Faculty Publications
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Item Mineralogical study of concretes prepared using carbonated flyash as part replacement of cement(Springer, 2019) Sahoo, S.; Das, B.B.Cement production is excessive energy intensive, responsible for depletion of natural layers and high carbon foot print. Thus search for an environmentally benign cement substitute still is an on-going process. Fly ash is a well-established concrete admixture enhancing the strength, durability and micro-structural properties. As well as it is a good reagent to sequester atmospheric carbon dioxide. Concretes prepared through part replacement of cement by carbonated fly ash demonstrate good resistance against chloride, acid and sulfate attack. In the present research mineralogical study of CFC (Carbonated Fly ash concrete) has been conducted through XRD analysis. XRD of control concrete (CC) and fly ash concrete (FC) have also been carried out to study the comparative distributions of mineral crystallites present in concretes. The tests have been conducted in the concrete specimens cured in water for 28 days and 90 days to study the effect of hydration and extent of pozzolanic reaction on the mineralogical composition. Two replacement levels of 25 and 40% were considered for experimentation. The qualitative XRD investigation yielded a higher intensity of CaCO3 in the concretes prepared using Carbonated Fly ash. The presence of CaCO3 helped the concretes in developed chemical resistances dense and improved microstructure. The thermogravimetric analysis further confirmed the presence of higher Carbonates in the CFC specimens. © Springer Nature Singapore Pte Ltd. 2019.Item Mechanical properties of fiber-reinforced concrete using coal-bottom ash as replacement of fine aggregate(Springer, 2019) Goudar, S.K.; Shivaprasad, K.N.; Das, B.B.The present investigation aims to study the significance of coal coal-bottom ash as a partial replacement to natural river sand in fiber-reinforced concrete (FRC). Hooked-end steel fibers were used to produce fiber-reinforced concrete at a fiber content of 1.5% by volume concrete. About 30% of natural sand was replaced with coal coal-bottom ash to produce M30 grade concrete with a water–cement ratio of 0.45. The prolonged curing period has a positive effect on the coal, coal-bottom ash replaced concretes. There was a slight increment in the compressive strength of FRC because of inclusion of steel fibers. However, significant improvements were observed in flexural and split tensile strength of FRC due to the inclusion of steel fibers. The optimum content of coal, coal-bottom ash replacement to natural sand was found to be 20%. © Springer Nature Singapore Pte Ltd. 2019.Item Durability studies of steel fibre reinforced concrete(Springer, 2019) Yadav, S.; Das, B.B.; Goudar, S.K.In the present investigation, the effect of different dosage of steel fibres on bond strength between steel and concrete in reinforced concrete was investigated. As a part of durability study, the combined effect of marine environment and varying levels of pH on the ultimate bond strength retention and compressive strength retention of steel fibre reinforced concrete was also investigated. Durability studies were carried out by exposing the 28 days cured cubical specimens into marine environment having different pH levels (1, 4, 7, 10 and 13). The marine environment was simulated in the laboratory by adding 3.5% NaCl to the tap water. Designed quantity of sulphuric acid was added to salt solution to maintain pH of 1 and 4 in marine environment. Similarly, designed quantity of sodium hydroxide was added to the salt solution to maintain pH of 10 and 13 in marine environment. The specimens were exposed for the durations of 60 and 90 days. The resistance of concrete to marine environment with varying pH was measured through compressive strength retention and ultimate bond strength retention in steel fibre reinforced concrete. The addition steel fibres reduced workability of concrete, especially 1.5% of steel fibres yielded considerably low slump value. The ultimate bond strength and compressive strength values increased due to the addition of steel fibres. The pH of the marine environment has a significant influence on the compressive strength retention and bond strength retention. Exposure to marine environment with pH 1 underwent severe loss in compressive strength and ultimate bond strength with very low strength retention values. However, exposure to marine environment with pH 10 and 13 had minimal strength losses with higher values of compressive strength and ultimate bond strength retention. The alkaline nature of marine environment was not susceptible to strength reduction when compared to neutral (pH 7) and acidic (pH 1) marine environment. The steel fibre reinforced concrete performed better in acidic marine environment compared to control concrete without steel fibres. © Springer Nature Singapore Pte Ltd. 2019.Item Combined effect of marine environment and pH on the impedance of reinforced concrete studied by electrochemical impedance spectroscopy(Springer, 2019) Goudar, S.K.; Das, B.B.; Arya, S.In the present investigation, behavior of OPC and fly ash based concretes were assessed by electrochemical impedance spectroscopy (EIS) technique after exposing the samples to the marine environment in combination with five pH levels (1, 4, 7, 10, and 13). Three different dosages of fly ash (15, 25, and 35%) were used to produce fly