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In Germany, multiple lanes of porous asphalt (PA) road surfaces should be constructed with a longitudinal hot joint construction over the full pavement width according to the ‘Technical Instruction for Porous Asphalt Surfacing’. In this way, longitudinal cold joints are avoided and the transverse drainage is not impeded. Therefore, the construction of PA always requires the closure of all lanes in one direction of traffic. However, such measures are only possible in exceptional cases with heavily loaded road sections on motorways with 6–8 lanes. In this research, different variants of joint construction methods for PA were realised in practice. The performance of each variant was investigated with respect to the tensile strength, the tensile strain at break, the permeability and the resistance against ravelling of the joint. After comparing the different construction methods for longitudinal joints, three of them proved to be able to ensure both the structural durability and the water permeability in the joint area. [ABSTRACT FROM PUBLISHER]

The objective of the research was the development, optimisation and evaluation of thin noise-reducing surface layers in Germany intended to be more durable than porous asphalts, thus providing better long-term acoustical properties. The basic approach was to create a smooth, open-textured surface with a stone mastic asphalt-based aggregate skeleton across the whole thickness of the layer. The test pavements in Düsseldorf were subjected to both optical 3D measurements of surface texture parameters and the continuous close-proximity method monitoring of the noise emission. The test pavements had significant noise reduction and very low changes in acoustical properties over time, and when compared to other common types of surface layers they showed the highest noise-reducing capacity. On the basis of the research results and past experience, recommendation on the specification according to the relevant European standards was developed, thus contributing to the adoption of European specifications for noise-reducing asphalt pavements. [ABSTRACT FROM AUTHOR]