Characterizing Strength and Failure of Calcium Silicate Hydrate Aggregates in Cement Paste under Micropillar Compression

A new methodology is proposed for investigating compressive failure behavior of cement paste at the micrometer scale. Micropillar geometries are fabricated by focused ion-beam milling on potential calcium-silicate-hydrate (C-S-H) locations identified through energy dispersive spectroscopy (EDS) spot analysis. Uniaxial compression testing of these pillars is performed using nanoindentation equipment. The compressive strength of C-S-H aggregates (225-606 MPa) measured from microcompression tests is found to be consistent with values from multiscale damage and molecular dynamic models. From posttest images, two primary deformation mechanisms at failure were identified; axial splitting and plastic collapse of the entire sample were observed. (C) 2017 American Society of Civil Engineers.