Based on a road reconstruction case study, the advantages and disadvantages of two alternative road pavement rehabilitation techniques, a hypothetically defined comparable traditional approach and an actually used cold-in-place-recycling approach, both of which enable a comparable extension of road service life of about 20 years, were investigated by means of Life Cycle Assessment. The results showed that the considered environmental impacts of the traditional approach exceeded those of the cold-in-place-recycling approach: by only 1% with regard to Global Warming, by 18% with regard to Acidification, by 15% with regard to the Abiotic Depletion of Fossil Fuels, and by 16% with regard to primary energy consumption. In the case of the traditional approach, the use of larger amounts of natural aggregate and the transportation of materials significantly contributed to emissions and the consumption of fossil fuels and energy, whereas the cold-in-place-recycling approach was sensitive to the use of cement, whose production results in relatively high emissions, especially of greenhouse gasses. In the case of the traditional approach, sensitivity analyses were carried out with regard to the use of aggregate from a quarry instead of a gravel pit, and to the delivery distance of material hauled away from the distressed road during rehabilitation works (extending the one-way delivery distances from 20 to 100 km). It was found that, if aggregate from a quarry is used instead of from a gravel pit, then the various environmental impacts of the traditional approach would exceed those of the cold-in-place-recycling approach by factors which range between 1.3 and 1.7. Increasing the transportation distance of hauled-away materials from 20 km to 100 km, the impacts of the traditional approach would exceed the impacts of the cold-in-place-recycling approach by a factor of 1.4 (Global Warming) and 1.6 (Acidification and Abiotic Depletion of Fossil Fuels). A further sensitivity analysis was carried out in the case of the cold-in-place-recycling approach, with regard to the use of Portland cements containing different amounts of clinker. It was found that the use of cements with a higher clinker content results in an increase in the Global Warming impact to a level significantly higher than that of the traditional approach.
COBISS.SI-ID: 2177127
The aim of the present work was to characterize the efficiency of a corrosion inhibitor on steel in a simulated concrete pore solution. Laboratory measurements were performed at various chloride and inhibitor concentrations in order to simulate different applications of the inhibitor when used for the protection or rehabilitation of steel reinforcement in concrete. Two electrochemical techniques, i.e. potentiodynamic polarization scans and electrochemical impedance spectroscopy, were used for this study. The exposed surfaces of the steel specimens were subsequently investigated by Raman spectroscopy and scanning electron microscopy. It was found that the inhibitor can efficiently retard the corrosion of steel in a simulated concrete pore solution at concentrations of the inhibitor )2.0% and of chlorides (0.3% at a pH 10.5. On the other hand, when these conditions are not fulfilled, localized corrosion was observed. The results of the Raman and SEM/EDS analysis showed various morphologies of corrosion products and different types of corrosion attack depending on the pH of the pore solution, and the applied concentrations of the chlorides and the inhibitor.
COBISS.SI-ID: 2232167
Pool fires of light fuel oil (LFO) in above-ground storages with steel-aluminium containers are discussed. A model is developed for assessmentsof risks of between-tank fire spread. Radiative effects of the flame body are accounted for by a solid flame radiation model. Thermal profiles evolved due to fire in the adjacent tanks and the their consequentialstructural response is pursued in an exact (materially and geometrically non-linear) manner. The model's derivation is demonstrated on the LFO tank storage located near the Port of Koper (Slovenia). In support of the model, data from literature are adopted where appropriate. Analytical expressions are derived correspondingly for calculations of emissive characteristics of LFO pool fires. Additional data are collected from experiments. Fire experiments conducted on 300cm diameter LFO pans and at different wind speeds and high-temperature uniaxial tension tests of the analysed aluminium alloys types 3xxx and 6xxx are presented. The model is of an immediate fire engineering practical value (risk analyses) or can be used for further research purposes (e.g. sensitivity and parametric studies). The latter use is demonstrated in the final part of the paper discussing possible effects of high-temperature creep of 3xxx aluminium.
COBISS.SI-ID: 2163047
This paper presents numerical simulations of two full scale masonry structures which were tested on the shaking table within the scope of the workshop ˝Methods and challenges on the out-of-plane assessment of existing masonry buildings˝. The numerical models have been developed on the basis of the blind-prediction models which have been improved after the publication of the test results. The solution procedure is divided into two steps with separate numerical simulations for each one. In the first step the collapse mechanism of the structure is determined by means of pushover analysis using a continuum, plasticity based model. In the second step the dynamic response of the structure is simulated using a multibody model approach and frictional contacts. Results of the tests show reasonable, yet far from perfect predictive capabilities of the used numerical methods used.
COBISS.SI-ID: 2239847
The surface of a model red organic pigment, 3,6-bis(4-chlorophenyl)pyrrolo[3,4-c]pyrrole-1,4-dione, was modified using a mixed-micelle system containing different surfactants and polymers to improve the dispersibility of the pigment. It is shown that modifying the surface using a non-ionic surfactant and a mixed-micelle solution leads to good dispersibility of the pigment. The surface-modified pigment particles were additionally encapsulated with a SiO2 shell to improve the UV/TiO2 fastness. The influence of the synthesis parameters, such as the temperature and the pH,on the formation of the SiO2 protective layer around the pigment particles and, consequently, on the UV/TiO2 protection were investigated. The conditions leading to a compact and uniform protective silica layer over the majority of the pigment particles are discussed in detail.
COBISS.SI-ID: 2163559