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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 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 Effect of pH on Electrodeposition of Ni–Cd Alloy Coatings and Their Anticorrosion Performance(Springer Nature, 2022) Gonsalves, C.N.; Sneha, I.M.; Hegde, A.C.Electroplating is a complex process controlled by bath composition and operating parameters. Among many operating parameters, the pH of the bath plays an important role in the process of deposition and properties of coatings. The present paper reports the effect of pH in the electrodeposition process of Ni–Cd alloy coatings from a low concentration bath of Ni–Cd alloy, using glycine as an additive. The experimental results revealed that change of pH over a wide range (from lower acidic to higher basic conditions) has a significant effect on the structure, morphology, and composition of the alloy electrodeposits. A considerable increase in the uniformity of coatings was found with an increase in bath pH. Electrochemical corrosion study carried out in 3.5% NaCl medium demonstrated higher corrosion resistance for Ni–Cd alloy coating, deposited at pH 8.0 compared to those deposited at lower pH. A change in the process of electro-crystallization was found with the change of pH, confirmed by the scanning electron microscopy (SEM) study. The improved corrosion resistance of alloy coatings was ascribed to the change of codeposition from anomalous to normal type, known by its Ni content confirmed by the energy dispersive X-ray spectroscopy analysis (EDAX). A change in phase structure was found with the change of pH, confirmed by the X-ray Diffraction (XRD) technique. Experimental results are analyzed in light of the theory of alloy deposition, and results are discussed. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.