L'objectif de ce travail est d'obtenir, par homogénéisation périodique, des modèles macroscopiques de transfert hydrique dans les milieux poreux partiellement saturés à partir des équations de transfert de l'eau liquide et de vapeur d'eau écrites à une échelle microscopique. La dimensionnalisation des équations fait apparaître naturellement des nombres sans dimension caractérisant les problèmes de transfert hydriques dans les milieux partiellement saturés. Nous nous sommes intéressés à trois différents régimes de transfert (diffusion de vapeur prédominante, couplage diffusion/convection, convection de l'eau liquide prédominante). Pour chaque modèle homogénéisé, nous avons obtenu une expression différente du tenseur de diffusion hydrique homogénéisé. Nous avons ensuite calculé les tenseurs de diffusion hydrique homogénéisés obtenus dans les deux régions hygroscopique et super-hygroscopique, sur des géométries plus ou moins complexes décrivant la microstructure en 2D et 3D. Des comparaisons avec des valeurs expérimentales ont été ensuite effectuées. Pour finir, une résolution numérique de l'équation de transfert hydrique macroscopique homogénéisée a été effectuée en se basant sur les données expérimentales d'un béton BHP. / We propose in this work to construct, by periodic homogenization, macroscopic models of moisture transfer in unsaturated porous media. To do this, the liquid water and water vapor transport equations are averaged from the microscopic scale. The dimensional analysis of transport equations naturally lets appear dimensionless numbers characterizing the moisture transfer in unsaturated porous media. Three different transfer regimes are addressed (predominant water vapor diffusion, coupling diffusion / convection, predominant liquid water convection). For each transfer regime, the associated homogenized moisture diffusion tensor has a different expression. Then, the homogenized moisture diffusion tensors are calculated in both hygroscopic and super-hygroscopic regions on several geometries with varying complexity, describing 2D and 3D microstructures. Comparisons with experimental values are also addressed. Finally, based on experimental data of a BHP concrete, a numerical resolution of the homogenized macroscopic moisture transfer equation is performed.

Moisture damage in asphalt mixes refers to the loss of serviceability due to the presence of moisture. The extent of moisture damage, also called moisture susceptibility, depends on internal and external factors. The internal factors relate to the properties of the materials and the microstructure distribution, while the external factors include the environmental conditions, production and construction practices, pavement design, and traffic level. The majority of the research on moisture damage is based on the hypothesis that infiltration of surface water is the main source of moisture. Of the two other principal mechanisms of water transport, permeation of water vapor and capillary rise of subsurface water, the latter has been least explored. A laboratory test and analysis methods based on X-ray computed tomography (CT) were established to assess the capillary rise of water. The amount and size of air voids filled with water were used in the capillary rise equation to estimate the distribution of the contact angles between the water and the mastic. The results were able to show the influence of air void size on capillary rise and contact angles. The relationship between air void structure and moisture susceptibility was evaluated using a fundamental fracture model based on dissipated energy of viscoelastic materials. Detailed description is provided in this dissertation on the deduction of the model equation, the selection of the model parameters, and the required testing protocols. The model parameters were obtained using mechanical tests and surface energy measurements. The microstructure of asphalt mixes prepared in the laboratory having different air void structures was captured using X-ray CT, and image analysis techniques were used to quantify the air void structure and air void connectivity. The air void structure was found to influence the mix resistance to moisture damage. To validate the fracture model, asphalt mixes with known field performance were tested. The results demonstrated that the fracture model is an effective tool to characterize moisture susceptibility. In addition, the model showed good correlation with the reported field performance of the asphalt mixes. The findings of this study will be useful to highway engineers to evaluate asphalt mixes with alternative mix designs and internal air void structures and to estimate the rate of moisture infiltration in order to maximize the resistance of asphalt mixes to moisture damage.

