Construction and Building Materials 301 (2021) 124197 Available online 31 July 2021 0950-0618/© 2021 Elsevier Ltd. All rights reserved. Utilization of cashew nut-shell ash as a cementitious material for the development of reclaimed asphalt pavement incorporated self compacting concrete Adithya Tantri * , Gopinatha Nayak * , Muralidhar Kamath , Adithya Shenoy , Kiran K. Shetty Department of Civil Engineering, Manipal Institute of Technology, MAHE, Manipal, Karnataka, India A R T I C L E INFO Keywords: Self compacting Concrete Recycles asphalt pavement Cashew nut-shell ash Bailey gradation Workability Xradia Non-destructive testing Destructive testing Compressive strength Elastic modulus ABSTRACT This paper focuses on developing sustainable self-compacting concrete (SCC) through the optimization process by incorporating Reclaimed Asphalt Pavement (RAP) as coarse and fine aggregates and also utilizing Cashew Nut-shell Ash (CNA) as a cementitious material. To achieve this optimization technique is implemented in four stages, which are the RAP aggregate treatment process, gradation selection process, RAP replacement percent- age, and considering the CNA replacement percentage. RAP has been treated by a novel freeze–thaw cyclic procedure followed by the abrasion treatment method. Bailey’s Aggregate Grading Technique (BAGT) has been implemented to line up the aggregate packing gradation. Mechanical and rheological properties have been conducted and analyzed based on compliance requirements of SCC at ambient temperature. Paste properties are analyzed through Field Emission Scanning Electron Microscopy, X-ray diffraction, Energy-Dispersive- Spectroscopy, and Thermo Gravimetric Analysis. Further, quality assessment of SCC has been performed through X-ray μCT (Xradia, XCT-500) and Ultrasonic Pulse velocity tests. In addition, compressive and flexural strength of selected SCC mixes have been performed at 50 ◦ C, 100 ◦ C, and 150 ◦ C. Based on the results, with the incorporation of 75% coarse RAP, 50% fine RAP along 15% CNA as a binder constituent it becomes possible to achieve a sustainable SCC and it was found to be most suitable for real-time practices. 1. Introduction Concrete is a versatile material that encompasses cement as a pri- mary binder, aggregates as the skeleton and mineral-chemical admix- tures as the promoters of rheological properties of concrete. As a composite matrix, concrete relies on aggregates and cement, but the present scenario exposes the scarcity of natural aggregates [1] and high demand for cement production [2]. A survey found that cement pro- duction will reach up to 3000 MT in India and up to 5800 MT globally, which is estimated to produce 2.5 billion tonnes of CO 2 emissions in the year 2050 globally [3,4]. Thus, the ecological and monetary threats of Portland cement will be reduced through the utilization of agro- industrial waste including fly ash, rice husk ash, ground granulated blast furnace slag, Metakaolin, which have been widely utilized as a supplementary cementitious material in the production of concrete [5–8]. India is the third-largest producer of cashew nuts in the world, 620000 tonnes is the yearly production of cashew nuts [9–11]. However, most of the cashew nut production industries of India generate a large amount of cashew nut-shell as a waste byproduct that is being arbitrarily disposed of. In the view of environmental benefits or in other terms as supplementary to cement, utilization of Cashew Nut-shell Ash (CNA) as a pozzolanic product will be a great opportunity [12]. Until now, limited studies have utilized CNA as a supplementary cementitious material to Portland Cement. Oxide-composition comparison of CNA revealed the huge variation from source to source and it has been found that variations in CaO and SiO 2 contents are in the range of 0.86% to 35.67% and 8.18% to 62.85% [10,12–17]. These oxides have a major influence on the fresh and hardened properties of conventional concrete. Oyebisis et al. [12] have investigated lower calcium oxide-based (0.86%) CNA which increases the compacting factor and slump flow as replacement increases between 5% and 20% in CNA-based concrete. Pandi et al. [18] have experimented with higher calcium oxide-based (35.67%) CNA and this results in a decrease of slump flow as CNA replacement increases between 5% and 30% in CNA-based concrete. * Corresponding authors. E-mail addresses: aditya.tantry001@gmail.com (A. Tantri), nayak.gopinath@manipal.edu (G. Nayak), muralidhar.kamath@learner.manipal.edu (M. Kamath), adithya.shenoy@learner.manipal.edu (A. Shenoy), kiran.shetty@manipal.edu (K.K. Shetty). Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat https://doi.org/10.1016/j.conbuildmat.2021.124197 Received 20 May 2021; Received in revised form 7 July 2021; Accepted 7 July 2021