Project Status: Completed

Overview

In the quest for innovative practices that might be applied in WA, three exciting research areas were explored for potential larger scale investigations.

  • Solar pavements, although highly suitable for our sunny WA and with promising technology in development, is still in its infancy and would probably be better used in parking applications rather than pavement at the moment.
  • Recycled plastic roads would be a great stride forward environmentally and certainly warrants more research on many levels in order to develop applications that would work in WA. This technology is one to watch but isn’t quite at the level where it can be applied large scale.
  • Nanotechnology opens up the door to self-healing pavements and improved binders which could be significant game changers in longevity of our WA roads. These certainly warrant research on large scale applications to see if the nano-scale results can be achieved in large scale applications. Watch this space for further research into this technology.

Summary

During March – December 2016 WARRIP investigated the use of nanotechnology in road pavement applications. The review included the technical benefits and limitations of using nanotechnology in asphalt and concrete.

Background

In flexible pavement construction, the interconnection of large scale bituminous material components typically relies on material particle on the micro and nanoscale. Therefore, improved nanomaterials may be used to enhance pavement properties.

Approach

  • Reviewing current international and national practice
  • Identifying products that have been developed and/or are in use
  • Evaluating these technologies, particularly regarding likely application into practice
  • Conducting an assessment of the relevance of current practice, products and recent research to Main Roads
  • Providing recommendations on further investigation of these technologies and what research should be conducted to better inform decisions regarding

Types of Nanomaterials

There is a significant amount of nanomaterials currently available that may have applications for asphalt and/or concrete pavements. These technologies include:

  • nanoclay (NC)
  • carbon nanotubes (CNTs)
  • titanium dioxide (TiO2)
  • shape memory foam (SMF)
  • embedded bacteria.

Review of Use in Bituminous Materials

Research into the effect nanomaterials have on the performance of asphalt is relatively limited due to the novelty of the technology. However, there have been numerous studies focused on the effect nanomaterials have on the properties of binders.

Research has indicated that NC can be successfully used as a modifier to improve the properties of bitumen. Similarly, studies have indicated that CNT applications of less than 0.1% (by mass of binder) may be able to improve asphalt properties and reduce pavement thicknesses.

However, it is important to note that the cost of nanomaterials is relatively high and research has primarily been carried out at the nanoscale.

Larger-scale investigations and cost-benefit analyses will be required to verify applicability.

Review of Use in Concrete

The application of nanotechnology in concrete engineering has the potential to generate concretes with self-sensing, self-cleaning and notably, self-healing characteristics.

To date, various studies have assessed self- healing using a number of nanomaterials. Findings indicate that these materials have the potential to seal micro-cracks, thus preventing macro-crack propagation.

References

Partl, MN, Gubler, R & Hugener, M 2004, ‘Nano- science and technology for asphalt pavements’, in Special publication-Royal Society of Chemistry: international symposium on nanotechnology in construction, Cambridge, UK, pp. 292; 343-56.

De Heer, WA 2004, ‘Nanotubes and the pursuit of applications’, Materials Research Society Bulletin, vol. 29, no. 04, pp. 281-285.

Pianoforte, K 2013, ‘AMI offers polymers for seal- healing coatings technologies’, Coatings World, 26 June 2013, viewed 23 June 2016, <http://www.coatingsworld.com/contents/view_onli ne-exclusives/2013-06-26/ami-offers-polymers-for- seal-healing-coatings-technologies/>.

National Nanotechnology Initiative n.d., ‘Size of the nanoscale’, NNI, viewed 14 June 2018, <https://www.nano.gov/nanotech-101/what/nano- size>


During March – December 2016 WARRIP investigated the use of recycled plastic in road applications including asphalt binder and modular pavement. The review included technical benefits and limitations, recent case studies and a review of plastic recycling practices in Western Australia.

Background

Increasing volumes of plastic entering landfill and growing costs of petroleum-based products have made the management of waste plastic a major sustainability issue. Rates of plastic recovery, recycling and reuse are low in WA by national and international standards. The purpose of this investigation was to determine whether this highly valuable resource could be beneficially utilised in road pavement applications.

Approach

  • Reviewing current national and international practice
  • Identifying products that have been developed and/or are in use
  • Evaluating identified technologies, particularly regarding likely application in WA
  • Conducting an assessment of the relevance of current practices, products and recent research to Main Roads
  • Providing recommendations on further investigation of these technologies and what research should be conducted to better inform decisions regarding implementation into practice

Types of Plastics

Common plastics are categorised according to Plastics Identification Code (PIC), distinguished by a number within the sustainability triangle. Plastics in categories 1, 2 and 3 are generally recycled, whereas the plastics in categories 4-7 are not; often due to the difficulty and expense associated with the recycling process. A summary of plastic types is presented in Table 1.