La durabilité des structures en béton armé ainsi que leur durée de vie sont étroitement liées à la mise en œuvre simultanée de nombreux phénomènes physiques et chimiques. Ceux-ci sont de diverses natures mais restent, en général, fonction des propriétés hydriques des matériaux étudiés. Ainsi, la prédiction des dégradations potentielles d'un matériau cimentaire requiert l'étude du transport de l'eau liquide et des phases gazeuses à travers ce dernier, considéré comme un milieu poreux. En milieu naturel, les structures subissent des variations périodiques de l'humidité relative extérieure (HR). Cependant, la plupart des modèles de transfert hydrique préexistants dans la littérature, s'intéresse uniquement au processus de séchage. Il existe peu de modèles décrivant à la fois l'humidification et le séchage du matériau (ces deux phénomènes se produisent dans le matériau en condition naturelle d'humidité relative (HR)). Tenir compte des phénomènes d'hystérésis dans les transferts hydriques réduit à nouveau le nombre de modèles à disposition. Ainsi, cette thèse s'attache à proposer une meilleure compréhension de l'état hydrique du béton en fonction des variations d'humidité relative extérieure, sur la base d'une nouvelle campagne expérimentale et de modélisations numériques. Un soin sera apporté afin de tenir compte dans les modèles numériques des effets d'hystérésis. Dans ce travail, nous détaillerons, tout d'abord, un modèle multi-phasiques complet. Un modèle simplifié est obtenu, sur la base de considérations théoriques et de vérifications expérimentales dans le cas où la perméabilité intrinsèque à l'eau liquide reste très inférieure à la perméabilité intrinsèque au gaz. Une étude comparative des modèles d'hystérésis couramment utilisés permet d'obtenir un jeu de modèles proposant les meilleures prédictions d'isothermes de sorption d'eau et de leurs hystérésis. Par la suite, le modèle de transport simplifié est couplé avec les modèles d'hystérésis sélectionnés afin de simuler les transferts hydriques dans des bétons soumis à des cycles d'humidification-séchage. La comparaison avec des données expérimentales révèle que la prise en compte de l'hystérésis de l'isotherme de sorption d'eau ne peut pas être négligé. De plus, il est montré que les prédictions obtenues avec des modèles d'hystérésis théoriques, sont les plus cohérentes avec les résultats expérimentaux, en particulier, pour des chemins secondaires d'hystérésis. Plusieurs scénarios (conditions environnementales, bétons différents) sont également simulés. Les résultats obtenus pointent à nouveau la nécessité de tenir compte de l'hystérésis lors de la modélisation des transferts hydriques à travers des matériaux cimentaires soumis à des variations d'humidité relative. La définition d'une profondeur pour laquelle le profil hydrique du béton est modifié par les variations périodiques d'humidité relative permet de mieux comprendre comment la modélisation de la pénétration des espèces ioniques est influencée par les cycles d'humidification-séchage. Par ailleurs, notre analyse révèle qu'il est pertinent de considérer l'effet de Knudsen pour la diffusion de la vapeur afin d'améliorer la prédiction de la diffusivité apparente / The durability of reinforced concrete structures and their service life are closely related to the simultaneous occurrence of many physical and chemical phenomena. These phenomena are diverse in nature, but in common they are dependent on the moisture properties of the material. Therefore, the prediction of the potential degradation of cementitious materials requires the study of the movement of liquid-water and gas-phase transport in the material which is considered as a porous medium. In natural environment, structures are always affected by periodic variations of external relative humidity (RH). However, most moisture transport models in the literature only focus on the drying process. There are few researches considering both drying and wetting, although these conditions represent natural RH variations. Even few studies take into account hysteresis in moisture transport. Thus, this work is devoted to better understand how the moisture behaviour within cementitious materials responds to the ambient RH changes through both experimental investigations and numerical modelling. In particular, hysteretic effects will be included in numerical modelling. In