冻融循环作用下泡沫和乳化沥青冷再生混合料损伤特性与细观机理

Damage Characteristics and Microscopic Mechanism of Foamed and Emulsified Asphalt Cold Recycled Mixture under Freeze-Thaw Cycles

为了揭示冻融循环作用下泡沫沥青和乳化沥青冷再生混合料的疲劳损伤规律,基于劈裂强试验、无侧限抗压强度试验、贯入剪切试验研究冻融循环作用对泡沫/乳化沥青冷再生混合料力学性能的劣化影响,以工业电子计算机断层扫描(computed tomography,CT)无损检测技术为研究平台,研究冻融循环作用对泡沫/乳化沥青冷再生混合料微细观空隙级配、空隙直径的影响规律。结果表明,冻融循环作用显著降低了泡沫/乳化沥青冷再生混合料的力学性能,总体上,泡沫沥青与乳化沥青冷再生混合料表现出了基本相同的力学性能,乳化沥青比泡沫沥青冷再生混合料有更好的抗损害性能。随着冻融循环次数增加,泡沫/乳化沥青冷再生混合料的平均空隙直径和最大空隙直径增大,大空隙数目增加,小空隙比例和空隙数目减小,随着平均空隙直径增大,泡沫/乳化沥青冷再生混合料劈裂强度、贯入剪切强度均呈指数函数关系减小。可见冻融循环作用下,泡沫/乳化沥青冷再生混合料内部微空隙数目减少、平均空隙直径增大是其力学性能衰减的主要原因之一。

In order to reveal the law of fatigue damage caused by freeze-thaw cycles on foamed asphalt and emulsified asphalt cold recycled mixtures,unconfined compressive strength test,and penetration shear test were used to study the effects of freeze-thaw cycles on the deterioration of the mechanical properties of foamed(emulsified)asphalt cold recycled mixtures.Using industrial computed tomography(CT)non-destructive testing technology as a research platform,the influence law of freeze-thaw cycles on the microscopic void levels of foamed(emulsified)asphalt cold recycled mixtures were studied.The results show that the freeze-thaw cycle significantly reduces the mechanical properties of the foamed(emulsified)asphalt cold recycled mixture.In general,the foamed asphalt and the emulsified asphalt cold recycled mixture exhibit basically the same mechanical properties.The emulsified asphalt is colder than the foamed asphalt.Recycled mixture has better resistance to damage.As the number of freeze-thaw cycles increases,the average void diameter and maximum void diameter of the foamed(emulsified)asphalt cold recycled mixture increase,the number of large voids increases,and the proportion of small voids and the number of voids decrease.As the average void diameter increases,the splitting strength and penetration shear strength of foamed(emulsified)asphalt cold recycled mixture decrease exponentially.Under the action of freeze-thaw cycles,the decrease in the number of microvoids in the foamed(emulsified)asphalt cold recycled mixture and the increase in the average void diameter are one of the main reasons for the degradation of its mechanical properties.