A new approach for exploring the microstructure of low-clinker cements: The role of water mass balance

A comprehensive investigation into the microstructure of low clinker binders with cement content below 45% is fundamental for understanding the mechanisms governing their mechanical and durability performances in practical applications. This study introduces a novel water mass balance approach to characterize the complex microstructure of low clinker binders, incorporating limestone and calcined clay or natural pozzolana at varying replacement levels. The approach quantifies water content and its distribution across different hydration products and pore sizes, integrating multiple analytical techniques to provide a deep understanding of the microstructural evolution. The interlayer and gel water contents of the natural pozzolana mixtures calculated from DVS measurement reflect the solid volume of C-(A)-S-H gel phases. In contrast, calcined clay mixtures exhibit inconsistencies interlayer and gel water associated with C-(A)-S-H gel, likely due to the limited availability of saturated spaces at later ages and the inherent complexity of the calcined clay material. Despite individual uncertainties, the combined techniques yield consistent water quantification across the hydrated systems.