Browsing by Author "Yaragal, S.C."
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Item 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 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.Item Assessment of thermally deteriorated concrete by drilling resistance test and sound level(Maik Nauka Publishing / Springer SBM compmg@maik.ru, 2017) Kulkarni, K.S.; Yaragal, S.C.; Babu Narayan, K.S.; Vardhan, H.Concrete being the most versatile and widely used construction material finds application in varied range of structures. Many of these like chimneys, furnaces and reactors have to sustain high temperatures and perhaps all structures have to perform at elevated temperatures in the event of fire accidents. Concrete at elevated temperatures undergoes changes in its physical structure and chemical composition and loses its strength characteristics. Need for quick assessment of fire damaged concrete for strength characteristics, has motivated this work, which explores the potential of drilling resistance test on concrete as a Non Destructive Testing (NDT) tool. Drilling times, penetration depths and sound level measurement while drilling have been recorded and analysed to provide monograms that are handy as reckoners in failure forensics. © 2017, Pleiades Publishing, Ltd.Item Characteristics of normal strength concrete with and without chemical admixtures at elevated temperatures(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Yaragal, S.C.; Warad, S.A.; Babu Narayan, K.S.; Venkataramana, K.Fire is one of the most destructive powers to which a building structure can be subjected. Behavior of concrete when exposed to fire in cases like nuclear plants, cooling towers or any accidental fire in industrial buildings, is a serious concern, on the strength retention property of concrete. This work reports strength retention studies on compressive and split tensile strength of normal concrete with and without the chemical admixture (Reobuild 918, BASF make) at elevated temperatures. Concrete cubes of size 100 mm have been cast as per prior mix design for M30 grade of concrete, 28 days water cured and tested by destructive method for strength before exposure. Later these specimen were subjected to elevated temperatures of 200°C, 400°C, 600°C and 800°C with a retention period of 2 hours and were allowed cool within the furnace to reach ambient temperature. Later their appearance, colour and cracks were observed and also weight losses were determined. Further, destructive tests were conducted to estimate residual compressive and residual split tensile strengths and prediction equations are proposed to ascertain splitting tensile strengths from compressive strengths. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.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 Combined optimisation simulation model for groundwater management policy options(2007) Yaragal, S.C.; Nagaraj, M.K.Water resources system being quite complex in-nature, modelling involves several variables and parameters. A large number of models have been developed for analysis of water resources system. Most of the models developed are of simulation optimisation type. In general water management models which generally use the governing partial differential equation of now, the problem is formulated using either finite difference techniques or finite element method. In this paper, a hybrid model is formulated which simulates the groundwater system and optimises the same. The model developed has been used to study the effects of variation in pumping factors on the optimal values and on the yearly yield from the system, for a chosen pattern of pumping. The model has been analysed for three different boundary conditions. The aquifer model is descritised into 64 grids and a particular pumping pattern is chosen in the present study. The governing partial differential equation for groundwater now is reduced to algebraic linear equations using finite differences scheme and they are then embedded as a set of constraints in the model. For the chosen pumping pattern, the pumping factor plays a key role, depending on the boundary conditions, in achieving an optimum solution. Here, minimisation of heads is considered for optimisation. The model helps in simulating a complex groundwater system and evaluating certain policy for groundwater management.Item Core recovery: a damage diagnosis tool for thermally deteriorated concrete(Emerald Group Holdings Ltd., 2019) Kulkarni, K.S.; Yaragal, S.C.; S.k, B.N.Purpose: This paper aims to study and assess residual strengths of concrete specimen exposed to elevated temperatures by core recovery