Paper Title
Laboratory Investigation on Evolving the Mix Design of RCC Containing Rap Aggregates and Silica Fume

India has one of the largest road networks in the world. Regular maintenance and rehabilitation of asphalt pavements that comprise 80-90% of this network generate a huge amount of Reclaimed Asphalt Pavement (RAP) aggregates, which lead to stockpiling causing negative effects on the environment. Reconstructing asphalt pavement with RAP is easy but it requires additional asphalt addition, which is quite costly. The use of RAP in pavement quality concrete (PQC) is not conducive due to reduced bonding with cement paste. Roller compacted concrete (RCC) offers an alternative as its strength also depends upon the friction between the constituting particles thereby reducing cement demand, and it is stiff enough to support the compaction under roller load. This study investigates the feasibility of using RAP aggregates in the RCC and PQC mix. The evolution of the RCC mix was initiated from a reference PQC mix designed as per IRC: 44-2017. Combined coarse and fine aggregates were replaced by 50% coarse & fine RAP aggregates by volume in PQC and RCC mixtures. Results showed that RAP addition leads to a reduction of compressive & flexural strength in PQC and RCC mixes by 24% & 20% and 24% & 14%, respectively. Silica fume addition (15% by volume of cement) improved the compressive & flexure tensile strength of the RCC-RAP mix such that these values (32.8 MPa & 3.9 MPa) are just 29% lesser than the PQC mix, though the mix qualifies the strength criteria of an RCC, thus encouraging RCC-RAP usage along with silica fume in rigid pavement construction. Advantages of RCC, such as roller compaction, lesser cement requirement, use of waste materials like RAP and SCMs, and early traffic opening certainly make it a sustainable concrete. Keywords - Reclaimed Asphalt Pavement (RAP), Pavement quality concrete (PQC), Roller compacted concrete (RCC), Interfacial transition zone (ITZ).