this thesis, we first recalled a complicate multi-phase continuum model. By theoretical analysis and experimental verification, a simplified model can be obtained for the case of that the intrinsic permeability to liquid-water is smaller than the intrinsic permeability to gas-phase. The review of commonly-used hysteresis models enabled to conclude a set of best models for the prediction of water vapour sorption isotherms and their hysteresis. After that, the simplified model was coupled with selected hysteresis models to simulate moisture transport under drying and wetting cycles. Compared with experimental data, numerical simulations revealed that modelling with hysteretic effects can provide much better results than non-hysteresis modelling. Among different hysteresis models, results showed that the use of the conceptual hysteresis model, which presents closed form scanning loops, can provide more accuracy predictions. Further simulations for different scenarios were also performed. All comparisons and investigations enhanced the necessity of considering hysteresis to model moisture transport for varying relative humidity at the boundary. The investigation of moisture penetration depth could provide a better understanding of how deep moisture as well as ions can move into the material. Furthermore, the analysis revealed that the consideration of Knudsen effects for diffusion of vapour can improve the prediction of the apparent diffusivity

The diploma thesis deals with the analysis of temperature and humidity in the construction of flat roofs with influence even without influence of solar radiation. It was necessary to study and verify the properties of building materials, the physical nature of the influence of solar radiation on building structures and the transport mechanisms of moisture. The theoretical part describes the basic physical theory on solved problems, the essence and division of solar radiation, the description of thermal moisture properties of building materials and the calculation method of determination of moisture in structures according to valid standards. Practical part deals with description of work in software DEKSOFT - Thermal technology 1D and WUFI 2D software, description of individual models and analysis of achieved results. At the end of the practical part the achieved theoretical knowledge is validated by analyzing the obtained data from the practical model.

I dagsläget finns en stor mängd byggnader i Sverige där fasaden består av puts direkt anliggande mot antingen lättbetong eller tegel. Dessa fasader kan skapa problem för brukaren p.g.a. fukttransport via putsen direkt in i konstruktionen. Problemen som kan uppstå som följd av dessa konstruktioner är inte bara estetiska utan kan även påverka inomhusmiljön. Syftet med detta arbete var att undersöka om det gick att med ny teknik visa de resultat som framkommit från erfarenheter från praktiskt arbete samt undersöka hur en renovering påverkar de fasader som består av puts direkt mot lättbetong eller tegel. Arbetet har utförts med hjälp av simuleringsprogrammet Wufi Pro för att sedan analyserats med hänsyn till fukttransporter och vatteninnehåll. Resultaten som framkommit påvisar en förhöjd risk för problem med de ursprungliga fasaderna samt slutsatsen att en renovering enligt ett av de två förslagen är att föredra. / Today there’s a great deal of buildings in Sweden where the facade is constructed by plaster directly connected to either aerated concrete or masonry brick. These facades could create problems for the user on accord of the moisture transport via the plaster directly into the construction. The problems that could follow these types of facades aren’t just esthetical but could also affect the indoor environment. The purpose with this study was to examine if it would be possible using today’s technology to show the results coming from past experiences by practical work, and at the same time examine how a remodel affects the facades that consists of plaster directly on aerated concrete or masonry brick. The work has been conducted with the simulation program Wufi Pro, later to be analyzed  according to moisture transport and water content. The results that came from this has shown an increased risk for problems with the original facades and at the same time that a remodel according to one of the two proposed remodel ways to prefer.

