The missing link in the bottom-up theory of mechanical properties of calcium silicate hydrate

Calcium silicate hydrate (C-S-H) is the primary binding phase in modern concrete. While significant progress has been made in understanding the structure and behavior of C-S-H at atomistic scale and macro scale, there lacks a theory that links them. This review paper focuses on identifying the key challenges in bridging the gap between the atomic-scale characteristics of C-S-H and its larger scale mechanical behaviors. Recent experimental and simulation work on the multiscale mechanical properties of C-S-H is summarized. The need for integrating experimental observations, theoretical models, and computational simulations to establish a comprehensive and predictive bottom-up theory of the mechanical properties of C-S-H is highlighted. Such a theory will enable a deeper understanding of C-S-H behavior and pave the way for the design and optimization of cementitious materials with tailored mechanical performance.