Faculty Publications
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Item An experimental investigation to determine the properties of fly ash based geopolymers as per indian standards(Springer, 2019) Saha, S.; C, C.Production of ordinary Portland cement requires huge quantity of natural resources and also releases huge quantity of carbon dioxide into the atmosphere. Research efforts have been continuing to establish geopolymer as an alternative cementitious material for the replacement of ordinary Portland cement. This paper presents the study to find out the properties of fly ash based geopolymer paste and 28 days compressive strength of geopolymer mortar. Standard consistency, setting time of geopolymer paste has been determined using vicat’s apparatus (according to Indian Standards), which is followed for cement paste, varying the concentration of sodium hydroxide solution from 6 to 16 M. Results indicate higher standard consistency, more time required for setting for fly ash based geopolymer than that of cement paste. Compressive strength of the geopolymer paste and mortar 17 specimens increases with the increase of the concentration of sodium hydroxide solution and decrease beyond 14 M. © 2019, Springer Nature Singapore Pte Ltd.Item Replacement of River Sand with Coal Bottom Ash as Fine Aggregate in Cement Mortar(Springer Science and Business Media Deutschland GmbH, 2022) Wasnik, S.; Pavan, G.S.; Padhi, S.River sand is used as fine aggregate in concrete and cement mortar. The rapid expansion in construction activity witnessed in the country over the last decade has led to an incessant demand for river sand. Hence river sand is being excessively mined at the riverbeds and is leading to fast depletion of the precious natural resource. This presses the need for exploration of alternative materials which can be adopted as fine aggregate by construction industry to build concrete and masonry buildings. One possible candidate is coal bottom ash. Coal-based thermal power plants produce tonnes of coal bottom ash along with fly ash during power generation. Coal bottom ash is coarse particles settled at the bottom of cooling towers. The coarse nature of coal bottom ash particles can be harnessed and explored. The present study focuses on utilization of coal bottom ash as fine aggregate in cement mortars. River sand is fully and partially replaced by coal bottom ash. Five different proportions of river sand being replaced with coal bottom ash are adopted, namely 0, 25, 50, 75 and 100%. Performance of replacement of river sand with coal bottom ash is assessed in terms of particle size distribution (PSD) curves, workability and mechanical properties. Sieve analysis and mortar flow table test are conducted to assess the PSD curves and workability. Compression tests are conducted on cement mortar cubes (with different proportion of coal bottom ash) to determine compressive strength. Further, compression test is conducted on cement mortar cylinders in a displacement-controlled universal testing machine (UTM) to obtain the stress–strain curve and modulus of elasticity. The study found that river sand replaced with up to 50% coal bottom ash exhibited satisfactory performance as fine aggregate in cement mortar. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.Item Studies on Uniaxial compressive strength of laterite masonry prisms(2011) Unnikrishnan, S.; Narasimhan, M.C.; Venkataramana, K.Laterite is a well known conventional building material in Asian countries. In spite of its large popularity in construction, a systematic characterization of this material, as a building block, has not been seriously attempted so far. The strength and elastic properties of laterite masonry are influenced by the individual properties of the laterite blocks and the mortar. In the present study, characterization of the laterite block and the mortar and compressive strength of laterite masonry prisms have been investigated using detailed laboratory experiments and numerical analysis. The experimental results, related to the compressive strength and stress-strain characteristics of laterite and mortar and compressive strength of laterite masonry prisms are presented. Finite element analysis of laterite masonry prism has also been carried out. The studies have shown that the modulus of elasticity of laterite blocks tested is less than that of mortar used in making the laterite masonry. Further, the laterite masonry prisms have been observed to have failed by bond failure and subsequent splitting of laterite blocks. Also, increase in thickness of mortar joint gives rise to a decrease in laterite tensile stresses in mortar joint leading to higher prism strengths, if bond remains intact. © 2011 CAFET-INNOVA technical society. All right reserved.Item Influence of fineness of fly ash on compressive strength and microstructure of bottom ash admixed geopolymer mortar(Associated Cement Companies Ltd., 2018) Shivaprasad, K.N.; Das, B.B.; Renjith, R.Investigations were conducted to find out the suitability of bottom ash as a possible replacement to fine aggregates in geopolymer mortar. Experimental work was done to study the influence of fineness of fly ash (with three levels of Blaine's fineness, 2043 cm2/g, 2602 cm2/g and 3113 cm2/g on compressive strength and microstructure development of fly ash based geopolymer mortar with natural river sand and bottom ash as fine aggregates. three different water to solids ratios of 0.246, 0.349, and 0.443 were chosen for this study and the curing of the specimens was at ambient temperature (28 ± 3°c). compressive strength development for all eighteen mortar mixes was measured at 7, 14, 28 and 56 days. Further, the effect of fineness of fly ash on degree of polymerization, microstructure and properties of geopolymers was studied using Fourier transform Infrared Spectroscopy (FtIR) and Scanning Electron Microscopy (SEM). It was observed from the compressive strength of the geopolymer mortar that the degree of polymerization is gradual for both types of mortar. there is a continuous increase in the development of compressive strength noticed till the age of 56 days for both types of mortar, sand as well as bottom ash admixed. However, the increment of compressive strength for bottom ash found to be significantly less as compared to natural sand. Improvement in compressive strength due to fineness of fly ash were characterised by SEM and FtIR and it is revealed that with increase in fineness levels, the microstructure significantly enhanced the characteristics of geopolymer mortar. © 2018 Associated Cement Companies Ltd.. All rights reserved.Item Study on performance of infilled wall in RC framed structure using basalt fibre in cement mortar(Structural Engineering Research Centre, 2019) Jagadeesan, P.; Palanisamy, T.Normally, Reinforced Concrete (RC) framed structure is built by combination