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The daily utilization of a large amount of raw materials is causing a rapid depletion of natural resources. The growth of the human population is accompanied by higher activities in the agricultural and manufacturing sectors that resulted in a larger volume of waste materials being disposed of in landfills each year. Researchers are seeking ways to reduce the adverse impact of waste materials on the environment. One method for managing waste materials is using them as a substitute for natural materials, for example, as aggregate replacement in the construction of road pavements. This paper reviews the previous studies that explored the use of waste materials as aggregate replacement in stone matrix asphalt (SMA) mix and the performance of asphalt pavements constructed using these materials. A systematic literature search of four databases revealed that waste materials could be used as an alternative to the natural aggregates. Future studies on the SMA mixes should investigate using other waste materials that could improve mix design and enhance pavement performance. There is a need to establish a standard code of practice and train material technologists to use different types of waste in SMA pavement construction. In summary, it is essential to perform a life cycle cost analysis (LCCA) and life cycle assessment (LCA) to quantify the economic and environmental impacts of the different waste materials used as aggregates in SMA.

Aggregate composition has a pivotal role in ensuring the quality of pavement materials. The use of waste materials to replace the aggregate composition of asphalt pavement leads to green, sustainable, and environmentally friendly construction, which ultimately preserves nature by reducing the need to harvest materials from natural sources. Using the Marshall mix design, the main objective of this paper is to investigate the effects of waste palm oil clinker (POC) as fine aggregates replacement on the properties of stone mastic asphalt (SMA) mixture. Six groups of asphalt mixtures were prepared using different percentages of palm oil clinker content (0%, 20%, 40%, 60%, 80%, and 100%). To determine the Marshall properties and select the optimum binder content, asphalt mixture samples with different percentages of asphalt binder content (5.0%, 5.5%, 6.0%, 6.5%, and 7.0%) were prepared for each group. The results showed that the palm oil clinker was appropriate for use as a fine aggregate replacement up to 100% in SMA mixture and could satisfy the mix design requirements in terms of Marshall stability, flow, quotient, and volumetric properties. However, the percentage of palm oil clinker replacement as fine aggregate has merely influenced the optimum binder content. Furthermore, there were improvements in the drain down, resilient modulus and indirect tensile fatigue performances of the SMA mixture. In conclusion, the use of POC as fine aggregates replacement in SMA mixture indicates a good potential to be commercialized in flexible pavement construction.

The palm oil industry has been projected to increase annually, hence resulting in a large number of waste materials being dumped into landfills. In order to decrease the adverse effects of these wastes on the environment, they may be used to substitute conventional aggregates in building roadway pavements. Having that said, this study assessed the effect of using palm oil clinker (POC) as a substitute to fine aggregate on the mechanical properties of SMA mixtures. A range of asphalt mixtures were prepared by replacing the fine aggregate with different POC contents (0%, 20%, 40%, 60%, 80%, and 100%). Additionally, 50% of palm oil fuel ash (POFA) was used as filler in the asphalt mixtures. Resilient modulus, wheel tracking, dynamic creep, indirect tensile strength, and Cantabro durability tests were conducted on all the prepared asphalt mixtures. The results signified the suitability of POC for 100% substitution of fine aggregate in SMA mixture, as it enhanced resilient modulus, resistance to rutting, tensile strength, and resistance to moisture damage. Conclusively, SMA20 mixture between 40% and 60% displayed better mechanical properties, when compared to other mixtures.