Investigation on the designing method of asphalt emulsion cold recycled mixture based on one-time compaction

The asphalt emulsion cold recycled mixture (CRME) technology is one of the main utilization method when RAP is used in the asphalt pavement construction. However, there is not a unified material design method for this technology. In this paper, according to the Marshall test method, the test samples were prepared by two molding methods: one-time compaction and two-time compaction. The effects of compaction work and moisture content on the performance of CRME were studied. The test results showed that after the one-time compaction of CRME, as the compaction work increased, the air void of the mixture gradually decreased, and indirect tensile strength (ITS) gradually increased. When the first compaction times exceeded 125 times, the density of CRME could meet the requirement, only limited changes could be observed when the compaction work was continuously increased. However, the increase in compaction work may cause lead to the occurrence of internal cracks and reduce the strength of the mixture. The moisture content of CRME was basically the same at 60 °C for 120 h and 70 °C for 48 h, indicating that the moisture content parameters of CRME met the principle of time-temperature equivalence. CRME was cured for 8 h at 60 °C, which had met the requirements of the technical specification with a moisture content of less than 2%. When the samples were cured for more than 24 h, there was no remarkable difference in ITS and air void of the mixtures formed by one-time compaction and two-time compaction. Therefore, there was no need to perform a second compaction for the mixture. On this basis, a material design method for CRME with one-time compaction was proposed.