Civil Engineering and Architecture 11(3): 1576-1588, 2023 http://www.hrpub.org DOI: 10.13189/cea.2023.110337 Experimental Investigation on Durability Study of Portland Slag Concrete with Influence of High-Volume Recycled Aggregate T. Sujatha 1,* , D.S.R. Murty 2 1 Research Scholar, Department of Civil Engineering, Andhra University, Visakhapatnam, Andhra Pradesh, India 2 Professor, Department of Civil Engineering, Andhra University, Visakhapatnam, Andhra Pradesh, India Received December 11, 2022; Revised January 23, 2023; Accepted March 12, 2023 Cite This Paper in the Following Citation Styles (a): [1] T. Sujatha, D.S.R. Murty , "Experimental Investigation on Durability Study of Portland Slag Concrete with Influence of High-Volume Recycled Aggregate," Civil Engineering and Architecture, Vol. 11, No. 3, pp. 1576 - 1588, 2023. DOI: 10.13189/cea.2023.110337. (b): T. Sujatha, D.S.R. Murty (2023). Experimental Investigation on Durability Study of Portland Slag Concrete with Influence of High-Volume Recycled Aggregate. Civil Engineering and Architecture, 11(3), 1576 - 1588. DOI: 10.13189/cea.2023.110337. Copyright©2023 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract The importance of environmental protection and conservation, as well as the utilization of sustainable materials, in modern construction, has more concern on the scarcity of natural aggregates. Because of this increasing interest in using recycled aggregates in construction, the use of recycled aggregates in concrete needs more concern about durability aspects rather than strength. Normally Recycled Aggregate concrete (RAC) contains more porosity and water absorption. More studies reveal that recycled aggregate concrete has less durability than conventional concrete. In this regard, current experimental investigation was carried out to determine the durability of RAC with the use of sustainable materials i.e., Portland slag cement was used instead of OPC. M-sand as an alternative for river sand, Natural coarse aggregate (NCA) was replaced with recycled aggregate by various percentages (30, 45 and 60 percent) and Nano silica. The cube strength of concrete was optimum at 45% replacement of recycled aggregates with natural coarse aggregates at all grades, the percentage of strength difference between 28 and 180 days compressive strength about 27%. Concrete durability properties (RCPT, Permeability, water absorption and Acid resistance) were tested at various replacement percentages for M20, M25, M30 and M35 grades. Chloride ion permeability was reduced about 56% at higher concrete grades (M30 & M35) due to Nano silica at 180 days. At 90 days, the acid effect on RAC strength loss was reduced by roughly 5%. Nano silica is added to higher grades to decrease the water demand and enhances the durability and strength properties. Keywords Portland Slag Cement, M-Sand, Recycled Coarse Aggregate (RCA), Recycled Aggregate Concrete (RAC), Nano Silica (NS) 1. Introduction The influence of recycled aggregate on Mechanical and Durability Properties of concrete is noted that, in comparison to conventional concrete, the mechanical properties are subpar, while the durability properties were enhanced due to the replacement or addition of GGBs, fly ash, steel fibers, rice husk, etc. with RAC [1]. Durability studies were done on recycled aggregate concrete with OPC and OPC mixed with Pozzolanic materials, but resulted in RCA having lower strength and durability due to the residual material on the surface, which is unproductive to the well-built link between aggregate and cement paste, moreover it has high permeable and water absorption and low acid resistant [2]. This study was focused on the durability of high volume recycled aggregate concrete with Portland slag replaced by Nano silica at 1.5% by weight of cement for higher grades.