The requirements imposed on road pavements are ever increasing nowadays, necessitating the improvement of the properties of paving materials. The most commonly used paving materials include bituminous mixtures that are composed of aggregate grains bound by a bituminous binder. The properties of bitumens can be improved by modification with polymers. Among the copolymers used for modifying bitumens, styrene–butadiene–styrene, a thermoplastic elastomer, is the most commonly used. This article presents the results of tests conducted on bitumens modified with two types of styrene–butadiene–styrene copolymer (linear and radial). Two bitumen types of different penetration grades (35/50 and 160/220) were used in the experiments. The content of styrene–butadiene–styrene added to the bitumen varied between 1% and 6%. The results of the force ductility test showed that cohesion energy can be used for qualitative evaluation of the efficiency of modification of bitumen with styrene–butadiene–styrene copolymer. The determined values of the cohesion energy were subjected to the original analysis taking into account the three characteristic elongation zones of the tested binders. The performed analyses made it possible to find a parameter whose values correlate significantly with the content of styrene–butadiene–styrene copolymer in the modified bitumen. With smaller amounts of added modifier (approximately 2%), slightly better effects were obtained in the case of linear copolymer styrene–butadiene–styrene and for larger amounts of modifier (5–6%) radial copolymer styrene–butadiene–styrene was found to be more effective. This is confirmed by the changes in the binder structure, as indicated by the penetration index (PI).

The research focuses on the assessment of the potential use of microwave radiation as alternative heating method for reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) production. Recent studies on the use of microwave radiation in road engineering mostly focused on the cracked asphalt pavement. In the study, microwave heating performance was assessed based on the physical and mechanical characteristics of HMA with different RAP contents containing various amount of moisture. Results were compared to the HMA consisting of high amount of RAP containing Styrene–Butadiene–Styrene (SBS) polymer modified binder. The test results confirmed the possibility of microwaves utilization in order to heat the HMA without adversely affecting its basic properties. The research also shows the possibility of heating RAP in the process of HMA production, especially if the RAP moisture level is above 3%. In addition, the tests on HMA did not reveal any negative impact of microwave heating in the case of using wet RAP for the production of HMA. The susceptibility of the SBS polymer to microwave radiation was indicated by comparing the behavior of the two HMA types under its influence. HMA containing modified bitumen appears to achieve higher temperatures than HMA with unmodified bitumen after the same time of microwave heating.

The paper describes heavy maintenance projects carried out on two regional roads located in the West Pomerania region of Poland. The projects started in 2017 on two sections of these roads. Completely different methods were used on these two sections. On the regional road No. 142 in-place crushing, specifically the rubblizing technique was used over an almost 20 km long stretch of pavement. In the second case the old pavement was left in place and a layer of bituminous-aggregate mixture was placed to control reflective cracking. Pros and cons of these methods are presented in the paper, together with the problems noted during the works.

The environmental considerations need to be taken into account in any road resurfacing and upgrading project, for example, by reusing asphalt rubble for production of new pavement courses. Mixtures containing larger amounts of recycled asphalt pavement are improved by adding rejuvenator additives. The tests performed on the recycled asphalt mixtures containing lard imidazoline confirm the suitability of this agent for paving applications. Lard imidazoline was found to improve the stiffness modulus, fatigue performance and resistance to the action of water and freezing temperatures. The parameters obtained at the optimum content of additive complied with the criteria defined for virgin asphalt concrete and other mixtures of that kind.

This paper presents a case study of the application of an innovative asphaltic mixture used for making protective layers on bridges. This mixture, called stone mastic asphalt rich in bitumen mastic (shortened to SMA-MA) produces an impervious surface, resistant to permanent deformation and fatigue, easily produced and laid down on bridge decks. The authors analyzed the state of knowledge on the asphalt mixtures used on bridges. This article describes the first trials with the SMA-MA mixtures and an example of the most spectacular application.

Compaction of hot mix asphalt (HMA) is a process of altering the internal structure of the material and, as a consequence, also its performance characteristics. The process should ensure the adequate viscosity of binder, a property depending on the temperature and the material-specific property (hardness) of the binder (in the case of HMA). One of the external factors that can affect the process of compaction is the presence of water quickly decreasing the HMA temperature. This paper presents a theoretical model for determining the HMA temperature variation under the effect of water. One of the model parameters is the heat transfer coefficient α for the outward flow of heat. Its value varies strongly in the interfacial zones of the HMA layer (i.e., near the top and bottom surfaces) due to the effect of external factors. The paper presents the attempt to estimate the average value for the whole paving process depending on the precipitation rate (amount of water involved in the process). The temperatures obtained from the model were verified experimentally on laboratory specimens cooled with water. The temperature was measured on the surface and across the specimen section. The drop of temperature of HMA was almost instantaneous on the surface—due to the thermal processes involving water (boiling and evaporation)—and much slower across the layer thickness.