Research on biochar as a sustainable asphalt binder modifier: A systematic and bibliometric review

Abstract

Biochar, a carbon-rich byproduct of biomass pyrolysis, has garnered increasing attention as a sustainable additive for asphalt binder modification due to its environmental and mechanical advantages. This study combines a systematic and bibliometric review to explore the development, performance metrics, and research trends of biochar-modified asphalt. Drawing from 104 peer-reviewed articles published from 2015 to 2025, including 2025 early-access records available at the time of data retrieval sourced from Scopus and Web of Science, the review investigates the diversity of biochar feedstocks, pyrolysis conditions, and modification strategies affecting binder performance. Experimental findings highlight enhancements in rheological properties, aging resistance, and VOC emission suppression, particularly from sources such as corn straw, oil palm mesocarp fiber, and hazelnut shells. Through bibliometric mapping using Bibliometrix and Biblioshiny in R, this study identifies influential authors, journals, countries, and keyword clusters shaping the research landscape. The analysis reveals a surge in scholarly output since 2020 and increasing interdisciplinary engagement. Despite laboratory-scale successes, limitations persist in standardization, field validation, and life-cycle assessment. This review provides a consolidated knowledge base for researchers and practitioners seeking to advance eco-efficient asphalt technologies through biochar integration.