Faculty Publications

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Author: search.filters.author.Das, B.B.Subject: search.filters.subject.Compressive strength

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    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.
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    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.
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    A Review on Mechanical and Microstructure Properties of Reinforced Concrete Exposed to High Temperatures
    (Springer, 2021) Goudar, S.K.; Santhosh, S.K.; Das, B.B.
    This paper presents the recent research progress on the response of concrete exposed to fire or high temperatures. The main highlight of this review paper is a compilation of previously reported data regarding the variations in mechanical properties and microstructure properties of concrete when exposed to high temperatures. The concrete structures get deteriorated at the macro- and microscopic levels due to high-temperature exposure. The macro-level damages can be measured with degradation in mechanical properties such as the reduction in compressive strength, weight loss, changes in elastic properties, reduction of bond strength in reinforced concrete, etc. The macro-cracks on the surface of concrete causes spalling which can be observed after exposing the concrete samples to more than 300 ℃. The compressive strength of the concrete reduces slightly till 400 ℃, and when the temperature increased to 600 ℃, there was an exponential reduction in the compressive strength of concrete. Another important parameter is bond strength degradation, which plays a crucial role in durability issues. To understand the deterioration phenomenon and changes in mechanical properties, the changes at the level of the microstructure of concrete need to be understood. Dehydration of products causes deterioration of mechanical properties and weight loss of concrete when exposed to high temperatures. At different temperatures, the microstructure changes and the response of hydration products such as calcium hydroxide (CH), CSH gel, unhydrated cement and capillary water reported by previous researchers are compiled and discussed. © 2021, Springer Nature Singapore Pte Ltd.
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    Engineering Properties of Heavyweight Concrete—A Review
    (Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Sharath, B.P.; Das, B.B.
    Heavyweight concrete which differs from normal weight concrete by having a higher density and special compositions to improve its attenuation properties, the density and cost of the material are really important in order to absorb gamma rays. If the main aim of developing heavyweight concrete is focussed to attenuate neutrons, then the material with less atomic weight should be embodied in the concrete mix which can in turn produce hydrogen. It is used in counterweights of bascule and lift bridges, but its general application includes in radiation shielding structures, offshore, ballasting of pipelines etc. The evolution of nuclear power into peaceful applications has given rise to an expanding use of heavy weight concrete in construction industries nowadays. Heavyweight concrete employs bulky conventional aggregates such as barites or magnetite or artificial aggregates such as Fe ore or Pb shots. This paper states a review on impact on engineering properties of Heavyweight concrete such as compressive, split tensile and flexural strength with different heavyweight aggregates as per the investigations conducted by researchers. © 2021, Springer Nature Singapore Pte Ltd.
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    Influence of Particle Size of Bottom Ash on Mechanical Properties of M30 Grade Concrete
    (Springer Science and Business Media Deutschland GmbH, 2021) Goudar, S.K.; Das, B.B.
    Thermal power plants produce fly ash and bottom ash as by-products. A total of 70% of by-product from thermal power plants accounts for fly ash and remaining 30% is bottom ash. One of the most common uses of bottom ash at the present scenario is structural fill in its coarser form only, and it is reported that the disposal leads to leaching of heavy metals to the groundwater table. These disposal problems and potential health hazards can be reduced by large usage of bottom ash in construction industry. A larger percentage of usage of the bottom ash in concrete will significantly reduce the potential health hazards and will give solution to disposal problems. With this in view, bottom ash collected from the Udupi thermal power plant was classified into two different levels according to their particle size and replaced against fine aggregates for different replacement levels, in producing M30 grade concrete. The raw bottom ash was coarse and classified as Zone-I after sieve analysis. The classification of bottom ash according to the particle size was carried out into different zones such as Zone-II and Zone-III, according to the specifications from IS 383–1970. The attainment of required compressive strength is directly correlated to particle size of bottom ash. Results show 47% reduction in compressive strength of concrete when raw bottom ash was (Zone-I) was replaced by 50% in place of natural river sand (NRS). A little effort in grading the bottom ash and converting coarser raw bottom ash from Zone-I to finer Zone-II bottom ash has proved beneficial in improving the compressive strength of concrete. It was observed that lower specific gravity of bottom ash directly influences density of concrete, which intern has adverse effect on compressive strength. The bottom graded as Zone-II can be replaced to NRS by 15–20%, with little compromise in compressive strength. Through value addition of 5% extra cement content, there is a possibility to increase the replacement level of Zone-II bottom ash to 30% with similar compressive strength as that of control concrete. Through cost analysis, it was found that 30% replacement of Zone-II bottom ash in place of NRS with 5% extra cement content as value addition was found to be economical. © 2021, Springer Nature Singapore Pte Ltd.
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    A comprehensive review on the use of hemp in concrete
    (Elsevier Ltd, 2022) Barbhuiya, S.; Das, B.B.
