Nanomechanical Properties of Individual Phases in Cement Mortar Analyzed Using Nanoindentation Coupled with Scanning Electron Microscopy

A commonly used hardened cement mortar was analyzed via the grid-nanoindentation coupled with scanning electron microscope image analysis. In the microscopic scale, the elastic modulus of sand, unhydrated cement particles and portlandite are 105.55, 107.06 GP and 60.88 GPa, respectively. The co-existence of low density hydration products and high density hydration products was found, and their calculated elastic moduli were 18.42 GPa and 32.53 GPa, respectively. The results show that the testing value of unhydrated cement particle is similar to the published value, while the testing value of portlandite is much higher than the published value. The results also reveal that the statistical values of hydration products are in accord with the published values, however, the existence of ultra-high density hydration products is still an assumption.