마이크로 강섬유로 보강된 단위용적질량 1,500 kg/m3, 압축강도 60 MPa 수준의 경량골재 콘크리트의 인성 평가

This study determined the mixture proportions for lightweight aggregate concrete (LWAC) with a compressive strength of approximately 60 MPa and a unit weight in the range of 1,500 kg/m3. It then evaluated the improvement in compressive and flexural toughness achieved by adding 0.5 % microsteel fibers by volume to the LWAC mixtures. To meet the performance targets for LWAC, the coarse aggregate content was minimized, resulting in fine aggregate-to-total aggregate volume ratios of 70 % and 75 %, with unit water contents of 120 kg/m3 and 130 kg/m3, respectively. The compressive and flexural toughness indices of the microsteel fiber-reinforced LWAC specimens were assessed in accordance with ASTM C1018 (1997) and ASTM C1609 (2007), respectively. Residual flexural strength was estimated using the fib 2010 Model Code. The test results showed that microsteel fiber reinforcement induced a highly ductile response in high-strength LWAC beams, promoting hardening behavior in the flexural load–deflection and flexural stress–crack mouth opening displacement responses after the initial flexural crack occurred. Consequently, the microsteel fiber-reinforced LWAC specimens exhibited higher flexural toughness indices and residual flexural strengths compared to normal-strength LWAC reinforced with conventional steel fibers, despite the inherently brittle nature associated with a high strength/unit weight ratio.