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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 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 Effect of various additives on the properties of fly ash based geopolymer mortar(Springer, 2019) Mustafa, R.; Shivaprasad, K.N.; Das, B.B.In the present study, setting time and variation in strength of fly ash based geopolymer mortar prepared from natural sand as fine aggregates. Blast furnace slag (GGBS), micro silica and lime dust used as additives to fly ash based geopolymer mortar at 5, 10 and 15% of weight of fly ash. Alkaline activator used in the present study is combination of sodium silicate solution and sodium hydroxide solution. Concentration of sodium hydroxide solution was maintained 10 M and sodium silicate to sodium hydroxide ratio was fixed as 2.5:1 by weight. From the test results, it is observed that setting time and compressive strength geopolymer samples were significantly influenced by the type of additive added in the preparation of the geopolymer mortar. © Springer Nature Singapore Pte Ltd. 2019.Item Fast Setting Steel Fibre Geopolymer Mortar Cured Under Ambient Temperature(Springer, 2021) Prasanna, K.M.; Theodose, I.; Shivaprasad, K.N.; Das, B.B.Cement and cementitious materials are being used worldwide as the most popular multipurpose construction materials but the greenhouse gas such as carbon dioxide (CO2) produced during its manufacturing process creating a huge environmental hazard, thus efforts have been made for alternative binders. Geopolymer binder is new age binder alternative to ordinary Portland cement in infrastructure projects because it is produced from eco-friendly and industrial waste materials. This study was aimed to produce fast setting with ground-granulated blast-furnace slag (GGBS) in fly ash-based geopolymer mortar incorporated with steel fibres cured under ambient temperature. In this research, alkaline to binder ratio was varied from 0.5 to 0.8, crimped steel fibre are varied from 0.5 to 1.5% by total volume of binder and combination of fly ash (FA) and GGBS (100%:0%, 90%:10%, 80%:20%, 70%:30%, 60%:40% and 50%:50%) as binder were used for preparation of fibre geopolymer mortar. The tests conducted include stetting time and flowability of geopolymer mortar, compressive strength and microstructural characterisation of steel fibre geopolymer mortar. The tests for compressive strength were carried out on standard size of mortar samples at curing period of 3, 7 and 28 days. It is noted from the test results that increase in GGBS content setting times were decreased; however, the compressive strength of fly ash-based geopolymer mortar increased. The highest compressive strength at 28 days of curing period was found to be 69.5 MPa, which is obtained with content of 1% of steel fibres and alkaline to binder ratio of 0.6 with 50%:50% binder’s proportions. Further, it is observed that the incorporation of steel fibres in plain geopolymer mortar have enhanced the compressive strength and optimum dosage of fibres was found to be 1%. © 2021, Springer Nature Singapore Pte Ltd.