Effect of curing and compaction on volumetric and mechanical properties of cold-recycled mixture with asphalt emulsion under different cement contents

Abstract

Cold-recycled mixture with asphalt emulsion (CMAE) has been widely used in pavement rehabilitation due to its environmental and economic advantages. Curing condition and compaction method can both affect the volumetric and mechanical properties of CMAE. The main objective of this paper is to propose a relative reasonable fabrication method of CMAE in consideration of curing and compaction history in the laboratory. The two fast curing conditions (single curing: 2 days curing at 60 °C and mixed curing: 3 days curing at 20 °C followed by 2 days curing 60 °C) and three impact compaction methods (single compaction-50 blows, single compaction-75 blows and double compaction) using Marshall compactor were used to evaluate the volumetric and mechanical properties of CMAE with different cement contents. The result analysis indicates that the single curing condition is beneficial to decreasing the voids content and increasing the indirect tensile strength (ITS), failure strain and critical strain energy density (CSED) of CMAE with low cement content. However, the mixed curing can decrease the voids content and greatly improve the ITS and CSED of CMAE with high cement content. This is because the single curing is better for the film formation of asphalt emulsion but more harmful to the cement hydration than the mixed curing. It is recommended to adopt single curing under relatively low cement content and mixed curing under relatively high cement content in the laboratory. Meanwhile, increasing the number of compaction blows and employing double compaction can greatly reduce the voids content and improve the ITS and CSED with different cement contents, which is beneficial to the mechanical properties of CMAE. Since the double compaction can better simulate the field construction, it is recommended to employ the double compaction to fabricate specimens in the laboratory.