tests. Design/methodology/approach: The appraisal of concrete structures is typically carried out by means of partially destructive tests such as tests on concrete cores taken from the structure and non-destructive testing. Findings: This paper presents results associated with determination of residual compressive strengths of plain and reinforced concrete elements exposed to elevated temperatures by core recovery test. Physical observations and results of compressive strengths of cores extracted from plain cement concrete, as well as from reinforced concrete beam elements exposed to elevated temperatures, have been presented. Originality/value: The empirical relations have been proposed between standard cube and core extracted for compressive strength of concretes exposed to elevated temperatures are useful for damage diagnosis. © 2019, Emerald Publishing Limited.Item Decision Tree Model for Predicting Exposure Temperature and Retention Period-Dependent Behavior of Blended Concrete(Springer Science and Business Media Deutschland GmbH, 2023) Kulkarni, K.S.; Babu Narayan, K.S.; Yaragal, S.C.The major objective of the study is to estimate the behavior of blended concrete at various sustained exposure temperatures and retention times. The study examines the properties of four different types of concrete mixes, including unblended and blended mixes with fly ash and ground granulated blast furnace slag used to partially replace cement at exposure temperatures between 100 °C and 800 °C for varying exposure times of 1, 2, and 3 h. Concrete quality has been evaluated using measurements of density, porosity, and ultrasonic pulse velocity. Residual compressive and splitting tensile strengths have also been determined. The experimental study indicates that blended concrete has better fire-endurance characteristics than unblended concrete. The exposure temperature and retention time dependent behavior of unblended and blended concrete is predicted using classification and regression decision tree techniques. © 2023, The Author(s), under exclusive licence to Shiraz University.Item Durability studies on concrete with partial replacement of cement and fine aggregates by fly ash and tailing material(Techno Press technop2@chollian.net, 2017) Sunil, B.M.; Manjunatha, L.S.; Yaragal, S.C.Commonly used concrete in general, consists of cement, fine aggregate, coarse aggregate and water. Natural river sand is the most commonly used material as fine aggregate in concrete. One of the important requirements of concrete is that it should be durable under certain conditions of exposure. The durability of concrete is defined as its ability to resist weathering action, chemical attack or any other process of deterioration. Durable concrete will retain its original form, quality and serviceability when exposed to its environment. Deterioration can occur in various forms such as alkali aggregate expansion, freeze-thaw expansion, salt scaling by de-icing salts, shrinkage, attack on the reinforcement due to carbonation, sulphate attack on exposure to ground water, sea water attack and corrosion caused by salts. Addition of admixtures may control these effects. In this paper, an attempt has been made to replace part of fine aggregate by tailing material and part of cement by fly ash to improve the durability of concrete. The various durability tests performed were chemical attack tests such as sulphate attack, chloride attack and acid attack test and water absorption test. The concrete blend with 35% Tailing Material (TM) in place of river sand and 20% Fly Ash (FA) in place of OPC, has exhibited higher durability characteristics. © 2017 Techno-Press, Ltd.Item Durability studies on ferrochrome slag as coarse aggregate in sustainable alkali activated slag/fly ash based concretes(Elsevier B.V., 2020) Yaragal, S.C.; Kumar, B.; Jitin, C.Utilization of industrial byproducts in concrete reduces carbon footprint, associated with production of ordinary Portland cement (OPC), and also indirectly controls rapid depletion of natural resources in the form of natural coarse aggregate (NCA). This study reports the durability effect of alkali activated slag/fly ash concretes (AASFC) with ferrochrome slag (FCS) as coarse aggregate. Different AASFC mixtures were prepared with two control factors i.e., fly ash (FA) content (0, 25, and 50% by weight as a replacement to Ground granulated blast furnace slag (GGBS)), and FCS content (0, 50, and 100% by volume as a replacement to NCA). Total nine mixtures were examined for three different durability tests i.e., volume of permeable voids (VPV), acid resistant test, and sulphate resistant