Lignin integration in bituminous road applications

LIBRA aims to develop a comprehensive analytical framework to evaluate lignin as a sustainable alternative to bitumen in asphalt pavements. Asphalt, a mixture of mineral aggregates and bitumen, is the most commonly used material in road construction but faces economic and ecological challenges due to its reliance on crude oil. To address this, renewable biomaterials like lignin are being explored. As one of the main components of trees, lignin is highly abundant and produced industrially as a by-product of the paper and pulp industry. Due to the large quantities available, its underutilisation, and chemical similarities to bitumen, it has great potential as an alternative binding material in road applications. However, the chemistry of lignin is very heterogeneous and depends on the biomass source and the processing method, which affects compatibility and durability of asphalt mixtures. To optimise the use of diverse lignin feedstocks, LIBRA will investigate how these chemical variations influence the performance of lignin-modified binders (LMB). In addition, the project will assess the recyclability and the emission of volatile and water-soluble pollutants to determine the direct environmental impact of LMBs. Combining expertise from pavement engineering, biomaterials chemistry, environmental sciences and analytical chemistry, LIBRA will correlate mechanical and chemical properties, examine fundamental (molecular) processes and predict performance and applicability of the LMBs. Techniques such as dynamic shear rheometry, dynamic mechanical analysis, multidimensional nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry will be employed. The resulting framework will facilitate a sustainable transition to lignin-based asphalt, contributing to more eco-friendly road infrastructure, supporting the EU’s leadership in sustainable construction and addressing global priorities for greener materials and reduced carbon emissions.