A Thoroughgoing Study on Engineering Properties of High Strength Concrete at Elevated Temperatures

摘要

Using high strength concrete, instead of the conventional one, has been increasingly growing in popularity over recent years. However, the safety concerns associated with their fire performance, resulting from higher density, can call its advantages into question. As opposed to data circumscribed on compressive and tensile strength, rare are studies that have been focused on other aspects of high strength concrete, like shear strength or durability properties, in hot conditions. To conduct a thorough investigation, an experimental program embodying mechanical, durability, and microstructural aspects was performed on normal and high strength concrete in nine specific temperatures (ranging from 100 degrees C to 800 degrees C). Furthermore, a sort of relations to estimate the reduction values of mechanical properties were proposed, discussed, and compared with previous studies and standards. Although high strength concrete samples enjoyed higher capacity than normal specimens in all temperatures, their reduction rate intensified when the temperature exceeded 400 degrees C. The initial values for compressive, tensile, and shear strength of HSC, which were about 91.7, 5.6, and 9.5 MPa at room temperature, reduced to 28.4, 0.87, and 8.97 MPa at 800 degrees C, respectively. Furthermore, when temperature surpassed 400 degrees C, decay in high strength concrete microstructure manifested itself at durability (more than 90% growth in water absorption) and SEM images (increase in porosity) conspicuously.