Abstract
Recycled concrete powder (RCP) exhibits pronounced variability in mineral component contents, which leads to competitive adsorption of superplasticizers in RCP-Portland cement (PC) pastes and consequently to mineral composition-dependent deviations in rheological properties. In this study, limestone powder (LSP), quartz powder (QZP), and hardened paste powder (HPP) were used to simulate the main components of RCP. Effects of RCPs with target components on the rheological properties of blended cement paste were investigated, and a competitive-adsorption coefficient (CC) was proposed to quantify the competitive adsorption of superplasticizer. Results showed that increasing LSP-enriched RCP content reduced the yield stress of cement paste, primarily due to the adsorption of superplasticizer via coordination bonding on LSP. Conversely, the yield stress of cement pastes significantly increased as increasing HPP-enriched RCP content due to the low superplasticizer affinity of HPP. Additionally, a significant portion of superplasticizers existed in the solution of pores within HPP, thereby reducing its dispersing efficiency. The competitive adsorption coefficient of RCP (CCRCP) was calculated based on the content of each component and superplasticizer dosage. CCRCP was governed by HPP proportion of RCP at low RCP content but by LSP proportion of RCP at high RCP content in RCP-PC paste, reflecting the competition between surface-complexation-dominated and pore-sequestration-dominated components. RCP content and superplasticizer dosage exhibited a coupled effect on CCRCP. Incorporating CCRCP improved dramatically the rheology prediction accuracy of RCP-PC pastes. The coefficient provides a practical basis for adjusting superplasticizer dosage to accommodate RCP compositional variability, facilitating efficient utilization of RCP in cement-based materials.
Recommended Citation
J. Du et al., "Mineral Composition-driven Competitive Adsorption Behavior of Superplasticizer in Recycled Concrete Powder-cement Pastes: Quantification and Validation," Construction and Building Materials, vol. 535, article no. 146972, Elsevier, Aug 2026.
The definitive version is available at https://doi.org/10.1016/j.conbuildmat.2026.146972
Department(s)
Civil, Architectural and Environmental Engineering
Publication Status
Full Text Access
Keywords and Phrases
Competitive adsorption; Mineral component; Recycled concrete powder; Superplasticizer; Surface coverage
International Standard Serial Number (ISSN)
0950-0618
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2026 Elsevier, All rights reserved.
Publication Date
15 Aug 2026
