Application of structural health monitoring techniques for tracing fire-induced spalling in concrete structures

Fire-induced spalling is a major concern in newer concretes with higher strengths and this is detrimental to the performance of concrete structures. One of the primary reasons for the occurrence of fire-induced spalling in concrete is the buildup of high pore pressure and associated stresses. The development of pore pressure in heated concrete is dependent on several factors including heating rate, concrete type, specimen conditions, as well as sensitivity of instrumentation used for measurements. Currently, there is no standardized guidance for measuring pore pressure variations in concrete at elevated temperatures. In addition, there is lack of instrumentation to measure pore pressure at elevated temperatures. To overcome these gaps, the presented study undertook the design and fabrication of sensors for measuring the variation of pore pressure at elevated temperatures. Using the developed sensors, an experimental study was undertaken to measure the pore pressure in heated concrete specimens. Results from the tests are utilized to show the comparative pore pressure generated in normal strength concrete (NSC) and ultra-high performance concrete (UHPC) specimens.