Faculty Publications
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Item Optimization of ferrochrome slag as coarse aggregate in concretes(Techno Press technop2@chollian.net, 2019) Yaragal, S.C.; Kumar, B.C.; Mate, K.The alarming rate of depletion of natural stone based coarse aggregates is a cause of great concern. The coarse aggregates occupy nearly 60-70% by volume of concrete being produced. Research efforts are on to look for alternatives to stone based coarse aggregates from sustainability point of view. Response surface methodology (RSM) is adopted to study and address the effect of ferrochrome slag (FCS) replacement to coarse aggregate replacement in the ordinary Portland cement (OPC) based concretes. RSM involves three different factors (groUnd granulated blast furnace slag (GGBS) as binder, flyash (FA) as binder, and FCS as coarse aggregate), with three different levels (GGBS (0, 15, and 30%), FA (0, 15, and 30%) and FCS (0, 50, and 100%)). Experiments were carried out to measure the responses like, workability, density, and compressive strength of FCS based concretes. In order to optimize FCS replacement in the OPC based concretes, three different traditional optimization techniques were used (grey relational analysis (GRA), technique for order of preference by similarity (TOPSIS), and desirability function approach (DFA)). Traditional optimization techniques were accompanied with principal component analysis (PCA) to calculate the weightage of responses measured to arrive at the final ranking of replacement levels of GGBS, FA, and FCS in OPC based concretes. Hybrid combination of PCA-TOPSIS technique is foUnd to be significant when compared to other techniques used. 30% GGBS and 50% FCS replacement in OPC based concrete was arrived at, to be optimal. © 2019 Techno-Press, Ltd.Item Characterization and performance of processed lateritic fine aggregates in cement mortars and concretes(Elsevier Ltd, 2019) Yaragal, S.C.; Basavana Gowda, S.N.; C, C.Availability of river sand is becoming scarce, due to rapid increase in infrastructure projects in India. Acute shortage of river sand, has led to indiscriminate sand mining. Adverse effect of sand mining includes river bank erosion, river bed degradation, loss of biodiversity and deterioration of river water quality and ground water availability. To address the above issues, research efforts are on, to find substitutes for river sand to be used as fine aggregate in mortars and concretes. One among the locally available resources is laterite. Laterite is a product of tropical or sub-tropical weathering, which is an abundant soil material in many parts of India. An attempt has been made to characterize the processing technique to obtain good quality lateritic fine aggregates (lateritic FA). Experiments were designed and conducted to study the performance of lateritic FA as replacement to river sand, in cement mortars and concretes. Processed lateritic FA in replacement levels of 0, 25, 50, 75 and 100 wt% to river sand at all fineness levels (Zone I to Zone IV as per Indian standards) is considered. Microstructure studies were conducted to understand the arrangement of river sand and lateritic FA with cement matrix and their Interfacial Transition Zones (ITZ) using Scanning Electron Microscope (SEM). The workability and compressive strength characteristics of cement mortars and concretes are evaluated. Laterized mortars with Zone III and Zone IV fine aggregates, at all replacement levels, result in the same compressive strengths as those of control mortars. Suitable strength enhancement technique has been attempted to achieve strengths of Zone I and Zone II lateritic fine aggregates based mortars at 100 wt% replacement, to achieve strength at least equal to or more than those of control mortars. Laterized concretes have achieved nearly the same strengths as those of control concretes, at all replacement levels and for all fineness levels (Zone I to Zone IV). © 2018 Elsevier LtdItem Multi-criteria optimization of fly ash and iron ore tailing based concretes subjected to elevated temperatures(Associated Cement Companies Ltd., 2019) Yaragal, S.C.; Babu Narayan, K.S.; Kumar, B.; Francis, J.G.Due to the rapid increase in concrete utilization all over the world, there is increased consumption of Ordinary Portland Cement (OPC), natural fine aggregate (NFA), and natural coarse aggregates. Increased use of OPC, is posing a serious threat due to excess CO2 emissions, and its production is highly energy intensive. On the other hand, extraction and processing stone-based fine and coarse aggregates too, is energy intensive, and the virgin resources are fast depleting. Therefore, for sustainable development, efforts are on all over the world to look for alternative materials in place of conventional ones. In this study, it is attempted to partly replace OPC with fly ash (FA) and partly replace NFA by iron ore tailings (IOT) in concretes. The performance of such concretes at ambient and elevated temperatures is also presented. Full factorial design of experiments was adopted with two control factors under three levels of replacement, i.e., FA (0, 15, and 30% by weight of OPC) and IOT (0, 50, and 100% by volume of NFA). Total nine concrete mixes were prepared and tested for their compressive strengths at room temperature, and residual compressive strengths when subjected to various levels of elevated temperatures (200, 400, 600, and 800°C), and cost of these concretes has also been analyzed. Further, three traditional multi–criteria optimization methods, i.e., grey relational analysis (GRA), technique for order of preference by similarity to ideal solution (TOPSIS), and desirability function approach (DFA) were used to optimize concrete mixes. Results showed that TOPSIS based optimization method is more significant when compared to other two methods. Further, FA-based concrete mixes showed improved performance under multi-criteria optimization. © 2019, Associated Cement Companies Ltd. All rights reserved.