Assessment of the Suitability of Reclaimed Asphalt Pavement (RAP) for Use as a Base Course Material in Road Construction

B. Kadai, I. S. Muhammad, A. G. Bukar

Abstract


This study investigates the compaction characteristics, mechanical strength, and suitability of Reclaimed Asphalt Pavement (RAP) blended with crushed stone base (CSB) for potential use in pavement structures. The stone base exhibited the lowest Optimum Moisture Content (OMC) of 7.76% and a relatively low Maximum Dry Density (MDD) of 2.21 g/cm³, typical of clean granular materials. In contrast, 100% RAP showed the highest OMC (10.70%) and MDD (2.46 g/cm³), attributed to the presence of bituminous binder enhancing particle cohesion. OMC increased with RAP content up to 20% but declined beyond 40%, suggesting interaction effects that enhance compaction efficiency at intermediate blends. MDD values consistently increased with RAP content, indicating improved packing density. Aggregate Impact Value (AIV) and Aggregate Crushing Value (ACV) tests confirmed that all material combinations complied with the Federal Ministry of Works (1997) specifications. CBR results revealed that 100% stone base achieved the highest strength (100.6%), while 100% RAP had the lowest (22%). Mixtures with 20–40% RAP demonstrated significantly improved CBR values (97% and 75%, respectively), approaching the performance of the virgin stone base. These findings suggest that incorporating up to 40% RAP into stone base can achieve acceptable strength for base layer applications, supporting material reuse while maintaining structural integrity and sustainability.


Full Text:

PDF

References


Alotaibi, S., and Al-Mutairi, N. (2025). Using Reclaimed Asphalt Pavement in Backfilling Works Beneath the Structures. Transportation Infrastructure Geo-technology, 12, Article 54. https://doi.org/10.1007/s40515-024-00503-6

Alhassan, M., and Mohammed, M. (2021). Effect of Reclaimed Asphalt Pavement Stabilization on the Microstructure and Strength of Black Cotton Soil. Academia.edu.

British Standard (1990). Testing aggregates – Method for determination of particle size distribution (sieve analysis). BS 812: Part 103:1990

British Standard (1990). Methods of test for Soils for civil engineering purposes – Compaction-related tests. BS 1377: Part 4:1990

British Standard (1990). Methods of test for soils – In-situ tests including CBR. BS 1377: Part 9:1990

British Standard (1990). Testing aggregates – Methods for determination of aggregate crushing value (ACV). BS 812: Part 110:1990

Costa, L. F. da, Mendes, L. P. T., Melo Neto, O. de M., Lucena, L. C. de F. L., & Lucena, L. de F. L. (2025). Economic and environmental benefits of recycled asphalt mixtures: Impact of reclaimed asphalt pavement and additives throughout the life cycle. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-025-36362-y

Federal Highway Administration (FHWA). (2022). Reclaimed Asphalt Pavement in Roadway Base and Subbase Applications. FHWA-HRT-22-134.

Federal Ministry of Works, Nigeria Specification (1997). Standard specifications for roads and bridges construction in Nigeria.

Hamzah, M. O., Valentine, R. I., & Ismail, H. (2012). Performance of warm mix asphalt containing reclaimed asphalt pavement with Sasobit additive. Jurnal Teknologi, 60(3). Retrieved from https://journals.utm.my/jurnalteknologi/article/view/4287

Local Government Engineering Department (LGED), Bangladesh. (2023). Use of Reclaimed Asphalt Pavement (RAP) in Road Construction – Field and Laboratory Investigations. LGED Report. https://lged.portal.gov.bd

Lo Presti, D., Airey, G., & Partl, M. N. (2023). Use of reclaimed asphalt in unbound layers and other civil engineering applications. Infrastructures, 9(8), 128. https://doi.org/10.3390/infrastructures9080128

National Asphalt Pavement Association (2021). Recycling. Retrieved from https://www.asphaltpavement.org/expertise/sustainability/sustainability-resources/recycling

Nunez, M., and Perez, F. (2023). Physical and Mechanical Properties of Reclaimed Asphalt Pavement (RAP) Incorporated into Unbound Pavement Layers. Applied Sciences, 13(1), 362. https://doi.org/10.3390/app13010362.https://www.fhwa.dot.gov/publications/research/infrastructure/structures/97148/rap134.cfm

Zaumanis, M., Mallick, R. B., & Frank, R. (2022). Long-term performance of high-RAP asphalt mixtures: A review. Polymers, 14(21), 4736. https://doi.org/10.3390/polym14214736

Zhou, F., Scullion, T., & Hu, S. (2015). Balanced Mix Design for Recycled Asphalt Pavements: A Case Study. Transportation Research Record: Journal of the Transportation Research Board, 2507(1), 1–9. https://doi.org/10.3141/2507-01.


Refbacks

  • There are currently no refbacks.