No abstract

The aim of this research was to define the effect of oxidative aging on the chemical and rheological properties of neat and styrene-butadiene-styrene (SBS) polymer-modified bitumen. The experimental research had two objectives: firstly, the short and long-term effects of aging on the properties of neat and polymer-modified bitumen were investigated. Then, the aging indexes based on chemical and rheological properties to describe the age of unknown bitumen were established. Aging characteristics such as the Gaestel index, sulfoxide and carbonyl indexes, linear viscoelastic strain range, crossover temperature, and Glover–Rowe parameter were analysed for laboratory aged and naturally aged neat and polymer-modified bitumen. The functional composition of aged bitumen was evaluated by measuring absorption with Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectrometer. The saturates, aromatics, resins, and asphaltenes (SARA) fractions were determined with thin layer chromatography with flame-ionization detection (TLC-FID) to determine the colloidal instability index (Gaestel index). Finally, the complex shear modulus was determined with dynamic shear rheometer (DSR) to evaluate the influence of aging on the bitumen mechanical performance.

Low-noise pavements are used as an effective method of traffic noise mitigation. Low-noise pavements reduce the noise that arises due to interactions between tires and road surfaces (tire/road) via the implementation of three main components: low pavement roughness, negative pavement texture, and a high pavement air-void content. The tire/road noise reduction capabilities of the wearing layer vary depending on the aggregate type, gradation, bitumen and air-void content, and density. Consequently, the demand for an accurate tire/road noise prediction model has arisen from the design of asphalt mixtures. This paper deals with how asphalt mixture components of the wearing layer influence tire/pavement noise reduction and presents a model for tire/road noise level prediction based on the asphalt mixture composition. The paper demonstrates that the noise reduction level of low-noise asphalt pavements is dependent on the composition of the asphalt mixture. Asphalt wearing layer mixture composition parameters were tested in the laboratory from cores taken from 18 road sections, where acoustic properties were measured using a close-proximity (CPX) method. The proposed linear model is based on the bitumen amount, the air-void content of the mixture and aggregate shape and involves materials that comply with the general requirements for high-quality asphalt mixtures. The model allows for the prediction of the tire/road noise level at the asphalt mixture design stage using asphalt mixture components and volumetric properties. The proposed model is the first stage in the building of a complex model with a much wider range of low-noise asphalts components, pavement profile depth and CPX-value relationships.

No abstract

In the European Union, more than 140 million tonnes of municipal solid waste is incinerated annually. It generates about 30–40 million tonnes of residues known as municipal solid waste incinerator bottom ash, which is typically landfilled. To deal with growing landfills, there is a need to utilize municipal solid waste incinerator bottom ash as a building material. It has been known that municipal solid waste incinerator bottom ash properties strongly depend on waste composition, which is directly influenced by people’s habits, economic policy, and technologies for metals recovery of bottom ash. Thus, municipal solid waste incinerator bottom ash produced in a specific country or region has primarily to be tested to determine its physical and mechanical properties. The main aim of this study is to determine municipal solid waste incinerator bottom ash physical and mechanical properties (aggregate particle size distribution, water content, oven-dried particle density, loose bulk density, Proctor density, optimal water content, California Bearing Ratio after and before soaking, permeability, Flakiness Index, Shape Index, percentage of crushed and broken surfaces, resistance to fragmentation (Los Angeles coefficient), water absorption and resistance to freezing and thawing). Municipal solid waste in-cinerator bottom ash produced in the waste-to-energy plant in Klaipėda (Lithuania) was used in this research. Ferrous and non-ferrous metals were separated after more than three months of municipal solid waste incinerator bottom ash ageing in the atmosphere. The study showed promising results from considering municipal solid waste incinerator bottom ash as possible aggregates for road building materials.