of structural and non-structural elements that may satisfy the design and architectural purpose. When RC framed structures are subjected to the static lateral loading, infilled wall and RC frame elements does not react together. At this time, infilled wall is subjected only compressive forces and does not support the tensile force. So, failure is happened due to lacking of ductility and poor interaction between frame elements and infilled wall. Therefore, the objective of this study is to improve the ductility and interaction between RC frame elements and infilled wall through suitable method of strengthening of infilled wall. In this research work, the two types of specimens such as infilled RC framed structure and infilled RC framed structure strengthened by reinforced cement mortar using basalt fibre were cast and tested under experimental and analytical investigation. One-fifth scale model of single-bay, two-storey plane RC framed structure were prepared and tested under cyclic loading with the help of 1000 kN capacity loading frame and foundation block. This study focuses the significant parameters such as load-deflection curve, ductility, energy dissipation capacity, initial stiffness and failure mechanism of infilled RC frame and infilled RC frame with basalt fibre in cement mortar. The result proves that basalt fibre reinforced cement mortar improves the strength, stiffness and ductility of infilled RC framed structure and make infilled wall as integral unit in RC framed structure. © 2019 Structural Engineering Research Centre. All rights reserved.Item Investigation on the potential use of recycled fine aggregate to produce geopolymer mortar mix(ASTM International, 2019) Saha, S.; C, C.The utilization of construction and demolition waste (C&DW) partially or fully for various purposes in construction industries is one of the most significant solutions to overcome the scarcity of raw materials and disturbances of the environmental system. On the other hand, geopolymer is being tried to be established as an alternative sustainable binder material for ordinary portland cement. In the present study, with the thought of promoting of sustainability, an attempt has been made to use concrete wastes as recycled fine aggregate (RFA) partially to produce fly ash (FA)-based geopolymer mortar. The workability, water absorption, compressive strength at 3, 7, 28, and 56 days, volume change behavior, and chloride permeability of the produced FA-based geopolymer mortar were determined. The effects of RFA, the ratio of alkali liquid (AL) to FA, and different curing regimes on these properties of mortar mix also discussed. The morphology and microstructures of the samples taken from the mortar mix, which were observed having the highest strength under different curing regimes, were studied using scanning electron microscopy (SEM). The experimental results indicate lower workability, higher water absorption capacity, and higher drying shrinkage of geopolymer mortar mix that has more RFA content in the mix, but the compressive strength of the geopolymer mortar mix started decreasing after a certain percentage of RFA content in the mix. Utilization of that certain percentage of RFA will help us to minimize the consumption of natural fine aggregates and reduce the disturbances generated by unorganized dumping of C&DW. © 2019 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959.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 Laboratory Evaluation of SMA Mixtures Made with Polymer-Modified Bitumen and Stabilizing Additives(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2019) Shiva Kumar, G.; Ravi Shankar, A.U.; Ravi Teja, B.V.S.Stone matrix asphalt (SMA) is a gap-graded mixture that consists of two parts, a high concentration coarse aggregate skeleton and a high binder content mortar. The coarse aggregate skeleton provides the mixture with stone-on-stone contact, giving it strength, while the high binder content mortar adds durability. The mortar is typically composed of fine aggregate, mineral filler, asphalt binder, and a stabilizing additive. A stabilizing additive such as natural fibers, mineral fibers, or polymers is added to SMA mixtures to prevent draindown. In addition, it has the potential of reinforcing and improving the tensile strength and cohesion of SMA mixtures. In this study, banana fiber (BF) and pelletized fiber (VP) are used as stabilizing additives to prepare SMA mixtures with conventional viscosity-graded (VG) 30 bitumen. Mixtures were prepared with different levels BF and VP content, and another mixture without any stabilizers was also prepared using polymer-modified bitumen (PMB). Superpave mix design, draindown, fatigue, rutting, workability, and moisture-induced damage properties were evaluated. Results indicated that addition of natural and pelletized fiber controls binder draindown and improves resistance to rutting, fatigue, and moisture-induced damage of SMA mixture. Further, polymer-modified SMA mixtures take less energy for densification compared to SMA mixtures with natural and pelletized fiber. Results also showed that even though polymer-modified SMA mixtures performed better, SMA mixtures with pelletized fiber provided comparable results. © 2019 American Society of Civil Engineers.Item Performance evaluation of cement mortar compositions at elevated temperatures(Associated Cement Companies Ltd., 2019) Yaragal, S.C.; Vivek, S.; Kumar, B.Natural river sand is becoming scarce day by day due to rapid growth in construction sector. There is need for alternatives to be used in place of river sand. The performance of alternatives to river sand at elevated temperatures is also important in the likely event of fire accidents. In this study, the effect of elevated temperatures on the compressive strength of mortars containing Crushed Rock Fines (CRF) and Lateritic Sand (LS) is investigated. Cement mortar cubes were cast for varied proportion of lateritic soil and quarry dust as fine aggregate. Lateritic content was varied from 25%-100%, and 50% quarry dust was adopted. After 28 days of water curing, specimens were exposed to temperatures of 200, 400, 600, and 800°C. At room temperature, the compressive strength decreases with increase in level of lateritic fine aggregate. The lateritic mortar mixes (50, 75, and 100%) have exhibited superior elevated temperature endurance characteristics at 400, 600, and 800°C when compared to control mix. Even the 25% laterized mortar has performed equally well as that of control mix. At elevated temperatures, CRF blended mix has performed very poorly. Mortar containing lateritic sand has potential for utilization in buildings and other structures, for better fire endurance in the likely event of fire accidents. © 2019 Associated Cement Companies Ltd.. All rights reserved.Item 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.