Abstract:
The performance of high strength concrete (HSC) under fire conditions is an established
concern in concrete industry. The kinetics and mechanisms involved in processes that affect
the fire behavior of HSC are mostly controlled by its mechanical and material properties,
thermo-mechanical interactions, and type of structural component exposed to fire. The
weaknesses of HSC in infrastructure under fire conditions preclude its applications in fire
resistance applications unless significant modifications are done either to concrete mix or the
structural design. For many years, polypropylene fibers have been used to attain a certain
amount of essential porosity in HSC under fire resistance applications. Sawdust high strength
concrete (SD-HSC) however, can provide a suitable alternative to conventional HSC under
fire conditions, especially due to its improved thermal properties in hardened state. An
experimental program was designed to study the performance of sawdust high strength
concrete at elevated temperatures in 23 to 800°C temperature range. In this study, material
and thermal properties of sawdust high strength concrete (SD-HSC) were investigated with
various content of sawdust (5, 10 and 15%) replacement as the total dry volume wt of sand
and compared with control HSC under residual fire testing condition. Mechanical tests such
as compressive and splitting tensile strength, stress-strain response, elastic moduli,
compressive toughness and spalling behaviour under a heating rate of 5°C/min were studied.
Additionally, visual inspection, mass loss and ultra-sonic pulse velocity test (UPV) was
carried out on control and sawdust modified high strength concrete specimens. Forensic
analysis was also carried out to asses to microstructure and cracking behavior of concrete
specimens. Results shows that 10SD-HSC performed better at elevated temperature with
improved residual mechanical properties compared to that of reference HSC and the spalling
mitigation at elevated temperatures. Conversely, an increase in sawdust showed a minor
degradation in the mechanical properties at ambient temperature conditions.