Prestressed concrete is a popular construction material for highway bridges. A variety of girder span values, cross-sectional shapes, and prestressing strand layouts has been used in bridges across the United States. A major concern for such bridges is the possibility of corrosion damage in the prestressing strands or reinforcing bars, which is commonly caused by the use of deicing salts on the deck or saltwater spray in coastal regions. The present study aims at establishing analytical tools for the accurate simulation of chloride ingress, corrosion and mechanical damage (cracking) in the concrete, and for the evaluation of the impact of corrosion on the flexural and shear strength of bridge girders. First, an efficient and accurate analytical scheme is formulated to enable the calculation of the load-carrying capacity of corrosion-damaged girders. The analyses rely on two types of models, namely, beam models and nonlinear truss models. The latter are deemed necessary to obtain reliable estimates of the shear capacity, as beam models are not well-tailored for capturing shear failures. A procedure to account for the reduction in area and deformability of corroded strands, based on visually observed corrosion damage, is proposed and implemented. The models are calibrated and validated with the results of experimental tests on prestressed girders which exhibited varying levels of corrosion damage. Further analyses allow the comparison of the capacity of corrosion-damaged girders to that of their undamaged counterparts. The accuracy of a simplified procedure, using equations in the AASHTO code to determine the flexural and shear capacity of the damaged girders, is also determined. Subsequently, a computation scheme was proposed to describe the intrusion of chloride ions in prestressed bridge girder sections. The approach accounts for multiple, coupled processes, i.e., heat transfer, moisture transport, and chloride advective and diffusive transport. The constitutive models for moisture and chloride transport rely on previous pertinent work, with several necessary enhancements. The modeling scheme is calibrated with data from previous experimental tests on concrete cylindrical and prismatic specimens. The calibrated models are then validated using data from chloride titration tests conducted on girders removed from two bridges in Virginia after 34 and 49 years of service. The results indicate that the proposed framework can accurately reproduce the experimentally measured chloride content. The modeling approach also allows the evaluation of the accuracy of simplified, design-oriented tools for estimating the evolution of chloride content with time. The multi-physics simulation scheme is further refined to account for the corrosion-induced mechanical damage (cracking), by incorporating a phenomenological description of the electrochemical reaction kinetics, generation of expansive corrosion products, and subsequent development of tensile stresses and cracking in the surrounding concrete. The impact of cracking on the chloride and moisture transport mechanisms is also taken into account. The last part of this dissertation pursues the quantification of the uncertainty governing the chloride ingress in bridge girders, through the use of a stochastic collocation approach. The focus is on understanding how the inherent uncertainty in the value of input parameters (e.g., material transport parameters, ambient conditions etc.) is propagated, leading to uncertainty in the evolution of chloride content and the expected corrosion initiation time for a given bridge. / Doctor of Philosophy / Prestressed concrete is widely utilized in the construction of highway bridges in the United States. A significant concern arises regarding potential corrosion damage in the prestressing strands or reinforcing bars, which is commonly attributed to the application of deicing salts on the deck or exposure to saltwater spray in coastal regions. This study aims to develop analytical tools that can accurately simulate the intrusion of corrosive agents (namely chloride ions), and subsequent damage (cracking) in concrete. Furthermore, the research seeks to assess the impact of corrosion on the bearing capacity of bridge girders. Two different classes of analytical approaches are pursued. The first class employs purely mechanical (stress/deformation) models for capturing the strength, deformability and failure modes of girders with visual corrosion damage. These models rely on two approaches to capture the flexural and shear capacity of specimens, namely, beam-based models and truss-based models. The impact of corrosion is established through appropriate modification of the model parameters, based on the extent of visually observed corrosion damage. The analytical approaches are validated through a series of experimental tests previously conducted on corrosion-damaged girders. The second class of analytical approaches employs multi-physics models, to describe the mechanisms leading to corrosion-induced damage. The models account for heat transfer, moisture transport, and chloride transport in prestressed beam sections. Model parameters are calibrated with experimental tests in literature. The computational scheme is used to quantitatively describe the chloride ingress on bridge girders decommissioned from two different bridges in Virginia, after 34 and 49 years of service. The analysis results are found capable of capturing the actual chloride content at various depths from the exposure surface, as determined by chloride titration tests. The temporal evolution of chloride on the surface of prestressing strands indicates that corrosion has been taking place over a period of time for the two bridges. The multi-physics simulation approach is further enhanced to account for the corrosion-induced mechanical damage (cracking), by explicitly incorporating a description of the reaction kinetics, generation of expansive corrosion products and subsequent development of cracking in the surrounding concrete. The last part of this dissertation pursues the quantification of the uncertainty in the expected service life of prestressed concrete bridge structures. Given the inherent uncertainty to key values of model parameters, a parametric study is employed to investigate the propagation of uncertainty to the time history of chloride content at particular locations of the section and the probability of corrosion initiation at specific age values.

