The APSE (Asphalt Pavements for a Sustainable Environment) project was a European initiative focused on significantly reducing the environmental and carbon footprint of road construction by developing and validating a new concept for sustainable asphalt pavements.
The core solution involved maximizing the use of recycled and bio-based materials in different pavement layers, aiming for performance comparable to or greater than conventional pavements, while ensuring cost-effectiveness.
🎯 Core Objectives and Innovative Solutions
The main objective of APSE was to establish a new concept of asphalt pavement with ecologically oriented attributes. This was achieved by focusing on the two main components of asphalt mixture: bitumen (binder) and aggregates.
Innovative Materials and Technologies
| Pavement Layer/Component | APSE Solution | Environmental/Technical Benefit |
| Bitumen (Surface Course) | Lignin-Polymer Modified Bitumen (Lignin-PMB): Lignin (a by-product of 2nd generation bioethanol production) partially replaces crude-oil derived bitumen and SBS polymer. | Reduces reliance on petroleum-derived materials (SBS polymer reduced by up to 15%, bitumen by up to 9%). |
| Bitumen/RAP (Structural Layers) | Bio-fluxing Agents (e.g., vegetable oils): Plant-based products that fluidize aged bitumen, acting as rejuvenators. | Enables the use of higher rates of Reclaimed Asphalt Pavement (RAP) (increasing the limit from 20% to 30% in conventional plants) and allows production at lower temperatures. |
| Aggregates (Subbase) | High-Grade Recycled Construction & Demolition Waste (C&DW) Aggregates. | Utilizes waste material, reducing demand for virgin aggregates. Pozzolanic properties allow for a reduction in cement content in cement-stabilized layers. |
Project Objectives (Validation & Demonstration)
- Technical Validation: Design and validate the performance of new materials at the laboratory and pilot scales (e.g., testing with Accelerated Loading Testing at TRL’s Pavement Testing Facility).
- Industrial Scaling: Scale up the production of innovative solutions to industrial capacity.
- Real-World Demonstration: Validate performance in two full-scale road trials in Poland and Spain to check the influence of local materials and weather conditions.
- Impact Analysis: Conduct a Life Cycle Analysis (LCA) and economic feasibility study to quantify environmental and cost benefits.
📈 Main Results and Economic/Environmental Impact
Technical Validation and Performance
- Lignin-PMB: Laboratory tests confirmed that the addition of lignin did not negatively impact the performance of the resulting asphalt mixtures compared to conventional PMB.
- Bio-fluxing Agents: The bio-flux agents allowed the replacement of up to 30% RAP in Hot Mix Asphalt (HMA) using conventional HMA plants. Asphalt mixtures with the bio-agent showed better fatigue resistance and low-temperature properties than those without.
- C&DW Aggregates: Developed an “Advanced Stone Recycling” concept using NIR and color-sorting technologies to produce high-grade recycled concrete aggregates. C&DW can totally replace granular material in unbound layers and, when stabilized with cement, significantly increase the California Bearing Ratio (CBR).
Demonstration and Usability
- The road trials in Poland and Spain confirmed that the APSE pavement concept is suitable for industry and asset managers, demonstrating that performance is good as long as mixture designs are adapted to local conditions.
Environmental and Economic Profile
- LCA and Economic Modelling: The combined analysis showed that the use of APSE technologies is environmentally and cost-effective.
- Significant Cost Savings: The project demonstrated that there are significant cost savings throughout the life cycle of the road when compared to conventional pavement alternatives, primarily due to reduced material costs and energy consumption.
🖼️ Conceptual Context
The APSE concept directly responds to the challenge of making road infrastructure more sustainable by moving away from materials reliant on crude oil and virgin aggregate extraction. The focus on using waste products (lignin, C&DW) and higher levels of recycled asphalt (RAP) contributes to a circular economy approach in the construction sector.
