| 1. |
- Carneiro, Erica, et al.
(författare)
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Potential improvements in the life-cycle performance of support structures for onshore wind turbines – an interview study in Sweden
- 2022
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Ingår i: Proceedings of XXIV Nordic Concrete Research Symposium.
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Konferensbidrag (refereegranskat)abstract
- 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.
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| 2. |
- Cusumano, Linda, 1981, et al.
(författare)
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Current benefits and future possibilities with digital field reporting
- 2024
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Ingår i: International Journal of Construction Management. - 1562-3599. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- Mobile phones and tablets enable contractors to digitally collect large amounts of production remarks and facilitate the acquisition. The increased data access and machine learning techniques allow the construction industry to take a significant step forward in shifting from implicit to explicit knowledge. However, this step requires both standardisation and data quality assurance combined with project incitements ensuring continuous data collection. Therefore, this study examines the current data quality and standardisation of inspection data generated using the production software Dalux Field, mining a dataset of more than 95000 production issues. Additionally, a survey of production software users assesses project and project member benefits and future possibilities with digital inspection reporting. The results show considerable benefits with digital inspection reporting, such as time savings, cost reductions and increased general quality control. However, the standardisation in reporting between projects and team members is low. Finally, this paper suggests methods for improving data quality and standardization for automation of the data analysis, allowing new projects in project-based organisations to benefit from previous project experiences.
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| 3. |
- Cusumano, Linda, 1981, et al.
(författare)
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Current benefits and future possibilities with digital field reporting
- 2024
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Ingår i: INTERNATIONAL JOURNAL OF CONSTRUCTION MANAGEMENT. - 1562-3599 .- 2331-2327.
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Tidskriftsartikel (refereegranskat)abstract
- Mobile phones and tablets enable contractors to digitally collect large amounts of production remarks and facilitate the acquisition. The increased data access and machine learning techniques allow the construction industry to take a significant step forward in shifting from implicit to explicit knowledge. However, this step requires both standardisation and data quality assurance combined with project incitements ensuring continuous data collection. Therefore, this study examines the current data quality and standardisation of inspection data generated using the production software Dalux Field, mining a dataset of more than 95000 production issues. Additionally, a survey of production software users assesses project and project member benefits and future possibilities with digital inspection reporting. The results show considerable benefits with digital inspection reporting, such as time savings, cost reductions and increased general quality control. However, the standardisation in reporting between projects and team members is low. Finally, this paper suggests methods for improving data quality and standardization for automation of the data analysis, allowing new projects in project-based organisations to benefit from previous project experiences.
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| 4. |
- Cusumano, Linda, 1981, et al.
(författare)
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Intelligent building contract tendering - potential and exploration
- 2022
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Ingår i: IABSE Symposium Prague, 2022: Challenges for Existing and Oncoming Structures - Report. - Zurich, Switzerland : International Association for Bridge and Structural Engineering (IABSE). ; , s. 1902-1909
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Konferensbidrag (refereegranskat)abstract
- 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' 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.
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| 5. |
- Cusumano, Linda, 1981, et al.
(författare)
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Natural language processing as work support in project tendering
- 2022
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Ingår i: Current Perspectives and New Directions in Mechanics, Modelling and Design of Structural Systems. - London : CRC Press. - 9781003348443 ; , s. 1583-1588
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Konferensbidrag (refereegranskat)abstract
- When producing a tender, contractors manually analyze client requirements contained within many different text documents. The combination of requirements lead to crucial design decisions and every decision is related to costs and risks. This study explores the possibility of making the client requirement analysis in design-bid contracts automated to reduce the risk of conceptual design mistakes. The research approach chosen includes developing a work support tool based on natural language processing and analyzing its usefulness through a combination of surveys and a workshop for tendering specialist. The results show that applying digitalized working methods and using artificial intelligence in the tender phase can enable data-informed decision making and generate benchmarking and risk management opportunities. The study contributes to insights regarding automation and digitization possibilities in tender projects and how artificial intelligence tools can be designed for supporting data-driven decisions.
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| 6. |
- Huang, Liming, 1993, et al.
(författare)
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Moisture and ion transport properties in blended pastes and their relation to the refined pore structure
- 2022
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 161:106949
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a study of the moisture transport properties 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 percolation of liquid. Fly ash and slag increase the percentage of mesopores or “ink-bottle” pores with a mesoscale neck 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 limestone filler has 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, pore structure and moisture transport or chloride migration coefficient is discussed.
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| 7. |
- Huang, Liming, 1993, et al.
(författare)
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Non-destructive test system to monitor hydration and strength development of low CO2 concrete
- 2023
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Ingår i: Construction and Building Materials. - 0950-0618. ; 408
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Tidskriftsartikel (refereegranskat)abstract
- Application of supplementary cementitious materials for production of low CO2 concrete affects the reaction kinetics, which alters the setting time and strength development. The different early-age behavior is of concern for quality control of concrete. Non-destructive test is very useful for monitoring the quality of low CO2 binder systems. This paper presents a new technique to monitor the electrical conductivity and temperature at different depths of hydrating concrete. Indices from monitoring system (conductivity, maturity and formation factor) are compared with data from widely-used methods (ultrasonic pulse velocity, penetration resistance and isothermal calorimetry). Results show that indices from the system can replicate the hydration evolution, setting time and compressive strength of low CO2 concrete. Electrical conductivity of concrete is very sensitive to mineral reactions and it reflects the hydration kinetic consistent with evolution of heat release. Linear correlations are found for penetration resistance in relation to ultrasonic pulse velocity, formation factor and maturity, respectively. The effects of binder type and water-to-binder ratio on hardening are strongly dependent on temperature. The proposed approach enables to include all these factors in characterizing the hardening process of concrete onsite. It is shown that formation factor performs better than ultrasonic pulse velocity on indicating the setting process. Formation factor is also a good parameter for quantitative description of compressive strength development, which is independent of the binder types, mixture proportions and curing ages.
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| 8. |
- Huang, Liming, 1993, et al.
(författare)
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Real-time monitoring the electrical properties of pastes to map the hydration induced microstructure change in cement-based materials
- 2022
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Ingår i: Cement and Concrete Composites. - : Elsevier BV. - 0958-9465. ; 132
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Huang, Liming, 1993, et al.
(författare)
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Using water vapour and N2 isotherms to unveil effects of SCMs on nanopores and evaluate hydration degree
- 2023
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Ingår i: Cement and Concrete Research. - : Elsevier BV. - 0008-8846. ; 164:February 2023
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Tidskriftsartikel (refereegranskat)abstract
- 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 sorption 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 w/b produces 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.
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| 10. |
- Olsson, Nilla
(författare)
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Experimental studies of ion transport in cementitious materials under partially saturated conditions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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