Effect of Curing Procedure to Foamed Asphalt Cold Recycled Mixture Properties

In order to simulate field curing condition, uncovered curing, semi-covered curing and semi-covered + covered curing (“combination” curing) of three methods were designed. Mechanics tests were used to study development law of moisture content, indirect tensile strength (ITS), unconfined compressive strength (UCS) and the shear parameters. At the same time, the internal void structure of mixture was analyzed by CT scanning test. Results show that the difference of the strength development law results in the difference of moisture migration path and loss rate at three curing conditions. Moisture content is closely correlative with mixture strength, and the change law of internal friction angle of mixture seemes similar and the cohesive force is significantly influenced by the moisture content. The void structure which was formed by hydration products is destroyed by water vapor pressure due to the slow evaporation rate of semi-covered curing and “combination” curing procedure. Therefore, the strength presents lower than that of uncovered curing. According to the research of mechanical properties and voids distribution, semi-covered curing 36h+covered curing 36h is recommended as a long term curing procedure in foamed asphalt cold recycled mixture design.