Tension/Extension Test Device for Ultra High Strength Concretes

The overall goal for this project is to develop a test system and innovative instrumentation schemes that, when combined with state-of-the-art servo-controlled electro-hydraulic test frames, will facilitate measuring the mechanical behaviors of UHPC in direct tension/extension, including its post-peak behavior. The apparatus must be capable of testing 2-inch-diameter by 4.5-inch-long UHPC specimens under confining pressures up to 200 MPa, and measuring up to 10% lateral and axial strain with a precision of 0.025%. In addition, the test apparatus is to be functional, relatively easy to use, and cost-effective. Several concepts were evaluated during Phase I, and ultimately, an innovative concept was selected for the test apparatus consisting of parallel, configurable, and servo-controlled stiffeners positioned in a new pressure vessel design. This concept rendered the test system suitable for measuring post-peak behavior of ultra-high performance concrete. In this second phase of the project our goals are to complete the design of the test apparatus concept developed in Phase I ¯including the required instrumentation and servo-control architecture¯ and ultimately fabricate a functional prototype of the test system.