Spatially-Resolved Characterization Techniques to Investigate Impact Damage in Ultra-High Performance Concretes
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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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 OPC 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 C-S-H, 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 SEM and chemical composition using Energy Dispersive X-ray microanalysis EDX. 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.
- Structural Engineering and Building Technology