多孔性基层混合料抗冻融耐久性试验方法

水泥稳定粒料等多孔性基层混合料在多年冻土等冻融循环频繁剧烈的地区应用时,设计中应重视抗冻融耐久性的试验评价,但目前尚无统一的试验方法。以多年冻土地区广泛使用的水泥稳定砂砾基层混合料为对象,通过控制试件湿度,模拟基层实际使用中的最不利湿度状况下的冻融循环试验,分析了冻融循环次数和试件湿度状况对基层混合料耐冻系数的影响。研究得出:模拟混合料使用最不利湿度状况进行冻融试验时,水泥稳定砂砾的耐冻系数随冻融循环次数的增加而不断减小,约8次循环后基本处于稳定状态;湿度对多孔性基层混合料的抗冻融耐久性评价结果有明显影响,不宜直接采用水泥混凝土的饱水冻融试验方法。结果表明:对于多孔性基层混合料的抗冻融耐久性评价,采用控制试件湿度模拟基层的最不利湿度状况进行冻融试验,以10次冻融循环时弯拉强度损失表示的耐冻系数作为评价指标,评价结果稳定,更符合实际使用情况。

Test Method for Durability of Frost Thaw Resistance of Porous Base Mixture

While the porous base mixture,such as the cement stabilized granular,is applied to the special area where the frost-thaw cycle is frequent and violent,for example the permafrost area,the frost resistance testing evaluation should be regarded during the design period.But there is still not have a uniform testing method to evaluate the frost resistance of the porous base mixture. By the frost-thaw cycle testing controlling the sample moisture to simulate the worst humidity condition of the base course during the actual employ process,the influences of the frost-thaw cycle times and the sample humidity on the frost resistance index of the base mixture are analyzed.It is pointed that the frost resistance index of the cement stabilized gravel gradually decreased with the cycle times increased,and primarily reached the steady state after about eight cycles in the process of the frost-thaw test simulating the worst humidity during the base mixture applying.The humidity evidently affects the evaluating results of the frost resistance of the porous base mixture,and the frost-thaw test while the sample is full-water is not feasible to directly using to evaluate.The results indicate that the frost-thaw testing method,controlling the sample moisture to simulate the worst humidity of the base mixture during the actual employ process,taking the frost resistance index of the tenth cycle which expressed by the flexural strength as the evaluating index,can well evaluate the frost resistance of the porous base mixture.The evaluating results are steady and more accord with the fact.