High-Temperature, Bond, and Environmental Impact Assessment of Alkali-Activated Concrete (AAC)

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🔬研究者:Provides microstructural-mechanical correlations and LCA methodology for AAC, useful for further optimization studies.

🏢実務担当者:Offers data on AAC mix design and cost implications under carbon tax, aiding sustainable material selection for construction projects.

🏛政策担当者:Highlights the potential of AAC to reduce construction emissions and the impact of carbon pricing on material competitiveness.

first_page settings Order Article Reprints Font Type: Arial Georgia Verdana Font Size: Aa Aa Aa Line Spacing:    Column Width:    Background: Open AccessAbstract High-Temperature, Bond, and Environmental Impact Assessment of Alkali-Activated Concrete (AAC) † by Kruthi Kiran Ramagiri 1,*, Patricia Kara De Maeijer 2 and Arkamitra Kar 1 1 Department of Civil Engineering, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad 500078, India 2 Built Environment Assessing Sustainability (BEASt), EMIB, Faculty of Applied Engineering, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium * Author to whom correspondence should be addressed. † Presented at the 1st International Online Conference on Infrastructures, 7–9 June 2022; Available online: https://ioci2022.sciforum.net/. Eng. Proc. 2022, 17(1), 24; https://doi.org/10.3390/engproc2022017024 Published: 2 May 2022 (This article belongs to the Proceedings of The 1st International Online Conference on Infrastructures) Download Download PDF Download PDF with Cover Download XML Download Epub Versions Notes Alkali-activated binder (AAB) has been extensively researched in recent years due to its potential to replace Portland cement (PC) and lower carbon footprint. However, major barriers to its commercialization are related to the inadequate characterization of mechanical properties and long-term durability. The mechanical and durability performance of AAB is highly influenced by its microstructure. There is minimal research on correlating the microstructural changes to the specimen-level performance of AAB [1]. Among AAB's primary advantages as a building material is its superior performance at high temperatures and lower environmental impact [2]. The performance of reinforced concrete to function as a composite at high temperatures is evaluated through its bond strength. Several studies reported the effect of mix proportions, curing conditions, and rebar specifications on the bond strength of thermal-cured alkali-activated concrete (AAC) [3,4,5,6]. However, there is no reported study on the bond strength of ambient cured (fly ash + slag)-based AAC. To validate the practical sustainability of AAC, life cycle assessment (LCA) can be used to evaluate the environmental impact. Therefore, the present study evaluates the effect of varying precursor proportion (fly ash: slag varied as 100:0, 70:30, 60:40, and 50:50), activator modulus (Ms, varied as 1.0 and 1.4), and high temperatures (538 °C, 760 °C, and 892 °C) on the mechanical properties and microstructure of AAC. The microstructural characteristics are evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). The effect of varying precursor proportions and Ms on the mechanical performance of AAC is evaluated through compressive strength, bond strength, flexural strength, and split tensile strength testing. The performance of AAB at extremely high temperatures is assessed in terms of residual compressive and bond strength. LCA of AAC is conducted using the ReCiPe 2016 methodology. Furthermore, since the commercialization of any novel alternative material depends on cost-effectiveness, a simplified cost analysis is performed.The results from microstructural experiments show the formation of new crystalline phases and decomposition of reaction products when exposed to high temperatures, and they correlate well with the observed mechanical performance. The 28-day compressive strength with slag content is enhanced by 151.8–339.7%, depending on the mix. In ambient conditions, lower Ms improves mechanical performance. When exposed to high temperatures, specimens with a high slag content and a low Ms suffered significant deterioration. AAC with a fly ash: slag ratio of 70:30 and Ms of 1.4 is proposed as optimal from the results obtained in the present study [7]. The results reveal that the biggest impact on climate change comes from transport (45.5–48.2%) and sodium silicate (26.7–35.6%). Environmental impact is determined to be primarily influenced by sodium hydroxide. The proposed optimal AAC mix has a global warming potential 42.6 % lower than PC concrete [8]. A comparison with the default procedures in the International Reference Life Cycle Data System (ILCD) handbook reveals that the ReCiPe midpoint approach is more efficient in analyzing all impact categories, except freshwater ecotoxicity (FETP) and human toxicity potentials (HTPs). An evaluation of FETP and HTP is recommended with USEtox [9]. The proposed AAC mix has a higher cost than PC concrete in the present scenario. In contrast, if a carbon tax is enacted, the cost of the proposed AAC mix will rise by only 18.4%, whereas PC concrete prices will rise by 81.7%. This proposed AAC mix is an environmentally sustainable replacement for PC concrete specifically intended for applications requiring the superior high-temperature performance of reinforced concrete. Author ContributionsConceptualization, K.K.R. and A.K.; methodology, K.K.R.; writing—original draft preparation, K.K.R.; writing—review and editing, A.K. and P.K.D.M.; supervision, A.K.; funding acquisition, A.K. All authors have read and agreed to the published version of the manuscript.FundingThis research was funded by BITS Pilani, Hyderabad campus, through the Outstanding Potential for Excellence in Research and Academics (OPERA) grant.Institutional Review Board StatementThis study does not involve any studies on humans or animals.Informed Consent StatementNot applicable.AcknowledgmentsThe authors would like to acknowledge the central analytical laboratory facilities at BITS Pilani, Hyderabad campus, for providing the necessary setup to conduct XRD, FTIR, and SEM-EDS analyses.Conflicts of InterestThe authors declare no conflict of interest.ReferencesKar, A. Characterizations of Concretes with Alkali-Activated Binder and Correlating Their Properties from Micro-to Specimen Level. Ph.D. Thesis, West Virginia University, Morgantown, WV, USA, 2013. [Google Scholar]Ramagiri, K.K. Evaluation of High-Temperature, Bond, and Shrinkage of Alkali-Activated Binder Concrete. 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High-Temperature, Bond, and Environmental Impact Assessment of Alkali-Activated Concrete (AAC). Eng. Proc. 2022, 17, 24. https://doi.org/10.3390/engproc2022017024 AMA Style Ramagiri KK, Kara De Maeijer P, Kar A. High-Temperature, Bond, and Environmental Impact Assessment of Alkali-Activated Concrete (AAC). Engineering Proceedings. 2022; 17(1):24. https://doi.org/10.3390/engproc2022017024 Chicago/Turabian Style Ramagiri, Kruthi Kiran, Patricia Kara De Maeijer, and Arkamitra Kar. 2022. "High-Temperature, Bond, and Environmental Impact Assessment of Alkali-Activated Concrete (AAC)" Engineering Proceedings 17, no. 1: 24. https://doi.org/10.3390/engproc2022017024 Find Other Styles Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here. Article Metrics No No Article Access Statistics Multiple requests from the same IP address are counted as one view.

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