Fire performance and spalling mitigation in high-strength and eps-modified mortars under transient thermal exposure

Area of Science:

• Materials Science
• Civil Engineering
• Fire Safety Engineering

Background:

• High-strength cementitious composites face explosive spalling risks at high temperatures.
• Innovative fire resilience strategies are crucial for these materials.

Purpose of the Study:

• To investigate expanded polystyrene (EPS) beads as lightweight aggregate and spalling mitigator in mortars.
• To evaluate the performance of EPS-modified mortars under rapid thermal exposure up to 600°C.

Main Methods:

• Mortars (high-strength mortar and EPS-modified mortar) were subjected to temperatures up to 600°C with short dwell times.
• Residual properties and microstructural evolution were analyzed after furnace or water cooling.
• Thermal insulation effects and spalling behavior were systematically evaluated.

Main Results:

• EPS incorporation prevented explosive spalling at 400°C by dissipating vapor pressure through induced porosity.
• Both mixtures showed strength gains at 200°C, with attenuated improvements in EPS mortar.
• At 400°C, EPS mortar strength decreased due to decomposition and increased porosity.
• EPS provided enhanced thermal insulation, reducing core temperatures.
• Catastrophic spalling occurred in EPS mortar at 600°C due to decomposition.

Conclusions:

• EPS beads are viable for spalling mitigation in moderate fire scenarios (up to 400°C).
• Careful temperature management is essential for effective EPS application in fire resilience.
• Material performance evaluation under realistic transient heating conditions is critical.