[pt] A dissertação apresenta um estudo da resolução de problemas de acoplamento termo-hidráulico através do uso técnicas numéricas. O estudo tem por objetivo a validação de implementações de efeitos de gradientes de temperatura no fluxo de umidade. Para isto utiliza-se o programa UNSATCHEM- 2D que simula o fluxo bidimensional de umidade em meios de saturação variável, transporte de calor, transporte de CO2 e transporte de solutos. O programa desenvolvido por Simunek e Suarez (1993), possui código aberto (escrito em Fortran 77), onde as equações governantes de fluxo e transporte de calor são resolvidas por elementos finitos. A partir do programa UNSATCHEM-2D, foram realizadas implementações no código a fim de permitir o acoplamento parcial (staggered) do fluxo de umidade e o fluxo de calor que reproduz o fenômeno descrito por de Vries (1958). Paralelamente, desenvolveram-se mudanças no programa MTool(Tecgraf/PUC- Rio), utilizado como pré- e pós-processador. Posteriormente, foram validadas as implementações realizadas no programa comparando-se os resultados da solução numérica com resultados experimentais a partir de um ensaio de coluna (Bach, 1989), com resultados considerados satisfatórios. Finalizando, são apresentadas simulações com fontes de calor interna e externa paralelamente com o emprego de condições de contorno atmosféricas que simulam coberturas de resíduos de minério. / [en] The dissertation presents a study of the resolution of thermo-hydraulic coupling problems, through the use of numerical techniques. The study has the objective the implementations validation of the temperature gradients effects in the moisture flux. For this, the program UNSATCHEM-2D is used to simulate the flow of water in mediums of variable saturation to two dimensions, transport of heat, transport of CO2 and solute transport. The program developed by Simunek and Suarez (1993), has open code (written in Fortran 77), where the governing equations of flow and transport of heat are solved for the method of the finite elements. Starting from the original program UNSATCHEM-2D, alterations were carried out in the code in order to allow the partial coupling (staggered) of moisture flow and heat flow as described by de Vries (1958). In parallel, changes were developed in the software MTool (Tecgraf/PUC-Rio), used as pre- and posprocessor. Later, the modifications carried out in the program were validated by the comparison of the numeric solution results with experimental results starting from a column test (Bach, 1989), with acceptable results. Concluding, simulations are presented with internal and external sources of heat together with the use of atmospheric boundary conditions, one that simulates covers for mining wastes.

Quatre événements El Niño extrêmes ont eu lieu durant les cinq dernières décennies (1972/1973, 1982/1983, 1997/1998 et 2015/2016) et étaient caractérises comme forts dans la région Niño 3.4. Ils présentent des différences significatives dans leur évolution qui induisent des anomalies distinctes de précipitations le long du versant Pacifique Péruvien illustrant la non-linéarité de la téléconnexion ENSO sur les précipitations dans cette région. Les pluies extrêmes ont un impact néfaste sur la population et les secteurs productifs en raison des inondations et des glissements de terrain qui s'ensuivent. Néanmoins, à ce jour, les patrons de circulation climatique clé de leurs évolutions et magnitudes différentes sont encore très peu connus. Dans cette thèse, nous montrons que les différentes configurations de précipitations lors de ces événements sont associées au transport de l'humidité provenant de différentes sources d'humidité à grande échelle. Lors des événements 1983-1998 (2016), ils sont respectivement liés à une forte (faible à modérée) humidité provenant du réchauffement du Pacifique (également mais aussi provenant de L'Atlantique via l'Amazonie). La caractéristique de ces transports d'humidité est due à une réponse atmosphérique opposée entre les événements de 1983-1998 (qui sont similaires) et l'événement de 2016 qui présente des patterns de transport d'humidité déphasés. Ces précipitations sont liées à l'humidité provenant de ces sources et la circulation atmosphérique régionale des vents de niveau supérieur (100 à 300 hPa) influe sur la quantité d'humidité qui pénètre dans la région Nord-Centre du versant Pacifique Péruvien. L'interaction de la circulation