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 Acid, alkali and chloride resistance of high volume fly ash concrete(Indian Society for Education and Environment indjst@gmail.com, 2015) Sahoo, S.; Das, B.B.; Rath, A.K.; Kar, B.B.Objectives: To find variation in compressive strength and mass of high volume fly ash concrete samples subjected to different chemical solutions of sodium chloride, sodium sulphate and sulphuric acid. Methods: A total of 900 numbers of cubes were cast and cured with four levels of curing period of 28, 56, 90 and 120 days. After certain duration of curing period, specific numbers (60) of cubes were submerged each in 5 percent sodium sulphate solution (Na2SO4), 5 percent sodium chloride solution (NaCl) and 1percent of sulphuric acid solution (H2SO4) separately in chemical exposure containers for an exposure period of 30, 60, 90 and 120 days. Findings: Investigations with respect to acid, alkali and chloride resistance were carried out on high volume fly ash concrete, HFC (40 percent replacement with cement), low volume fly ash concrete, LFC (25 percent replacement with cement) and their performances against control concrete (NC) is presented in this paper. Their performance was measured with respect to the loss in compressive strength and weight of the concrete cubes over the period of exposure time. It is found that the resistance of control concrete to all the three chemical attack is better only up to 28 days of water curing. At 56 days of water curing LFC shows better resistance against the control and HFC. However, with prolonged water curing of cubes of 90 days and more, HFC has consistently shown highest resistance; whereas the control concrete faced a great loss in strength.