基于振动法的抗疲劳断裂水泥稳定碎石强度标准研究

强度是水泥稳定碎石材料设计与施工质量控制重要指标。当集料类型、矿料级配和成型方式一定情况下,水泥稳定碎石强度取决于水泥剂量。强度标准越高,则水泥剂量越大,水泥稳定碎石抗荷载破坏能力越强,但抗收缩开裂能力越差；反之亦然。为此,以水泥稳定碎石基层施工期和运营期在荷载作用下不发生疲劳破坏所需材料最小强度为准则,研究了水泥稳定碎石力学强度特性、疲劳特性及施工期与运营期水泥稳定碎石基层荷载响应,提出抗疲劳断裂的水泥稳定碎石强度标准。结果表明：为防止施工车辆荷载作用下基层发生极限断裂破坏,水泥稳定石灰岩碎石基层必须养护7d后,且其劈裂强度达到0.68MPa以上,方可进行下结构层施工；为防止设计年限内基层在施工车辆和运营车辆反复作用下产生疲劳断裂,水泥稳定石灰岩碎石7d劈裂强度不小于0.70MPa。为了便于应用,结合抗压强度和劈裂强度之间关系,提出水泥稳定石灰岩碎石7d抗压强度不小于7.0MPa。

Strength Standard of Anti Fatigue-fracture Cement Stabilized Macadam Based on Vibration Testing Method

Strength is an important index for the design and construction quality control of cement stabilized macadam meterial. When aggregate type, gradation and forming method are fixed, strength of cement stabilized macadam depends on cement dosage. The higher the standard is, the higher the cement dosage needed is. And then the anti-damage ability of cement stabilized macadam will be greater, but meanwhile, the anti shrinkage cracking ability will get worse, and vice versa. The standard should be determined by the minimum strength needed to avoid the fatigue damage of cement stabilized macadam base under loading. Therefore, taking cement stabilized limestone macadam as object, researches into the mechanical strength characteristics and fatigue property, and also the load response of cement stablilized macadam base during the construction and operation period are conducted, and the cement stabilized macadam stength standard for fatigue fracture controlling is proposed. The researches show that: aiming at preventing the ultimate damage of base course caused by construction vehicle load, the construction of next structure layer should not be conducted until the curing age of cement stabilized limestone macadam is no less than 7d, and the splitting strength is no less than 0.68MPa; aiming at preventing the fatigue damage of base course under repeated load effect of the construction and operation vehicle during the designed usage, the 7d splitting strength should be no less than 0.70MPa. In order to facilitate application, considering the relationship between compressive strength and splitting strength, it is proposed that the 7d compressive strength of cement stabilized limestone macadam should be no less than 7.0 MPa.