à grande échelle et régionale et le transport de l'humidité du Pacifique est expliqué par le mode Ep qui est associé à des précipitations dans la région Centre-Nord. La forte dispersion des précipitations dans les régions montagneuses est expliquée par le mode Cp pendant les phénomènes El Niño modérés (extrêmes) et est liée au transport d'humidité de niveau moyen-bas (haut) de l'Amazonie (Pacifique) atteignant les hautes terres. / Four strong El Niño events took place within the last five decades (1972/1973, 1982/1983, 1997/1998 and 2015/2016) recorded as strong in the Niño 3.4 region. They can exhibit significant differences in their evolution associated with a distinct rainfall anomaly evolution along the PPB (Peruvian Pacific Basin), which illustrates the strong nonlinearity of the ENSO teleconnection on the rainfall in this area. These extreme rainfalls have harmful impacts on the population and productive sectors due to floods and landslides which are trigged by them. Yet the key climatic circulation pattern for their different evolution and magnitude are still unknown. Here we show that different rainfall patterns during these events are associated with moisture transport originated from different large-scale moisture sources. For example, in the 1983 -1998 (2016) events appear as related with strong (weak to moderate) moisture coming from the Pacific warming (also coming from Atlantic Ocean through the Amazon basin). Characteristic of these moisture transports is due to an atmospheric response opposite between the 1983-1998 events (that are similar) and 2016 event experiencing out-of-phase moisture transport patterns. Although these rainfalls are linked to the moisture arrival from those sources, the moisture amount entering the PPB can be also influenced by regional atmospheric circulation of upper level winds (100 to 300 hPa) leading to different enhanced moisture transport associated with different rainfall anomalies in the North-Centre PPB. The interplay of large-scale and regional circulation and Pacific moisture transport explains the Ep mode associated with rainfall in the north-Centre PPB. The high dispersion of rainfall in highlands (Cp mode) during the moderate (extremes) El Niño appears as linked to low-middle (high level) moisture transport from the Amazon (Pacific) reaching highlands.

Funktionskläder utgör idag en stor marknad över hela världen med stigande efterfrågan där syntetiska material står för en betydande andel av de producerade textilierna. Ett plaggs totala miljöpåverkan kan till stor del härledas till materialvalet. Materialkompositionen i underställ består ofta av blandningar av textila fibrer, vilket komplicerar återvinningsprocessen och gör den nästintill omöjlig. För att kunna 'sluta cirkeln' måste innovativa textila lösningar tas fram för att styra textilindustrin i rätt riktning. Studien undersöker alternativa fibrer och jämför dem med de konventionella för textilier till underställ där man vill uppnå god fukttransport och värmeisolering. Vidare kartläggs materialens användningsområden för att skapa ett mångsidigt funktionsplagg och därmed möjliggöra en klimatsmartare garderob. Studien identifierar och jämför de termofysiologiska egenskaperna hos materialen bambuviskos, merinoull, Tencel, PCM och Coolmax. Textilprover stickades i hundraprocentiga materialkompositioner med en utvald trikåbindning i en rundsticksmaskin. Textilprovets termofysiologiska egenskaper utvärderades med hjälp av testutrustningarna Hudmodellen och WickView för att bestämma värmemotstånd och fukttransport. Därefter analyserades resultaten på materialens termofysiologiska komfort för att sedan kartlägga deras användningsområde baserat på aktivitetsnivå och omgivningsfaktorer. Resultaten från studien indikerar att merinoull och Coolmax kan rekommenderas för användning i underställ där både värmeisolering och fukttransport är viktiga, där merinoull är mest lämplig för kalla klimat. Vidare kan bambuviskos och Tencel vara lämpliga alternativ för användning i underställ vid aktiviteter av måttlig intensitet i varierande klimatförhållanden. PCM, med sitt låga värmemotstånd och medelhöga fukttransport, gör materialet mindre lämpligt för underställ. Testresultaten från studien ger insikt i materialens termofysiologiska komfort, men bör inte ses som en heltäckande bild av denna komfort. För att erhålla en mer valid slutsats krävs ytterligare tester och