Conference

AustStab Conference 2023: Sustainable Pavements for Future Generations Home Introduction AustStab is the Australian Pavement Recycling and Stabilisation Association. It is a not-for-profit industry association to help provide a unified approach to the recycling and stabilisation of road pavements and to develop national standards of research and performance. AustStab held the 2nd Australian Pavement Recycling and Stabilisation Conference on 22 August 23. The theme was Sustainable Pavements for Future Generations. It was well attended by the industry and proved to be a very collegiate and informative affair.  The full list of conference presentations and speaker biographies are here. In this article we will summarise some of the more notable presentations. Key Points / Summary Australia’s roads are not resilient and not sustainable. A rapid pivot in approach is required. Experts agree that pavement recycling and stabilisation is the way forward, with several key advantages over conventional unbound granular pavements: Lower cost of ownership (low construction cost, longer life) Resilient (to flooding [climate change] and high wheel loads) Truly sustainable (high recycled content, low carbon, no landfill) There are various stabilisation approaches available (goals, methods, binders). The optimal approach is project/context specific. Sustainable Pavements for Future Generations The first keynote presentation was delivered by Michael Caltabiano, CEO of the National Transport Research Organisation (NTRO). The Australian Road Research Board (ARRB) is transitioning into the NTRO – expanding its work across all modes of transport – road, rail, ports and airports. Michael presented the Flood Recovery Response Case Study, where the Victorian Department of Transport and Planning engaged NTRO to conduct asset performance assessments using NTRO’s state-of-the-art iPAVe technology. NTRO completed network wide surveys in 2021 & 2022, assessing road roughness, rutting, cracking, strength/deflection and profile. Many millions of dollars were spent after the 2021 iPAVE survey, resulting in the percentage of ‘good’ or better roads had increasing from 2% to 19% in 2022. In October 22, the Victorian road network was affected by floods. The 2023 iPAVe surveys revealed a worrying degradation of the flood impacted roads, beyond the obvious visible problems (potholes etc). By 2023, there were no ‘good’ or better roads.  Moreover, the percentage of roads classed as ‘fair’ or better dropped from 70% in 2022 to just 9% in 2023.  Clearly, despite significant recent investment, the network was not resilient. Michael presented his vision for achieving 100% recycled roads, which hinged on making better, data driven decisions for our road assets. He explained that pavement recycling and stabilisation technology will be central to delivering the sustainable and resilient transport infrastructure required by Australia. He noted that conventional unbound granular pavements are not resilient, as evidenced by recent major failures of new pavements in high load applications. With the predicted trends of higher wheel loads and increasing frequency & severity of flood events, he encouraged the industry to emphasize the technical benefits of stabilisation to the roads market. 2022 Flood Response – North East Victoria Keynote speaker Charles Webster is the Alliance Program Manager for the North Eastern Maintenance Alliance (NEMA). NEMA manages the VicRoads (Department of Transport and Planning) network in the Hume region, one of five regions overseen by Regional Roads Victoria. In October 2022 Victoria experienced extensive flooding, particularly across the Northern and North East regions of Victoria. The flood required a significant initial response to manage the large amount of road closures that needed to be implemented. Close coordination occurred with emergency services during the acute stages of the flooding as well as mobilising a large workforce at short notice to deal with the response. After the initial response, the team focused on recovery and rectifying the damage that occurred across the 4,000km network. Rectification works included 254,000m2 of granular stabilisation digouts, using 2% cement insitu stabilised to 200mm depth. The process was successful. However, a comparison with recent NSW “Heavy Patch Program” projects suggested that a ‘heavier’ stabilisation treatment would yield a much longer pavement life at a marginal increase in construction cost. Charles emphasised that resilient pavements were possible, but relied on getting the basics right. The primary defence (against water) was good maintenance – surface seals, drains and mowing. Stabilised pavements are much more resistant to water ingress than granular pavements and provide an effective secondary defence. A Simplified Approach to the Selection of Pavement Structures Containing Stabilised Materials Kenny Festing from Apexx Engineering Consultants presented the results of his Master of Pavement Technology research thesis on the topic: “Can the use of stabilised material in pavement structures be categorized into a holistic pavement selection framework for use in the Australian context?”. The context for the topic and benefits to the road pavement industry are: Pavement stabilisation will continue to increase in popularity as road asset owners seek more economical ways of maintaining networks. Circular economy an increasing driver – less quarried material, more beneficial reuse. Traffic volumes continuing to increase – mitigating impacts to road users a significant benefit of stabilising. Kenny began with a series of ‘Stabilisation 101’ slides; briefly covering stabilisation definition, standards, techniques, pavement layers, stabilisation categories, binders and structures. Next, he summarised the 2001 and 2022 survey results on stabilisation methods and performance of local government roads in Australia. In 2001 it was found that there was general doubt when specifying stabilised pavement materials, leading to poor outcomes. The 2022 survey confirmed that selection processes varied significantly: ‘Pavement Experts’ undertaking detailed design using Austroads specification supplemented with industry publications. ‘General Practitioners’ adopting historical designs or relying on local knowledge, often resulting in suboptimal outcomes. So, the aim was to develop a methodology that was usable by both experts and practitioners. A 3 tiered selection framework was modelled. To illustrate the methodology, he presented a worked example of a local council that has an existing flood affected rural road that is exhibiting signs of fatigue cracking in the wheel paths and is beyond maintenance activities of pothole repairs and patching. Key points / Summary Stabilisation has been documented as an effective treatment for rehabilitation of road pavements