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This paper presents an experimental investigation for evaluating the effects of fire exposure on properties of structural elements retrofitted by carbon fiber–reinforced polymers (CFRPs). Mechanical properties of CFRP-strengthened reinforced concrete (RC) 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% to 20% for CFRP-strengthened RC beams and 15% to 34% for CFRP-strengthened RC columns. Furthermore, a similitude analysis was developed for a heat transfer relationship between full-scale and small-scale specimens, allowing a one-fourth exposure time reduction for the latter. Results from the experimental investigations demonstrated the benefits of employing secondary fire protection to CFRP-strengthened structures, despite 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 structure to retain integrity throughout the duration of the fire exposure and on return to ambient temperature. The conclusions of this investigation will lead to recommendations and guidelines to designers and practicing engineers for using CFRP materials in retrofitting RC structures with adequate fire resistance by contributing to the missing information for fire protection requirements not available in codes of practice.

Long term durability of recycled materials continues to be a major concern for their wide-scale use in civil engineering construction. The purpose of this study is to provide an insight into the damaging effects of combined wet-dry cycles, and repeated mechanical loading in a roller-compacted concrete pavement base course, made from recycled crushed aggregate (80 % by weight) and cement. This laboratory-based investigation was divided into three phases, each consisting of specimens subjected to prior wetdry cycles (WD specimens), and control specimens which were not exposed to wet-dry cycles (NWD specimens). Phase I experiments involved monotonic loading tests, under compression and flexure, to evaluate the strength properties. Phase II involved testing cylindrical specimens in cyclic compressive (fatigue) loading at three different stress ratios. After each regime of cyclic loading, residual compressive strengths were determined. In addition, the loaddeformation hysteresis loops, and the accumulated plastic deformation, were continuously monitored through all loading cycles. Phase III included an evaluation of flexural fatigue behavior and fatigue endurance limit of beam specimens. It was found that the specimens subjected to wet-dry cycles suffered significantly higher damage characterized by permanent deformation, residual compressive and flexural strengths, and fatigue resistance, compared to specimens not exposed to wet-dry cycles. These findings should be important design considerations when recycled products are incorporated in the pavement structure as promising alternative materials for achieving sustainable growth, environmental benefits, and possible economic savings.