Numerical and Experimental Analysis of the Raise-Temperature Effect of Quicklime in Cold Recycled Mixtures

Abstract

This study focuses on the development of a thermodynamic model to individuate the increment of temperature generated by the addition of quicklime as an active filler in cold recycled mixtures (CRMs). CRMs are increasingly popular mixtures primarily composed of reclaimed asphalt pavement (RAP) and produced at low temperatures. CRMs are composed of RAP aggregates, an asphalt stabilizing agent (emulsified or foamed asphalt), fillers and active fillers (traditionally cement or hydrated lime), and water. One of the main limitations of CRMs consists of their workability that requires high air temperature. For this reason, the construction season for the application of cold recycling technologies is usually limited to summertime, especially in colder areas. A solution to this limitation is the use of quicklime as an active filler in the mixture. As shown by previous research, calcium oxide causes an exothermic reaction with water generating heat and increasing the temperature (20°C–25°C) of the entire mixture. This paper presents a thermodynamic model to identify the temperature increase and its evolution during preparation and transportation to the site of CRMs. The scope is to individuate the correct procedure to identify the most suitable application rate of quicklime in the mix design in order to reach the desired CRM temperature and workability.