Using waste plastic in road construction?
INSA Lyon: Does the bitumen industry generate waste? How is it treated?
Jean-Michel Michou, Eurobitume France (J-MM): Our industry does not generate waste. In addition, bitumen and bituminous materials in general are 100% recyclable. In fact, asphalt roads are re-usable, which is a step above recyclable in the waste hierarchy.
It is important to know that bitumen is primarily a building material subject to severe quality standards and CE marking.
INSA Lyon: Do you think waste plastic is interesting? Is there any place for innovation? Why?
J-MM: We do not know because, to date, we are not aware of any serious study concerning them in France.
INSA Lyon: Would you be willing to drive on this type of road? Why?
J-MM: As a driver, my opinion would depend on the safety performance of this type of road and in particular knowing if this is reached - in terms of roughness and drainage, to ensure good conditions of adhesion - in case of braking, especially in rainy conditions.
Noise is also an important parameter, but there it is my opinion as a resident.
INSA Lyon: Do you think this solution is really ecological? Why?
J-MM: Until there is a serious life cycle analysis study of this material, I think it is difficult to have an opinion on its ecological impact. Personally, I think there are better uses for plastic waste.
INSA Lyon: In your opinion, can all plastic waste be used for this project? If not, why?
J-MM: To my knowledge, road construction in France does not use waste because this kind of product has to fulfil very specific regulations that limit its use in construction projects. In particular, it must be proved that they are not toxic.
INSA Lyon: What could be the advantages and disadvantages of this type of road?
J-MM: According to the EU Commission waste hierarchy, the best thing to do with waste plastic is to make new plastic items – as the carbon footprint of plastic is much higher than that of asphalt.
Constructing roads with this kind of product you need to at least match the performance standards of asphalt mix in new condition and ensure these roads are durable enough and recyclable, in comparison to existing roads constructed using bitumen.
I think that the cost of plastic waste is also a key parameter, because infrastructure owners have limited budgets and if there is no economic advantage compared to traditional solutions they will not be interested.
INSA Lyon: What would be your motivations for the implementation of this type of road?
J-MM: As long as there are no studies that guarantee the quality, the absence of risk for the health of the workers during implementation and recycling, the economic interest and that this was the most environmentally-beneficial end-use for such materials, I do not see any motivation for the stakeholders to develop this type of solution.
INSA Lyon: What could be the restraints for the implementation of plastic roads?
J-MM: I think mainly about the risks related to occupational exposure during the laying down of asphalt mix, the quality and durability, their cost and possible problems related to their recycling.
INSA Lyon: According to you, do you need special training to manufacture these roads?
J-MM: Probably as a minimum, the asphalt mix manufacturing teams will need special training so they know the best way to introduce plastic waste in the industrial process. But all this is possible only after prior technical studies in the laboratory.
INSA Lyon: Do you think that laboratory tests should be carried out? If yes, which ones? (tests to find beforehand)
J-MM: In my opinion, it should be necessary to carry out all the tests relating to bituminous materials (fatigue resistance rutting resistance, aging ...), the measurement of occupational exposure (eg PAH) and the aptitude for recycling.
Plastic waste must comply with the regulations in all respects, in particular with regard to the REACh regulation, as it is already demonstrated for asphalt mix.