Ultra-high Performance Concrete Materials Research Articles

Thermal Expansion Study and Microstructural Characterization of High-Performance Concretes

Ultra-high performance concrete (UHPC) is a family of emerging materials for building and construction applications. Behavior of UHPCs at high temperature is very important to their reliability and safety. In the current study, two UHPC materials were studied using the thermomechanical analysis (TMA) technique between room temperature and 800°C. Both reversible and irreversible phase transformations were observed from the TMA results, which were likely attributable to the α-β quartz transformation and the dehydroxylation transitions, respectively. Thermal expansion coefficients exhibited significant variations in different temperature regimes. Postmortem scanning electron microscopy (SEM) examinations revealed extensive cracking in the heated samples. In addition, microporosities were observed in the calcium-silicate-hydrate (C-S-H) phase as a result of phase changes during heating.