Carbon fiber to improve the resistance of high strength PVA-ECC to elevated temperatures

Engineered cementitious composite (ECC) with polyvinyl alcohol (PVA) fiber shows great potential in buildings and infrastructure constructions due to its characteristics of strain-hardening and multiple-cracking. However, its fire resistance shall be paid with great attention since the fibers would melt and components are prone to spall under elevated temperatures, especially for cement-based materials with high strength. Present study focuses on the fire resistance improvement of high strength ECC (HSECC) by adopting carbon fiber with higher thermal performance. Behaviors were qualitatively compared in the aspects of visual observation, surface cracking and spalling in HSECC with and without carbon fiber. Mass loss, residual strength and brittleness of all groups are quantitatively analyzed. Results show that carbon fiber enhances high temperature-exposed residual strength of HSECC and shows hysteresis effect on the decomposition of calcium hydroxide (CH) and calcium carbonate. The bridging and take-over effect of carbon fiber contributes to microcrack inhibition at elevated temperatures observed from surface cracking and micro-morphologies. HSECC with higher carbon fiber content shows greater resistance to high temperatures.