界面过渡区微力学性质对高周疲劳性能的影响

为了解界面过渡区性质对混凝土高周疲劳性能的影响,采用纳米压痕技术测试了矿渣取代水泥的质量分数分别为0%、30%、50%、80%的混凝土中实际界面过渡区及邻近区域的压痕硬度分布,并测试相应配合比混凝土在不同应力水平下的抗弯疲劳寿命.试验结果显示:随矿渣取代水泥质量分数的增加,基体与界面过渡区之间压痕硬度的差异减少;当应力水平低于0.85时,混凝土的疲劳寿命对数值随基体压痕硬度与界面过渡区压痕硬度的比值的降低而增大;基体与界面过渡区间压痕硬度差异的减少,相对提高界面过渡区抑制疲劳损伤的能力,从而改善混凝土高周疲劳性能.

Effects of Micro-mechanics Property of Interface Transition Zone on High-cycle Fatigue Behavior of Concrete

To understand effects of the mechanical property of interface transition zone on concrete high-cycle fatigue behavior,the microhardness of interface transition zone and neighboring zone of concrete with 0%,30%,50%,80% cement replaced by blast furnace slag was tested by nano-indentation, the fatigue life at different stress levels of concrete with different blast furnace slag content were also tested under flexural fatigue load.Results show that the ratio of hardness of matrix to that of interface transition zone decreases with the increase of cement replacement level by blast furnace slag;when stress level is lower than 0.85,fatigue life of concrete increases as this ratio decreases.The reduced difference on hardness between interface transition zone and matrix means the higher ability of interface transition zone to resist the evolution of fatigue damage in this zone,and this can account for the relationship between high cycle fatigue behavior and property of interface transition zone.