Measurement of elastic properties of calcium silicate hydrate with atomic force microscopy

Atomic force microscopy (AFM) based indentation is compared to conventional nanoindentation for measuring mechanical properties of cement pastes. In evaluating AFM as a mechanical characterization tool, various analytical and numerical modeling approaches are compared. The disparities between the numerical self-consistent approach and analytical solutions are determined and reported. The measured elastic Young's modulus determined from AFM indentation tests are compared to elastic Young's modulus determined from nanoindentation tests of cement paste. These results indicate that the calcium silicate hydrate (C-S-H) phase of hydrated Portland cement has different properties on the different length scales probed by AFM versus nanoindenters. Packing density of C-S-H particles is proposed as an explanation for the disparity in the measured results. (C) 2011 Elsevier Ltd. All rights reserved.