Gary Schofield and Rick Ashton of Total Bitumen presented two papers at the 17th Annual International Conference on Asphalt, Pavement Engineering and Infrastructure last month at Sensor City, Liverpool. Here, Highways presents an abstract of each paper.
Day 1 Presentation
Historically, the asphalt industry has been known for its conservatism and reluctance to change. As a result the development of new ideas and concepts has proven very difficult to progress from a laboratory scale to live sites. There have, however, always been selected authorities where a risk management approach has been utilised and where innovation was easier to get to the road network.
Recent times has seen an acceleration of change in the industry and a growing potential for new ideas to enter the market. Nonetheless, risk ownership remains a key stumbling block. Supply chain collaboration is key to managing the risk and providing a route to market for new ideas.
This also rightly demands transparency and honesty among the partners in the supply chain. It also should require a risk-based approach to understanding the 'unintended consequences' that may arise from innovations. Responsibility therefore lies with the innovating party to look to technically assess all parameters of performance and not just the areas of alleged improvement.
In this paper Gary Schofield considered how this risk-based approach might look and what should be required to provide a gateway for the innovation. Where innovations are not fully controlled and incomplete technical assessment has been carried out up front; the client must be responsible for finding out more information to ensure unintended consequences do not become an issue. Poorly controlled technology create barriers for future good quality innovations and the industry must be careful of this.
Day 2 Presentation: Polymer modified bitumen (PMB) Optimising Highways Asset Management
This paper considered how to achieve ‘sustainability through durability’ with consideration of whole-life costing. It givesan explanation of the engineering demands asphalt materials are subjected to and the limiting factors for bitumen performance. Rick discusses enhancing these parameters using PMB with a comparison of Total Styrelf® over 50 penetration grade (pen) and 20 pen bitumen. Quantified examples of advantages are then presented as well as life-cycle costing against initial installations costs.
The advantage of long-term funding programmes and how material costs pale into insignificance when calculating the whole-life cost if the road is truly durable is also analysed.
The paper gives consideration of previous failure modes and how to design accordingly - designing to mitigate risk and potential failure using value engineering. It looks at our understanding of the materials to be installed and optimizing the installation according to latest available technology and working collaboratively with the supply chain.
It provides a discussion of the many types of bitumen and asphalt additives available and their benefits and limitations, then gives an explanation of why SBS elastomeric PMB’s are becoming the binder of choice in the UK. Proof of performance with a long-term road trial of more than 20 years (The Lavoc Study) is presented. This is followed with practical laboratory data on fatigue performance to explain how Total Styrelf® outperformed 16 other binders in this long-term test on asphalt ageing.
In conclusion, the presentation cites international references for high stress sites where Total Styrelf® has been successfully used. These sites include Monaco Grand Prix Circuit, Hamburg bridges, civil and military airfield applications and the recent new Mersey Gateway Crossing.
For more information contact Richard Ashton - richard.ashton@total.com
