Erika Holt - Academia.edu (original) (raw)
Papers by Erika Holt
EPJ Nuclear Sciences & Technologies, 2022
EPJ Nuclear Sciences & Technologies
Before the final disposal of radioactive wastes, various processes can be implemented to optimise... more Before the final disposal of radioactive wastes, various processes can be implemented to optimise the waste form. This can include different chemical and physical treatments, such as thermal treatment for waste reduction, waste conditioning for homogenisation and waste immobilisation for stabilisation prior to packaging and interim storage. Ensuring the durability and safety of the waste matrices and packages through performance and condition assessment is important for waste owners, waste management organisations, regulators and wider stakeholder communities. Technical achievements and lessons learned from the THERAMIN and PREDIS projects focused on low- and intermediate-level waste handling is shared here. The recently completed project on Thermal Treatment for Radioactive Waste Minimization and Hazard Reduction (THERAMIN) made advances in demonstrating the feasibility of different thermal treatment techniques to reduce volume and immobilise different streams of radioactive waste ...
VTT Technical Research Centre of Finland, 2009
Safety of nuclear waste disposal, Nov 10, 2021
In the study the CO 2-emissions of two real buildings (apartment and office building) were calcul... more In the study the CO 2-emissions of two real buildings (apartment and office building) were calculated during the whole service life of the buildings. The construction phase, use phase, maintenance and the demolition phase were separated. The construction phase was further divided into construction materials and site operations. From the construction materials special attention was focused on the precast concrete elements In near future, significant changes are expected to take place in the heating energy consumption of buildings as well as on the CO 2-emissions profiles of the energy. In the study these future changes in energy consumption and in CO 2-profile were evaluated. In addition to changes in energy, future development in the production of building materials was estimated. The results show that the share of the use phase will significantly decrease due to the changes in energy consumption and in the CO 2-profiles of energy. However, the use phase still remains the biggest source of CO 2-emissions of the building.
Three of the five demonstration plugs within the DOPAS project had extensive monitoring systems i... more Three of the five demonstration plugs within the DOPAS project had extensive monitoring systems installed to evaluate material and structural performance. The massive full-scale tunnel end plugs were placed in-situ and their performance was evaluated for both the earlyand late-ages. The evaluated properties included aspects of concrete hydration, such as temperature rise, as well as any potential responses of the structure and materials to accelerated pressurization to simulate the design-life. Concrete structural monitoring includes properties such as strain and displacement, while the total and water pressure are evaluated behind and around the plug, and in some cases within a bentonite clay layer. The selection of monitoring systems, including both sensors and data collection, has provided insight which can be utilized in various other applications for material performance in challenging environments.
Finland has typically been considered a country with very durable granitic aggregate that is used... more Finland has typically been considered a country with very durable granitic aggregate that is used in a wide range of construction applications. In general, the chemical reaction between Finnish aggregates and their surrounding environment is usually quite low. In this regard, the risk of Alkali Aggregate Reactions (AAR), where the alkalinity of concrete harmfully reacts with certain aggregates to cause expansion and cracking, has been considered negligible in Finland. However, when investigating reinforced concrete infrastructure in Finland for other types of deterioration attack, such as chloride ingress and frost-salt exposure, AAR has been found. AAR deterioration is limited to certain rock types. The geology of Finnish bedrock and soil is well studied and therefore there is a good general view of the composition of aggregates in different parts of Finland. This helps to estimate the potentiality of AAR. AAR has been investigated at VTT-Technical Research Centre of Finland by use of petrographic thin section microscopy. This paper shares the findings of 25 years of review from in-service structures, with respect to ASR findings. In addition, as new alternative hydraulic binders and aggregate sources (including recycled materials) are used in future concrete production, the mechanisms and risks of AAR need to be addressed in Finnish practice. The hope is that by initiating open discussions within Finland and abroad, the potential risk of future AAR deterioration can be evaluated and a process to handle AAR can be created to ensure concrete durability and service life of our structures.
The workshop was held at VTT as part of the Finnish project “Effect of interacted deterioration p... more The workshop was held at VTT as part of the Finnish project “Effect of interacted deterioration parameters on service life of concrete structures in cold environments”. The 3-year project began in 2008 and is funded by Tekes. The goal of the workshop was to share results and experiences on current concrete durability research, especially with regard to correlation of accelerated laboratory tests with real-time field exposure sites. Presentations were given on topics of frost resistance, abrasion, chloride ingress and existing field station data. International researchers were invited to share their expertise and collaboration ideas for future partnerships.
The durability of concrete is traditionally assessed based on the deterioration of a single mecha... more The durability of concrete is traditionally assessed based on the deterioration of a single mechanism. Yet in practice, as a result of varying environmental exposure, concrete is typically affected by several deterioration mechanisms, possibly with synergetic effect on the degradation rate of concrete. Concrete infrastructure located in cold climates has to perform in rather difficult conditions due to the extremely harsh winters. This results in unique combinations of degradation mechanisms. Commonly occurring deterioration mechanisms are freeze-thaw, carbonation and chloride induced corrosion. In light of recent research more attention is now being drawn to assessing coupled deterioration mechanisms. For instance, evaluating how cracks resulting from freeze-thaw influence chloride ingress, or how carbonation changes the surface properties and thereby influencing frost-salt scaling and chloride penetration. In this paper, the results of research projects at VTT based on assessing c...
