Polyamide Fiber Reinforced Shotcrete for Tunnel Application

Area of Science:

• Civil Engineering
• Materials Science

Background:

• Shotcrete is a crucial construction material, but its mechanical properties can be enhanced.
• Polyamide fibers offer potential for improving shotcrete performance.

Purpose of the Study:

• To determine the mechanical properties (compressive and flexural strengths) of polyamide fiber reinforced shotcrete (PAFRS).
• To evaluate the influence of polyamide fiber content on PAFRS strength and toughness.
• To assess PAFRS performance in tunneling applications, including fiber rebound and constructability.

Main Methods:

• Mechanical properties tested according to ASTM C1609/C1609M-12.
• Toughness evaluated with proposed criteria for organic fibers.
• Fiber rebounding rate and tunneling application performance assessed.

Main Results:

• PAFRS with 0.6%–0.8% fiber content significantly improved flexural ductility, toughness, and ultimate load capacity.
• Fiber rebounding rate was low (8.5%) with minimal fiber drop (63.5%).
• Demonstrated stability and constructability in a Korean tunnel application.

Conclusions:

• Polyamide fiber reinforcement enhances shotcrete's mechanical performance.
• Specific fiber content optimizes ductility and load-bearing capacity for tunneling.
• PAFRS is a stable and constructible material for underground applications.