Department of Civil Engineering

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    Performance assessment and life cycle analysis of concrete containing ferrochrome slag and fly ash as replacement materials – A circular approach
    (Elsevier, 2022-09) Barai, Sudhir Kumar
    Climate change mitigation and resource efficiency have emerged as crucial challenges for long-term sustainability of concrete. Implementing circular approach through waste valorisation in concrete production with eco-efficient mix design is an efficient mitigation pathway to combat natural resources depletion and environmental issues. This paper investigates techno-environmental sustainability of concrete utilizing 100% ferrochrome slag as alternate coarse aggregate and fly ash as partial cement substitute (0–40%) adopting particle packing optimization technique (PPOT) as a sustainable mix design method. Total of ten types of concrete mixtures were prepared using the alternate materials and mix design methods (PPOT and IS:10262(2009)). Natural aggregate concrete prepared by IS:10262(2009) mix design was considered as the reference mixture. Technical assessment of concrete was performed experimentally in terms of compressive strength and tensile strength. Environmental performance was investigated through life cycle assessment (LCA) as per ISO 14040-44 guidelines using cradle-to-gate system boundary and two functional units: 1 m3 concrete and 1 MPa compressive strength. Results revealed that ferrochrome slag aggregate concrete (FCSAC) containing fly ash up to 30% prepared by PPOT has enhanced strength than reference concrete. Regardless of the functional units used, FCSAC with 30% fly ash designed by PPOT was ranked as the most sustainable mix with significant environmental savings (around 50–70%) without compromising desired requirements. Sensitivity analysis was performed by varying transportation distance, mode of transport and energy mix. Results showed that FCSAC with 30% fly ash is not sensitive to the scenarios investigated. The outcomes will be helpful for decision-makers to develop policy directives and frameworks on synergistic use of ferrochrome slag and fly ash towards concrete sustainability.
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    A study on environmental and economic impacts of using waste marble powder in concrete
    (Elsevier, 2017-09) Srivastava, Anshuman; Sangwan, Kuldip Singh; Bhunia, Dipendu
    Gainful utilization of waste marble powder in various construction practices has become a topic of interest in research areas. An overview of works reported regarding the use as partial replacement of sand and cement by marble powder in concrete is presented in the paper. Gaps in the studies to date have been pointed out. An environmental impact comparison of normal concrete with the use of marble powder as partial replacement of cement and sand is carried out using the UMBERTO NXT life cycle analysis software with ReCipe midpoint and endpoint methods. Finally, a detailed cost analysis study has been performed to justify the use of marble powder in concrete which has exhibited encouraging results in terms of strength and quality. It has also been found that the use of marble slurry in concrete reduces its environmental impact and is economically beneficial.
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    Environmental impact assessment of fly ash and silica fume based geopolymer concrete
    (Elsevier, 2020-05) Srivastava, Anshuman; Sangwan, Kuldip Singh
    Alkali activated geopolymer is an attractive solution to limit the adverse consequences of cement manufacturing. In this paper, an evaluation of environmental impacts of geopolymer containing fly ash and silica fume is conducted. Life cycle assessment is performed by benchmarking the environmental impacts of three geopolymer concrete mixes against the conventional cement concrete, namely: fly ash geopolymer (with hydroxide and silicate of sodium); fly ash–silica fume blend geopolymer (with hydroxide and silicate of sodium); and fly ash–silica fume blend geopolymer (with sodium hydroxide). Impact analysis is performed by using ReCiPe midpoint and endpoint methods in life cycle assessment software UMBERTO NXT using database of Ecoinvent 3.0. Sensitivity analysis is performed to determine the effect of transportation. One mix design for each concrete of equal water to binder ratio and 28-days compressive strength of more than 35 MPa is analysed. Results of life cycle assessment indicate that alkaline activators and cement are the major sources of negative environmental impacts for geopolymer and cement concrete, respectively. Global warming potential of geopolymer concretes is lower than conventional cement concrete. Fly ash–silica fume geopolymer concrete activated without sodium silicate has lowest environmental impacts. Transportation of raw materials is found to increase the overall negative of all four concrete mixes. Cost reduction of 10.87%–17.77% per unit volume is achieved with the use of fly ash – silica fume based geopolymer concrete. Sustainability in terms of cost and environmental benefits of geopolymer concrete can be further increased by using silica fume. It can be concluded that the use of fly ash – silica fume blended geopolymer in the construction industry has huge possibility to improve its sustainability. Furthermore, waste management can be effectively done by utilization of industrial by-products in concrete.
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    Life Cycle Assessment of Groundwater Supply System in a Hyper-arid Region of India
    (Elsiever, 2018) Singh, Ajit Pratap
    This paper addresses the life cycle assessment (LCA) of groundwater supply system in hyper-arid region of Bikaner block in the state of Rajasthan, India. The key objective of this research is to address potential environmental impacts of groundwater extraction for irrigation purpose and sustainable management of groundwater in water scarce regions. To assess the impact of groundwater extraction, the functional unit of the study has been taken as one kiloliter of freshwater withdrawal using submersible water pumps for irrigation purpose. The primary data for the water withdrawal and energy consumption are collected through semi-structured interview conducted among the end users in the region. The energy and material flow modelling of the ground water system have been developed using Umberto NXT Universal and Ecoinvent dataset v3.0. The environmental impact assessment is carried out using well-known ReCiPe method. It is observed from the analysis that copper used in equipment of ground water supply system and energy consumption for ground water extraction generate significant impacts to the environment. The results thus obtained are very helpful in decision making and to formulate a suitable ground water development/withdrawal policy while dealing with different environmental issues of groundwater management.
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    Influence of mechanical properties and CO2 emissions on the optimization of self-compacting based hybrid fiber reinforced concrete
    (Elsiever, 2021-03-10) Barai, Sudhir Kumar; Pradhan, Subhasis
    The paper deals with the development of high-performance self-compacting based concrete and optimization of the mix by accounting both mechanical and sustainability characteristics. Taguchi’s L16 orthogonal array is followed to consider 16 concrete mixes in combination of additives as four levels are considered for each additive/factor (class F type of fly ash, colloidal nano silica, crimped steel fiber, and polypropylene fibers). The global warming potential (GWP) is also estimated to account the sustainability parameter. To determine the optimized concrete mix satisfying both performance and sustainability characteristics the normalizing indices are used by accounting: (a) compressive strength and GWP, (b) split tensile strength and GWP, (c) flexural tensile strength and GWP, and (d) compressive strength, split tensile strength, flexural tensile strength and GWP. A detail comparison of normalizing indices is conducted, and the optimized concrete mix is determined based on the average rankings obtained from different normalizing index.