Department of Civil Engineering

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Author: search.filters.author.Srivastava, AnshumanSubject: search.filters.subject.Concrete

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Now showing 1 - 6 of 6
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    Reliability-based mix design of marble dust incorporated concrete and its assessment using the concept of performance index
    (Wiley, 2022-03) Srivastava, Anshuman
    Concrete is one of the most important and versatile construction materials and variation in its properties is inevitable. Mix design of concrete is done in such a way that the design compressive strength is typically higher than the actual values specified by the structural engineer. The concept of reliability has not been explicitly used in regard of calculation of compressive strength using mix design and demands attention. A design procedure based on the reliability-based index is presented. The design procedure is developed for the concrete mix with partial replacement of cement by marble dust. The mechanical property which is the compressive strength of the concrete mix design is considered as a random variable, assumed to be lognormally distributed. The present study makes an effort to design a concrete mix in accordance to theory of confidence level for various levels of reliability. Mix design guidelines and graphs for various levels of replacement of cement by marble dust have also been presented in the study. Also, the cost analysis of various design mix proportions used has been calculated and compared. Four different cases to illustrate the performance rating in accordance with replacement levels of Marble dust have been formulated. The concrete mixes with marble dust induced in concrete had lower partial safety factors than those without inclusion. The characteristics of Marble dust incorporated concrete have been assigned numerical performance index values. These values may constitute a reliable means for concrete producers in finding the rate of cement replacement by other cementitious materials. The compressive strength of most of mixes with marble dust had a coefficient of variation and within-test coefficient of variation value ranging between 2% and 3% and less than 1.5%, respectively. This indicates toward improvement in quality of concrete with cement partially replaced by marble dust.
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    Experimental investigation on paver blocks of fly ash-based geopolymer concrete containing silica fume
    (Taylor & Francis, 2021-12) Srivastava, Anshuman
    Utilisation of geopolymer may reduce the global warming potential of concrete. This study examines geopolymer concrete as interlocking paver blocks. Three concretes are compared: conventional cement, fly ash-geopolymer and fly ash–silica fume geopolymer. Sodium hydroxide solution is used in both geopolymer concretes, and sodium silicate solution is used in fly ash-based geopolymer concrete only. Rectangle and uni shape blocks are tested for compressive strength, flexural strength, abrasion resistance and freeze–thaw resistance. Dynamic drop loading test is conducted on block pavement with herringbone laying pattern . Results revealed that resistance to abrasion and water absorption of geopolymeris improved by adding silica fume . Freeze–thaw resistance is the lowest for cement concrete paver blocks. Lowest deflection occurred in block pavement of uni shape. Geopolymer concrete provides uniform load distribution than cement concrete. Cement concrete is slightly costlier than geopolymer concrete. This study concluded the geopolymer as suitable option for paver block applications
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    Bioconcrete-Enabled Resilient Construction: a Review
    (Springer, 2023-03) Lahoti, Mukund; Srivastava, Anshuman
    Concrete, the ubiquitous cementitious composite though immensely versatile, is crack-susceptible. Cracks let in deleterious substances causing durability issues. Superseding conventional crack-repair methods, the innovative application of microbially induced calcium carbonate precipitation (MICCP) stands prominent, being based on the natural phenomenon of carbonate precipitation. It is eco-friendly, self-activated, economical, and simplistic. Bacteria inside concrete get activated by contacting the environment upon the crack opening and filling the cracks with calcium carbonate—their metabolic waste. This work systematizes MICCP’s intricacies and reviews state-of-the-art literature on practical technicalities in its materialization and testing. Explored are the latest advances in various aspects of MICCP, such as bacteria species, calcium sources, encapsulations, aggregates, and the techniques of bio-calcification and curing. Furthermore, methodologies for crack formation, crack observation, property analysis of healed test subject, and present techno-economic limitations are examined. The work serves as a succinct, implementation-ready, and latest review for MICCP’s application, giving tailorable control over the enormous variations in this bio-mimetic technique.
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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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    Analytical and Experimental Investigations on Using Waste Marble Powder in Concrete
    (ASCE, 2019-04) Srivastava, Anshuman; Bhunia, Dipendu
    Research using marble powder as a partial replacement of cement in concrete has gained a lot of attention recently. In this paper,the effect of dried marble powder on particle packing of concrete has been demonstrated. Experimental investigations have been conducted onthe effect of marble powder on hydration reaction, strength activity index, and possible reasons for the gain in strength. In addition, statisticalmethods were used to develop two mathematical models for marble powder incorporated in concrete using experimental values. In the firstmodel, the ratios of 28-day compressive strength between concrete with cement partially replaced by marble powder and control concretehave been related to marble powder replacement percentage. In the second model proposed, modified and simplified relationships for thewater-cement law when cement is partially replaced by marble powder have been provided. The first model was validated for both standardcubes and cylinders used for testing by researchers and the predictions showed only 7.15% error as compared with the experimental values.The second model might serve as a useful tool for mix proportioning of concrete mixes incorporating marble powder in concrete. Finally,based on a review of the literature and experimental results, a set of guidelines has been proposed for the use of marble powder as a partialreplacement of cement in concrete
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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.