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 Numerical and experimental studies on sustainable alkali activated concretes at elevated temperatures(Emerald Publishing, 2023) Yaragal, S.C.; Kumar, B.; Abhinav, M.U.Purpose: To reduce environmental impact caused by excessive use of ordinary Portland cement (OPC) and to mitigate scarcity of base materials such as natural coarse aggregate (NCA), industrial by-products can be carefully used as alternatives to OPC and NCA, in production of concrete. This paper aims to describe the performance of using ground granulated blast furnace slag (GGBS), fly ash (FA) as a complete replacement to OPC and ferrochrome slag (FCS) as replacement to NCA in production of novel FCS based alkali activated slag/fly ash concretes (AASFC) and evaluate their performance at elevated temperatures. Design/methodology/approach: Two control factors with three levels each i.e. FA (0, 25 and 50 per cent by weight) and FCS (0, 50 and 100 per cent by volume) as a GGBS and NCA replacement, respectively, were adopted in AASFC mixtures. Further, AASFC mixture specimens were subjected to different levels of elevated temperature, i.e. 200°C, 400°C, 600°C and 800°C. Compressive strength and residual compressive strength were considered as responses. Three different optimization techniques i.e. gray relational analysis, technique for order preference by similarity to ideal solution and Desirability function approach were used to optimize AASFC mixtures subjected to elevated temperatures. Findings: As FA replacement increases in FCS based AASFC mixtures, workability increases and compressive strength decreases. The introduction of FCS as replacement to NCA in AASFC mixture did not show any significant change in compressive strength under ambient condition. AASFC produced with 75 per cent GGBS, 25 per cent FA and 100 per cent FCS was found to have excellent elevated temperature enduring properties among all other AASFC mixtures studied. Originality/value: Although several studies are available on using GGBS, FA and FCS in production of OPC-based concretes, present study reports the performance of novel FCS based AASFC mixtures subjected to elevated temperatures. Further, GGBS, FA and FCS used in the present investigation significantly reduces CO2 emission and environmental degradation associated with OPC production and NCA extraction, respectively. © 2019, Emerald Publishing Limited.Item 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 LtdItem Assessment of fly ash and ceramic powder incorporated concrete with steam-treated recycled concrete aggregates prioritising nano-silica(Springer Nature, 2024) Rao, A.U.; Shetty, P.P.; Bhandary, R.; Tantri, A.; S., S.; Yaragal, S.C.Present research involves determining the effects of a proposed novel nano-silica prioritized-steam-treated recycled concrete aggregate (RCA) on microstructural, mechanical, and durability aspects of concrete incorporated with waste ceramic powder (WCP). The study on novel nano-silica prioritized-steam-treated recycled concrete aggregate revealed that 3% nano-silica induction with 3-h steam treatment for 50% adhered mortar bonded RCA performed optimally. The physical characterization of treated RCA showed improvement compared to untreated RCA, which was confirmed by microstructure study indicating the formation of additional calcium silicate hydrates in the bonded adhered mortar of treated RCA. Furthermore, as WCP has significant contents of alumina and silica, an optimum ternary binder mix was developed with cement, fly ash, and WCP. Later, a study was performed to analyse the performance of treated RCA incorporated in WCP prioritized concrete mix. The mechanical performance of WCP prioritized concrete with treated RCA was investigated through compressive strength, flexural strength, split tensile strength, and modulus of elasticity. The quality was ensured through ultrasonic pulse velocity, water absorption, and density characterization. The durability of concrete was studied with 5% concentrated hydrochloric acid attack and sea water (pH = 8.3 to 8.7) exposure conditions for a duration of 148 days (including 28 days of portable water curing period). Overall, 30% of the ternary mixture based on WCP prioritization, 50% adhere mortar-based RCA, and 3% of nano-silica prioritization steam treatment (3 h) demonstrated the best performance in terms of both mechanical and durability aspects. The study concluded that due to its improved performance, the innovative nano-silica priority steam treatment approach could replace 100% of RCA in concrete. Furthermore, treated RCA being advantageous because of easy adoptable technique for real-time practices as well as maintaining consistency regards RCA characteristics throughout concrete mixture be the challenge. © The Author(s) 2024.