Watch webinar video: Sustainability in asphalt production
Date: Thursday May 28 2020
Dure: 65 minutes
Download the slides (pdf)
- Dineke van der Burg: coördinator van het MoU ‘transport en infrastructuur’ tussen Nederland en China;
- Inge van Vilsteren, adviseur wegenbouwmaterialen, Rijkswaterstaat, Ministerie van Infrastructuur en Waterstaat
- Mingliang Li, Associate Prof., Research Institute of Highway Ministry of Transport (RIOH), China
Content: This webinar is a follow-up of the webinar in May last year about OESA (Open Emulsion Sand Asphalt e.g. Gap Grated Micro Surfacing (GGMS)), as a maintenance tool for Porous Asphalt, with an aim for life extension. This time China organized the webinar about low temperature additives in asphalt. The additive can help to reduce the production temperature of asphalt mixture to 110-140 ℃ and the paving temperature to 100-110 ℃. It can be used for pavement in urban area or in tunnels, and it can also be used for pavement construction at low temperature (below 10℃. Meanwhile, it can effectively reduce carbon emissions and toxic gas emissions, which is an energy-saving and environment-friendly pavement engineering technology.
Notice: we added subtitles to this webinar. You can turn them on in the Youtube settings.
Below you will find the questions and answers that couldn't be answered during the webinar, due to time.
- Is it possible to use RAP in combination with the tech?
Re: Yes, it can be used with RAP material. It helps to reduce the mixing temperature, and leads to an increase of the RAP content.
- In the Netherlands the builder BAM infra has a product called LEAB. This asfalt is produced at 100 degrees Celcius and has compliance withe the Kyoto Treaty. Is this type of asfalt made possible with the mentioned additives?
Re: As I know, they use a foaming technology to reduce the mixture temperature of RAP materials and make the usage of asphalt motar possible. As the paving temperature of the LEAB is already low （around 100 ℃），I am not sure if it can further lower the paving temperature. However, when using the additive in the mixture, it will make the paving in a lower environmental temperature possible, as such 0 ℃ or even lower.
- Would you please tell us if the asphalt mixture included low temperature additive has good durability after aging, due to oxygen and sunlight for years? Maybe from the perspective of field observation.
Re: During the production process, the asphalt mixture is not heated by high temperature (forced aging). The loss of light components in asphalt is greatly reduced (compared with the hot mix asphalt by more than 90%), and the durability of the asphalt mixture is more than that of the hot mix asphalt mixture. However, as it is a new technology, the longest road we have observed is the 7 years.
- Does low temperature additive make asphalt mixture easier to be on fire?
No, the additive has a high ignition point (more than 200 ℃). And without an open fire, it cannot be burned.
- You are using additives to reduce the viscosity of asphalt. Are these additives degredable?
Re: Yes, it has certain degradable function.
- What about the weather conditions such as light rain and wind speed? What effect do these conditions have on low temperature additives?
Re: It is not allowed to pave in the raining condition, due to the requirement of asphalt construction. However, in practice, there is less influence of a little rain on the performance of the mixture. And of course, a strong wind will influence the construction by using the additive. It is the same as normal types of materials.
- Is this technology suitable for porous asphalt?
Re: Till now, they are not used in porous asphalt in China. In China, we always use high viscosity asphalt for porous asphalt, as we consider a high temperature performance and a high anti-raveling property. Even we used this type of additive, the viscosity is still very high, it cannot been paved in a very low temperature. What’s more, we have a strict control on the construction condition of porous asphalt. They are not allowed to constructed in low temperature, such as below 10 degree. That’s why the additive are not yet used in a porous asphalt in China.
However, I think it could be a good choice to be used in the porous asphalt in the Netherland. Because the porous asphalt are normally made from a grade 70 matrix asphalt, or some SBS modified asphalt. The additive can reduce the viscosity of those asphalt material to great extent. And it reduces the construction temperature, save energy, reduce carbon emission and harmful gas and so on.
- There are several LTA-additives available in the market. For what reason did you choose these?
Re: We will consider the price, the effect of reducing temperature and the workability etc. For the additive we introduced in the webinar, an advantage is that it makes the production and paving at low temperature (such as around or below 0℃) possible. It can be used for construction in special conditions, including winter time and high latitude area etc.
- How is the pavement behaving under high temperatures, like in summer?
Re: The rutting resistance of the mixture with low temperature additive will increase after the curing time, which is close to a normal asphalt mixture. Therefore, the behavior in summer is similar as that of 70# asphalt mixture or modified mixture (depends on what type of basic asphalt is selected).
- What would be the range of dosage of this additive to asphalt?
Re: The general dosage of the additive is 4%~10%. It should be selected based on the balance of a construction temperature and the performance of the mixture.
- Do you have made cost-benefit analyses?
Re: By reducing the construction temperature, it leads to more than at least 20% of VOC, Co, NOx and SO2 emissions reduced. The additive will cost more than normal asphalt. However, around 40% of fuel is saved and the construction cost is reduced.