Effect of curing on the physical and mechanical properties of cold-recycled bituminous mixtures

Abstract

Cold recycling of bituminous pavements is an effective way to reduce cost of pavement maintenance. Depending on composition, cold-recycled mixtures with a wide range of mechanical properties can be produced. However, regardless of composition, a distinctive feature of cold-recycled mixtures is the requirement for a curing period to develop the long-term mechanical properties. The main objective of this study was to characterize the curing process of cold-recycled mixtures by analysing the rate at which mixture properties evolve over time and their value in the long-term cured state. The study was focused on two mixtures with a fixed dosage of bituminous emulsion (3.3%) and two cement dosages (1% and 2.5%). Moisture loss by evaporation, ITS and ITSM were measured over time (100days), considering two curing temperatures (25°C and 40°C). The evolution of such properties was modelled using two asymptotic regression models. Results showed that the Michaelis–Menten model effectively describes the evolution of material properties over time, the relation between water loss and mechanical properties and the relation between ITSM and ITS. Cement dosage had an important impact on the long-term values of material properties, whereas curing temperature mainly influenced the rate of curing.