Potential improvements in the life-cycle performance of support structures for onshore wind turbines – an interview study in Sweden

Wind energy is one of the fastest growing renewable energy sources thanks to its cost-effectivity and sustainability. This paper investigates how construction and maintenance of support structures for onshore wind turbines can be improved. Interviews were performed to identify potential areas for improvement in design, construction, operation, maintenance, and end-of-life. Defects due to poor detailing in design and construction have been recurring and may have important consequences. More structured data collection during the construction stages and more robust inspection protocols can help to ensure adequate life-cycle performance of the support structures. Possibilities to reuse and recycle foundations by the end of the turbine’s operational lifetime, which remain unexploited and unresearched, are also discussed

Sprickvidd nära armeringsjärn 1 betongkonstruktioner.

Vid nybyggnation av betongkonstruktioner ställs höga krav på livslängd och kvalitet. En starkt bidragande faktor till ökad livslängd för etongkonstruktioner är täckskiktets tjocklek. Ett stort täckskikt skyddar armeringen då det hindrar att karbonatiseringen når in till armeringen. Användandet av större täckskikt resulterar dock i svårigheter att klara dagens krav på maximalt tillåtna sprickvidder. Storleken på sprickvidden är enligt våra normer starkt relaterad till tjockleken på täckskiktet. Stora sprickvidder anses öka risken för armeringskorrosion. Slutresultat vid en projektering blir ofta att en stor mängd extra armering används samt att det täckskikt som vore lämpligt inte kan användas

Real-time monitoring the electrical properties of pastes to map the hydration induced microstructure change in cement-based materials

The effect of the supplementary materials (SCMs) on the moisture content and ion diffusivity at different hydration time is important for the service life modelling of modern concrete. This study designed a simple but valid method to monitor the microstructure change in pastes during hydration. A procedure easy to implement was proposed to detect the water content in pastes. The electrical conductivity of pore solution was evaluated by the evaporable water content in pastes and chemical composition in the binders. Results show that the electrical properties of pastes (conductivity, formation factor and its growth rate) can effectively indicate the hydration reactivity of binder, pore connectivity and volume of pore solution in the hardened pastes. The effect of waterbinder ratio and SCMs on the structure of pastes are effectively indexed by the formation factor which is the conductivity of pore solution divided by that of paste. The inflection point of average growth rate of formation factor is a good index for the final setting of pastes. The relation between volume of evaporable water and formation factor is well demonstrated by the extended percolation theory. The real-time monitored electrical conductivity and formation factor of pastes can be used to calculate the chloride migration coefficient in hardened cement pastes

Intelligent building contract tendering - potential and exploration

Project tendering is the construction business “Tightrope-walking.” It is a time-limited balance act where technical and business specialists find the best technical proposal at the right price. The purpose and aim of this study were to explore artificial intelligence (AI) in the tender work and to identify challenges and possibilities with data-driven decision-making. An AI work support tool was adopted and used to extract and process client requirements. The tool and digital-work procedure were presented and discussed with tender specialists from a large contractor in a workshop. A two-step survey was performed in connection to the workshop, investigating the potential users\u27 insights and attitudes for implementation. The main result and conclusion were that AI and digitalization could support tendering; however, successfully generating business value will require higher levels of digitalization, well-structured databases, and access to historical project data

Moisture and ion transport properties in blended pastes and their relation to the refined pore structure

This paper presents a study of the\ua0moisture transport\ua0properties in blended pastes measured by a new procedure and setup. The dependence of moisture transport coefficient on relative humidity (RH) is confirmed. The differences in the moisture dependency may be due to discrepancies in the critical RH for the\ua0percolation\ua0of liquid. Fly ash and slag increase the percentage of mesopores or “ink-bottle” pores with a\ua0mesoscale\ua0neck and they strongly reduce the pore connectivity in pastes. These effects cause the evident reduction in the moisture and chloride diffusivity. The additional replacement with\ua0limestone filler\ua0has little effect on the pore connectivity. The formation factor controls the moisture transport at the high RH interval, but the volume of small pores (middle capillary and mesopores) is the major determinant at a low RH interval. The relationship between water-binder ratio,\ua0pore structure\ua0and moisture transport or chloride migration coefficient is discussed

Using water vapour and N2 isotherms to unveil effects of SCMs on nanopores and evaluate hydration degree

Nanopores are critical for the durability of cement-based materials, but the refinement of these pores by SCMs is yet to have a clear understanding. This paper studied effects of the water–binder ratio, SCMs and the drying on the distribution of nanopores using water vapour and N2\ua0sorption isotherms. Results show that data of water vapour sorption can be used for a practical evaluation of the hydration degree of SCMs with thermodynamic simulation. Fly ash increases the volume of large gel and capillary pores. It lowers the difference between the sorption of water vapour and N2. Slag evidently refines the nanopores by increasing the volume of ink-bottle gel pores with an interlayer-size neck. A higher\ua0w/b\ua0produces more large pores to reduce the effect of drying. Removal of water induces contraction of interlayer and reduces gel pores volume, which causes large difference between sorption of water vapour and N2

Études expérimentales du transport d'ions dans des matériaux cimentaires en conditions non saturées