ash based concretes. After 90 days of exposure to the aggressive environment, the OPC and fly ash based concretes were tested for impedance analysis and corrosion resistance by electrochemical studies. For the equivalent electrical circuit in EIS study, a total of four electrical circuits were tried for the possible best fit of obtained Nyquist plots. The equivalent electrical circuits proposed by previous researchers failed to provide the best fit for the obtained Nyquist plots. A new equivalent electrical circuit is being proposed in this study which will provide the possible best fit of Nyquist plots when the concrete is being exposed to acidic and alkaline marine environment. It is observed that the pH of the marine environment has a decisive influence on the impedance of reinforced concrete. As the acidity of marine environment reduces to pH 1, the impedance of OPC and fly ash based concrete reduced significantly due to the severe deterioration of concrete composites especially because of acid attack and Cl− ions migration. However, in the case of alkaline nature of the marine environment (pH 13), there was comparably less deterioration of concrete composites which reflected in higher impedance values. The higher dosage of fly ash addition has led to substantial improvement in concrete impedance and also lower corrosion rate. © Springer Nature Singapore Pte Ltd. 2019.Item Durability studies of polypropylene fibre reinforced concrete(Springer, 2019) Srikumar, R.; Das, B.B.; Goudar, S.K.A research programme was initiated to understand the durability of polypropylene fibre reinforced concrete (PFRC). PFRC was prepared with varying dosages of polypropylene fibre. Dosages used were 0.5–1.5% of cement content (by weight) with an interval of 0.5% and was added as a cement replacement to concrete mix. Durability studies were carried out by exposing the 28 days cured cubical specimens into marine environment having different pH levels (1, 4, 7, 10 and 13). The varying pH levels represent the pH of industrial effluents. The marine environment was simulated in the laboratory by adding 3.5% NaCl to the tap water. The specimens were exposed for the durations of 60 and 90 days. The resistance of concrete to marine environment was measured through compressive strength retention and ultimate bond strength retention. Scanning Electron Microscopy (SEM) studies were also carried out to understand the fibre dispersion. Test results show that compressive and bond strength increases with increase in pH and decreases with increase in immersion duration. Concrete with 0.5 and 1% fibre content are more desirable and have given higher residual compressive and residual bond strength when compared to concrete with 1.5% fibre content. © Springer Nature Singapore Pte Ltd. 2019.Item Implication of concrete with chemical admixture cured in low temperature on strength, chloride permeability and microstructure(Springer, 2019) Ghosh, A.H.; Das, B.B.Concrete does not gain complete strength when cured in low temperature as the hydration of cement does not take place completely. The concrete cured in cold weather does not gain early strength and leads to improper setting and uneven strength gain due to the freezing of the water mixed with the cement. Hence, there are many strength-related problems faced at site due to cold weather particularly in parts of north India where the temperature reaches below freezing point of water during the winter season. The study focused on the effect of combination of accelerator, superplasticizer and air-entraining admixture on microstructure, compressive strength and chloride ion penetration of concrete cured at +5 °C and a comparative study with normal cured concrete with chemical admixture. Five different mixes were used containing varying amount of accelerators, superplasticizers and air-entraining admixture of a manufacturer which are available for use in India. The results for compression strength show that the concrete mix with higher dosage of accelerator had higher strength. The strength results were nearly the value of normal cured concrete with chemical admixture. Rapid chloride permeability test showed very low permeability for all of specimens of last mix, and results were nearly comparable to normal cured concrete. The microstructure study of concrete with admixture ensures a dense structure formation resulting in higher strength at low temperature. © Springer Nature Singapore Pte Ltd. 2019.Item Techniques for preparation and dispersion of nano-SiO2 in Cementitious System—A Review(Springer, 2019) Snehal, K.; Das, B.B.Nowadays, the research in the field of concrete is driving its focus on novel technology by making use of nanosized particles so-called nanotechnology in concrete. The oxide nanoparticles have a great influence on concrete properties, amongst all the nanoparticles, nano-silica is the first nano product that replaced the micro silica or silica fume in concrete, and it is the most predominantly used nanoparticle amid all other nanoparticles in cementitious system. This paper states the overview on various methods involved in production of nano-SiO2 particles for the purpose of utilizing in cementitious system as well as the various techniques for well dispersion of nanosized SiO2 particles in cement matrices. © Springer Nature Singapore Pte Ltd. 2019.Item Study on mechanical properties and leaching of heavy metals in the artificially produced fly ash aggregates(Springer, 2019) Roshan, M.; Shivaprasad, K.N.; Das, B.B.The