PSI - Issue 73

Robert Jurczak et al. / Procedia Structural Integrity 73 (2025) 45–50 Robert Jurczak/ Structural Integrity Procedia 00 (2025) 000–000

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1. Introduction The pavement on the deck slab of an engineering structure significantly influences its durability and consists of a waterproofing layer, a protective layer, and a wearing course (Radziszewski et al. 2016). Its primary function is to transfer traffic loads and to protect the structure against the effects of water and de-icing agents. Therefore, in addition to the appropriate selection of materials and technologies, the proper execution of all works related to the installation of waterproofing and the placement of asphalt mixtures is of critical importance. Based on the author's experience gained during quality control of materials and works on projects carried out by the General Directorate for National Roads and Motorways in the West Pomeranian Voivodeship, it has been observed that, recently, the method of constructing protective layers using mastic asphalt has received the least attention (Fig. 1). a b

Fig. 1. (a) Example of a completed section of the protective layer on an engineering structure; (b) Typical longitudinal joint in mastic asphalt placed in separate operations.

Compared to other asphalt mixtures, mastic asphalt contains a higher proportion of bitumen and filler, and it differs in that it does not require compaction. Due to its advantages – including high resistance to permanent deformation, enhanced fatigue resistance, and complete impermeability – it is commonly used in Poland for constructing the protective waterproofing layer on engineering structures (Jurczak, 2014; Kołodziej et al., 2021; Sybilski, 2008). It can also be utilized in the wearing courses of road pavements (Hering et al., 2014). Modern mastic asphalt is produced in automated asphalt mixing plants at temperatures ranging from 200°C to 230°C. Transport is carried out using specialized boilers equipped with heating and mixing systems that maintain the required temperature and consistency of the mixture. The asphalt is laid mechanically using a specialized paver. Depending on the thickness of the protective layer, it may be constructed in one or two lifts. It is recommended that mastic asphalt be applied across the entire width of the carriageway. However, in practice, the material is often placed in two stages. This occurs when, due to traffic constraints or other justified reasons, the layer must be applied at different times. Consequently, a joint – either longitudinal or transverse – is created, where two segments of mastic asphalt installed at different times meet. Typically, joint formation involves laying a new strip adjacent to a previously laid, now cold, segment. For such technological joints in mineral-asphalt mixtures, asphalt tapes should be applied to the vertical edge of the existing layer. Considering previously observed issues with the proper execution of joints using the “hot to cold” method (Jurczak 2024), the research program was designed to evaluate the effectiveness of existing solutions and to identify