This paper focuses on investigating the fatigue properties of cold-recycled emulsified asphalt mixtures (CEAMs) designed via two different compaction methods. First, two different CEAM compaction procedures were investigated and evaluated, including the modified Marshall compaction method (MMCM) and the vertical vibration testing method (VVTM). Indirect tensile fatigue tests were then performed to research the fatigue lives of CEAMs fabricated via the two methods. Finally, a Weibull distribution was applied to analyze the fatigue test results, and the fatigue equation was constructed. The results indicated that the average mechanical strength ratio between the CEAM samples produced by VVTM and the field core samples was >92%, whereas the average ratio of the specimens shaped by the MMCM was <65%. Compared with MMCM-molded CEAMs, VVTM-fabricated CEAMs showed decreased optimal moisture and emulsified asphalt contents by 11% and 9%, respectively, but exhibited improved moisture stability, anti-cracking performance, and anti-rutting performance by 4%, 12%, and 35%, respectively. The fatigue equations established on the basis of the Weibull distribution could effectively assess the fatigue life of CEAMs. The VVTM-manufactured CEAMs showed good resistance of stress change sensitivity and fatigue failure under different stress ratios. The VVTM-compacted CEAMs demonstrated increased fatigue life by 36% at a stress ratio of 0.45 and by 325% at a repeated load of 0.27 MPa compared with the MMCM-fabricated CEAMs.

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Double-layer paving technology, which is a new technology for construction asphalt pavements, has received increasing research attention for several years. However, few studies have focused on the effect of asphalt pavement layer thickness and mixture-type combinations on the fatigue properties of a double-layer pavement. Therefore, the fatigue properties of the double-layer and traditionally paved asphalt pavements were studied in this work. The effects of two paving technologies, three mixture combinations, and two asphalt layer thickness combinations on the fatigue properties of asphalt pavements were studied through bending beam tests, and a fatigue equation of different asphalt pavements was established using the two-parameter Weibull distribution. Subsequently, the fatigue lives of different pavements were compared and analyzed under the same cyclic load. Results indicate that the flexural strength and fatigue life of the double-layer pavement increased by at least 10% and 54%, respectively, compared with those of a traditionally paved pavement structure. The goodness of fit of the equation established using the Weibull distribution exceeded 0.90. For the traditional paving technology, compared with the pavement structure combination of 4-cm AC-13 surface layer/6-cm AC-20 bottom layer, the fatigue life of a 3-cm AC-13 surface layer/7-cm AC-20 bottom layer can be increased by at least 8%, while the fatigue lives of other pavement structures are reduced significantly. The results also indicate that the fatigue life of the double-layer pavement structure with the 3-cm AC-13 surface layer/7-cm AC-20 bottom layer can be increased by at least 114% compared with that of the traditionally paved pavement structure (4-cm AC-13 surface layer/6-cm AC-20 bottom layer). Additionally, the fatigue lives of other pavement structures can be improved. To effectively improve the fatigue life of an asphalt pavement, a double-layer pavement structure with the 3-cm AC-13 surface layer/7-cm AC-20 bottom layer combination is recommended.

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