Effect of high-volume recycled concrete powder on microstructure and mechanical performance of alkali-activated slag mortar using response surface approach

Zou, Z; Li, J; Li, J; Gao, H; Zhang, Y; Yu, Y; Zhang, C

Effect of high-volume recycled concrete powder on microstructure and mechanical performance of alkali-activated slag mortar using response surface approach

Zou, Z Li, J Li, J Gao, H Zhang, Y Yu, Y

Zhang, C

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Publisher:: ELSEVIER SCIENCE INC
Publication Type:: Journal Article
Citation:: Structures, 2025, 79
Issue Date:: 2025-09-01

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Field	Value	Language
dc.contributor.author	Zou, Z
dc.contributor.author	Li, J
dc.contributor.author	Li, J
dc.contributor.author	Gao, H
dc.contributor.author	Zhang, Y
dc.contributor.author	Yu, Y https://orcid.org/0000-0001-9592-8191
dc.contributor.author	Zhang, C
dc.date.accessioned	2026-05-14T06:36:09Z
dc.date.available	2026-05-14T06:36:09Z
dc.date.issued	2025-09-01
dc.identifier.citation	Structures, 2025, 79
dc.identifier.issn	2352-0124
dc.identifier.issn	2352-0124
dc.identifier.uri	http://hdl.handle.net/10453/194995
dc.description.abstract	To optimize the mix design of high-volume recycled concrete powder (RCP) alkali-activated slag mortar (HRAASM) and improve its mechanical performance, this study utilizes Box-Behnken design-based response surface method (RSM) to evaluate the effects of RCP particle size, activator modulus (Ms), activator content (C), and water to solid ratio (W/S) on mechanical properties of HRAASM. XRD, FTIR, TG-DSC, and SEM are employed to investigate the relationship between compressive strength, reaction products, reaction processes, and microstructure under different mix design parameters. The results reveal that under optimal parameters (RCP size: 15.2 μm, Ms: 1.59, C: 7.42 %, W/S: 0.47), the compressive strength reaches a maximum of 57.5 MPa at 28 days. RCP particles of 15.2 μm promote the formation of amorphous phases (C-S-H/C-A-S-H), while larger RCP particles mainly act as inert fillers. When the Ms is 1.6 and the W/S is 0.46, the interaction reduces matrix porosity and crack formation, thus synergistically enhancing the matrix densification. However, a W/S of 0.5 reduces strength, especially when using 33.6 μm RCP particles. This research provides valuable insights into the high-value recycling of recycled concrete powder and presents a feasible approach for developing alkali-activated slag mortar with enhanced mechanical performance.
dc.language	English
dc.publisher	ELSEVIER SCIENCE INC
dc.relation.ispartof	Structures
dc.relation.isbasedon	10.1016/j.istruc.2025.109515
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	0905 Civil Engineering, 1202 Building
dc.subject.classification	4005 Civil engineering
dc.title	Effect of high-volume recycled concrete powder on microstructure and mechanical performance of alkali-activated slag mortar using response surface approach
dc.type	Journal Article
utslib.citation.volume	79
utslib.for	0905 Civil Engineering
utslib.for	1202 Building
pubs.organisational-group	University of Technology Sydney
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
utslib.copyright.status	open_access	*
dc.rights.license	This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0). To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/
dc.date.updated	2026-05-14T06:35:41Z
pubs.publication-status	Published
pubs.volume	79

Abstract:

To optimize the mix design of high-volume recycled concrete powder (RCP) alkali-activated slag mortar (HRAASM) and improve its mechanical performance, this study utilizes Box-Behnken design-based response surface method (RSM) to evaluate the effects of RCP particle size, activator modulus (Ms), activator content (C), and water to solid ratio (W/S) on mechanical properties of HRAASM. XRD, FTIR, TG-DSC, and SEM are employed to investigate the relationship between compressive strength, reaction products, reaction processes, and microstructure under different mix design parameters. The results reveal that under optimal parameters (RCP size: 15.2 μm, Ms: 1.59, C: 7.42 %, W/S: 0.47), the compressive strength reaches a maximum of 57.5 MPa at 28 days. RCP particles of 15.2 μm promote the formation of amorphous phases (C-S-H/C-A-S-H), while larger RCP particles mainly act as inert fillers. When the Ms is 1.6 and the W/S is 0.46, the interaction reduces matrix porosity and crack formation, thus synergistically enhancing the matrix densification. However, a W/S of 0.5 reduces strength, especially when using 33.6 μm RCP particles. This research provides valuable insights into the high-value recycling of recycled concrete powder and presents a feasible approach for developing alkali-activated slag mortar with enhanced mechanical performance.

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http://hdl.handle.net/10453/194995