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Item Processing of laboratory concrete demolition waste using ball mill(Elsevier Ltd, 2023) Rakesh Kumar Reddy, R.; Yaragal, S.C.; Sanjay, V.K.The demand for natural aggregates in the twenty-first century is at an all-time high due to rapid urbanisation and infrastructure development. Finding alternative aggregate materials is a challenge for achieving construction sustainability. Both the depletion of natural resources and the improper disposal of construction and demolition (C&D) waste can be ameliorated by the widespread use of recycled aggregates in construction. Due to the attached mortar, aggregates from C&D waste must be processed before using them in concrete. Various combinations of ball mill processing parameters were used to produce relatively higher-quality aggregates. Water absorption was used as the primary criterion for determining the quality of processed aggregates. The water absorption capacity of recycled coarse aggregate was found to be decreased from 5.8% to 1.5% as a result of effectively removing the attached mortar by employing ball mill processing. Specific gravity, impact, and crushing values are also improved after processing, as discussed and illustrated in this paper. © 2023Item A novel approach for optimizing the processing of recycled coarse aggregates(Elsevier Ltd, 2023) Rakesh Kumar Reddy, R.; Yaragal, S.C.This paper proposes an alternative method for processing the demolition waste into high-quality recycled coarse aggregate using the ball mill. Taguchi's design of experiments based on orthogonal array was used to minimize the number of trials for saving material and time. Experiments were carried out based on L25 orthogonal array with three processing parameters: charge, revolution duration, and aggregate weight with five levels. The revolution speed of the ball mill was set to 60 revolutions per minute. The Taguchi method was then combined with grey relational analysis to achieve the best combination of processing parameters for producing high-quality aggregate. Experimental studies on water absorption, specific gravity, impact value, and abrasion value were used to assess the quality of recycled coarse aggregates. The best combination for each performance characteristic was achieved by using the mean of Signal to Noise ratio graphs. The optimal combination of processing parameter levels to generate superior quality recycled aggregates and the most significant processing parameter were identified based on the response table of means of grey relation grade. © 2023 Elsevier LtdItem One-part eco-friendly alkali-activated concrete – An innovative sustainable alternative(Elsevier Ltd, 2023) Rakesh Kumar Reddy, R.; Yaragal, S.C.; Srinivasa, A.S.The primary objective of this study is to develop an eco-friendly one-part alkali-activated concrete (OPAAC) by incorporating a combination of fly ash (FA), ground granulated blast furnace slag (GGBS), and micro silica (MS). In this investigation, the proportion of MS is maintained at 20% of FA, while the maximum replacement of FA with GGBS is set to 60%, varying in 20% intervals (i.e., 0%, 20%, 40%, and 60%). Further, the natural aggregates (NA) are substituted with recycled coarse aggregates (RCAs), ferrochrome slag aggregates (FCSAs), or a combination of both. The influence of GGBS and alternative aggregates (RCAs, FCSAs) on the mechanical properties of OPAAC is thoroughly examined. To provide a comprehensive assessment, the properties of OPAAC are compared against Ordinary Portland Cement (OPC) concrete (CC) of equivalent grades. Additionally, microstructural and mineralogical investigations are conducted to determine the formation of distinct hydration products, utilizing scanning electron microscopy (SEM) and X-ray diffractometry (XRD) techniques. In OPAAC containing FA, the primary hydration products identified are alkaline alumino silicate hydrates (CASH and NASH). As the GGBS content increases, calcium silicate hydrate (CSH) becomes the predominant hydration product. Furthermore, in order to assess the sustainability of OPAAC, an analysis of embodied CO2 emissions is performed, and the results are compared with CC and alkali-activated concrete. Notably, OPAAC comprising 40% FA replaced with GGBS, 50% RCAs, and 50% FCSAs demonstrates the most favourable mechanical properties and exhibits lower CO2 emissions. © 2023 Elsevier Ltd