Effect of SiO2 aerogel on the thermal properties of RAP and the blending degree of new and old asphalt binder

SiO 2 aerogel has excellent thermal insulation properties , and utilizing SiO 2 aerogel to enhance the thermal resistance of reclaimed asphalt pavement (RAP) can broaden the application of RAP in heat-resistant asphalt pavements , as well as contribute to the reduction of environmental pollution and the solution of the problems caused by the shortage of aggregates. In this paper, by carrying out indoor thermal radiation tests and analyzing the inadequacy of temperature difference index, the index of barrier temperature coefficient (BTC) is proposed. The effects of SiO 2 aerogel solution type, modification method and SiO 2 aerogel solution dosage on the thermal conductivity , BTC and adhesion coefficient of RAP were explored based on the implementing orthogonal test. The results showed that the SiO 2 aerogel solution dosage had the most significant effect on the thermal resistance and adhesion properties of SiO 2 aerogel-modified RAP (M-RAP), and a suitable modification scheme could reduce the thermal conductivity of RAP by 9.70 %, increase the BTC by 4.72 %, and achieve an adhesion coefficient of 0.2. For the preferred M-RAP, an infrared thermographic camera was used to test the dynamic heat resistance performance of its and RAP materials at 55°C, and it was found that the temperature of the top surface of the 18.3 mm thick M-RAP specimen was always lower than that of the RAP during the 60 min heating time, and its lowest temperature could be 2.6°C lower than that of the RAP specimen. To explore whether SiO 2 aerogel solution affects the degree of blending of old and new asphalt binder on the RAP surface, RAP and M-RAP specimens were tested using a gel permeation chromatography test method based on layered dissolution (LD-GPCM). According to the results, the modification of RAP by SiO 2 aerogel solution reduces the degree of blending of old and new asphalt binder on the RAP surface by 7.25 %. • SiO 2 aerogel can enhance thermal resistance of RAPs. • M-RAP is 2.6 °C cooler than RAP. • M-RAP surface asphalt miscibility was 7.25 % lower than RAP.