Engineering Commons^™

Material Characterization Of Ultra-High Performance Fiber Reinforced Concrete At Elevated Temperatures, Richard T. Way

Master's Theses

With the recent development of Ultra High Performance Fiber Reinforced Concrete (UHPFRC), there has been limited investigation into the mechanical and material properties of this composite at elevated temperatures. At elevated temperatures concrete is shown to undergo several material changes which affect the residual mechanical properties. Additionally, fast heating rates are known to cause a phenomenon called explosive spalling. This research investigates the effect of high temperature on the residual mechanical properties and chemical degradation of two types of UHPFRC. This was accomplished by casting and testing two different UHPFRC mixes and exposing them to elevated temperatures at two rates …

Determing The Effect Of Thermal Treatment Timing On Ultra-High Performance Concrete Beams, Christopher H. Mullen

Dissertations, Master's Theses and Master's Reports - Open

The loss of prestressing force over time influences the long-term deflection of the prestressed concrete element. Prestress losses are inherently complex due to the interaction of concrete creep, concrete shrinkage, and steel relaxation. Implementing advanced materials such as ultra-high performance concrete (UHPC) further complicates the estimation of prestress losses because of the changes in material models dependent on curing regime.

Past research shows compressive creep is "locked in" when UHPC cylinders are subjected to thermal treatment before being loaded in compression. However, the current precasting manufacturing process would typically load the element (through prestressing strand release from the prestressing bed) …

Preliminary Investigation Of Ultra-High Performance Concrete Behavior At High Strain Rates Using The Split-Hopkinson Pressure Bar, Jacob Clark

Dissertations, Master's Theses and Master's Reports - Open

Ultra-high performance concrete (UHPC) displays several enhanced material properties compared to normal strength concrete (NSC). In past research, Split-Hopkinson pressure bar (SHPB) tests have been used for normal strength concrete to determine material behavior at high strain rates. The behavior of advanced concrete materials, such as UHPC, under high strain rates has not been thoroughly investigated. While it is generally accepted that concrete materials experience increases in compressive strength under increasing strain rates, a preliminary investigation was conducted to gain insight into the compressive behavior of UHPC under high strain rate SHPB testing.

In this research, 50 specimens were tested …