冻融循环作用下水泥稳定碎石抗冻特性
Freeze resistance characteristics of cement-stabilized macadam under freeze-thaw cycle

针对水泥稳定碎石（简称水稳碎石）等半刚性基层在青藏高原高海拔地区频繁冻融循环作用下，易造成材料强度与耐久性下降，影响路面整体使用性能问题。以拉萨―贡嘎机场专用公路新建工程为依托，从水稳碎石的抗冻融性能出发，采用室内试验模拟冻融循环过程，分析水稳碎石经不同次冻融循环作用后的强度损失规律，引入抗压强度耐冻系数与劈裂强度耐冻系数作为抗冻融性能评价指标，对比分析水泥用量、养生温度和冻融循环次数与水稳碎石耐冻系数的相关性；以水稳碎石耐冻系数为主参数，水泥用量、养生温度与冻融循环次数为变量，引入温度修正系数对基层养生温度影响进行修正，并对耐冻系数进行回归，建立二元线性预测模型，计算模型计算值与试验实测值的相对误差，验证模型的拟合精度。研究结果表明：水稳碎石的强度与耐冻系数随冻融循环次数的增加而降低，强度在0~5次冻融循环周期内下降较为明显；较高的水泥用量与养生温度可有效降低水稳碎石冻融后的强度损失，〖JP2〗建议工程中控制水泥用量为4%（质量分数，下同），同时保证养生温度大于10 ℃可有效提高材料抗冻融性能；所建二元线性预测模型具有较高的拟合精度和很好的再现性，可为水稳碎石抗冻融性能研究提供参考，为特殊地区半刚性基层设计施工提供技术指导。
Strength and durability of semi-rigid type bases, such as cement stabilized macadam base, will reduce under the action of frequent freeze-thaw cycle in high-altitude areas of Qinghai-Tibet Plateau, which affect the entire performance of pavement. Based on the new project of Lhasa to Gongga Airport Dedicated Road, starting from anti-freeze-thaw performance of cement-stabilized macadam under freeze-thaw cycle, this paper used indoor experiment to simulate freeze-thaw cycle and analyzed the strength loss law of cement-stabilized macadam base under different times of freeze-thaw cycle. Freeze-resistant coefficient of compressive strength and splitting strength was introduced as evaluation index to contrast and analyze the co-relationship among cement content, curing temperature, freeze-thaw cycle number and freeze-resistant coefficient of cement-stabilized macadam. Freeze-resistant coefficient was set as main parameter. Cement content, curing temperature, and freeze-thaw cycle time were set as variables. Temperature correction coefficient was introduced to revise the influence of primary curing temperature. Regression analysis was carried out on freeze-resistant coefficient and binary linear prediction model was established to calculate relative errors between calculated values and measured values, so as to verify the fitting precision. The results show that strength and freeze-resistant coefficient declines with the increase of freeze-thaw cycle number, and strength loss is more obvious when the freeze-thaw cycle number is 0 to 5. Higher cement content and curing temperature can effectively reduce the strength loss of freeze-thaw of cement-stabilized macadam, so the recommended cement content is 4% (mass fraction, the same below) and curing temperature should be kept above 10 ℃, which can effectively improve the anti-freeze-thaw properties of materials. The established binary linear prediction model has high fitting accuracy and good reproducibility, which can provide references for the anti-freeze performance research, and guide the