Investigation of the behaviour of high strength silica fume composite concrete at elevated temperature

The major component of the construction Industry is ‘Concrete’, the most durable and versatile material. Concrete these days is the undisputed leader in terms of construction material and consumes the second most substance, water being the first. Concerning tangibility and cohesiveness, concrete certainly would be the material that would continue binding bricks and clinks. Thus, in the process of modifying different properties of concrete, its behavioural study, many experiments are carried out replacing different percentages of cementitious material having pozzolanic activity characteristics, one such is silica fume. Furthermore, due to high strength and durability, High-strength concrete (HSC) is widely used in modern construction. In this research, silica fume was used for the partial replacement of cement content in order to densify the concrete matrix and improve its strength properties. Silica fume, a highly reactive SiO2-rich pozzolan, decreases permeability, porosity and bleeding through the pozzolan reaction with the calcium hydroxide formed during the hydration of ordinary Portland cement (OPC). Thus, adding sustainability by decreasing the natural resource consumption. In addition, BS EN 197-1 introduced a larger variety of cement constituents, which facilitated the research on Silica fume composite high-strength concrete made from CEMII/A-D cement.

Moreover, cracking and spalling of concrete subjected to fire reduce its load-carrying capacity and reparability. This study would explore high-strength silica fume composite concrete behaviour, with and without steel fibres, at elevated temperatures of 400 to 600 °C, with a sustained duration of 3 and 5 hours. In comparison to plain concrete, the addition of steel fibres enhanced residual strength, thermal resistance, crack control and spalling resistance. Mechanical tests, life cycle assessment and microstructure analysis by SEM were combined in the study to assess chemical composition, interphase behaviour and change in morphology of the HSC. CEM II/A-D high strength-composites enhances sustainability and performance, while steel fibres have a significant contribution to improving fire resistance. The Life Cycle Analysis (LCA) has contributed further, paving the way toward lower embodied carbon and more resilient concrete in sustainable construction.