Thesis on unsaturated cement materialsThèse sur les matériaux cimentaires en milieux non saturé

Experimental studies of ion transport in cementitious materials under partially saturated conditions

Cement production is responsible for a significant portion of manmade CO2 emissions. This motivates the development of cementitious binders with a lower carbon footprint. Considering the emissions in a longer perspective, the durability of concrete structures is absolutely essential. Most degradation of concrete structures is closely related to both moisture transport and ion transport. Many studies have investigated these areas under saturated conditions. Owing to varying exposure conditions and self-desiccation, most concrete structures undergo large variations in moisture state during their service life. The coupling between ionic transport and moisture transport in cementitious materials under partially saturated conditions is still poorly understood. This project aimed to contribute to the knowledge in this area.Service life models can be used to predict the performance of the material over time, but fundamental understanding of the underlying physical and chemical relations is critical for the development of accurate models. In this project, these physical relations of unsaturated ion transport were studied experimentally. The moisture dependency of ionic diffusion and ionic convection was investigated in two studies. The experimental investigations were performed on mortars with two water to binder ratios (0.38 and 0.53) and with four binders (OPC, 95% OPC + 5% silica fume, 60% OPC + 40% GGBFS, and 30% OPC + 70% GGBFS). In the diffusion study, resistivity measurements and the Nernst-Einstein equation were used to evaluate the moisture dependency of the chloride diffusion coefficient, i.e., DCl(RH) and DCl(S). Desorption isotherms were determined using a gravimetric box method, and the conductivity of pore solutions was evaluated in two different ways. First, a simplified method was used. The limitation of this method is that it can only assess the pore solution composition for the OPC mortars. Second, a thermodynamic modeling tool, GEMS, was used to assess the pore solution composition and the chloride diffusion coefficient for all mortars. It was found that DCl(S) is independent of w/b, but the relation differs between binders, and for the individual binders, there seems to be a relation between DCl(RH) and the desorption isotherm.Convective ion transport is more complicated to study because it is difficult to decouple ionic transport from moisture transport. For cementitious materials, it is difficult, or maybe impossible, to design an experimental setup where the ionic species are affected by convective transport only. Cementitious materials are by definition reacting with water, and therefore, there will be interactions between the solid phases and the pore solution, especially under non-saturated conditions. Wick action experiments in combination with measurements of material properties were chosen for the investigation of convective ion transport. Chloride profiles and moisture profiles were evaluated with microXRF and 1H NMR relaxometry, respectively. The measured profiles were discussed in relation to the moisture dependent material properties, such as chloride diffusion coefficients, moisture diffusion coefficients, chloride binding capacities, and desorption isotherms. It was concluded that there is a large variation in moisture dependency of the moisture diffusion coefficient, and that the variation cannot be related to the desorption isotherms. It was also shown that the composition of the binder is the key factor affecting the chloride penetration depth. The measured material properties are important parameters for prediction of chloride ingress and all are strongly affected by the binder composition

Se mig! Jag vill vara med : En litteraturstudie om närståendes upplevelse av delaktighet i somatisk vård

Syfte: Beskriva närståendes upplevelser av delaktighet i den somatiska vården. Bakgrund:När en människa drabbas av sjukdom blir även de närstående påverkade. Sjuksköterskans rollär att identifiera de närståendes behov och göra dem delaktiga i samband med att patientendrabbats av ohälsa. Sjuksköterskan kan göra detta bland annat genom att ge information,rådgivning och handledning. Metod: Studien genomfördes som en allmän litteraturstudie.Resultat: Sjukvårdspersonalens bemötande hade inverkan på de närståendes upplevelser avdelaktighet. De närstående ville bli respekterade och uppmuntrade av sjukvårdspersonalen.Flera kände ett missnöje med den information de fick, och på det sätt de fick den. De villehjälpa sjukvårdspersonalen, som verkade stressad, och medverkade därför iomvårdnadsarbetet. De närstående ville hjälpa till dels för att känna sig tillfredsställda, menäven för att kunna kontrollera att patienten fick rätt vård. Diskussion: Sjuksköterskan kanarbeta utifrån Calgarymodellen för att få förståelse för de närståendes behov av att få varadelaktiga och vilken roll de kan spela i omvårdnaden. Genom samtal och information kandetta åstadkommas. Konklusion: Det kan antas att närstående, oavsett vart de befinner sigoch oberoende av vårdverksamhet, har behov av information och delaktighet.The aim of this literature study was to describe relatives’ experience of participation insomatic care. Background: When a person gets struck by disease, the family will alsobecome affected. The nurses roll is to identify the relatives’ needs and make them a part of thepatients care. The nurse can do this in form of information, counselling and coaching.Method: This study was made as a general literature review. Result: The staffs’ treatmenthad influence on the relatives’ participation experience. The relatives wanted to beencouraged and respected by the staff. Many felt dissatisfied with the information they got,and in what way they got the information. The relatives wanted to help the staff with thenursing job, partly for their own satisfaction, but also to make sure that the patient got theproper care. Discussion: The nurse could follow the Calgary model. This would make iteasier understanding the relatives need for participation, and their part of the caring process.This can be achieved by conversation and information. Conclusion: It is assumable thatrelatives, regardless of where they are located or in what practice, have need of informationand participation