High-volume fly ash Self Consolidating Concrete with coal bottom ash and recycled concrete aggregates: Fresh, mechanical and microstructural properties. (1st January 2023)

• Record Type: Journal Article
• Authors: Meena, Amardeep; Singh, Navdeep; Singh, S.P.
• Is Part Of: Journal of building engineering. Volume 63(2023)Part A
• Publication Date: 2023-01-01
• Subjects: Coal bottom ash -- Recycled concrete aggregates -- High volume fly ash self-consolidating concrete -- Fresh properties -- Mechanical properties -- Microstructural properties; Building -- Periodicals; 690.05
• DOI: 10.1016/j.jobe.2022.105447
• Languages: English
• ISSNs: 2352-7102

Abstract

Abstract: The study focuses on the use of coal bottom ash (CBA) and recycled concrete aggregates (RCA) as partial replacements for natural fine aggregates (NFA) and natural coarse aggregates (NCA) in high-volume fly-ash self-consolidating concrete (HVFA-SCC). The CBA and RCA were replaced in combination from 0 to 30% and 0–50%, respectively. Experimental results showed that the combined use of CBA (20%) and RCA (25%) in HVFA-SCC significantly enhanced compressive, splitting tensile, flexural and direct shear strength at 120 days. Additionally, it was discovered that 25% of RCA and 20% of NFA substitution with NCA and CBA, respectively, were noted as optimum replacement levels considering the effects on designed HVFA-SCC mixes up to later-age strength. Microstructural investigations such as scanning electron microscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopic proved that micro level properties of HVFA-SCC improved with higher curing periods as Fly Ash (FA) and CBA exhibited the pozzolanic reactions. Such reactions lead to additional calcium-silicate-hydrates and dense microstructure formation consequently enhancing the mechanical properties. Highlights: Coal bottom ash-CBA was used partially as natural fine aggregates. Recycled concrete aggregates-RCA were used partially as natural coarse aggregates. Mechanical properties were evaluated for designed concretes (HVFA-SCC). Microstructural analysis was performed using SEM, EDS and FT-IR.