Carbon steel slag is quite commonly used in road construction to replace natural aggregate. Since it is important to evaluate such a replacement from the environmental point of view, a Life Cycle Assessment was carried out in order to compare the environmental impacts of the construction of asphalt wearing courses with the use of siliceous aggregates (the "conventional scenario"), and the use of alternative, steel slag aggregates (the "alternative scenario"). The main advantage of the alternative scenario is that a reduction can be achieved in the consumption of natural aggregate, as well as in the quantity of slag deposited on landfill sites. On the other hand larger amount of bitumen is needed as a binder. However, the results of the Life Cycle Assessment (based on consequential modelling) revealed that the alternative scenario is to be significantly preferred if the following impact categories are taken into account: Acidification, Eutrophication, Photochemical Ozone Creation and Human Toxicity. In the case of the discussed indicators, the impacts are reduced to a level equal to about 80 % of the conventional scenario impacts. This benefit was additionally evaluated by means of a transport sensitivity analysis, which provided results which could be useful for road managers working on case studies using similar construction materials. The alternative scenario is more sustainable than the conventional scenario with regard to the discussed impact categories even when taking into account long delivery distances of the steel slag aggregate (~100 km) and minimal delivery distances of the siliceous aggregate. Considering similar delivery distances in both scenarios, the alternative scenario was found to be beneficial also with regard to the Global Warming, but only when the delivery distance of the steel slag aggregates did not exceed 160 km.
COBISS.SI-ID: 2069863
Copper corrosion has been studied in simulated groundwater with and without added bentonite clay using different electrochemical techniques. The corroded surfaces were characterized by SEM/EDS, Raman spectroscopy and Auger depth profiling. In both environments small amounts of sulphide (0.005 mM) control the early corrosion behaviour. Under aerated conditions an initially formed Cu2S film is rapidly converted to a non-protective layer of cuprite and corrosion proceeds with the deposition of an outer layer of atacamite. In the presence of bentonite corrosion proceeds slowly under O2 transport control. Noatacamite is observed and the Cu surface appears slightly pitted.
COBISS.SI-ID: 2071655
Following the present directives for building products, the manufacturers of intumescent paints for fire protection of structural steel typically offer special tables for presentation of the product's insulating efficiency. From these tables only the final time of reaching this critical limit is obtained clearly. These data are only sufficient for the use of a more or less simplified design procedure and in every-day design practice often lead to one of the most simplified procedures such as EC3’s method of critical temperature (MCT). Although of a questionable adequacy for cases of restrained thermal dilatations this method is, thus, often applied regardless of the specifics of the structural assembly. This will need to be avoided in the future, thus, new advanced procedures will need to be developed for intumescent painted steel structures. One of such is proposed in this paper. First, fire test results are presented for 13 different steel members protected by different DFTs of a selected intumescent coating. Using these results and optimization procedures of multiple regression analysis a numerical procedure is first designed for deriving thermal parameters (i.e. time dependent thermal conductivity, specific heat, and density) of the selected intumescent coating. These are used further in a two-step performance-based numerical procedure composed for obtaining the real fire response of intumescent painted assemblies.
COBISS.SI-ID: 6789985
The efficiency of strengthening traditionally built three-leaf stone masonry walls with different types of composite reinforced coating has been investigated. Glass fibre grid in single component fibre reinforced mortar and glass fibre fabric in epoxy resin matrix were used as coating materials. Four different coating types have been applied, with coating placed on one or both sides of the walls, anchored or not anchored to the masonry at the corners of the walls. Ten walls have been tested by subjecting them to cyclic shear loading at constant precompression, among them two walls in the original state as the control specimens. Four walls have been first tested up to the occurrence of the first significant damage, strengthened and then re-tested up to collapse, whereas four walls have been strengthened undamaged and tested up to collapse. All walls failed in shear. Significant increase in lateral resistance with regard to control walls was observed in all cases, up to 2.5-4.0-times the resistance of the control walls. The degree of improvement did not depend on the type of coating but on the technology of application. Although the coating increased the rigidity of the walls, displacement and energy dissipation capacities have been also improved.
COBISS.SI-ID: 2073703
The paper presents a comprehensive study on oriented strand boards (OSB) and gypsum fiber boards (GFB) as sheathing materials for light-frame wall elements. The study is based on the experimental results of the research project “Optimization of multistory timber buildings against earthquake impact” (OptimberQuake). In the framework of this project, 20 light-frame wall elements and 58 sheathing-to-framing connections with different layouts have been tested under cyclic and monotonic loading. The experimental results have been analyzed and compared in terms of ductility, energy dissipation as well as deformation, and load-bearing capacity. Furthermore, the performance of the walls was evaluated with the probabilistic approach in accordance with current methodology. For this purpose, a simplified numerical model was used in which the walls were represented by an equivalent nonlinear shear springs. The characteristics of the springs were determined based on the experimental results wherein the response was described by a hysteretic model. As a result of probabilistic analysis, behavior factor (i.e., force reduction factor) was evaluated for walls with different types of sheathing. The analysis of the experimental results and probabilistic approach led to the same conclusions. The results show a comparable cyclic response of timber framed walls covered with OSB or GFB boards in terms of energy dissipation and deformation capacity. The probabilistic assessment also suggests that the same behavior factor can be used for both types of wall if the basic requirements regarding the minimum thickness and detailing of the connections are met. A higher value for the minimum thickness of GFB compared with OSB will be recommended.
COBISS.SI-ID: 2115687