Improvement of Rap Material with Fly-Ash/Chemicals

Abstract

The research involved preparing three different mix designs with varying percentages of RAP, FA and L. The mixtures were cured for 3, 7 and 28 days, respectively, and the UCS tests were conducted at each time interval. The results showed that the addition of L improved the strength development of the RAP-FA geopolymer mix, with the highest strength achieved for the mix, 14 and 28 days to evaluate the UCS. The results show that the addition of L significantly improves the strength development of RAP-FA geopolymer compared to the RAP-FA blend without L. Furthermore, the highest UCS was obtained from the mix with 80% RAP, 20% FA and 8% L (100% NAOH, 0% NA2SIO3) after 28 days of curing. This mix achieved a UCS of 22.77 KN/m3, which is higher than the minimum strength requirement for sub-base layers in road constructions. The research also suggests that the use of RAP-FA geopolymer as a road construction material can significantly reduce the environmental impact of asphalt waste and also reduce the use of natural resources. In conclusion, the study demonstrates the potential of using RAP-FA geopolymer as an alternative road construction material that can offer both environmental and economic benefits. The findings of this study can provide valuable insights for future research on the development of sustainable road construction materials. Additionally, the SEM analysis reveals that a denser microstructure is developed in the RAP-FA blend, indicating a better interlocking between the particles. This can be attributed to the pozzolanic reaction of the FA, which leads to the formation of a greater amount of C-S-H and C-A-H gels in the interfacial transition zone. Furthermore, the XRD analysis also confirmed therefore improved strength. This is attributed to the pozzolanic reaction between the RAP and FA, which contributes to the formation of C-S-H, a binding agent in concrete. The XRD analysis also shows the presence of other phases such as ettringite and monosulfate, which are known to contribute to the strength and durability of concrete.