Department of Civil Engineering
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Item An Experimental Investigation of Accelerated Carbonation on Properties of Concrete(ENGINEERING JOURNAL, 2016) Bhunia, Dipendu; Singh, Shamsher BahadurThis study deals with the effect of carbonation on the mechanical properties such as compressive strength, flexural strength and durability like depth of carbonation and volume of permeable voids of the concrete cast using ordinary Portland cement over a time period of up to 120 days. To study the behavior of carbonation front of concrete in presence of varying water content, water binder ratios of 0.35, 0.50 and 0.65 are chosen. It is observed that the volume of permeable voids of concrete has decreased, with an increase in compressive strength, flexural strength and depth of carbonation as the number of days of exposure of concrete specimen to high carbon dioxide increased.Item Comparative study of accelerated carbonation of plain cement and fly-ash concrete(Elsevier, 2017-03) Singh, Shamsher Bahadur; Bhunia, DipenduAccelerated carbonation of plain cement concrete and concrete with fly-ash replacing cement partially, is discussed in the present paper. Mechanical properties such as compressive strength, flexural strength, modulus of elasticity, durability aspects such as depth of carbonation and porosity of carbonated concrete are studied. To study the influence of water binder ratio on the above-mentioned properties, water-binder ratios of 0.35, 0.50 and 0.65 are used. It is observed that the mechanical properties of carbonated concrete have increased with the duration of carbon dioxide exposure. So did the depth of carbonation, whereas the volume of permeable voids has reduced leading to the decrease in porosity. An expression to predict the depth of carbonation of fly-ash concrete has also been developed.Item Mechanical strength and durability of mineral admixture concrete subjected to accelerated carbonation(Taylor & Francis, 2018-02) Bhunia, Dipendu; Singh, Shamsher BahadurBased on the experimental evaluation of blended cement concretes, its vulnerability to the potential carbonation threats have been discussed in this paper. Water binder ratios of 0.35, 0.50, and 0.65 have been adopted to study the mechanical properties and durability of the concrete mixes exposed to accelerated carbonation. Equations to predict the depth of carbonation under controlled conditions for these mixes have been established. The reliability of square root t law of diffusion to address the ingress of carbon dioxide into concrete has also been studied. Furthermore, conclusions have been drawn that the addition of fly ash and blast furnace slag as a partial replacement of cement decreased the carbonation resistance of concrete unless a water binder ratio of 0.35 is used, in which case the depth of carbonation remained almost same.Item Strength and Durability Parameters of Carbonated Mineral Admixture Concrete(Indian Concrete Journal, 2019-04) Bhunia, Dipendu; Singh, Shamsher Bahadurhe present paper deals with the influence of mineral admixtures such as fly ash and blast furnace slag on the carbonation resistance of concrete when partly replaced by cement. Concrete mixes with water binder ratios of 0.35, 0.50 and 0.65 had been used to investigate the mechanical properties and durability of the concrete specimens exposed to accelerated carbonation of over 1 year. Compressive strength, flexural strength and modulus of elasticity had been studied for strength parameters and for durability tests, depth of carbonation and volume of permeable voids had been carried out. Thermo gravimetric test had also been performed to compare the consumption of calcium hydroxide and the formation of calcium carbonate for the mixes with water binder ratio of 0.50Item Investigation of fatigue crack growth after a single cycle peak overload in IS 1020 steel(Elsiever, 1992) Singh, Shamsher BahadurCrack propagation experiments were conducted on IS 1020 steel for various overload ratios (1·2, 1·3 and 1·4). On the basis of these experiments one power law is developed to predict the crack propagation delay period. The delay period after application of a single overload was found to increase as the magnitude of the overload increased. Crack growth also decreased after the application of an overload cycle but after a certain number of cycles it tended to return to the crack propagation rate for constant amplitude loading (CAL).Item A study of fatigue crack growth IS-1020 steel under constant-amplitude loading(Elsiever, 1992) Singh, Shamsher BahadurCrack propagation experiments were performed on IS-1020 steel for various load ranges and stress ratios. At constant maximum load, the life of the specimen increased as the load