High-temperature performance of multilayer pavement with cold in-place recycling mixtures

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The cold in-place recycling (CIR) technique has been gradually accepted and applied in multiple areas of China as the lower layer of highway pavement. The overall pavement typically shows satisfactory resistance to permanent deformations. The objective of this research is to evaluate the high-temperature performance of a typical China pavement structure with CIR. Since the conventional creep test cannot adequately simulate the field conditions, an Advanced Cyclic Creep Test, which can replicate in the laboratory stresses and temperatures encountered in the field was developed and utilised to study the resistance of the CIR pavement to high-temperature deformations. Creep curves following three-stage creep models best fits were obtained to study the effects of cement contents (1.5%, 2.0%, 2.5%) in CIR mixtures and anti-rutting agent in the middle layer on the high-temperature performance of the composite specimens under different testing conditions. In the process of specimen preparation, the impact of the middle-layer compaction on the CIR mixtures was also quantified. According to the results of this research, 6 days of curing time is recommended to restrict the effect of paving and rolling of the hot mix asphalt (HMA) on top of the CIR layer. Adding 0.3% anti-rutting agent to the HMA in the middle layer can enhance the resistance of the composite specimen to high-temperature deformations. An increase in cement content of the CIR mixtures from 1.5% to 2.0% can improve the high-temperature performance of the CIR pavement. Comparing with newly constructed pavement, it is verified that the typical China highways pavement structure including CIR shows satisfactory high-temperature performance.