insufficient drying of the aggregates during mixing. Two years later, the Boral team returned to site to find this was not the case, corroborating observations of WMA at other studies around the world. The Gallipoli Grove mix incorporated reclaimed asphalt pavement, which had the additional effect of helping to stiffen the binder properties in WarmPave. Super heating helped dry the virgin aggregate even though the overall temperature of the WMA is lower once the reclaimed asphalt has been added to the mix. Cores taken from the pavement in 2013, which were laboratory-tested for rust resistance and moisture impacts, still passed the specification limits set for newly-produced hot mix asphalt.
Inspire Summer 15-16