Application and circular economy prospects of palm oil waste for eco-friendly asphalt pavement industry: A review

During the production of palm oil, a significant amount of waste is generated. However, because of inefficient handling and utilization, these wastes are becoming a larger issue. As a result, one initiative is to use these wastes in the pavement industry as sustainable materials. However, there is still a lack of understanding about the wider incorporation of palm oil waste in asphalt pavement and its performance. This study examines existing literature on the use of various wastes in the pavement industry, including palm oil clinker (POC), palm oil fibre (POF), palm kernel shell (PKS), and palm oil fuel ash (POFA). As a result, this paper presents a systematic review and scientometric investigation of related study publications on many uses of palm oil waste in the asphalt pavement industry and its performance from 2009 to 2022. The VOSviewer application was used to conduct the scientometric study analysis. The relationship between interactions detected in co-authored country studies cited sources of co-citation, and the keyword of the co-occurrence and publication source enabled the identification of the research gap. According to the systematic literature review, 40%-60% POC can be used to fine aggregate for optimal performance, while 0-100% PKS can be used to replace coarse aggregate. In addition, 50%-80% POFA or POC fine (POCF) can be used as a filler replacement, 5%-8% POCF or POFA as a bitumen modifier, and 0.3% POF as a stabilizing additive. Furthermore, the study demonstrates that the safety of utilizing wastes with more than 50% CO2 emissions can be curtailed with minimal heavy metal leaching and radioactivity levels. The scientometric analysis may encourage researchers to seek out gaps in the literature that will aid in the long-term, multifaceted use of palm oil wastes in the asphalt pavement industry. Furthermore, the study recommends employing and researching the enormous potential of using palm oil waste in the pavement sectors because they are more sustainable and have better performance. However, there are some barriers to using palm oil waste in the asphalt pavement industry, such as a lack of design standards and guidelines, inefficient raw material processing conversion facilities, and large-scale production equipment.