A Comprehensive Review of Biochar Utilization for Low-Carbon Flexible Asphalt Pavements

Abstract

A large amount of biomass waste is produced globally, and its production and improper management are major environmental issues. Pavement industries consume large amounts of natural resources and adversely impact the environment. Thus, the utilization of waste materials, such as biochar from biomass, has been prioritized as an innovative and sustainable strategy. However, there is currently a paucity of knowledge regarding the utilization and performance of biochar in flexible asphalt pavements. Thus, the purpose of this study was to provide a comprehensive literature review of studies conducted between 2010 and 2022 on the advancement and application of biochar in flexible asphalt pavement production. This review also highlights biochar production materials (feedstocks) and processes. This review further evaluates the viability of biochar as a carbon-neutral material utilized in producing asphalt pavements. Owing to its exceptional and variable physicochemical properties, biochar has demonstrated improved performance for a variety of applications in flexible asphalt pavements. According to the review, for optimum performance, a particle size < 75 µm is recommended as a modifier for asphalt binders and mixtures with a content range of 5–10 wt.% of the binder, while a particle size of 1–5 mm is recommended as a filter layer. In addition, the review concluded that as a carbon-neutral material, biochar has many possibilities that can aid in reducing CO2 emissions. The challenges and future perspectives, underlying study niches, and future research suggestions for biochar application in the flexible asphalt pavement industry are also highlighted. As a result, this review will contribute to the increased sustainability and eco-friendliness of flexible asphalt pavements by encouraging the transition to carbon-negative and emission-reducing pavements. The current review will assist researchers in identifying research gaps that will encourage the high-potential, sustainable, and multifaceted application of biochar in the pavement industry for greater environmental benefits.

The efficiency of bio-char as bitumen modifier

“…Biochar can have different origins making this material heterogeneous. This means that biochar from different sources shows different elemental composition, functional groups, structural properties and so on [ 65 ]. Nevertheless, the use of char is crucial in terms of the circular economy, and the possibility of its use in the bitumen or pavement sector in general may open up a new scenario.…”

Carbon storage in the built environment: a review

“…They report high-carbon biochar particles in this fly ash waste product, which could serve both as carbon storage and enhance early-stage strength of this material in road construction. Bio-asphalt can serve as a replacement for traditional asphalt as a road material made with bio-based binders, such as plant-based oils or manures (Al-Sabaeei et al 2020) and modifiers, such as biochar (Rondón-Quintana et al 2022, Yaro et al 2023. Despite growing popularity in recent years (Rondón-Quintana et al 2022), there is still a significant gap in literature addressing the carbon storage potential of these bio-based alternatives.…”

Performance Characteristics of Nano Palm Shell Ash (NPSA) in Asphalt Mixture

“…Modification of asphalt with natural materials has been widely carried out, such as modification of asphalt with natural materials, natural rubber, asbuton, zeolite and so on [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Current research focuses more on waste materials, reducing asphalt mixing temperatures, and energy replacement such as recycled RAP, crumb rubber, recycled aggregate, biochar, palm oil fuel ash, and bio-based binders can help reduce the environmental impact of production and maintenance of asphalt pavements as well as lower costs and improved performance of the mixture when compared with conventional materials [20][21][22][23]. Waste materials, such as palm fuel ash, rice husk ash and coconut shell rattan, have been utilized as additives in composite materials, and some waste materials have been used as nanomaterials [24][25][26][27][28][29][30], producing satisfactory results with improved performance.…”