Optical characterization of high temperature deformation in novel structural materials
The traditional fire resistant reinforced concrete assembly is changing. Sustainability and durability objectives are introducing novel structural materials to these assemblies. These novel materials include non-conventional reinforcement (glass fiber reinforced polymers - GFRP, high strength steel - HSS, etc.) and complex concrete mixtures (concrete with recycled aggregates - RA, etc.). Characterizing the high temperature properties of these novel structural components, including their deformation response, becomes essential to explain and model the behavior of contemporary reinforced concrete assemblies under fire exposure. The deformation of structural materials at high temperature can be characterized by uniaxial mechanical testing using a loading actuator equipped with a controllable heating furnace. Contact instruments to measure deformation can be expensive and are easily damaged upon material failure. Practice is to remove this instrumentation prior to material failure, at the expense of valuable data. Recently a non-contact optical measurement technique, also known as digital image correlation, has been proposed for high temperature deformation material testing. The technique herein utilizes a loading actuator onto which a furnace with a specimen viewing window is attached. A hi-resolution camera system measures deformation through the viewing window. Herein, this optical measurement technique is used and assessed in an attempt to characterize the high temperature deformation behavior of three different novel structural materials: concrete with RA, HSS and GFRP. Although RA and HSS could be characterized using this measurement technique, difficulty was encountered with GFRP. GFRP underwent partial degradation through pyrolysis and decomposition of its polymer matrix which affected its surface appearance thereby complicating deformation measurement using optical technology. Critical discussion of the aforementioned optical measurement technique is provided throughout where both advantages and limitations are considered.
Gales, J, & Green, M. (Mark). (2015). Optical characterization of high temperature deformation in novel structural materials.