Department of Civil Engineering

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Author: search.filters.author.Bhunia, DipenduSubject: search.filters.subject.Chemistry

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    Alkali-activation potential of stone wastes
    (Elsevier, 2023-03) Bhunia, Dipendu
    The industrial processing of dimensional stones generates a significant amount of waste. According to the data released in 2020 by the nations with active dimensional stone industries, it is estimated that out of 316 million tons of dimensional stones extracted each year, 161.5 million tons end up as mining or quarry waste. These are dumped in open locations creating noxious conditions for mine workers, residents of nearby communities, and the environment. In the current work, an effort has been made to manufacture alkali-activated materials (AAM) using sandstone waste (SW) and marble stone waste (MW) obtained from Rajasthan (India). The primary precursor is SW, whereas MW is partially substituted as an admixture. The elemental composition of stone wastes was determined using X-ray fluorescence spectroscopy (XRF). Stone waste-based geopolymer composite was prepared using alkaline activating solutions sodium hydroxide (NH, NaOH) and sodium silicate (NS, Na2SiO3) and tested for mechanical and physical properties. Characterization and microstructural analysis of geopolymer composite was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) fitted with energy dispersive X-ray spectroscopy (EDS). The findings suggest that the developed geopolymer composite can be employed as a construction material that will improve the re-utilization of stone wastes, offering a workable solution to the challenges associated with their disposal.
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    Numerical simulation of RC-masonry infill wall system strengthened with textile reinforced concrete
    (Elsevier, 2023-04) Bhunia, Dipendu
    Masonry walls are generally considered non-load-bearing elements in most concrete or steel-framed structures. Being a heterogeneous structure, the masonry system effectively enhances the strength and lateral stiffness of the overall panel when subjected to horizontal forces. But the recent unsatisfactory performance of unreinforced Masonry Infill Walls (MIW) during in-plane seismic loading has caught the attention of many researchers for the last few years. To overcome these detrimental effects, strengthening the MIW frame is considered the best procedure to enhance the horizontal load-carrying capability of the system. Numerous studies evaluating various parameters affecting the behaviour of MIW were conducted using Fiber Reinforced Cementitious Material (FRCM) as a strengthening material. This paper conducted a validation study that includes numerical simulation of the experimental research carried out at Wellington Institute of Technology in which nine 2:3 scaled single bay and single story Reinforced Concrete Frame with Masonry Infills (RCFMI) specimens strengthened with different fibers (basalt, carbon, and glass) of FRCM was tested under in-plane seismic/cyclic loads. The study went into detail on creating a numerical model replicating the non-linear structural cyclic behaviour of an infill wall bound by a reinforced Concrete frame and subjected to displacement-controlled in-plane lateral stress. The numerical analysis was performed in the Finite Element Method (FEM) programme ABAQUS using a streamlined micro-model approach. To simulate the non-linear behaviour of the masonry blocks and concrete, the Concrete Damage Plasticity (CDP) model was employed. The tested specimen was retrofitted with glass fiber grid diagonal bands, each with a width equal to 1/6 of the infill diagonal length. This analysis was used to create the numerical model. The validation demonstrated that the numerical model could faithfully simulate the behaviour and forecast the strength of masonry infill walls with RC frames. The findings of the observations are explained in the form of load–displacement hysteresis loops and excursion curves. The numerical results demonstrate excellent agreement with the experimental data, a significant impact of FRCM on the system's dynamic behaviour, and an improvement in MIW effectiveness with FRCM under cyclic loading is observed.