Asphalt concrete mixture produced using reclaimed asphalt pavement and fly ash as artificial aggregate and filler

This study presents the use of reclaimed asphalt pavement (RAP), and fly ash as artificial aggregate and filler in asphalt concrete. Because of the limited availability of natural materials, infrastructure development has become a concern. Therefore, it is necessary to reuse and recycle the waste materials. One such innovation is artificial aggregates. The disadvantage of RAP is that its gradation exceeds the standard; its asphalt penetration and ductility exceed the requirements. The weaknesses of artificial aggregate are high water absorption, spherical shape, and low aggregate interlocking. In this study, the artificial aggregate was produced using the fly ash and alkali activator. Alkali activator consisted of Na2SiO3 and 8M NaOH at a ratio of 2.5. The mixtures containing different percentages of artificial aggregate (45, 55, 65, and 75%) were produced, and the fly ash filler content was 5%. Different tests including XRF, SEM, and Marshall tests were conducted. The artificial aggregate is hydrophilic owing to the high silica content; thus, it has high water absorption. This results in a low adhesion between the asphalt and aggregate. The best composition of asphalt concrete is 55% artificial aggregate, RAP, fly ash filler, and asphalt. The asphalt concrete containing artificial aggregate has a high stability and is stiff and light. However, it requires a high asphalt content because of a high-water absorption. It is unsuitable for application in high traffic roads, but suitable for medium traffic ones.