Computational Shear Strength of Ultrahigh-Performance API Class H Cement-Silica-Fume Paste Cylinders via Direct Shear Tests

AbstractAn important type of ultra-high-performance concrete uses the hydrated mixture of the American Petroleum Institute (API) Class H cement and silica fume to produce the required binder. In this investigation a computational methodology is formulated to model the shear strength of this matrix, using the results of standard direct shear tests on ambient-hydrated samples. The procedure relies on the National Institute of Standards and Technology (NIST) Virtual Cement and Concrete Testing Laboratory (VCCTL) for the microstructure-based description of the stiffness of the assumed linear-elastic fully-hydrated brittle paste, and on subsequent finite-element analyses of the cylindrical sample. Computational iterations on the material Poisson’s ratio render the adjusted elastic properties. Convergence on the state of stress at the centroid of the critical element at fracture is attained on agreement with experimentally-complemented well-known theories of failure. The predicted inclination of the failure plane was validated by consistent experimental observations on the test samples at the U.S. Army Engineer Research and Development Center (ERDC).