Factors influencing pore pressure measurements in concrete during heating and its influence on fire-induced spalling

Measuring pore pressure build-up in concrete during heating is quite challenging due to a number of adverse factors that includes lack of instrumentation, test conditions, and interdependency of factors. This paper presents an experimental program undertaken to investigate different parameters that affect pore pressure measurements. A total of 21 specimens of varying shapes and sizes were made with conventional concrete and ultra-high-performance concrete (UHPC) and were tested under varying heating rates and exposure conditions. Measured results showed that the location of highest peak of pressure inside of the specimen is dependent on the type of concrete being tested and the heating rate used. The pore pressure development in UHPC specimens is fundamentally different than conventional concretes and is highly influenced by the presence of fibers. The complexities associated in measuring the pore pressure can be overcome by adopting certain key measures in the design of future experimental programs.