Performance evaluation of bio-based asphalt pavements: Accelerated pavement testing and field monitoring

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Abstract
This report presents the results of a project aimed at evaluating the performance of asphalt pavements incorporating bio‑extended bituminous binders, with a focus on long‑term structural behaviour and surface characteristics. The project focused on bio-extended penetration-graded bitumen containing Tall Oil Pitch (TOP) and a polymer-modified bitumen (PMB) with a biogenic component as alternatives to conventional bituminous binders. Both penetration-graded bitumen and PMB were investigated. The experimental program consisted of full‑scale accelerated pavement testing (APT) using a Heavy Vehicle Simulator (HVS) at the indoor testing facility of the Swedish National Road and Transport Research Institute (VTI), complemented by surface performance monitoring of a walking and cycling path constructed in Sundbyberg, Stockholm. Four full‑scale pavement structures, penetration-graded reference and its bio‑extended variant, as well as PMB reference and PMB with biogenic component, were constructed using asphalt mixtures produced in asphalt plants. The pavement structures were instrumented with asphalt strain gauges (ASGs) and temperature sensors to measure temperatures and tensile strains related to fatigue cracking. Rutting performance was evaluated through repeated loading at test temperatures of 10 °C and 20 °C. The APT results showed that the structures incorporating bio-based binders exhibited similar or improved resistance to permanent deformation compared with conventional reference structures, particularly at the elevated temperature of 20 °C. Measured tensile strains at the bottom of the asphalt layers were generally lower or comparable for bio-based variants, indicating favourable fatigue‑related condition. No operational challenges were observed during asphalt production, transportation, or paving, and the biobased mixtures demonstrated good workability and compaction characteristics. The walking and cycling path was monitored over a three‑year period to assess surface texture and roughness using Mean Profile Depth (MPD) and International Roughness Index (IRI). The measured values remained within the range of reference data for newly paved paths in Sweden throughout the monitoring period. Overall, the results demonstrate the technical feasibility of bio-based asphalt mixtures as a sustainable alternative for asphalt pavements without compromising performance.