Mechanical Properties and Freezing and Thawing Durability of Polypropylene Fiber-Reinforced Shotcrete Incorporating Silica Fume and High Volumes of Fly Ash

摘要

This paper describes the materials used, mixtureproportions, mixing and shotcreting operation, and properties ofthe fresh and hardened polypropylene fiber-reinforced shotcreteincorporating silica fume and high volumes of fly ash. Thepolypropylene fiber-reinforced high-volume fly ash shotcreteproduced had satisfactory workability, mechanical properties, andresistance to freezing and thawing cycling. The shotcretecontaining silica fume had negligible rebound compared with thatwithout silica fume. The incorporation of fly ash and silica fumeimproved the workability of the fresh shotcrete, and this resulted inlower operating pressure for the shotcreting. The sue ofpolypropylene fibers up to 0.5% by the volume of the shotcrete didnot affect significantly the compressive strength, and the shotcreteincorporating both fly ash and silica fume bonded well to the baseconcrete. The fiber-reinforced shotcrete showed satisfactoryperformance after 300 cycles of freezing and thawing with adurability factor >80 even though the air contents were relativelylow, and the spacing factor L was relatively high.