EXPERIMENTAL TECHNIQUES FOR MULTI-SCALE CHARACTERIZATIONOF MECHANICAL RESPONSE IN CEMENT-BASED MATERIALS

摘要

Multi-scale phase-resolved computational modeling approaches are far in advance of supporting experimental methodologies for predicting the mechanical response of cement-based materials. Recently, however, a variety of techniques including low-energy x-ray diffraction, neutron diffraction and photostimulated luminescence spectroscopy (PLS) have been applied to cement-based materials demonstrating that these techniques are viable multi-scale probes for the study of micro- and meso-scale mechanics of portland cement. Stress-strain responses for applied loading were demonstrated using both x-ray and neutron diffraction by utilizing the native portlandite in neat portland cement paste as in situ strain sensors. Likewise, micrometer-scale particles of aluminum oxide (corundum) were used as strain gauges in neat cement paste to illustrate PSL response to mechanically applied loads. This technique utilizes the strain sensitive response of the luminescence spectrum of Cr~(-3) doped corundum. Individual micrometer-sized particles were shown to respond to applied loads making it possible to directly study the transference of mechanical stresses at the interface of individual grains. This suite of new tools can now be used in conjunction with modeling to further the understanding of multi-scale mechanical response and prediction of macroscopic properties and performance of cement-based systems.