Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
35 results
Search Results
Item Analysis of shape parameters of coarse aggregate and their effects on packing density by DIP technique(2006) Nagendra, R.; Dhabale, A.K.; Bai, H.S.; Rajeeva, S.V.In this paper the particle shape parameters are analysed using a sophisticated technique called Digital Image Processing (DIP). The effects of shape parameters on the packing density are studied. The packing density determines the amount of cement paste required to fill the voids between aggregate particles. In this paper the details of experimental investigations carried out on coarse aggregates are presented. Aggregate samples from seven different sources have been used for experimental investigation. The shape parameters determined by DIP technique are correlated with packing density.Item Interactions Between Soils and Laboratory Simulated Electrolyte Solution(2010) Nayak, S.; Sunil, B.M.; Shrihari, S.; Sivapullaiah, P.V.To study the impact of salt water intrusion on two types of soils from west coast region of India were investigated in the laboratory. The key characteristics evaluated included Atterberg limits, compaction characteristics, hydraulic conductivity and chemical characteristics of selected soils. The sea at this coast receives effluent from different points and hence the characteristics change with time and locality. Therefore, to maintain uniform composition, 0.5 N sodium chloride solution (NaCl) was prepared in the laboratory and batch tests were used to determine the immediate effect on soils. Soil specimens were prepared by mixing the soils with 0.5 N NaCl in the increments of 0, 5, 10 and 20% by weight to vary the degree of contamination. Experimental results of soils mixed with 0.5 N NaCl showed that the maximum dry density increases and the optimum moisture content (OMC) decreases with increasing sodium chloride concentration. The study also revealed that the hydraulic conductivity of the soils tested increases with increase in sodium chloride concentration. The Atterberg limits of contaminated specimens show a remarkable change when compared with uncontaminated specimens. © 2010 Springer Science+Business Media B.V.Item Microfabric and mineralogical studies using sem and xrd on the lithomargic clay stabilized with cement and quarry dust(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2011) Sarvade, P.G.; Nayak, S.The infrastructural development activities due to rapid urbanization, low lying agricultural and marshy lands in and around Mangalore (India) are being converted into estates with locally available lithomargic clay. These filled up areas pose problems of low bearing capacity as well as excessive settlements. As long as this soil is confined and dry, there is a very little or no problem, when it comes in contact with water, it loses its strength. The engineering properties of this soil are enhanced by the addition of additives (cement, quarry dust and quarry dust +cement). In the present study the microfabric and mineralogical aspects of the stabilized lithomargic clay is studied using Scanning Electron Microscope (SEM) and X-ray diffractometer (XRD). The XRD analysis of lithomargic clay stabilized with cement, revealed the formation ettringite, CSH and CAH. The SEM analysis revealed change in the soil structure due to the addition of cement and quarry dust. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Study on the strength parameters of high volume fly ash concrete and geopolymer concrete(2011) Shetty, A.; Anand, V.R.; Hegde, P.Concrete has been the most preferred construction material. It is being increasingly used day by day all over the world due to its versatility, mould ability and high compressive strength. But the large-scale production of cement is causing environmental problems on one hand and the unrestricted depletion of natural resources on the other. So the issue of sustainable development in concrete construction is addressed in this paper through development of concrete mixes by replacing certain percentage of cement with fly ash. Trials on concrete mixes with replacement of 40%, 50%, 60% and 70% of cement with fly ash are carried out and the results depict that at the replacement level of 40% cement by fly ash, the required strength is achieved. It is also observed that the rate of early strength gain is retarded as the percentage replacement of cement increases. But in case of Geopolymer concrete (100% replacement of cement by fly ash) under a curing temperature around 600C and above, the strength gain rate is very high in initial stages. It is observed that design strength is achieved within 28 hours of oven curing. © 2011 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Effect of Cement and Quarry Dust on Shear Strength and Hydraulic Characteristics of Lithomargic Clay(2012) Nayak, S.; Sarvade, P.G.The lithomargic clay constitutes an important group of residual soils existing under lateritic soils. This soil is found on the western and eastern coasts of India over large areas. This soil is a problematic one and is very sensitive to water and loses a greater part of its strength when becomes saturated. These high silt deposits have invited many problems such as slope failures, foundation failures, embankment failures, uneven settlements etc. In this investigation an attempt is made to study the effect of cement and quarry dust on shear strength and hydraulic characteristics of the lithomargic clay after the stabilization. Microfabric and mineralogical studies were carried out to find out the reason for the strength development of the stabilized soil using SEM and XRD analysis. The results indicated that there is an improvement in the properties of the lithomargic clay with the addition of cement and quarry dust. The XRD results indicated the formation of CSH and CAH, which are responsible for strength development in the stabilized soil. © 2011 Springer Science+Business Media B.V.Item A study on the factors influencing the load transfer efficiency in concrete block pavements(2012) Thameel, S.S.; Amar Kumar, D.S.N.V.; Pancharathi, P.Concrete Block Pavements (CBP) are essentially precast blocks arranged in a specific pattern over a sub base and interlocked with graded bedding and jointing sand. The block size and shape, joint gap and joint filling sand size and laying pattern influence the effectiveness of the interlocking or the distribution of wheel loads. The measure of effectiveness - Load Transfer Efficiency (LTE), is the ratio of deflection between a loaded block to an adjacent unloaded block. In the present LTE study, joint filling sand of three particle sizes (1.18, 0.6 and 0.3mm), laying patterns of two types [stretcher and basket weave), concrete mixes with four variations (cement, cement with 20% fly ash, cement with steel fibre (0.5%) and cement with both fly ash and steel fibre] were tested. The test section consisted of 100 mm x 200 mm x 100mm blocks fixed over a 20 mm thick bed of 4.75 mm sand. A wet mix macadam layer over the sub grade supported the blocks. The study revealed that the joint filling with 0.6 mm sand gave a higher LTE than the other two sizes. The basket weave resulted in a higher average LTE than the stretcher bond and incorporating steel fibre and fly ash in concrete also showed an increase in the LTE.Item Durability studies on eco-friendly concrete mixes incorporating steel slag as coarse aggregates(Elsevier Ltd, 2016) Palankar, N.; Ravi Shankar, A.U.; Mithun, B.M.The present study discusses the durability performance of alkali activated concrete mixes containing steel slag as coarse aggregates. Steel slag aggregates, a waste product obtained from iron and steel industry are incorporated as coarse aggregates in alkali activated slag concrete (AASC) and alkali activated slag fly ash concrete (AASFC) by replacing traditional natural aggregates. The mix design for AASC and AASFC mixes are optimised to obtain sufficient strength for structural purposes and then steel slag coarse aggregates are incorporated at different replacement levels (0%, 50% and 100% by volume of total coarse aggregate content). Durability properties such as long term ageing performance, water absorption, volume of permeable voids, resistance to sulphuric acid attack and resistance to magnesium sulphate attack are studied in detail and compared with conventional Ordinary Portland Cement Concrete (OPCC). The ecological and economical analysis of concrete mixes is also carried out. It was found that the AASC and AASFC mixes displayed better durability performance as compared to OPCC. The inclusion of steel slag aggregates slightly reduced the durability performance of AASC and AASFC mixes. The AASC and AASFC with steel slag aggregates displayed lower energy requirement and lower production cost as compared to OPCC, thus proving it to be eco-friendly. © 2016 Elsevier Ltd. All rights reserved.Item Acid, alkali, and chloride resistance of concrete composed of low-carbonated fly ash(American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2017) Sahoo, S.; Das, B.B.; Mohammed Mustakim, S.This research investigates the effect of carbonated fly ash inclusion in concrete as partial replacement of cement on the durability performance when exposed to salt, sulfate, and acid solution. The effect of chemical exposure periods (30, 60, 90, and 120 days) on compressive strength and weight of concrete with low volume (25%) replacement of cement was investigated for various water curing ages (28, 56, 90, and 180 days). A comparative assessment with low volume (25% cement replacement) fly ash concrete and control concrete was also conducted. It was observed from the results that low volume carbonated fly ash concrete demonstrated a significant increase in resistance to loss in compressive strength and weight against salt, sulfate, and acid attack. Gray relation-based analysis was performed to determine suitable parameters for simultaneous minimization of strength loss and weight loss under chemical exposure. It can be recommended that, due to its cost-effectiveness, easy processing, and environmental friendly nature, carbonated fly ash can be adopted in construction as a partial replacement of cement in concrete. © 2016 American Society of Civil Engineers.Item Chitosan composites reinforced with nanostructured waste fly ash(Springer Japan, 2017) Patil, A.G.; Poornachandra, S.; Gumageri, R.; Rajkumar, K.; Anandhan, S.This paper outlines the preparation and characterization of chitosan (CS) composites reinforced with mechano-chemically activated fly ash (MCA-FA). A series of composite films was prepared by solution casting method with varying filler content. Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analyses showed good compatibility between the CS matrix and MCA-FA. The surface roughness and irregularity in shape of MCA-FA resulted in its efficient mechanical interlocking with the polymer matrix. This, in turn enhanced the mechanical properties of these composites. All the composite films exhibited a higher tensile strength and a lower percentage of elongation-at-break compared with the pure CS film. The highest tensile strength was observed for the composite films with 1 wt% of filler loading and the reduction in the tensile properties at higher filler loading was due to agglomeration of filler and polymer–filler interface debonding. The tensile strength data were analyzed using Nielsen and Pukanzsky models to understand the interface formation and polymer–filler interactions. Thermal properties showed a marginal improvement due to the incorporation of MCA-FA. Overall, this study indicates that MCA-FA could be used as value added filler in polymer matrix composites. © 2016, Springer Japan.Item Enhancement of the properties of fly ash based geopolymer paste by incorporating ground granulated blast furnace slag(Elsevier Ltd, 2017) Saha, S.; C, C.Research efforts have been made continuously to establish fly ash based geopolymer as an alternative binder material for the production of fresh concrete because production of Ordinary Portland Cement degrades the environment by huge emissions of carbon-di-oxide and also by consuming lot of natural resources. But most of the study reveals, fly ash based geopolymer paste needs more time to get set when it is cured at ambient temperature. As a result, it is quite impractical to use fly ash based geopolymer paste as an alternative to Ordinary Portland Cement in faster construction. In this study, an effort has been made to enhance the properties of fly ash based geopolymer paste by incorporating ground granulated blast furnace slag at various percentage levels. Microstructure of the geopolymer paste is studied using Scanning Electron Microscopy. Result of this investigation shows that significant improvement on setting time and compressive strength can be obtained by adding ground granulated blast furnace slag in the mixes. © 2017 Elsevier Ltd