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 benefits of the use of cold recycling mixtures (CRMs) in pavement rehabilitation are associated with both the reduction of natural resource consumption by replacing them with recycled materials and the reduction of energy consumption during their production and paving. The evolution of the stiffness of CRMs in road construction and the fatigue life of pavements with CRM base layers are still being investigated. In this paper, CRMs with 1% cement content, called bitumen-stabilized materials with bitumen emulsion (BSM-Es), were examined. Mixtures that were differentiated in terms of Reclaimed Asphalt Pavement (RAP) content, as well as the amount and type of bitumen emulsions, were subjected to indirect tensile stiffness modulus (ITSM) tests at 5 °C, 13 °C, and 20 °C. The thermal sensitivities of the BSM-E mixtures were analyzed. BSM-E mixture stiffness modulus levels at various temperatures were determined using a statistical approach. On the basis of the results obtained, a discussion on the mechanistic-empirical design of flexible pavements with BSM-E base layers is presented. The potential benefits of using BSM-E materials in road construction in certain aspects of pavement life are indicated.

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 purpose of the study is to investigate the energy performance of a PVT collector in combination with a heat pump. First, a test system combining a heat pump and PVT module is built, and then its performance is carefully measured, assessing the electricity and heat production. The paper focuses on increasing the efficiency of a photovoltaic (PV) panel (as part of the PVT module) by cooling it with a heat pump. The main idea is to use the heat generated by the warming panels as a low-temperature source for the heat pump. The research aims to maximize the use of solar energy in the form of both electricity and heat. In traditional PV systems, the panel temperature rise reduces the solar-to-electric conversion efficiency. Therefore, cooling with a heat pump is increasingly used to keep panels at optimal temperatures and improve performance. The tests confirm that cooling the panels with a heat pump results in an 11.4% improvement in electrical efficiency, an increase from 10.8% to 12.0%, with an average system efficiency of 11.81% and a temperature coefficient of –0.37%/°C. The heat pump achieves a COP of 3.45, while thermal energy from the PVT panel accounts for up to 60% of the heat input when the air exchanger is off. The surface temperature of the PVT panels varies from 11 °C to 70 °C, and cooling enables an increase in electricity yield of up to 20% during sunny periods. This solution is especially promising for facilities with year-round thermal demand (e.g., swimming pools, laundromats).

Artykuł przedstawia wyniki badań właściwości mieszanek mineralno-asfaltowych wyprodukowanych z dwóch rodzajów destruktu, zawierających asfalt modyfikowany oraz wysokomodyfikowany. Oba rodzaje destruktu pozyskano w warunkach rzeczywistych, a wyprodukowane z nich mieszanki nie zawierały dodatku środków odmładzających. Mieszanki doprowadzono do temperatury zagęszczenia wg wymagań krajowych, a tak- że poddano dodatkowym procesom starzenia w tym w temperaturze przekraczającej temperaturę degradacji obecnego w ich strukturze polimeru SBS (200°C). Wyniki badań zawartości wolnych przestrzeni oraz odporności na działanie wody i mrozu ITSR wykonanych po kondycjonowaniu w temperaturze zagęszczenia zgodnej z wymaganiami krajowymi wykazały korzystniejsze właściwości mieszanki zawierającej destrukt z asfaltem wysokomodyfikowanym (wartości ITSR w zakresie 87-90%) w porównaniu do mieszanki zawierającej destrukt z asfaltem modyfikowanym. Kondycjonowanie w 200°C ujawniło znaczące różnice w zachowaniu mieszanek. Mieszanka zawierająca asfalt modyfikowany umożliwiała rozkładanie i zagęszczanie, podczas gdy mieszanka zawierająca asfalt wysokomodyfikowany utraciła urabialność oraz możliwość zagęszczenia, uniemożliwiając uzyskanie próbek do badań.