Influence of the Application Method of Bitumen Emulsion on the Layer Bond

Asphalt is paved in several layers. A good layer bond between the individual asphalt layers is necessary for a long service life of the asphalt pavement. For many years, bitumen emulsions have been used to bond the layers together in accordance with the requirements. Usually, the emulsion is sprayed and the asphalt layer is paved in two steps. In the first step, the base is sprayed with the bitumen emulsion. In the second step, after the bitumen emulsion has broken, the asphalt is placed. However, paving can also be carried out using a spray paver with an integrated spraying device. In this case, spraying and paving are carried out in one work process. In this study, the influence of both paving methods on the layer bond is investigated. For this purpose, the two methods are simulated in the laboratory and the effect is analysed for different bitumen emulsions (C60 BP4-S; C40 BF5-S) and different spray rates. The aim of the study is to find out the suitability of bitumen emulsions for the spray paver method when paving asphalt wearing courses (4 cm), and to reveal possible damage potentials. It was detected that the amount of water in the bitumen emulsion has a significant impact on the quality of the layer bond. Therefore, the total amount of emulsion applied also has an influence on the layer bond as the amount of water increases with the total amount of emulsion.