Date of Completion

2-13-2013

Embargo Period

2-13-2013

Advisors

Arash E. Zaghi;Michael Accorsi

Field of Study

Civil Engineering

Degree

Master of Science

Open Access

Open Access

Abstract

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 of heating. Mixes were cast into 3 inch cylinders and steam cured for two days. Additionally, two small specimens without fibers were cast in order to run a DSC/TGA analysis. The DSC/TGA was done in order to observe the ranges during which the concrete underwent chemical changes or phase shifts. This experimentation showed that with an increase in temperature, the residual compressive strength and elastic modulus increased to a certain point. Beyond 500ºC, both mixes showed a decrease in residual mechanical properties. Chemical change and dehydration were shown to positively affect the residual mechanical properties up to 400ºC but negatively affect it at high temperatures. Increasing the rate of heating was shown to reduce residual mechanical properties and cause the onset of spalling at 300ºC.

Major Advisor

Kay Wille

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