Towards 90% warm re-use of porous asphalt using foaming technology

The growing needs for sustainability demand that porous asphalt (PA), one of the most critical types of asphalt mixtures, can be produced with high quality, low production temperature and using high percentages of reclaimed materials. With the support of the European Life+ program, a new decomposition technique was developed to decompose the reclaimed PA into the mortar sand (grain size ≤ 2 mm, bitumen content 10-14%) and the reclaimed stones in various fractions (bitumen content less than 1%). The reclaimed mortar sand can then be rejuvenated, enriched and homogenized to obtain a high quality mortar. When this mortar is mixed with the reclaimed stones, a high quality PA can be obtained with almost 95% reclaimed materials. This paper discusses the influence of different production techniques on the performances of this mixture. These techniques include (A) conventional hot production technique at 170 °C, (B) the cold feed of reclaimed mortar sand in combination with bitumen foaming obtaining a mix at 105 °C and (C) the hot production of mortar in combination with the newly developed mortar foaming method to obtain a mixture at 105 °C. Laboratory results indicate that the PA may be produced at 105 °C, containing up to 93% reclaimed materials and having a high quality.