ratio increased. The crack growth data were analysed in terms of as a function of stress ratio R. The data covered R values of 0, 0·1, 0·2, and 0·3, and a good relation was obtained for . A crack growth rate equation was also developed.Item Experimental observations of fatigue crack growth in IS-1020 steel under constant amplitude loading(Elsiever, 1993) Singh, Shamsher BahadurCrack propagation experiments were performed on a 0·2% C 0·9% Mn (IS-1020) steel for various load ranges and stress ratios. At constant load range, the life of the specimen decreased as the load ratio increased. The crack growth data were analysed in terms of as a function of stress ratio R. The data covered R values for 0, 0·15, 0·30, 0·35 and 0·40 and a good relation was obtained for . A crack growth rate equation was also developed.Item Progressive failure of symmetrically laminated plates under uni-axial compression, Structural Engineering and Mechanics(Korea Institute of Science and Technology Information, 1997) Singh, Shamsher BahadurThe objective of this work is to predict the failure loads, associated maximum transverse displacements, locations and the modes of failure, including the onset of delamination, of thin, flat, square symmetric laminates under the action of uni-axial compression. Two progressive failure analyses, one using Hashin criterion and the other using Tensor polynomial criteria, are used in conjunction with the finite element method. First order shear deformation theory and geometric nonlinearity in the von Karman sense have been employed. Five different types of lay-up sequence are considered for laminates with all edges simply supported. In addition, two boundary conditions, one with all edges fixed and other with mixed boundary conditions for (+45/−45/0/90)2s quasi-isotropic laminate have also been considered to study the effect of boundary restraints on the failure loads and the corresponding modes of failure. A comparison of linear and nonlinear results is also made for (±45/0/90)2s quasi-isotropic laminate. It is observed that the maximum difference between the failure loads predicted by various criteria depend strongly on the laminate lay-ups and the flexural boundary restraints. Laminates with clamped edges are found to be more susceptible to failure due to the transverse shear and delamination, while those with the simply supported edges undergo total collapse at a load slightly higher than the fiber failure load.Item Progressive failure of symmetric laminates under in-plane shear: Il-Negative shear(Korea Institute of Science and Technology Information, 1998) Singh, Shamsher BahadurThe objective of the present work is to estimate the strength and failure characteristics of symmetric thin square laminates under negative shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with the finite element method. First-order shear-deformation theory along with geometric nonlinearity in the von Karman sense has been incorporated in the finite element modeling. Failure loads, associated maximum transverse displacements, locations and modes of failure including the onset of delamination are discussed in detail; these are found to be quite different from those for the positive sheer load reported in Part I of this study (Singh et al. 1998).Item Progressive failure of symmetric laminates under in-plane shear, Part I-Positive Shear, Structural Engineering and Mechanics(Korea Institute of Science and Technology Information, 1998) Singh, Shamsher BahadurThe objective of this present work is to estimate the failure loads, associated maximum transverse displacements, locations and the modes of failure, including the onset of delamination, of thin, square symmetric laminates under the action in-plane positive (+ve) shear load. Two progressive failure analyses, one using the Hashin criterion and the other using a Tensor polynomial criterion, are used in conjunction with finite element method. First order shear deformation theory along with geometric non-linearity in the von Karman sense have been employed. Variation of failure loads and failure characteristics with five type of lay-ups and three types of boundary conditions has been investigated in detail. It is observed that the maximum difference between failure loads predieted by various criteria depends strongly on the laminate lay-up and the flexural boundary restraint. Laminates with clamped edges are found to be more susceptible to failure due to transverse shear (ensuing from the out of plane bending) and delamination, while those with simply supported edges undergo total collapse at a load slightly higher than the fiber failure load. The investigation on negative (-ve) in-plane shear load is in progress and will be communicated as part-II of the present work.