Enhancing fire resistance of masonry structures: The potential of ultra-high performance concrete (UHPC)

The potential of ultra high performance concrete (UHPC) for strengthening masonry structures is evaluated in this work, both under normal service conditions and after exposure to high temperatures, as a significant gap has been identified on this topic at the present time. The mechanical properties of UHPC exposed up to 800 ◦C are analyzed by means of destructive and non-destructive tests, and the UHPC-to-masonry bond capacity is tested, depending on temperature and substrate preparation. The strengthening of masonry columns by confinement is studied, proving that UHPC jackets can double the compressive strength and provide ductility, even after exposure to high temperatures. Strengthening of masonry walls to in-plane loads is also evaluated, finding that UHPC layers can increase the shear strength and prevent brittle failures. Experimental results are compared with the predictions of theoretical models from some design guides, slightly adapted to the context of this research, obtaining a good degree of accuracy.