Fire resistant materials

One of the major causes of structural repairs worldwide is the corrosion of reinforced
concrete structures, such as residential buildings and piers, which are exposed to harsh
marine environments. This investigation aims to provide experimental evidence of the
fire resistance of corroded high strength reinforced concrete. For this, 14 reinforced
concrete beams of three different concrete mix designs (different strengths) were
prepared along with concrete cylinders for compression strength testing (ASTM C39).
After proper moist curing, all beams were corroded, in two phases, with impressed
current, then “crack scored ”for corrosion evaluation, after which half were exposed to
fire, also in two phases, following the ASTM E-119-12 time-temperature curve, using a
gas kiln. The fire damage was evaluated and compared between phases by using
Ultrasonic Pulse Velocity technology. Finally, all specimens were tested for flexural strength by using the third-point loading method (ASTM C78) and the effects of fire on the corroded beams were analyzed according to the level of corrosion.

This thesis presents an experimental investigation for evaluating effects of fire exposure on properties of structural elements retrofitted by carbon fiber reinforced polymers. Mechanical properties of CFRP-strengthened reinforced concrete members, protected with secondary insulation, were investigated, before and after (residual) direct fire exposure. Direct fire contact resulted in a reduction in capacity of 9-20% for CFRP-strengthened RC beams, and 15-34% for CFRP-strengthened RC columns. Furthermore, a dimensional analysis was developed for a heat transfer relationship between full and small-scale specimens, allowing a ¼ exposure time reduction for the latter. Results from experimental investigations demonstrate benefits of employing secondary fire protection to CFRP-strengthened structures, in spite of the glass transition temperature being exceeded in the early stages of the elevated-temperature exposure. Therefore, it is suggested, that fire protection is necessary for a CFRP-strengthened structural member to retain integrity throughout the duration of the fire exposure, and upon return to ambient temperature.