Small scale tests of cement with focused ion beam and nanoindentation

Abstract

Nanoindentation is used for characterization of small scale material properties of hydrated cement. It is employed as a precise loading tool on samples fabricated with Focused Ion Beam milling (FIB). The effect of heat on the microstructure of cement during different FIB energy loads is studied. Milling currents as low as 0.1 nA can be considered as save and not damaging. Micrometer sized beams were bent to reveal strength and fracture characteristics. Small scale elastic properties, tensile strength and fracture energy of individual low scale microstructural constituents of cement paste like C-S-H rich phases and Portlandite were assessed. Very high tensile strengths at the micrometer scale were observed for cement paste hydration products (200-700 MPa) with fracture energies 4-20 J/m2 The results are consistent with atomistic simulations and multi-scale modeling from available literature.