High temperature mechanical and material properties of burnt masonry bricks

Recently, there have been an increased research in fire performance of both normal strength concrete (NSC) and high strength concrete (HSC) for structural members in buildings and built infrastructure. On the contrary, burnt masonry bricks (BBs) are used in structures due to advantages these provide, however, the studies on fire performance of BBs as a structural material are scarce. Further, limited studies are available on comparative fire performance studies of BBs to that of NSC or HSC. A test program was designed to undertake high temperature tests on BBs commonly used in buildings and domestic constructions. Mechanical properties namely compressive strength, tensile strength, and elastic modulus were investigated at elevated temperatures (hot state) from 20 to 800 °C following ASTM and RILEM test procedures. Results show that BBs lose compressive strength similarly to that of NSC and HSC. The measured tensile strength of BBs is quite low as compared to compressive strength, with a slight gain around 200 °C. High temperature properties also exhibit significant change in stress–strain response with increasing temperatures. Scanning electron microscope and X-ray fluorescence analysis revealed that microstructural and mineral transformations occur in BBs at elevated temperatures. To provide high temperature material properties of BBs for analytical studies, data generated from mechanical property tests were applied to develop simplified mathematical expressions as a function of temperature.