EPJ Nuclear Sciences & Technologies, 2022
EPJ Nuclear Sciences & Technologies
Before the final disposal of radioactive wastes, various processes can be implemented to optimise... more Before the final disposal of radioactive wastes, various processes can be implemented to optimise the waste form. This can include different chemical and physical treatments, such as thermal treatment for waste reduction, waste conditioning for homogenisation and waste immobilisation for stabilisation prior to packaging and interim storage. Ensuring the durability and safety of the waste matrices and packages through performance and condition assessment is important for waste owners, waste management organisations, regulators and wider stakeholder communities. Technical achievements and lessons learned from the THERAMIN and PREDIS projects focused on low- and intermediate-level waste handling is shared here. The recently completed project on Thermal Treatment for Radioactive Waste Minimization and Hazard Reduction (THERAMIN) made advances in demonstrating the feasibility of different thermal treatment techniques to reduce volume and immobilise different streams of radioactive waste ...
VTT Technical Research Centre of Finland, 2009
Safety of nuclear waste disposal, Nov 10, 2021
In the study the CO 2-emissions of two real buildings (apartment and office building) were calcul... more In the study the CO 2-emissions of two real buildings (apartment and office building) were calculated during the whole service life of the buildings. The construction phase, use phase, maintenance and the demolition phase were separated. The construction phase was further divided into construction materials and site operations. From the construction materials special attention was focused on the precast concrete elements In near future, significant changes are expected to take place in the heating energy consumption of buildings as well as on the CO 2-emissions profiles of the energy. In the study these future changes in energy consumption and in CO 2-profile were evaluated. In addition to changes in energy, future development in the production of building materials was estimated. The results show that the share of the use phase will significantly decrease due to the changes in energy consumption and in the CO 2-profiles of energy. However, the use phase still remains the biggest source of CO 2-emissions of the building.
Three of the five demonstration plugs within the DOPAS project had extensive monitoring systems i... more Three of the five demonstration plugs within the DOPAS project had extensive monitoring systems installed to evaluate material and structural performance. The massive full-scale tunnel end plugs were placed in-situ and their performance was evaluated for both the earlyand late-ages. The evaluated properties included aspects of concrete hydration, such as temperature rise, as well as any potential responses of the structure and materials to accelerated pressurization to simulate the design-life. Concrete structural monitoring includes properties such as strain and displacement, while the total and water pressure are evaluated behind and around the plug, and in some cases within a bentonite clay layer. The selection of monitoring systems, including both sensors and data collection, has provided insight which can be utilized in various other applications for material performance in challenging environments.
Finland has typically been considered a country with very durable granitic aggregate that is used... more Finland has typically been considered a country with very durable granitic aggregate that is used in a wide range of construction applications. In general, the chemical reaction between Finnish aggregates and their surrounding environment is usually quite low. In this regard, the risk of Alkali Aggregate Reactions (AAR), where the alkalinity of concrete harmfully reacts with certain aggregates to cause expansion and cracking, has been considered negligible in Finland. However, when investigating reinforced concrete infrastructure in Finland for other types of deterioration attack, such as chloride ingress and frost-salt exposure, AAR has been found. AAR deterioration is limited to certain rock types. The geology of Finnish bedrock and soil is well studied and therefore there is a good general view of the composition of aggregates in different parts of Finland. This helps to estimate the potentiality of AAR. AAR has been investigated at VTT-Technical Research Centre of Finland by use of petrographic thin section microscopy. This paper shares the findings of 25 years of review from in-service structures, with respect to ASR findings. In addition, as new alternative hydraulic binders and aggregate sources (including recycled materials) are used in future concrete production, the mechanisms and risks of AAR need to be addressed in Finnish practice. The hope is that by initiating open discussions within Finland and abroad, the potential risk of future AAR deterioration can be evaluated and a process to handle AAR can be created to ensure concrete durability and service life of our structures.
The workshop was held at VTT as part of the Finnish project “Effect of interacted deterioration p... more The workshop was held at VTT as part of the Finnish project “Effect of interacted deterioration parameters on service life of concrete structures in cold environments”. The 3-year project began in 2008 and is funded by Tekes. The goal of the workshop was to share results and experiences on current concrete durability research, especially with regard to correlation of accelerated laboratory tests with real-time field exposure sites. Presentations were given on topics of frost resistance, abrasion, chloride ingress and existing field station data. International researchers were invited to share their expertise and collaboration ideas for future partnerships.
The durability of concrete is traditionally assessed based on the deterioration of a single mecha... more The durability of concrete is traditionally assessed based on the deterioration of a single mechanism. Yet in practice, as a result of varying environmental exposure, concrete is typically affected by several deterioration mechanisms, possibly with synergetic effect on the degradation rate of concrete. Concrete infrastructure located in cold climates has to perform in rather difficult conditions due to the extremely harsh winters. This results in unique combinations of degradation mechanisms. Commonly occurring deterioration mechanisms are freeze-thaw, carbonation and chloride induced corrosion. In light of recent research more attention is now being drawn to assessing coupled deterioration mechanisms. For instance, evaluating how cracks resulting from freeze-thaw influence chloride ingress, or how carbonation changes the surface properties and thereby influencing frost-salt scaling and chloride penetration. In this paper, the results of research projects at VTT based on assessing c...