Abstract

From the early 1980’s, the New Austrian Tunneling Method(NATM) has been developed as one of the standard tunneling methods in Korea. Approximately 10 years ago, wet-mix shotcrete with sodium silicate (waterglass) accelerator was introduced and widely used to tunnel lining and underground support. However, this accelator had quality of the hardened shotcrete. In order to compensate for these disadvantages, recently developed alkali-free accelerator has been successfully demonstrated in numerous projects and applications as a new material to make tunnels more durable and safer. An experimental investigation was carried out in order to verify the strength behavior of wet-mix Steel Fiber Reinforced Shotcrete(SFRS) with alkali-free accelerator. Compressive strength, flexural strength, and flexural toughness were measured by testing specimens extracted from the shotcrete panels. From the results, wet-mix SFRS with alkali-free accelerator exhibited excellent strength improvement compared to the conventional shotcrete accelerator.