Influence of Moisture Content and Loading Rate on Flexural Toughness of Fiber Reinforced Shotcrete Remarked

Abstract

Influences of moisture content and loading rate on flexural toughness were experimentally studied for fiber reinforced shotcrete (FRSC) with steel fiber or macro synthetic polypropylene fiber. According to the four-point bending test method specified in ASTM C1609 and Chinese standard CECS 13, the flexural toughness of specimens after drying for 0h, 16h, 24h and 72h in condition of (20±2)°C and (60±5)% relative humidity was tested at a loading rate of 0.05 mm/min. For specimens after drying for 24h and 72h, flexural toughness was tested at loading rates of 0.05 mm/min, 0.10 mm/min, and 0.20 mm/min respectively. With the moisture content decreasing, the flexural toughness T100,2.0, first-peak flexural strength, and residual flexural strength at prescribed deflections of FRSC exhibited decreasing tendency. The specimens with 0.5 vol% of steel fiber showed higher T100,2.0 value than that with 0.9 vol% of macro synthetic fiber. The residual strength and flexural toughness of FRSC increased with the increase of loading rate.