beaktande av fler faktorer. / Functional clothing represents a significant global market with rising demand today, where synthetic materials account for a considerable proportion of the textiles produced. A garment's total environmental impact can largely be traced back to the choice of material. The material composition of base layers often consists of mixtures of textile fibers, which complicates the recycling process and makes it almost impossible. To 'close the loop', innovative textile solutions must be developed to steer the textile industry in the right direction. The study investigates alternative fibers and compares them with conventional ones for textiles in base layers where effective moisture transport and heat insulation are sought. Furthermore, the areas of use for these materials are mapped out to create a versatile functional garment, thereby enabling a more climate-smart wardrobe. The study identifies and compares the thermophysiological properties of the materials bamboo viscose, merino wool, Tencel, PCM, and Coolmax. Textile samples were knitted in 100% material compositions using a selected tricot stitch on a circular knitting machine. The thermophysiological properties of the textile samples were evaluated using the Skin Model and WickView testing equipment to determine heat resistance and moisture transport. Afterwards, the results on the materials' thermophysiological comfort were analyzed, and their areas of use were mapped out based on activity level and environmental factors. The results from the study indicate that merino wool and Coolmax can be recommended for use in base layers where both heat insulation and moisture transport are important, with merino wool being most suitable for cold climates. Furthermore, bamboo viscose and Tencel could be suitable alternatives for use in base layers for activities of moderate intensity in varying climate conditions. PCM, with its low heat resistance and medium-high moisture transport, makes the material less suitable for base layers. The test results from the study provide insight into the materials' thermophysiological comfort but should not be seen as a comprehensive picture of this comfort. To obtain a more valid conclusion, additional tests and consideration of more factors are required.

Trenden i byggbranschen är att efterfrågan på täta, energisnåla byggnader ökar. Passivhus och andra lågenergikonstruktioner blir vanligare och vanligare. Riskerna med att bygga in organiskt material som trä i dessa konstruktioner har fått branschen att börja titta på alternativa material. Lättbetong är ett material som både har bärande och isolerande egenskaper. Dessutom är det inte organiskt vilket gör det okänsligt för mikrobiell påväxt. Det som är intressant med lättbetong, ur fuktsynpunkt, är att materialet levereras från tillverkare med en stor mängd byggfukt. Våren 2014 färdigställde Bollnäs Bostäder passivhus- projektet Sundsbro i Bollnäs, där lättbetong ingår i utfackningsväggarna. Sett inifrån består väggen av ett tunt lager kc-puts, lättbetong, cellplast, mineralull, kc-baserad grovputs och ytputs. I detta arbete användes projektet i Bollnäs som referensobjekt och en risk- och känslighetsanalys av väggkonstruktionen utfördes. Arbetet utreder risken för fuktrelaterade problem med väggen vid de extra uttorkningsinsatser som vidtogs i referensobjektet och vid normala uttorkningsbetingelser. Vidare utreds vilka parametrar som är viktiga för väggens fuktfunktion och vad man behöver tänka på när man projekterar och bygger i lättbetong. Arbetet har genomförts i samarbete med AK-Konsult Indoor Air AB och deras senior konsult Anders Kumlin. Fuktberäkningsprogrammet WUFI Pro 5.3 har använts för simuleringar. Beräkningarna gjordes endimensionellt på väggkonstruktionen. Resultaten med den ökade uttorkning som utfördes i referensobjektet visar inget högre fuktinnehåll längst ut i väggen på grund av byggfukt från lättbetongen som vandrar utåt. Farhågan var att så skulle kunna ske och att det skulle kunna leda till mögelproblem. Däremot visar resultaten att bygg-fukt från putsen kan fukta upp mineralullen. Det finns dock inga kända skadefall av detta slag och därför dras ändå slutsatsen att konstruktionen är riskfri. Tack vare en förutseende fukt-projektering och väl utförd uttorkning eliminerades risken för mögel. Hade inte dessa åtgärder vidtagits så visar resultaten att en liten mängd byggfukt hade kunnat