test. Further, embodied energy (EE), and Embodied carbon dioxide emission (ECO2e) were also utilized to optimize the AASFC mixtures by grey relational analysis (GRA). Analysis of variance (ANOVA) is used as a statistical tool to investigate the effect of FA, and FCS content on the overall durability and ecological performance of AASFC mixtures. Results show that, addition of FA increases the durability performance (in % age), and addition of FCS decreases the durability performance (in % age) in AASFC mixtures. AASFC mixture with composition of 50% GGBS, 50% FA, and 100% FCS is considered as most suitable mixture. © 2019 Elsevier B.V.Item Effect of different curing regimes and durations on early strength development of reactive powder concrete(Elsevier Ltd, 2017) Hiremath, P.N.; Yaragal, S.C.The early strength development of Reactive Powder Concrete (RPC) has been investigated under different curing regimes and compared with standard water curing condition. Four different curing regimes have been considered: ambient air curing, hot air curing, hot water bath curing and accelerated curing. The effect of hot air curing on strength development of RPC at different temperatures and durations are studied in detail. The present study is focused on the effect of combined curing regimes on the early strength development of RPC. Test results indicate that, among the four different curing regimes, hot water bath curing gives higher strength. The combined curing regime has considerably enhanced the compressive strength of RPC by about 63% as is evident by the rise in compressive strength from 110 MPa (standard curing) to 180 MPa (combined curing). Microstructure studies were also conducted to understand the arrangements of hydrated particles and development of other secondary hydrated products under different curing conditions using scanning electron microscope and X-ray diffraction spectroscopy respectively. © 2017 Elsevier LtdItem Effect of elevated temperatures on ferrochrome ash based mortars(Associated Cement Companies Ltd., 2019) Kumar, B.; Yaragal, S.C.; Das, B.B.Due to boom in construction sector, large amount of Ordinary Portland Cement (OPC) is being consumed. Cement production is energy intensive and releases large amount of CO2 into atmosphere. Efforts are on to bring down cement consumption by the use of secondary cementitious materials. An attempt is made to study the influence of combined effect of various levels of ferrochrome ash (FCA) and lime, as replacement to OPC for different cement mortar mixtures at elevated temperatures. FCA replacement considered is in the range of 0% to 20% and along with 7% lime as replacement to cement. Compressive strength of cementitious materials is being an important parameter in the design of structures. The main objective of this work is to assess the residual compressive strengths at different levels of temperatures (200, 400, 600, and 800ºC) for a retention period of half an hour. Residual strengths of mortar mixtures produced, using FCA, have shown a good performance. Upto 20% FCA and 7% lime, mixture turns out to be a good elevated temperatures enduring material. This would increase the suggested application for environmental friendly materials. Important differences were seen in microstructural observations with scanning electron microscope (SEM) for various levels of FCA and lime incorporated mortars. © 2019, Associated Cement Companies Ltd. All rights reserved.Item Effect of recuring on compressive strength of thermally deteriorated concrete cubes(2011) Prasanth, S.; Yaragal, S.C.; Babu Narayan, K.S.Concrete is found to undergo degradation when subjected to elevated temperatures during an event such as fire and lose substantial amount of its strength. The loss of strength in concrete is mainly attributed to decomposition of C-S-H and release of chemically bound water, which begins when the exposure temperature exceeds 500°C. When thermally deteriorated concrete is supplied with water there is a substantive gain in strength as a consequence of rehydration of cement that is initiated. This paper presents results of an experimental program carried out to investigate the effect of recuring on strength gain of normal strength concrete specimens subjected to elevated temperatures from 500°C to 800°C, which were subjected to retention time of two hours at the designated temperatures. