Enhancing fire resistance of lightweight high-performance cementitious composites using hollow microspheres

Fire is detrimental to skyscrapers. Lightweight high-performance concrete (L-HPC) developed by combining lightweight microspheres and ultra-high-performance concrete binder is promising for future mega infrastructure projects. This study investigates the fire resistance of lightweight high-performance cementitious composites developed using hollow ceramic microspheres (HCMs) and hollow glass microspheres (HGMs) at different temperatures. Experimental results show that incorporating lightweight microspheres significantly increases the residual compressive strength of L-HPC by maintaining those of HGMs and HCMs groups at 92 % and 78 %, respectively, at 900 °C. Furthermore, these lightweight microspheres effectively mitigate thermal spalling and crack propagation in L-HPC. Microstructural analysis indicates that the lightweight microspheres facilitate steam-pressure release. The melting of HGMs realizes interconnections in the pore channel, which are subsequently strengthened by HGM and matrix-binder reactions. The HCMs feature perforated shells that provide inert and high-temperature-resistant steam channels. This study confirms that L-HPC developed using the abovementioned strategy exhibits excellent fire resistance.