2025/07/18 by Luca Michel, Michel, Luca, Antoine Sanner +7
Engineering · Materials Science · #Calcium Carbonate Crystallization and Inhibition #Concrete and Cement Materials Research #FOS: Physical sciences #Innovations in Concrete and Construction Materials #Soft Condensed Matter (cond-mat.soft)
paper · pdf · doi:10.48550/arxiv.2507.14029
openalex publication_date 2025/07/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The early stiffening of fresh cement paste plays a key role in shaping and stability during casting and 3D printing. In Portland cement systems, this phenomenon arises from the formation of calcium-silicate-hydrate (C-S-H), which stiffens grain-to-grain contacts. However, the role of powder characteristics such as particle size and morphology remains poorly understood. Here, we vary the fineness and grain shape by blending Portland cement with either coarse or fine limestone, leveraging the affinity of C-S-H to nucleate on limestone surfaces. By coupling calorimetry and rheometry, we relate the amount of formed hydration products to the increase in stiffness, and show that the mechanism of contact stiffening through C-S-H formation remains unchanged with limestone addition. Nevertheless, the rate of stiffening varies across blends. We find that these rates correlate with a characteristic length scale that captures particle size and shape. These results demonstrate that early stiffening depends not only on the amount of hydration products formed, but also on the geometry of the contacts where these products form, offering a framework for understanding more complex systems such as limestone-calcined clay cements.