Characterization of Impact Damage in Ultra-High Performance Concrete Using Spatially Correlated Nanoindentation/SEM/EDX
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Little work has been done to study the fundamental material behaviors and failure mechanisms of cement-based materials including ordinary Portland cement concrete and ultra-high performance concretes (UHPCs) under high strain impact and penetration loads at lower length scales. These high strain rate loadings have many possible effects on UHPCs at the microscale and nanoscale, including alterations in the hydration state and bonding present in phases such as calcium silicate hydrate, in addition to fracture and debonding. In this work, the possible chemical and physical changes in UHPCs subjected to high strain rate impact and penetration loads were investigated using a novel technique wherein nanoindentation measurements were spatially correlated with images using scanning electron microscopy and chemical composition using energy dispersive x-ray microanalysis. Results indicate that impact degrades both the elastic modulus and indentation hardness of UHPCs, and in particular hydrated phases, with damage likely occurring due to microfracturing and debonding.
Keywordscharacterization EDX elastic moduli high performance concrete nanoindentation SEM ultra-high performance concrete
The authors would like to thank Dr. Todd Rushing of the Geotechnical and Structures Laboratory, US Army Engineer Research and Development Center (ERDC), for supplying the specimens for this study. Financial support for this work was provided by the ERDC and the U.S. Department of Defense SMART Scholarship Program. Permission to publish was granted by the Director, ERDC Geotechnical and Structures Laboratory.
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