present study focusses on fly ash as an industrial by-product which can be utilised in the production of artificial lightweight aggregates using activator solution as a binder. Artificial aggregates in the form of pellets would be an alternative for the natural coarse aggregates which is currently being used in the construction industry. The production of pellets was done such that the water content in the pellets were fixed at 20% of the weight of fly ash, and the Na2O content in the pellets was varied between 4 and 7% of the weight of the pellets. The mechanical properties were studied such as specific gravity, particle-size distribution (sieve analysis), water absorption, crushing strength of individual pellets and aggregate impact value. Further, the leaching tests were carried out to estimate the leaching of metals such as iron, chromium and sodium from the pellets. The effect of different curing conditions such as ambient, heat and solution was also studied in this study. From the test results, the pellets size distribution was found to be well graded and specific gravity of pellets was found to be in the range from 1.88 to 1.96. There was an improvement in the mechanical properties of the artificially produced fly ash aggregates as the Na2O content increased in the alkaline solution. It was found that heat-cured pellets showed a significant advantage over solution and ambient-cured pellets in crushing strength. It was found that leaching of the heavy metals are decreased as the percentage of Na2O content increased, indicating that the addition of Na2O enhances the encapsulation of heavy metals. © Springer Nature Singapore Pte Ltd. 2019.Item Durability studies on glass fiber reinforced concrete(Springer, 2019) George, R.M.; Das, B.B.; Goudar, S.K.In the present experimental study, glass fibers were used in varying dosages of 0.5, 1.0, and 1.5% of cement content (by weight) as partial cement replacement to cement in concrete mix. The effect of different dosage of glass fibers on the bond strength between steel and concrete in reinforced concrete was investigated. As a part of durability study, the combined effect of marine environment and varying levels of pH on the ultimate bond strength retention and compressive strength retention of glass fiber reinforced concrete was also studied. Durability studies were carried out by exposing the 28-day cured cubical specimens into marine environment having different pH levels (1, 4, 7, 10 and 13). The salt solution was simulated in the laboratory by adding 3.5% NaCl to the tap water. Calculated amount of sulphuric acid was added to salt solution to maintain pH of 1 and 4 in marine environment. Similarly, calculated amount of sodium hydroxide was added to salt solution to maintain pH of 10 and 13 in marine environment. The specimens were exposed to aggressive environment for a period of 60 and 90 days. As the fiber dosage increased the workability reduced, and 1.5% fiber dosage had the least slump value. The addition of glass fibers had very minimal influence on compressive strength of glass fiber reinforced concrete. The ultimate bond strength of concrete increased due to the addition of glass fibers. The increase in ultimate bond strength was confirmed through SEM images which shows proper bonding between cement paste and glass fibers. As for as the exposure studies are concerned, 1.0% fiber dosage of glass fiber reinforced concrete had shown better compressive strength and ultimate bond strength retention compared to 0.5 and 1.5% fiber dosage. The pH of the marine environment has a decisive influence on the compressive strength retention and bond strength retention. Exposure to marine environment with pH 1 suffered severe loss in compressive strength and ultimate bond strength with very low strength retention values. However, exposure to marine environment with pH 10 and 13 had minimal strength losses with higher values of compressive strength and ultimate bond strength retention. Increase in exposure period to aggressive media leads to decrease in compressive strength and ultimate bond strength, but the strength retention values for glass fiber reinforced concrete were comparatively better compared to control concrete. © Springer Nature Singapore Pte Ltd. 2019.Item Optimization of resources by real-time correlation study for maximizing the productivity(Springer, 2019) Agrawal, A.; Das, B.B.; Malik, S.K.Time and cost are two of the most important factors to consider in each construction project. In order to maximize performance, both the client and the contractor will work to optimize both the duration of the project and its cost. The fundamental beginning is to support the same production for the different equipment to achieve the maximum efficiency in each period of time. With the limited availability of resources, the work must be continuous and the period of time between operations and final must be kept. This paper aims to minimize the project total time and cost by means of the assignment of equipment of work to the different production lines of the activities. Construction project refers to a high-stake endeavor aiming at time-bound predetermined performance objective. Matching resources are planned and procured so that all activities can be executed according to a prefixed time schedule. Result shows that the optimization of resources is highly dependent on proper planning mechanism and efficient monitoring of its execution. © Springer Nature Singapore Pte Ltd. 2019.