 

 

 

 

 

 

Recycling Practice in Western Australia

Perryman and Green (2015) found that plastic constitutes only 0.5-0.6% of the total 2.6 million tonne of waste recycled in WA, representing approximately 8% of the 0.2 million tonne consumed annually. There are currently five semi-automated waste processing facilities within WA that sort recovered plastic into HDPE, PET and mixed plastic groups. Perryman and Green (2015) provide a summary of recycled plastic by type.

 

 

 

 

Barriers to Using Recycled Plastic

  • Concerns about the presence of impurities
  • Lack of financial incentive for using recycled materials, similar cost compared to virgin
  • Lack of local demand in WA, approximately 71-73% exported overseas or interstate
  • Indicative HDPE, PET and mixed plastic prices
  • $1000, $300 and $180 per tonne respectively

Recycled Plastic in Asphalt

Numerous studies have investigated the addition of waste plastics to asphalt binders. Generally, the studies found that recycled waste polymers could be utilised to enhance desirable binder/mix properties including stiffness, fatigue and cracking. However, enhanced performance as compared to unmodified binders was considered successful and comparison to equivalent virgin polymers was not pursued. Additionally, the health and safety issues associated with the production and laying of these materials were not addressed. Sources of risk include fumes and odours from waste plastic and associated impurities.

Conclusions and Recommendations

References

Perryman, G & Green, S 2015, Recycling activity in Western Australia 2013-14, ASK Waste Management, Perth, WA.

PHS Pallet n.d., Guide to plastic recycling numbers, web page, viewed 11 June 2018, <https://phspallet.com/guide-plastic-recycling- numbers/>.

 

 

 


During March – December 2016 WARRIP investigated the implementation of solar road technologies currently trialled and/or implemented globally. The review included technical benefits and limitations of solar technologies in Western Australia.

Background

Australia has the highest average solar radiation per square kilometre of any continent. Western Australia’s climate is well-suited to embrace solar power generating electricity that could be used to power roadside infrastructure, including adjacent buildings, or sold to the electrical grid as a potential revenue source.

Approach

  • Review of current international and national practice
  • Identifying products that have been developed and/or are in use
  • Evaluating these technologies, particularly regarding likely application into practice
  • Conducting an assessment of the relevance of current practice, products and recent research to Main Roads
  • Providing recommendations on further investigate these technologies and what research should be conducted to inform decisions regarding implementation into practice.

Current Research and Practice

Research and development into the ability of roads and roadside infrastructure to harness solar energy related to pavements include solar collector systems embedded into pavement layers or solar collector panels placed over, or next to, the road.

Novel projects include those that aim to charge moving electric vehicles (EV) and solar-powered EV charging stations. Other solar advances include the incorporation of solar panels into roadside infrastructure, pedestrian paths, highway noise walls and car park canopies.

Review of Solar Technologies

Solar roads

Solar Roadways, a project being developed in Idaho, USA aims to integrate light emitting diodes (LEDs), providing lane-marking and thermal control elements. Theoretically, over time, the generation of electricity would cover construction costs. However, it has not been tested on public roads and thus, its safety and durability are unknown.

Solar electric vehicle charging stations

Main Roads has already trialled and implemented electric vehicle (EV) charging stations connected to the traditional electricity grid. However, there is potential for Main Roads to trial solar-powered electric vehicle charging stations in the future.

Solar collector systems

Research has indicated that solar thermal energy collected by an asphalt pavement may be harvested using a pipe system installed below the asphalt (Bobes-Jesus et al. 2013). If the heat can be collected with reasonable efficiency and cost, it may be considered an energy source as well as reducing the development of thermal stresses on the pavement.

Conclusions and Recommendations

 

 

References

Bobes-Jesus, V, Pascual-Munoz, P, Castro-Fresno, D & Rodriguez-Hernandex, J 2013, ‘Asphalt solar collectors: a literature review’, Applied Energy, vol. 102, pp. 62-70.

Ecofriend (n.d.). Solar-powered charging stations to keep your EV commutes completely zero emission, webpage, EcoFriend, viewed 15 June 2018, <https://ecofriend.com/10-solar-powered-charging-stations-ev-commutes-completely-green.html>.

Solar Roadways 2016, Solar energy, webpage, SR, Sandpoint, Idaho, USA, viewed 22 June 2016, <http://www.solarroadways.com/Home/Specifics>.

Technovelgy, n.d., Use roads as solar energy collectors, webpage, Technovelgy, viewed 15 June 2018, <http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1383>.