The influence of metakaolin-to-vaterite ratio on the properties of vaterite-calcined clay cement: fresh mortar rheology, microstructure, and mechanical performance
This study investigates the influence of the metakaolin-to-vaterite (MK/V) ratio on the fresh properties, mechanical performance, and microstructural development of vateritecalcined clay cement (VC3) mortars. Eight mixtures were produced with MK/V ratios between 1.0 and 3.0, alongside a limestone-ca...
| Autores: | , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | Dadun. Depósito Académico Digital de la Universidad de Navarra |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:dadun_______::58ea9c935bdebae17e9bfc9a7afc2666 |
| Acceso en línea: | https://hdl.handle.net/10171/124689 |
| Access Level: | acceso abierto |
| Palabra clave: | Metakaolin-to-vaterite Vaterite-calcined clay cement Limestone-calcined clay |
| Sumario: | This study investigates the influence of the metakaolin-to-vaterite (MK/V) ratio on the fresh properties, mechanical performance, and microstructural development of vateritecalcined clay cement (VC3) mortars. Eight mixtures were produced with MK/V ratios between 1.0 and 3.0, alongside a limestone-calcined clay cement (LC3) reference. Fresh- and hardened-state behaviors were assessed using flow-table testing, rheological characterization, setting-time measurements, isothermal calorimetry, compressive strength testing, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. Replacing calcite with vaterite enhanced flowability and reduced both static and dynamic yield stresses due to the spherical morphology of vaterite. Increasing metakaolin content, however, progressively elevated yield stresses and thixotropy. Vaterite addition slightly prolonged setting time relative to LC3 due to ion sequestration effects, although higher MK/V ratios accelerated hydration and offset this delay. Earlyage compressive strengths were comparable to LC3, while all VC3 mixtures exceeded LC3 performance after 7 days. Strength increased with MK/V ratio up to an optimum range of 2.0-2.5, where a maximum improvement of 42% at 91 days was recorded. Thermogravimetric and XRD analyses showed efficient portlandite consumption and the formation of a multiphase assemblage dominated by C-(A)-S-H and AFm-type carboaluminate phases. SEM-EDS confirmed the development of a dense, chemically complex matrix underpinning the superior strength performance. Overall, the MK/V ratio was found to regulate the interplay between rheology, hydration, and microstructure, identifying 2.0-2.5 as the optimal range for balanced performance. Given vaterite’s capacity for CO2 capture and potential carbon-negative synthesis routes, ternary samples including metakaolin emerge as a technically robust and environmentally beneficial alternative for next-generation low-clinker cements. |
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