vandra utåt och kondensera i mineralullen under första vintern. Då hade det funnits risk för mikrobiell påväxt. Detta visar att det är av största vikt att utföra en noggrann fuktprojektering vid byggnation av välisolerade hus i allmänhet och i synnerhet när lättbetong används. Lyckligtvis gjordes detta på ett bra sätt i referensprojektet. Känslighetsanalysen visar att isoleringens diffusionstäthet är avgörande för hur stor del av bygg-fukten som kan vandra utåt och därmed hur stor risken för problem blir. Lägre täthet ger större risk och högre täthet reducerar risken. Resultaten visar också att det är viktigt att inte montera täta skikt på insidan för tidigt. Den allmänna rekommendationen från leverantör är att lättbetongen skall torkas till 15 % fuktkvot på 50 millimeters djup innan målning och tapetsering på insida vägg får ske. Studien visar att detta är ett för högt fukttillstånd om det skikt som appliceras på insida vägg är tätt. Lättbetongen bör torkas till 5 % på 50 millimeters djup innan helt täta skikt kan monteras utan mögelrisk. / The trend in the construction industry is that the demand for tight, energy-saving buildings is rising. Passive houses and low energy constructions are becoming more and more common. The risk with using organic material in this type of constructions has made the industry look at alternative materials. Aerated concrete is a material that has both load-bearing and insulating properties. In addition to that it is not organic, which makes it insensitive to microbial growth. What is interesting with aerated concrete, from a moisture point of view, is that the material is delivered from the producer with a large amount of construction moisture. In the spring of 2014, the passive-house project Sundsbro in Bollnäs with aerated concrete in the wall construction, was finished by Bollnäs Bostäder. In this study the project in Bollnäs was used as reference object and a risk- and sensitivity analysis was made. The study examines the risk of moisture related problems with the wall construction during normal dehydration conditions and after the increased dehydration efforts that were taken in the reference project. The study also examines which parameters are important for the moisture function of the wall construction and what you need to think about when you project and build with aerated concrete. The job has been done in cooperation with AK-Konsult Indoor Air AB and their senior consultant Anders Kumlin. The moisture calculation program WUFI Pro 5.3 has been used for simulations. The results with the increased dehydration that was used in the reference project show no increased moisture content in the outer parts of the construction due to construction moisture from the concrete that wanders outwards. The concern was that so could happen and that it would lead to mould problems. However the results show that construction moisture from the exterior plaster can moisten the mineral wool. There are no known damage cases of this sort and therefore the conclusion is that the construction is free of risk. Thanks to a foreseeing moisture projection and a well performed dehydration the risk of mould was eliminated. If these measures would not have been taken, the results show that a small amount of construction moisture could have wandered outwards and condensed inside the mineral wool during the first winter. Then there would have been a risk of microbial growth. This shows that it is very important to carry out a detailed moisture projection when constructing well insulated houses in general and when using aerated concrete in particular. Fortunately this was properly done in the reference project. The sensitivity analysis shows that the diffusion resistance of the insulation decides how much of the construction moisture that can wander outwards and consequently the size of the problem risk. Results also show that it is crucial not to apply sealing layers on the inside of the wall too early. The general recommendation from the supplier is that the aerated concrete should be dried to 15 % moisture ratio on 50 millimeter depth before painting and paper hanging on the interior surface of the wall can be done. The study shows that the concrete still is too damp at that stage if the layer applied on the inside of the wall is impermeable. The concrete should be dried down to 5 % moisture ratio before sealing layers can be applied without mould risk.