In the world of infrastructure development, the choices we make can have lasting consequences. A recent project with Huesker in Germany, highlights the importance of carefully considering different approaches and innovative materials in road construction, taking into consideration the whole lifecycle. Led by ORIS Materials Intelligence, this project underscores the significance of making informed decisions for sustainable outcomes.

Context

This project was carried out on Rosenstrasse in Ochtrup, Germany. The width of the road is 7 m and the length that had to be renovated is 1000 m. The renovation consisted of milling off the existing 5 cm thick asphalt surface layer, the subsequent installation of the HaTelit asphalt reinforcement and a new 5 cm thick asphalt surface layer. ORIS Materials Intelligence had two scenarios to compare:

• Scenario 1: Renewal of the top layer with asphalt reinforcement HaTelit® C 40/17 (renovation carried out in 1996); Base layer untouched
• Scenario 2: Renewal of the binder and top layer (standard construction method); Base layer untouched
  
  

                      Scenario 1                                                  Scenario 2

Methodology

In accordance with EN 15804+A2, ORIS enabled the calculation of the carbon footprint of materials, using the cradle-to-gate method which takes into account life cycle phases A1-A5. Our calculation approach has received the assurance statement by Intertek (link).

The analysis was based on various data sources, including the available EPD for the asphalt reinforcement product as well as data from ecoinvent for LCA modelling of the asphalt surface course and the asphalt binding course. 

To model the A1-A3 effects of the asphalt surface and binder layers, we referred to the EN 13108 standard, which provides some instructions for the typical composition of different types of asphalt. 

The evaluation for  A1 phase - which is the production of raw materials such as bitumen or aggregates - is based on ecoinvent. 

The transportation of raw material to the asphalt plant, which is the  A2 phase - and the manufacturing processes - the A3 phase   of the asphalt production vary depending on many parameters and are very specific for each project. Therefore, we used the average values suggested in the PIARC report (link)*. Finally, the evaluations  of A1-A3 were aggregated.

A4 is the phase where ORIS evaluates the carbon footprint related to the transportation of finished products (i.e., asphalt and asphalt reinforcement product) in the local and realistic context of material suppliers to the construction site.

Finally, the A5 phase evaluated the carbon footprint of product placement, represented by energy consumption for engine uses. The energy consumption was assumed by ORIS default modelling of engines characterised with engine load factor, unit fuel consumption, average daily hour of work. Further modelling can be performed on the ORIS Materials Intelligence platform towards the most accurate and contextual results for A2 and A3, provided that operational elements are known and input (e.g. emission factors, exact consumptions, distances).

Results

With the conventional method in scenario 2, the carbon footprint is more than twice as high as with the asphalt reinforcement method in scenario 1. The construction method with asphalt reinforcement therefore makes a significant contribution to achieving the climate goals.

Explanation

The analysis clearly shows that the largest share of environmental pollution is caused by the removal and installation of the asphalt binder layer. This process is associated with increased CO2 emissions and contributes significantly to overall emissions.

The discrepancy in the environmental impact between the asphalt binder layer and the wearing course  can be attributed to the different layer thicknesses. While the wearing course is 5 cm thick, the binder layer is 8 cm thick. This means that the binder course causes more emissions overall than the surface layer, despite its lower emission factor.

Interestingly, it turns out that the production of polyester materials has a higher emission factor than, for example, the production of asphalt or concrete. Nevertheless, the material consumption when using polyester materials is significantly lower than when laying a completely new asphalt binder course.

In this context, the HaTelit asphalt reinforcement proves to be extremely advantageous as it ultimately causes a significantly lower environmental impact than replacing the entire asphalt binder layer. Their use therefore contributes significantly to reducing global warming potential (GWP) and represents a more sustainable alternative.

This project impressively shows how important it is to evaluate different scenarios and the use of innovative products in road construction in order to make informed and data-based decisions. We are pleased that ORIS Materials Intelligence was once again able to make a contribution to transparently and objectively evaluating sustainable solutions in road construction.