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Effect of slag and solid activator on flowability and compressive strength of fly ash based one-part geopolymer pastes(Elsevier Ltd, 2023) Srinivasa, A.S.; Swaminathan, K.; Yaragal, S.C.The geopolymerization process has led to the transformation of industrial by-products into sturdy and long-lasting construction materials, such as geopolymer binders, which can be used to mitigate the massive CO2 emissions associated with the production of Ordinary Portland Cement (OPC). These binders are produced from aqueous solutions of alkali activators and alumina and silica rich industrial waste materials. Strong, caustic, and viscous aqueous solutions are used in alkali activation. Its handling, usability, and mass production are all tough, even transport and site difficulties compound these issues. The solid alumina-silica rich components, solid alkali activators, and free water are dry mixed in this work to create a unique “one-part” or “simply add water” geopolymer binder that is equivalent to OPC in its manufacture. Researchers looked at the flowability and compressive strength properties of fly ash based one-part geopolymer mixes while adding ground granulated blast furnace slag and a solid activator (anhydrous sodium metasilicate powder). At the 25 and 50% replacement levels, GGBS was used in place of fly ash. Solid activator content varied from 8 to 16% at an interval of 2% for each replacement level of GGBS. Microstructural and mineralogical alterations were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. According to the findings of the tests, the flowability and compressive strength improved with decreasing slag and solid activator concentration. It was found that activator content increments beyond 12% result in minor reduction in compressive strength, and that the highest compressive strength was measured at 50% GGBS and 12% activator content. Both flowability and compressive strength were improved by the 50% GGBS and 12% activator mixture, which also displayed symptoms of having a dense and compacted microstructure. © 2023Item Environmental sustainability of waste glass as a valuable construction material - A critical review(EM International rktem@pn3.vsnl.net.in, 2018) Sudharsan, N.; Palanisamy, T.; Yaragal, S.C.The increased demand for concrete as a construction material leads to increase in cement production. The formulation of cement, emits a significant amount of CO2 to the atmosphere, which causes severe environmental pollution. Many efforts are being made to reduce the use of Portland cement in concrete to avoid environmental issues. These efforts mainly involve the utilization of value added materials in concrete. In this context, the waste glass powder has excellent pozzolanic properties, to use glass powder as a supplementary cementitious material in concrete. The use of waste glass powder in concrete has many economic and environmental benefits. This paper summarizes the literature regarding the utilization of waste glass powder as a supplementary cementitious material in mortar and concrete. © 2018 EM International. All rights reserved.Item Experimental investigation on utilization of waste shredded rubber tire as a replacement to fine aggregate in concrete(Springer, 2019) Hiremath, P.N.; Jayakesh, K.; Rai, R.; Naganna, N.S.; Yaragal, S.C.Depletion of natural resources in the past few decades due to rapid construction activities all around the world has forced a threat to the availability of natural resources for future generation. The utilization of waste industrial by products, in the form of supplementary cementitious materials and waste tire rubber products replacing natural aggregates in production of concrete. In the present study performance of concrete mixes incorporating 2.5, 5, 7.5 and 10% Waste Shredded Rubber Tire (WSRT) as partial replacement of fine aggregate is investigated. Numerous research works have been conducted on replacement of aggregate by waste crumb rubber but data scarce on utilization of waste rubber in concrete directly. Hence to examine characteristics of shredded rubber tire based concretes, two sets of concrete specimen were produced. In the first set, shredded rubber tire is added directly without any pretreatment and in the second set the shredded rubber tire was immersed in NaOH solution for 24 h and then washed with water thoroughly and rubbed with sand paper to obtain the rough surface finish to facilitate improved bonding properties with cement matrix. To evaluate the performance of WSRT based concretes, fresh and hardened properties were determined by conducting slump tests on fresh mixes, and compression, flexural and impact tests on hardened concrete cubes and prisms. Proving results were obtained for potential use of WSRT in concretes for generalized applications. © Springer Nature Singapore Pte Ltd. 2019.Item Feasibility of gurpur river