Multi-Variable Optimization of Sustainable Alkali-Activated Mortar with High Waste Concrete Powder Dosage for Enhanced Drying Shrinkage Resistance

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

Multi-Variable Optimization of Sustainable Alkali-Activated Mortar with High Waste Concrete Powder Dosage for Enhanced Drying Shrinkage Resistance

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

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Publisher:: MDPI
Publication Type:: Journal Article
Citation:: Buildings, 2025, 15, (21)
Issue Date:: 2025-11-01

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Field	Value	Language
dc.contributor.author	Zou, Z
dc.contributor.author	Gao, H
dc.contributor.author	Zhang, Y
dc.contributor.author	Li, J
dc.contributor.author	Li, M
dc.contributor.author	Yu, Y https://orcid.org/0000-0001-9592-8191
dc.date.accessioned	2026-05-12T06:11:15Z
dc.date.available	2026-05-12T06:11:15Z
dc.date.issued	2025-11-01
dc.identifier.citation	Buildings, 2025, 15, (21)
dc.identifier.issn	2075-5309
dc.identifier.issn	2075-5309
dc.identifier.uri	http://hdl.handle.net/10453/194944
dc.description.abstract	This study presents a comprehensive strategy for mitigating drying shrinkage of alkali-activated slag mortar (AASM) with the high-dosage incorporation of waste concrete powder (WCP). Response surface methodology (RSM) coupled with microstructural analysis is used to investigate the synergistic effects of WCP particle size (R), activator modulus (AM), activator content (AC), and water to solid ratio (W/S) on shrinkage behavior and matrix development. The optimized mix—WCP-R = 33.6 µm, AM = 1.23, AC = 6.03%. and W/S = 0.49—exhibits a 120-day drying shrinkage of only 1450.1 µε, significantly lower than that of conventional AASM. Microstructural observations reveal that coarser WCP particles act predominantly as fillers, enhancing stability, whereas finer particles promote gel formation but increase shrinkage. A high AM (1.6) refines the pore structure by reducing large pores (>0.05 µm), while a low W/S (0.46) decreases total porosity to 7.67%, collectively restricting moisture transport. The coexistence of C-(A)-S-H gel and hydrotalcite improves matrix integrity. Notably, this optimized HWAASM achieves a substantially reduced carbon footprint of 180 kg CO<inf>2</inf>-eq/t, underscoring its significant environmental advantage. The findings advance the understanding of shrinkage mechanisms in high-WCP-AASM and offer an eco-friendly route for valorizing construction waste and developing low-carbon building materials.
dc.language	English
dc.publisher	MDPI
dc.relation.ispartof	Buildings
dc.relation.isbasedon	10.3390/buildings15213903
dc.rights	info:eu-repo/semantics/openAccess
dc.subject	1201 Architecture, 1202 Building, 1203 Design Practice and Management
dc.subject.classification	3301 Architecture
dc.subject.classification	3302 Building
dc.subject.classification	4005 Civil engineering
dc.title	Multi-Variable Optimization of Sustainable Alkali-Activated Mortar with High Waste Concrete Powder Dosage for Enhanced Drying Shrinkage Resistance
dc.type	Journal Article
utslib.citation.volume	15
utslib.for	1201 Architecture
utslib.for	1202 Building
utslib.for	1203 Design Practice and Management
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	2026-05-12T06:10:59Z
pubs.issue	21
pubs.publication-status	Published
pubs.volume	15
utslib.citation.issue	21

Abstract:

This study presents a comprehensive strategy for mitigating drying shrinkage of alkali-activated slag mortar (AASM) with the high-dosage incorporation of waste concrete powder (WCP). Response surface methodology (RSM) coupled with microstructural analysis is used to investigate the synergistic effects of WCP particle size (R), activator modulus (AM), activator content (AC), and water to solid ratio (W/S) on shrinkage behavior and matrix development. The optimized mix—WCP-R = 33.6 µm, AM = 1.23, AC = 6.03%. and W/S = 0.49—exhibits a 120-day drying shrinkage of only 1450.1 µε, significantly lower than that of conventional AASM. Microstructural observations reveal that coarser WCP particles act predominantly as fillers, enhancing stability, whereas finer particles promote gel formation but increase shrinkage. A high AM (1.6) refines the pore structure by reducing large pores (>0.05 µm), while a low W/S (0.46) decreases total porosity to 7.67%, collectively restricting moisture transport. The coexistence of C-(A)-S-H gel and hydrotalcite improves matrix integrity. Notably, this optimized HWAASM achieves a substantially reduced carbon footprint of 180 kg CO2-eq/t, underscoring its significant environmental advantage. The findings advance the understanding of shrinkage mechanisms in high-WCP-AASM and offer an eco-friendly route for valorizing construction waste and developing low-carbon building materials.

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http://hdl.handle.net/10453/194944