ORCID

Abstract

The weak interfacial transition zone (ITZ) and high porosity of recycled coarse aggregates (RCA) limit their use in structural concrete. A sequential triple-treatment: HCl chemical treatment, mechanical abrasion, and cement slurry coating, was developed to densify the ITZ. Testing 198 specimens across six mix designs (0–100% RCA), TTRCA at 25% and 50% retained 92.1% and 87.3% of compressive strength, 93.6% and 87.7% of flexural strength, and 95.6% and 89.9% of splitting tensile strength versus the NCA control. Resistivity reached 81–91% of control; shrinkageremained 8–18% above control. XRD confirmed reduced Ca(OH)2 content with enhanced C–S–H formation; SEM revealed reduced ITZ porosity. ITZ densification was identified as the primary governing mechanism, supported by microstructural, mechanical, and durability evidence. Statistical analysis confirmed significant treatment effects (ANOVA, p<0.001). A critical 50% replacement threshold was established, supporting regulatory RCA limit revision and circular economy goals.

Publication Date

2026-06-22

Publication Title

Journal of Sustainable Cement-Based Materials

Volume

2026

ISSN

2165-0373

Acceptance Date

2026-06-15

Deposit Date

2026-08-18

Funding

First author Ashita Singh acknowledges the support of the Science and Engineering Research Board, Department of Science and Technology, Govt. of India, for funding this research and providing fellowship support through grant PDF/2022/000424. Grammarly was used to improve clarity, grammar, and overall language quality.

Keywords

Abrasion treatment, chemical treatment, cement slurry treatment, mechanical properties, microstructural characteristics, sustainable concrete, triple-treated recycled coarse aggregates

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