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Experimental studies of sustainable concrete modified with colloidal nanosilica and metakaolin

Experimental studies of sustainable concrete modified with colloidal nanosilica and metakaolin IntroductionAlthough the use of Colloidal Nanosilica (CNS) has shown significant advantages on strength and durability development of cement composites. However, the impact of CNS with Metakaolin (MK) has not been established well.ObjectiveThis study presents a novel amalgamation of nano and micro-sized supplementary cementing materials in cement composites. The rationale behind this was to study their effects on strength and durability properties. Besides this, the microstructural investigation was carried out using FESEM and XRD to explore the underlying mechanisms.MethodsBefore casting, the workability of concrete were tested. The mechanical and durability properties including compressive strength, splitting tensile strength, flexural strength, Rapid chloride permeability tests, water absorption, sulfate, and acid attack resistance tests were carried out. Furthermore, besides strength and durability studies, an extensive microstructural investigation was carried under FESEM and XRD to explore the underlying mechanisms.ResultsTwenty different concrete mixtures were designed and explored. The results indicate that the incorporation of CNS and MK in cement composites has increased the admixture demand. The strength of all mixtures increased at various curing ages up to 90 days compared to normal concrete. The maximum increase in strength parameters at 0.44 w/b ratio was observed at 0.45% CNS and 10% MK content. The durability parameters studied like water absorption and RCPT showed an increase in resistance to permeability. Which indicated less porosity of modified mixtures. In acid and sulfate attacks, the normal concrete showed the poorest performance, and CNS and MK enabled some resistance to sulphuric acid and sulfate attack at 120 days. The microstructural characterization conducted during this study has shown that the replacement of cement by MK and CNS has improved the microstructure compared to normal concrete.ConclusionThe simultaneous incorporation of MK and CNS has reduced workability. In terms of mechanical strength, it is observed that the optimum amount of CNS and MK was 0.45% and 10% respectively. Also, the MK and CNS addition has decreased the water absorption, increased resistance to chloride ion permeability, acid, and sulfate attack compared to normal concrete. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Building Pathology and Rehabilitation Springer Journals

Experimental studies of sustainable concrete modified with colloidal nanosilica and metakaolin

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References (90)

Publisher
Springer Journals
Copyright
Copyright © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2021
ISSN
2365-3159
eISSN
2365-3167
DOI
10.1007/s41024-021-00157-8
Publisher site
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Abstract

IntroductionAlthough the use of Colloidal Nanosilica (CNS) has shown significant advantages on strength and durability development of cement composites. However, the impact of CNS with Metakaolin (MK) has not been established well.ObjectiveThis study presents a novel amalgamation of nano and micro-sized supplementary cementing materials in cement composites. The rationale behind this was to study their effects on strength and durability properties. Besides this, the microstructural investigation was carried out using FESEM and XRD to explore the underlying mechanisms.MethodsBefore casting, the workability of concrete were tested. The mechanical and durability properties including compressive strength, splitting tensile strength, flexural strength, Rapid chloride permeability tests, water absorption, sulfate, and acid attack resistance tests were carried out. Furthermore, besides strength and durability studies, an extensive microstructural investigation was carried under FESEM and XRD to explore the underlying mechanisms.ResultsTwenty different concrete mixtures were designed and explored. The results indicate that the incorporation of CNS and MK in cement composites has increased the admixture demand. The strength of all mixtures increased at various curing ages up to 90 days compared to normal concrete. The maximum increase in strength parameters at 0.44 w/b ratio was observed at 0.45% CNS and 10% MK content. The durability parameters studied like water absorption and RCPT showed an increase in resistance to permeability. Which indicated less porosity of modified mixtures. In acid and sulfate attacks, the normal concrete showed the poorest performance, and CNS and MK enabled some resistance to sulphuric acid and sulfate attack at 120 days. The microstructural characterization conducted during this study has shown that the replacement of cement by MK and CNS has improved the microstructure compared to normal concrete.ConclusionThe simultaneous incorporation of MK and CNS has reduced workability. In terms of mechanical strength, it is observed that the optimum amount of CNS and MK was 0.45% and 10% respectively. Also, the MK and CNS addition has decreased the water absorption, increased resistance to chloride ion permeability, acid, and sulfate attack compared to normal concrete.

Journal

Journal of Building Pathology and Rehabilitation – Springer Journals

Published: Dec 1, 2022

Keywords: Metakaolin; Nanosilica; Workability; Mechanical strength; Chloride permeability

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