Chloride Binding Mechanisms in Cement-Based Materials
Summary
Chloride binding in cementitious systems arises from a combination of chemical and physical interactions that hinder the ingress of free chloride ions and thus mitigate reinforcement corrosion. Chemical binding is chiefly governed by the formation of chloroaluminate phases within the AFm (alumina-ferric oxide-mono) family, notably Friedel’s salt and Kuzel’s salt, which incorporate chloride ions into their layered structures via ion-exchange reactions. Physical binding occurs when chloride ions are adsorbed onto the surfaces of calcium silicate hydrate (C–S–H) gels and other hydration products through electrostatic interactions or van der Waals forces. The balance between these mechanisms is influenced by pore solution chemistry, in particular pH and ionic strength, as well as by the composition of the binder, supplementary cementitious materials and exposure conditions such as carbonation and leaching. Understanding these processes is essential for accurate modelling of chloride transport, for the design of durable concrete in marine or de-icing environments, and for the development of novel low-carbon binders with enhanced resistance to chloride penetration.
Research from Nature Portfolio
No recent Nature Portfolio content available.
Chloride Binding Mechanisms in Cement-Based Materials publication trend
The graph below shows the total number of articles in chloride binding mechanisms in cement-based materials across all publications each year (not limited to Nature Index journals).
Technical terms
AFm phases: Layered calcium aluminate hydrates that exchange interlayer anions, key for chemical chloride binding.
C–S–H (calcium silicate hydrate): Amorphous to poorly crystalline gel responsible for most of the cement matrix strength and physical chloride adsorption.
Friedel’s salt: A chloroaluminate AFm phase with general formula Ca₂Al(OH)₆Cl·2H₂O, formed by direct ion exchange with sulphate.
Kuzel’s salt: An intermediate chloro-sulphoaluminate phase that precedes the formation of Friedel’s salt under certain chloride concentrations.
Ion exchange: A chemical process in which chloride ions replace original interlayer anions (e.g. sulphate or hydroxide) in AFm phases.
References
- The effect of artificial leaching with HCl on chloride binding in ordinary Portland cement paste. Cement and Concrete Research (2020).
- Chloride binding in Portland composite cements containing metakaolin and silica fume. Cement and Concrete Research (2022).
- Chloride sorption by C-S-H quantified by SEM-EDX image analysis. Cement and Concrete Research (2022).
About these summaries
This Nature Research Intelligence Topic summary is created with the cited references and a large language model. We take care to ground generated text with facts, and have systems in place to gain human feedback on the overall quality of the process in line with our AI principles. We strive to create accurate and useful summaries for people unfamiliar with the research topic and that supports this goal. These pages are a beta release and will be updated as we learn how best to help people gain value from a research topic summary.
Turn complex research questions into confident strategic decisions
When you're under pressure to set direction, justify investment, or understand your competitive position, you need more than raw data — you need trusted insights you can act on.
Benchmark your performance against global peers using robust, methodologically sound analysis.
Combine quantitative metrics with qualitative expert insight to uncover strengths, gaps and emerging opportunities.
Gain tailored, decision-ready recommendations aligned to your strategic priorities.
Talk to us to learn more about our data dashboards and bespoke strategy reports.
Grow research skills, confidence and careers with training built for every stage of the research lifecycle.
Developed with Nature Portfolio journal Editors and internationally renowned experts. Discover three ways to learn:
Self-paced, online courses in convenient bite-sized units, covering key skills across scientific writing, publishing, grant writing, data analysis, and more.
Expert trainer-led workshops with hands-on exercises and real-time feedback across core research skills, delivered via interactive group sessions.
Editor-led workshops combining core principles in writing and publishing, personalised 1:1 feedback from Nature Portfolio Editors and hands-on exercises.
Explore course catalogues and workshop agendas, enquire about the options or request institutional pricing.