Fire Resistance of High-Volume Fly Ash RC Slab Inclusion with Nano-Silica

Area of Science:

• Materials Science
• Civil Engineering
• Fire Safety Engineering

Background:

• Reinforced concrete (RC) structures require robust fire performance evaluation.
• Incorporating supplementary cementitious materials like fly ash and nano-silica can enhance concrete properties.
• Understanding the behavior of novel concrete composites under extreme thermal loads is crucial for structural safety.

Purpose of the Study:

• To investigate the fire resistance of reinforced concrete slabs made with high volume fly ash and nano-silica (HVFANS).
• To evaluate the structural integrity and thermal response of HVFANS concrete slabs under ISO 834 standard fire conditions.
• To determine key performance indicators including residual strength, temperature distribution, spalling, and thermal conductivity.

Main Methods:

• A 1850 mm × 1700 mm × 200 mm HVFANS concrete slab was subjected to a 1100 °C fire for 120 minutes in an electrical furnace.
• The slab was tested under the ISO 834 standard load curve.
• Performance was assessed by measuring residual compressive strength, internal temperature profiles, spalling depth, crack patterns, and determining thermal conductivity.

Main Results:

• The HVFANS concrete slab retained 62.19% of its original compressive strength after the fire exposure.
• Temperatures at the concrete cover and bottom reinforcement remained below 300 °C.
• Maximum spalling depth was observed to be 11 mm, occurring between 680 °C and 840 °C.
• The determined thermal conductivity of HVFANS concrete was 0.35 W/mK, indicating low thermal conductivity.

Conclusions:

• HVFANS concrete exhibits significant fire resistance, maintaining structural capacity under severe fire conditions.
• The material's low thermal conductivity contributes to reduced heat transfer, protecting internal reinforcement.
• This study validates the potential of HVFANS concrete as a high-performance material for fire-resistant structural applications.