This study aims to evaluate and compare the mechanical and interfacial performance of self-compacting concrete (SCC) and vibrated concrete (VC) after exposure to elevated temperatures. Particular emphasis is placed on bond behaviour with high-ductility SD reinforcing bars, an area that remains insufficiently explored for SCC under fire-like conditions.
SCC and VC mixes were designed for a target 28-day compressive strength of approximately 45 MPa and exposed to temperatures ranging from 200°C to 800°C. Experimental investigations included compressive strength, split tensile strength, flexural strength, modulus of elasticity and pull-out bond tests using 12 mm diameter SD bars. Bond–slip behaviour and residual mechanical properties were systematically evaluated to assess thermal degradation trends.
Results show that SCC exhibits superior retention of mechanical properties and ductility up to 400°C, attributed to its dense microstructure and improved interfacial transition zone. At 800°C, SCC retained approximately 20–25% of its compressive strength, compared to 15–20% for VC. However, VC demonstrated marginally better bond resilience at higher temperatures (500–800°C), retaining about 9% residual bond strength compared to 7% for SCC, due to its more porous structure facilitating vapour pressure dissipation.
This study provides a direct experimental comparison of the thermal bond and mechanical performance of SCC and VC reinforced with high-ductility SD bars. The findings offer valuable guidance for material selection in fire-resistant structural applications such as tunnels and high-rise buildings.
