Multiscale Mechanical Behavior of Calcium Silicate Hydrates: Insights from Experiments and Coarse-Grained Computation.

Probing the mechanical mechanisms of aggregating nanograins is the key to advancing nanostructural material science; however, it is a great challenge due to the complex molecular behaviors and packing texture, spanning from the molecular scale to hundreds of nanometers. In this paper, we investigate the strength origin of aggregating cementitious nanograins, C-S-H gel. A statistical indentation analysis technique on decalcified hardened cement paste is conducted to decode the mechanical information on C-S-H molecules and their effective interactions. Then, these molecular-level attributes serve as parameter references for the coarse-grained computation of the tensile properties of the aggregating C-S-H grain cluster. The results unveil the nanoscale behaviors, including the packing configuration, stress-strain relation, stress spatial distribution, and fracture of the C-S-H cluster, and provide insight into the manner and extent to which molecular interactions and packing configuration impact the mechanical behaviors of the C-S-H gel. Load transfer mechanisms of the single/multi-interface and pores/cracks effect underlie the huge mechanical disparities between the multiscale.