Assessment of the Sustainability of Concrete by Ensuring Performance during Structure Service Life

The article presents an original method to assess the sustainability of concrete. The method uses three parameters, namely, performance, lifetime and environmental impact, to calculate a sustainability index. The originality and simplicity of the proposed method is shown when finding the sustainability index, where the first two factors (service life and performance) are kept constant. This approach is possible within the context of the new proposals that specify the durability of structural concrete in EN 1992 and EN 206. It allows the classification of concrete according to its performance, through environmental action resistance classes (ERC). For this purpose, specific experimental methods were used in order to determine the performance of concrete exposed to carbonation. The concretes were prepared with two cement types with additions (CEM II/A-S and CEM II/A-M (S-LL)). Based on the carbonation resistance classes (first parameter—performance) and exposure classes, the thickness of the concrete cover layer was determined to ensure a certain service lifetime (second parameter—service lifetime). Lastly, the global warming potential was calculated for each composition, allowing the users of the method to select the compositions with the lowest environmental impact.

COATINGS AND PERMANENT MEANS OF ACCESS – THE ANTI-CORROSION CHALLENGES

The introduction of new regulations for Means of Access (MA) has led to an increase in the number and complexity of access openings, an increase in the size of the access openings in the ship’s structure, and a stricter maintenance regime which presents new challenges throughout the life of modern vessels. Several of the major issues at the design stage of Permanent Means of Access (PMA); the construction of ships; the application of protective coatings during new building, together with coating maintenance during the service lifetime; problems related to cleaning holds after cargoes have been removed; action by the Butterworth crude oil washing action and the challenges of maintenance in ballast tanks, are discussed in this paper.

Assessment of the Sustainability of Concrete by Ensuring Performance During Structure Service Life

The article presents an original method to assess the sustainability of concrete. The method uses three parameters, namely: performance, lifetime and environmental impact, to calculate a sustainability index. The originality and the simplicity of the proposed method presented in the article consists in the fact that by applying the relation to determine the sustainability index, the first two factors service life and performance are constant. This approach is possible in the context of the new proposals to specify the durability of structural concrete in EN 1992 and EN 206. That allows classification of concrete according to its performance, through Environmental action Resistance Classes (ERC). For this purpose, specific experimental methods were used in order to determine the performance of concrete exposed to carbonation. The concretes were prepared with two cement types with additions (CEM II / A-S and CEM II / A-M (S-LL)). Based on the carbonation resistance classes (the first constant - the performance) and exposure classes, the thickness of the concrete cover layer was determined to ensure a certain service lifetime (second constant - the service lifetime). Finally, the global warming potential was calculated for each composition, consequently allowing the users of the method, to select the compositions with the lowest impact on the environment.

STUDY ON THE RELATIONSHIP BETWEEN VEHICLE MAINTENANCE AND FUEL CONSUMPTION

A contemporary road vehicle (RV) is a rather complex system, consisting of a large number of subsystems, assemblies, units, and elements (parts). While operating, an RV interacts with the environment, and its elements interact with each other. Consequently, the properties (parameters) of these elements change in the process - hardness, roughness, size, relative position, gapping, etc. A partial solution to the presented problems can be the search for a technique for assessing the RV technical condition by a generalised criterion, which is quite sensitive to changes in the technical state. One of these criteria may be fuel consumption in litres per 100 kilometres. This paper investigates the possibilities of using the fuel consumption indicator as a criterion for assessing the technical condition of the vehicle and the vehicle maintenance and repair technologies have been generalised to obtain a given technical solution. Thus, the possibility of using the fuel consumption indicator as a criterion for assessing the technical condition of the vehicles was explored using the Volkswagen Touran 1.9 TDI operating in urban conditions using a driving cycle. A clear correlation between the fuel consumption and the service lifetime of the vehicle has been established; therefore, it depends on the frequency and quality of the maintenance and repair (MR). The vehicle MR technology has been generalised to obtain a specified technical solution. The process of creating an RV MR Technology model is implemented based on an iterative approach (repetition) with the possibility to specify their features.

Investigating Wear and Predicting Lifetime of the Roller Cavities for the Net-shape Blade Rolling

The die undergoing severe loads which induces inevitably wear in the pressure forming process, and the wear of die arouses obsessions about the die’s service lifetime. In order to obtain the geometrical shape transformation caused by wear and predict the service lifetime for a pair of rollers in net-shape blade rolling process, this paper quantified the distributions and evolutions of the local wear over roller cavities based on the local contact load responses, and predicted the lifetime which related to wear by a mathematical models. Firstly, the net-shape blade rolling process and the local contact load responses were summarized. Then, an improved wear model was provided based on the Archard formula, and the impact factors of the model was standardized by a regression analysis experiment. The transient wear distributions and evolutions over the roller cavities were enumerated, and the wear distribution for one rolling cycle was calculated based on wear accumulation effect. Finally, a lifetime prediction model was proposed to predict the service lifetime of the rollers according to the wear accumulation effect, and an experimental verification was carried out to validate the model. The results showed that the wear model and lifetime prediction model can be used for investigating the wear and lifetime prediction of the roller cavities for the net-shape blade rolling process.

Characterization and Thermal Aging Tests of Cr Based Multilayer for Unconcentrated Solar Thermal Applications

Optical characterization and thermal aging tests are performed on a sputter-deposited coating, consisting of SiO2/Cr2O3/Cr/Cr2O3 layers, designed and developed as a selective solar absorber to be used for unconcentrated solar thermal applications. Both measurements are performed by using a home-made apparatus, which mimics a flat plate collector under high vacuum. A Performance Criterion (PCη(T)), based on absorber efficiency is proposed, and a forecast of service lifetime is obtained. As a result of the thermal aging tests, the selective solar absorber under study appears to be highly efficient at mid temperatures (up to 573 K) and thermally stable at temperatures (up to 690 K).