at Malavoor as a sink for Bajpe town domestic waste disposal - A case study(2009) Babu Narayan, K.S.B.; Kumar, J.P.; Yaragal, S.C.; Shrihari, S.Mangalore is one of the fast growing cities in Karnataka with improved infrastructure taking place in recent days. In view of rapid development in and around Mangalore city, the sub urban or rural areas around the city have started developing at a rapid rate. One such place is Bajpe where the town is growing very fast due to the expansion of activity of Bajpe Airport and upcoming SEZ projects. An attempt has been made to find out the load on River Gurupur, if the Bajpe town domestic waste is assumed to be disposed to River Gurupur at Malavoor bridge point downstream without any treatment. Experiments were conducted to find the parameters used to find out the dissolved oxygen (DO) consumption and replenishment in teh river body using BOD-DO river quality model developed by Streeter-Phelps (1925). Model formulation, analysis and the results obtained are discussed in the paper. Copyright © Enviromedia.Item Ferrochrome ash – Its usage potential in alkali activated slag mortars(Elsevier Ltd, 2020) Kumar, K.B.; Yaragal, S.C.; Das, B.B.This study is an attempt to develop a sustainable construction material, i.e., alkali activated slag (AAS) in combination with ferrochrome ash (FCA) as a replacement to ordinary Portland cement (OPC). The effect of the various levels of FCA (0, 25, and 50%) replacing ground granulated blast furnace slag (GGBS) in AAS mortars with 4% of Na2O dosage is studied. Further, five levels of the modulus of silica (Ms = 0.75, 1.00, 1.25, 1.5, and 1.75) are chosen to achieve targeted compressive strength at 28 days under ambient temperature curing conditions. The compressive strength decreases with the increase in level of the FCA replacement. The targeted design compressive strength is achieved with 25% FCA replacement to GGBS in the AAS mortar system with Ms = 1.25. In addition, microstructure and mineralogical studies are undertaken to ascertain the formation of different hydration products with the aid of the scanning electron microscope (SEM) and the X-ray diffractometer (XRD). Gismondine and calcium aluminate silicate hydrate (C-A-S-H) are the major hydration products in the AAS mortar mixes. Sodium aluminate silicate hydrate phases (N-A-S-H) are also observed prominently as the FCA replacement level increases in the AAS mortar mixes. The Fourier-transform infrared spectroscopy (FTIR) confirms the presence of the Si–O-(Si or Al) functional group. The addition of FCA in the AAS system is of vital significance in the reduction of the embodied carbon dioxide (ECO2eq), embodied energy (EEeq) and cost. © 2020 Elsevier LtdItem Influence of curing regimes and duration on the early strength development of fibers based reactive powder concretes(Elsevier Ltd, 2025) Yaragal, S.C.; Annigeri, H.V.; Krishna K M, N.; Allikatti, C.; Dinesh, G.; Prashanth, M.H.Curing regimes play a crucial role in enhancing the early strength and overall performance of reactive powder concrete (RPC). This study focuses on the influence of different curing regimes on the early strength development of various fibers based RPC mixes. RPC mixes were produced adopting four-stage mixing method. The hot water curing (HWC) and steam curing (SC) regimes achieved a strength of 84 MPa at 24 and 48 h, respectively, being equivalent to the strength of RPC under 28 days of conventional method of water curing (WC). The combined curing (CC) (1 day HWC at 100 °C followed by 7 days of oven hot air curing at 200 °C) and air curing (AC) resulted in the highest and lowest strength of 120 and 74 MPa, while hot air curing (HAC) gave a strength of 96 MPa. Different fibers adopted showed negligible influence on the variation in strength. SEM results revealed that HWC and SC produced predominantly a plate-like tobermorite and dense thick fibrous tobermorite. The HAC and CC regimes showed the presence of tobermorite and xonotlite in the diffraction pattern, whilst HWC and SC displayed tobermorite alone. Nuclear magnetic resonance spectroscopy (NMR) results showed that there is an increase in the hydration degree for hydrothermally treated curing regimes (SC, HWC, and CC) except heat treated (HAC), resulting in higher strength. At higher temperature, the existing chain-like silicates get converted to sheet-like silicates, increasing the mean chain length of C-S-H and degree of connectivity. In summary, the CC regime can be adopted in the construction industry, as it stands out as the most favourable one among all the curing methods for attaining high early strength. © 2025 Elsevier Ltd