RESUMO
This paper presents the results of an analysis of the changes in the stiffness of asphalt binders modified with a bio-flux additive and subjected to the processes of foaming and short-term ageing. The purpose of the analyses was to determine changes in the rheological properties of asphalt binder as a result of technological processes characteristic of hot and warm mix asphalt technology. Three asphalt binders with similar penetration but varying degrees of polymer modification were tested: 50/70, 45/80-55 polymer-modified bitumen, and 45/80-80 highly modified bitumen. Tests were carried out on four groups of binders: original binders, foamed binders after 14 days of storage, non-foamed binders after Rolling Thin Film Oven Test (RTFOT) ageing, and foamed binders after 14 days of storage subjected to RTFOT ageing. The master curves of the complex shear modulus G* were analysed, and three indexes of binder stiffening were determined, characterising the investigated effects. The tests showed that some of the stiffening indices significantly depended on the degree of polymer modification and the content of the bio-flux additive. Moreover, it was found that the foaming process in the case of paving-grade bitumen and polymer-modified bitumen did not contribute to the additional stiffening of the binders.
RESUMO
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.
RESUMO
Sleep disturbances constitute one of the important yet underestimated aspects of functioning of patients with multiple sclerosis (MS). The objective of this study was to evaluate sleep disturbances in patients with MS, with regard to demographic factors, disease-related variables, co-existing conditions and fatigue. In 100 MS patients, Epworth Sleepiness Scale (ESS) and a questionnaire about sleep disturbances (SlD) were implemented. ESS and SlD results were analyzed with regard to age, gender, duration of MS, type of its course, degree of disability in Expanded Disability Status Scale (EDSS), MS therapies, coexisting diseases, results of Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS). ESS score indicated increased daytime sleepiness in 19 patients. In SlD, 49 subjects reported sleep disturbances and 35 more than one of their kind (most commonly terminal and middle insomnia). No relationships were found between ESS and SlD scores and age, gender, MS duration, type of its course, EDSS or coexisting diseases. In 36 patients, somatic complaints interfered with sleep. The patients with depression had significantly lower ESS result and those currently treated with immunomodulation had significantly lower SlD score. SlD score correlated positively with FSS and MFIS. Sleep disturbances in MS patients may occur independently from demographic and disease-related variables, but they are often influenced by the symptoms of MS and therapies used. Sleep disturbances may contribute to fatigue in the course of MS.