    A simple mixture of hemp hurd, water, and lime is used to make hemp concrete. It is indeed one of the few materials that can continue to absorb carbon after being employed in construction, storing more carbon in the atmosphere over the building's lifetime than was emitted during construction. Furthermore, hemp can be harvested in as little as 60 days. Hemp concrete is a “carbon-negative” or “better-than-zero-carbon” substance because the hemp plant absorbs more carbon from the atmosphere than it emits during its production and application on site. It is a bio-composite material that can be utilised as an alternative to concrete and standard insulation in building. Hemp concrete is also recyclable at the end of the building's lifespan. This study summarises the fast-developing body of knowledge about hemp concrete, which was recently developed. © 2022 Elsevier Ltd
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    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.
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    Acid, alkali, and chloride resistance of concrete composed of low-carbonated fly ash
    (American Society of Civil Engineers (ASCE) onlinejls@asce.org, 2017) Sahoo, S.; Das, B.B.; Mohammed Mustakim, S.
    This research investigates the effect of carbonated fly ash inclusion in concrete as partial replacement of cement on the durability performance when exposed to salt, sulfate, and acid solution. The effect of chemical exposure periods (30, 60, 90, and 120 days) on compressive strength and weight of concrete with low volume (25%) replacement of cement was investigated for various water curing ages (28, 56, 90, and 180 days). A comparative assessment with low volume (25% cement replacement) fly ash concrete and control concrete was also conducted. It was observed from the results that low volume carbonated fly ash concrete demonstrated a significant increase in resistance to loss in compressive strength and weight against salt, sulfate, and acid attack. Gray relation-based analysis was performed to determine suitable parameters for simultaneous minimization of strength loss and weight loss under chemical exposure. It can be recommended that, due to its cost-effectiveness, easy processing, and environmental friendly nature, carbonated fly ash can be adopted in construction as a partial replacement of cement in concrete. © 2016 American Society of Civil Engineers.
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    Influence of fineness of fly ash on compressive strength and microstructure of bottom ash admixed geopolymer mortar
    (Associated Cement Companies Ltd., 2018) Shivaprasad, K.N.; Das, B.B.; Renjith, R.
    Investigations were conducted to find out the suitability of bottom ash as a possible replacement to fine aggregates in geopolymer mortar. Experimental work was done to study the influence of fineness of fly ash (with three levels of Blaine's fineness, 2043 cm2/g, 2602 cm2/g and 3113 cm2/g on compressive strength and microstructure development of fly ash based geopolymer mortar with natural river sand and bottom ash as fine aggregates. three different water to solids ratios of 0.246, 0.349, and 0.443 were chosen for this study and the curing of the specimens was at ambient temperature (28 ± 3°c). compressive strength development for all eighteen mortar mixes was measured at 7, 14, 28 and 56 days. Further, the effect of fineness of fly ash on degree of polymerization, microstructure and properties of geopolymers was studied using Fourier transform Infrared Spectroscopy (FtIR) and Scanning Electron Microscopy (SEM). It was observed from the compressive strength of the geopolymer mortar that the degree of polymerization is gradual for both types of mortar. there is a continuous increase in the development of compressive strength noticed till the age of 56 days for both types of mortar, sand as well as bottom ash admixed. However, the increment of compressive strength for bottom ash found to be significantly less as compared to natural sand. Improvement in compressive strength due to fineness of fly ash were characterised by SEM and FtIR and it is revealed that with increase in fineness levels, the microstructure significantly enhanced the characteristics of geopolymer mortar. © 2018 Associated Cement Companies Ltd.. All rights reserved.
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    Mechanical and permeability properties of hybrid fibre reinforced porous concrete
    (Associated Cement Companies Ltd., 2019) Snehal, K.; Das, B.B.
    Experimental investigation was carried out to determine the enhancement of compressive strength, flexural strength and abrasion resistance along with water permeability of porous concrete introduced with hybrid fibres (consists of equal proportion of steel, polypropylene and glass) and with two different sizes of coarse aggregate. The varying parameters in the preparation of porous concrete mix were coarse aggregate of two sizes, i.e., 6 mm and 12 mm and five different percentages of hybrid fibres (0.25 - 0.65 with an increment of 0.1). Compressive strength and flexural strength were measured at the end of two curing periods (7 and 28 days) whereas water permeability and abrasion test values were measured at the end of 28 days of curing. From the experimental findings, it is observed that compressive strength and flexural strength values increase with decrease in the size of the aggregate for control as well as fibre reinforced porous concrete. However, with respect to the measured values of permeability, it is found that with increase in size of coarse aggregates, permeability values also increases. For 28 days samples it is observed that 0.35% addition of hybrid fibres to porous concrete found to be optimum and it improved the compressive strength values by 20.24% and 19.06% for coarse aggregate sizes of 6mm and 12mm, respectively as compared to porous control concrete (without addition of hybrid fibres). Whereas, maximum flexural strength was obtained at 0.45% of addition of hybrid fibres and 31.6% (6mm coarse aggregate) increment and 24.26% (12mm coarse aggregate) increment were noticed as compared to porous control concrete. The best values for permeability were found at 0.35% of hybrid fibres and 12 mm coarse aggregate combination, whereas for abrasion resistance it was at 0.35% of hybrid fibres and 6mm coarse aggregate combination. © 2019 Associated Cement Companies Ltd.. All rights reserved.