Hi, I was invited by ACS Langmuir to contribute a Perspective article discussing future directions in research on calcium silicate hydrate (C–S–H). Understanding the behavior of C–S–H is essential for elucidating the mechanisms governing various physical properties of cementitious materials. Moreover, when re-utilizing industrial by-products that supply SiO₂ and Al₂O₃—such as supplementary cementitious materials (SCMs)—a fundamental understanding of the formation mechanisms of C–(A–)S–H is also required.

In this paper, I particularly emphasized that the pore structure of synthetic C–S–H often differs significantly from that of C–S–H formed in real cement systems, and that even among synthetic samples, the pore structure varies depending on the synthesis route. Therefore, the appropriate form of C–S–H must be selected according to the research objective, and it is not appropriate to combine data sets obtained from different researchers when validating numerical simulations.

From this standpoint, the article highlights the importance of understanding:the formation of C–S–H aggregation structures from the atomic scale, stress-transfer mechanisms between aggregated domains, and how changes in these structures under drying or elevated temperature lead to macroscopic variations in material properties.

Thanks to decades of dedicated research since J. D. Bernal’s pioneering project about seventy years ago, our understanding of C–S–H has greatly advanced. Nevertheless, a comprehensive picture has yet to be achieved. While research devoted solely to C–S–H may be challenging to fund today, I have attempted to outline numerous promising research topics that can be developed within the broader context of cement-based materials science.

The article is Open Access, and I would be delighted if you could take a moment to read it.


I. Maruyama, Formation mechanism and resulting physical properties of colloidal calcium silicate hydrates, Langmuir (2025).