Use of Reclaimed Asphalt Pavement to Asphalt Concrete Base Course

Reclaimed Asphalt Pavement (RAP) is an asphalt pavement material which is acquired from removed or reconstructed asphalt roadways. When properly crushed and screened, RAP consists of high-quality, well-graded aggregates coated by asphalt cement. A study done showed that the use of RAP in asphalt mixture, guarantees the required pavement durability with reduced cost of asphalt mixtures production. European product standards and Polish technical guidelines contain all relevant regulations and requirements regarding hot asphalt mixtures. There are two main methods to introduce the RAP into asphalt mixtures at the asphalt mixing plant: cold and hot method. The most popular method in Poland is the cold method, where the cold RAP is added directly to the mixer. In many European countries maximum amount of RAP is 30% in cold method. Polish technical guidelines WT- 2:2010 reduce also the maximum amount of RAP in HMA without taking into consideration the technical capabilities of asphalt mixing plants. It may be used only a maximum of 15% to asphalt mixture according to the WT-2:2010. The paper presents the research results of asphalt mixtures with 10%, 15% and 20% addition of RAP stored on the square of the asphalt plant near Bialystok. In the first stage of the study the amount of foreign impurities in the RAP, granulation of aggregates and asphalt content was performed. It was found that, despite the large heterogeneity tested RAP meets the standard requirements. Positive results have enabled the design of the initial composition of asphalt mixtures to base course, namely Asphalt Concrete (AC) for different categories of road traffic. AC prepared with 10%, 15% and 20% addition of the RAP and without the addition of RAP were tested on water resistance, rutting, fatigue life and stiffness modulus. The research results showed that RAP is a valuable material that can be used for the production of asphalt concrete designed for the base course for all categories of road traffic. It was found that the addition of RAP can reduce the amount of asphalt in asphalt mix up to 26% and the consumption of natural aggregate by approximately 20%. It should be noted the influence of RAP on the performance and the durability of the asphalt mixtures as compared to virgin asphalt mixtures (without RAP).