Development of Sustainable bio-asphalt mixtures with renewable biopolymer lignin
The company “Vianova”, " in collaboration with the "VIEDO MATERIĀLU UN TEHNOLOĢIJU KOMPETENCES CENTRS" initiated the implementation of a research project titled "Development of Sustainable Bio-Asphalt Mixtures with Renewable Biopolymer Lignin."
Project number
2
Project contract number
5.1.1.2.i.0/1/22/A/CFLA/005
In February 2023, the company "Vianova" in collaboration with the company "Viedo materiālu un tehnoloģiju kompetences centrs" initiated the implementation of a research project titled "Development of Sustainable Bio-Asphalt Mixtures with Renewable Biopolymer Lignin."
Project goal
The aim of the research project is to create sustainable bio-asphalt mixtures by partially replacing bitumen with renewable biopolymer lignin.
The asphalt production industry has been working for many years to reduce harmful emissions by developing cleaner technologies. These technologies include equipment that runs on biofuels, producing warm mix asphalt, or recycling and reusing reclaimed asphalt in new road construction or maintenance. Additionally, they involve incorporating bio-materials into new asphalt mixtures. The reuse of recycled asphalt (RA) in road construction, especially in asphalt production, has already proven its effectiveness in cost reduction, the utilization of new resources, and environmental impact reduction. Therefore, alternatives to bitumen, which is produced from fossil resources, are being explored worldwide.
Lignin is the second most common biopolymer in the world after cellulose and is found in all vascular plants. Several studies have demonstrated the usefulness of lignin in improving the aging resistance of bitumen. However, it is not entirely clear how the addition of lignin to bitumen will affect not only aging resistance but also other properties of bitumen, such as its resistance to rutting and cracking at low and moderate temperatures. Within the project, research will be conducted to develop at least two sustainable bio-asphalt mixture compositions and introduce at least two new biopolymer asphalt products to replace bitumen.
Project progress report for the period
02.2023 - 08.2023
During the reporting period from February 2023 to August 2023, a significant exploration of theoretical foundations and testing was conducted. This involved a thorough examination of literature sources, identification of scientific publications, meticulous analysis, risk assessment, and consolidation of key findings.
In addition to these activities, the inception of the design process for reference asphalt concrete (AC) and stone mastic asphalt (SMA) mixtures was set into motion, this included the formulation of work formulas and the laboratory investigation of the properties of lignin and bitumen.
Based on literature analysis, the selection of source materials for reference mixtures was initiated, in accordance with Latvian National Standard (LVS) requirements. A comparison of the economic availability of source materials was carried out, along with the design of reference asphalt mixtures: AC 11surf and SMA 11, including the formulation of work formulas and the testing of bitumen properties.
09.2023 - 11.2023
During this reporting period, sample preparation was carried out, along with testing of various asphalt concrete mixtures. The goal was to assess the influence of the bio-polymer lignin on the properties of asphalt mixtures during the rejuvenation process. At the asphalt plant, four representative asphalt AC 11 surf mixtures were produced using polymer-modified bitumen 45/80-55.
The conventional bitumen binder was partially replaced with rejuvenating bio-polymer lignin in four different proportions of the total binder content. Based on the obtained test results and the properties of the recovered binder, the optimal lignin content in the mixture was determined. To evaluate the performance properties of the mixtures, further testing of these mixtures and analysis of the obtained results are necessary.
12.2023 - 02.2024
During this reporting period, 11 SMA mix samples with polymer-modified bitumen were prepared (MIX0, MIX1, MIX2, MIX3, MIX4, MIX5, MIX6) - including a reference mixture. The mix composition included RAP (Reclaimed Asphalt Pavement), a bio-renewable additive, and lignin (from various suppliers). A repeated aging simulation in the laboratory was conducted for one of the mixes, simulating 10 years of service life.
The test results received from the State Joint Stock Company "Latvian State Roads" regarding the operational properties of the mixes - the wheel tracking test, TSRST, were evaluated as very good and in compliance with the specifications and standards.
A market study on the provision of lignin testing services was conducted - a contract was signed with the derived public person "Latvian State Institute of Wood Chemistry" (LVKĶI).
03.2024 - 05.2024
During this period, the chemical composition of lignin was thoroughly analyzed and evaluated. Following this, bio-asphalt mixtures (MIX 0, MIX1, MIX2) were produced at the asphalt concrete plant. Necessary adjustments were made to ensure a successful production procedure. The basic properties of the produced mixtures were tested, and the results of operational properties testing were analyzed. This analysis aimed to determine the most suitable prototype mixtures for the experimental phase.
A contract has been concluded with the State Joint Stock Company "Latvian State Roads" for the construction of an experimental section on the main state highway section "A2 highway Riga—Sigulda—Estonian border (Veclaicene)" km 12.430-12.880. Documentation for the construction of the experimental section has been prepared in accordance with regulatory requirements.
06.2024 - 07.2024
In June this year, SIA "Vianova" built the first section of bio-asphalt pavement in Latvia, an important step towards more sustainable road construction. The trial section was made on the main national highway A2 (Riga—Sigulda—Estonian border), between kilometers 12.430 and 12.880. Three different asphalt mixtures were used for this section. Samples were taken during and after the construction to carefully test the bio-asphalt's sustainability, durability, and performance.
The test results show that the bio-asphalt mixtures fully meet the requirements for high-intensity roads. This means these mixtures are suitable for roads with heavy traffic and high durability demands, like main national highways.
The testing shows that bio-asphalt provides the needed strength, flexibility, and long-lasting performance, proving it can handle heavy traffic and harsh weather conditions. These positive results may lead to using more eco-friendly solutions in future road construction. Publications are being prepared to share the results.
