THE DYNAMIC MATERIAL RESPONSE OF CSA CEMENT USING A SPLIT HOPKINSON BAR

The University of Kentucky Center for Applied Energy Research (CAER) Cementitious Materials Group is developing a pourable Calcium Sulphoaluminate (CSA) cement-based concrete for rapid repair applications. Due to dynamic events like vehicle strikes, ballistic events, or other dynamic loading events, the dynamic material characteristics are important for understanding how the material will respond. A large diameter Split Hopkinson Pressure Bar (SHPB) was used to test samples of the pourable CSA cement and determine its dynamic material properties in the early strength development phase. 24 samples were tested in 7 day intervals for 28 days. Samples were prepared targeting a length to diameter ratio (L/D) of 0.5. The data acquired from these tests was then used to create stress-strain curves as well as charts depicting failure stress across the testing period. The samples were collected from a flat panel of poured concrete that was cured in ambient conditions. Samples were found to have a lower strength in compression when dynamically loaded compared to quasi-static loading. The samples also continued to decrease in strength when compared to the quasi-static strengths as they aged, starting out at roughly 10 MPa, weaker on day 7, and finishing at almost 15 MPa weaker on day 28. The material also showed that as the strain rate increased, material strength decreased. Further testing is required to determine if this is due to the ambient curing conditions or an actual material characteristic.