Case history study: field monitoring and performance prediction of a field-blended rubber asphalt mixture in Brazil

Among the fabrication processes available for obtaining asphalt rubber, terminal blend is the most commonly used in Brazil. On the other hand, the use of field-blended rubber asphalt has been around in the United States for decades, especially in the state of Arizona. The lack of information regarding this technique in Brazil, however, inhibits a more common use in pavement construction/rehabilitation. This case history study was conducted in order to characterise the field performance of the first pavement rehabilitation job in Brazil using a field-blended rubber asphalt mixture and attempt to predict its future performance. A 500-m test section using a field-blended rubber asphalt mixture with a gap-graded aggregate as a surface course was monitored periodically through pavement deflection tests, roughness, rutting and surface conditions. Pavement monitoring revealed good functional and structural conditions after 4 years of service life. Accelerated pavement testing (f-sAPT), conducted in a representative test section using a full scale, mobile traffic simulator, exhibited promising performance. No cracking was observed in the test section and the average maximum rut depth was below limits after simulating 7 years of service life. Results from the f-sAPT simulation were then used to calibrate the performance cracking and rutting models in the Highway Development and Management Model (HDM-4).