Researchers from both Portugal and Brazil continued a trend of introducing rubberized asphalt to the international community at the Third International Conference on Sustainable Construction Materials and Technologies from August 18-21, 2013 in Kyoto, Japan.
Asphalt-rubber, defined by ASTM D6114, is commonly manufactured using high rubber contents in the range of 20% +/- 2% rubber by weight of the blended binder.
It was introduced in Portugal in the late 1990s with the first International Asphalt-Rubber 2000 conference held in Portugal from November 14-17, 2000. The AR 2000 conference led to substantial growth in European countries and was followed by AR 2003, held in Brazil from December 1-4, 2003, which introduced rubberized asphalt into South America.
A paper titled “The Use of Asphalt Rubber Mixtures to Improve Pavement Overlays” was presented at ths year’s event by Liseane Padilha Thives, of the Federal University of Santa Catarina State, Brazil; Glicério Trichês Rua João Pio Duarte Silva, of UFSC Florianópolis, Brazil; and Jorge Pais and Paulo Pereira, of the University of Minho, Portugal.
Their paper studies asphalt modified with crumb rubber to produce asphalt rubber mixtures for pavement overlays subjected to heavy loads and high temperatures.
Laboratory research was conducted to determine the performance properties of overlays with asphalt rubber mixtures produced through wet processes using a gap graded mixture. The asphalt rubber was prepared by the continuous blend process and its properties were measured by means of current tests. An identical study for a conventional mixture used as a reference was performed. The permanent deformation and the fatigue test of two different mixture designs manufactured with modified and conventional binders, with the same aggregates and different binder contents, were evaluated.
Besides the use of rubber as a high-performance additive in conventional asphalts, the use of asphalt rubber is attractive from the standpoint of environmental preservation, the study concludes.