Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites
Engineered cementitious composite (ECC) is a unique group of fiber-reinforced strain-hardening cementitious composites exhibiting crack self-healing. Due to the absence of coarse aggregates in the ECC mix design, high amount of supplementary cementitious materials (SCM) are generally used to reduce...
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sg-ntu-dr.10356-846092020-03-07T11:43:35Z Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites Qiu, Jishen Tan, Han Siang Yang, En-Hua School of Civil and Environmental Engineering Engineered cementitious composites Autogenous healing Engineered cementitious composite (ECC) is a unique group of fiber-reinforced strain-hardening cementitious composites exhibiting crack self-healing. Due to the absence of coarse aggregates in the ECC mix design, high amount of supplementary cementitious materials (SCM) are generally used to reduce the cement content. The inclusion of slag not only changes the chemical compositionss of the matrix but also alters the crack width of ECC. Both may influence the autogenous healing potential of the slag-based ECC. This paper systematically investigates the influence of the individual factor, i.e. slag content, crack width, and environmental alkalinity, on the autogenous healing efficiency of ECC. Specifically, single-cracked ECC specimens with different slag content and crack width were conditioned under water/dry or NaOH/dry cycles. The autogenous healing performance was evaluated based on crack width reduction, resonant frequency recovery and microstructure analysis. The results show that autogenous healing is determined by a couple effect of physical properties (crack width), chemical compositionss (slag content), and environmental conditions (conditioning alkalinity). At a given slag content and certain alkalinity, there exists a maximum allowable crack width for complete healing, beyond which only partial or no healing would happen. The dominant healing product for the water/dry conditioning is CaCO3 while the NaOH/dry cycles promote slag hydration and results in the formation of Csingle bondSsingle bondH and CaCO3 as main healing products. It is concluded that CaCO3 precipitation is more effective to engage autogenous healing than the formation of Csingle bondSsingle bondH. The concept to associate allowable crack width and slag content is proposed, which would guides ingredients selection and component tailoring to engage robust autogenous healing in ECC in the future. MOE (Min. of Education, S’pore) Accepted version 2016-12-20T03:14:55Z 2019-12-06T15:48:16Z 2016-12-20T03:14:55Z 2019-12-06T15:48:16Z 2016 Journal Article Qiu, J., Tan, H. S., & Yang, E. -H. (2016). Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites. Cement and Concrete Composites, 73, 203-212. 0958-9465 https://hdl.handle.net/10356/84609 http://hdl.handle.net/10220/41895 10.1016/j.cemconcomp.2016.07.013 en Cement and Concrete Composites © 2016 Elsevier Ltd. This is the author created version of a work that has been peer reviewed and accepted for publication by Cement and Concrete Composites, Elsevier Ltd. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1016/j.cemconcomp.2016.07.013]. 41 p. application/pdf |
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Engineered cementitious composites Autogenous healing Qiu, Jishen Tan, Han Siang Yang, En-Hua Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
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Engineered cementitious composite (ECC) is a unique group of fiber-reinforced strain-hardening cementitious composites exhibiting crack self-healing. Due to the absence of coarse aggregates in the ECC mix design, high amount of supplementary cementitious materials (SCM) are generally used to reduce the cement content. The inclusion of slag not only changes the chemical compositionss of the matrix but also alters the crack width of ECC. Both may influence the autogenous healing potential of the slag-based ECC. This paper systematically investigates the influence of the individual factor, i.e. slag content, crack width, and environmental alkalinity, on the autogenous healing efficiency of ECC. Specifically, single-cracked ECC specimens with different slag content and crack width were conditioned under water/dry or NaOH/dry cycles. The autogenous healing performance was evaluated based on crack width reduction, resonant frequency recovery and microstructure analysis. The results show that autogenous healing is determined by a couple effect of physical properties (crack width), chemical compositionss (slag content), and environmental conditions (conditioning alkalinity). At a given slag content and certain alkalinity, there exists a maximum allowable crack width for complete healing, beyond which only partial or no healing would happen. The dominant healing product for the water/dry conditioning is CaCO3 while the NaOH/dry cycles promote slag hydration and results in the formation of Csingle bondSsingle bondH and CaCO3 as main healing products. It is concluded that CaCO3 precipitation is more effective to engage autogenous healing than the formation of Csingle bondSsingle bondH. The concept to associate allowable crack width and slag content is proposed, which would guides ingredients selection and component tailoring to engage robust autogenous healing in ECC in the future. |
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School of Civil and Environmental Engineering |
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School of Civil and Environmental Engineering Qiu, Jishen Tan, Han Siang Yang, En-Hua |
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Article |
author |
Qiu, Jishen Tan, Han Siang Yang, En-Hua |
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Qiu, Jishen |
title |
Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
title_short |
Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
title_full |
Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
title_fullStr |
Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
title_full_unstemmed |
Coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
title_sort |
coupled effects of crack width, slag content, and conditioning alkalinity on autogenous healing of engineered cementitious composites |
publishDate |
2016 |
url |
https://hdl.handle.net/10356/84609 http://hdl.handle.net/10220/41895 |
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1681044118405382144 |