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| 3. |
- Borg, Mathias, 1970-
(författare)
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Environmental Assessment of Materials, Components and Buildings Building Specific Considerations, Open-loop Recycling, Variations in Assessment Results and the Usage Phase of Buildings
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The building sector is a major contributor to theenvironmental loads generated by the society. The recognitionof this fact by the sector and a general strive toward asustainable society have lead to afocus on different toolsthat can be used to enhance the environmental performance ofthe sector and the society. Life Cycle Assessment (LCA) is oneof these tools. The LCA methodology was initially developed forassessments of short-lived consumer products. The increasinginterest in using the LCA methodology in the context of thebuilding sector has initiated a development of the methodologyto be able to consider the specific characteristics andconsiderations of the building sector. These are specific forthe building sector, but not always unique. Examples ofcharacteristics and considerations are: that each building isunique, the functional output is not always a physical productbut rather a service, the long service lives of buildings.These have implications on several elements in the LCAmethodology. The influenced elements that are dealt with inthis thesis are in particular the modeling of the system, thefunctional unit, boundary setting, life cycle scenarios,scenarios and inventory of the usage phase and allocationprocedures.Buildings and constructions are commonly not static systems.The systems are rather dynamic in the sense that the systemwill provide different services based on the same physicalstructure during its service life. To be able to model thedynamic system sequential life cycle thinking is introduced anda list of topics is derived. The list of topics is a structuredpresentation of issues that are of interest in the pursuit of aflexible LCA methodology. The goal is to find out if amethodological approach is suitable for modeling dynamicsystems with a functional unit that is based on the providedservice rather than the physical building.Boundary setting, life cycle scenarios, allocationprocedures, predicted service life and the modelling of theusage phase are all elements of the LCA methodology that havean potential to influence the result of an LCA in a significantway. The magnitude of the potential influence has beenmonitored based on the results of three case studies, whichhave been elaborated further to be able to estimate themagnitude of the potential influence.There is a multitude of available allocation procedurespresented and used in different contexts. The procedures aredeveloped based on different considerations and with differentintended applications. Two alternative allocation proceduresare presented in this thesis. The first is a proceduredeveloped with multi recyclable materials in mind and it isbased on the recyclability of materials and products. Thesecond procedure is quite recently developed and it is based ona combination of economic parameters and recyclability.The importance of the usage phase for buildings andconstructions has previously been recognised. The maincontributors to the environmental loads generated during theusage phase are energy use, maintenance and emissions fromproducts. It is, however, not very common to consider the usagephase in assessments conducted on materials and components,even though it is stipulated in e.g. ISO 14025 that the wholelife cycle should be considered. A proposal of a model toestimate the environmental loads is, therefore, presented.Keywords:Life cycle assessment, Building materials andcomponents, Buildings and constructions, Allocation, Resultvariation, Usage phase, Energy demand
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| 4. |
- Bryne, Lars-Elof
(författare)
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Aspects on wettability and surface composition of modified wood
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood is often combined with other materials such as thermoplastics, adhesives and coatings. In general, combinations of wood and polymers especially in outdoor exposure have poor long-term durability. This behaviour can be related to an insufficient wood-polymer adhesion due to the low intrinsic compatibility between the wood substance and the polymers used. Another source for woodpolymer de-bonding is the high hygroscopicity of wood and great difference in hygro-thermal properties between the components. The basic conceptual idea related to this work is to reduce the hygrosensitivity of wood by applying different wood modification methods, in particular, acetylation, furfurylation and heat treatment. The effects of such chemical modifications of wood, also accompanied with ageing effects, on its adhesion properties with commonly used synthetic polymers are, however, not well understood. In this context, the over-all purpose of this thesis is to achieve a better understanding of wood-polymer adhesion and interfacial forces which also may guide us to tailor the interaction between modified wood and e.g. thermoplastics and adhesives. The main focus of this thesis is therefore to apply contact angle analysis based on the Chang-Qin-Chen (CQC) Lewis acid-base model in order to estimate the work of adhesion (Wa) between the wood, modified wood and certain polymers. Contact angle measurements on wood samples were performed based on the Wilhelm plate principle. Related to this, an effort was also made to characterize the studied modified wood surfaces according to morphology and chemical composition. The methods that have been used are low vacuum scanning electron microscopy (LV-SEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Results show that so-called interaction parameters can be successfully estimated for prediction of Wa between wood and polymers using the applied CQC model. Furthermore, such wetting analysis was successfully related to spectroscopic findings of the chemical composition of the wood samples surface. Ageing effects, i.e. the time after preparation of the wood surface, play a central role for the surface characteristics. In most cases, ageing resulted in a significant decrease of Wa between wood and water and a moderate decrease between wood and thermoplastics. The surface characteristics of acetylated wood were, however, more stable over time compared to unmodified, furfurylated and heat treated wood. The predicted Wa with the adhesives for heat treated and acetylated wood was increased due to ageing. Future work is planned to involve studies in order to relate such predicted adhesion properties with the actual performance of various wood-polymer systems.
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| 7. |
- Ekstedt, Jan, 1946-
(författare)
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Studies on the barrier properties of exterior wood coatings
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Coatings for exterior wood have two basic functions. One isto give an aesthetically acceptable surface appearance andcolour. The other is to provide protection against wooddegradation by microbiological or physical attack. Theseprotective properties, often called the barrier properties,play an important role in the selection of proper material forsupreme durability. The assessment of these barrier propertiesis of great importance. Within the CEN Technical Committee 139,Working Group 2, Coatings for exterior wood test methods andperformance specifications have been established. Forassessment of water protection efficiency a standard testprocedure, EN 927-5, has been launched. The present work hasfocused on its applicability in assessing water protectionefficiency in relation to the degradation of coatings duringexposure.Assessments according to EN 927-5 is shown to givesignificant differences in water absorption values fordifferent types of coatings on wood. The proposed performancespecifications in ENV 927 - 2 for the water absorption valuesfor coatings to be used in different constructions seem to beset at acceptable levels. It has been shown that there is agood correlation between the level of water absorption andpractical experience of the performance of paints inScandinavia. However, it has also been shown that thecombination of a standard procedure for water absorptionmeasurement and an artificial weathering procedure gives moreinformation regarding expected durability and longtermperformance than a single measurement of water absorption onfresh, unweathered coated wood. A combination of waterabsorption measurement and artificial weathering could become auseful tool in product development as well as in benchmarking.Together with statistical tools, such as reliability-basedservice life prediction methodologies for predicting theservice life of coating systems a reduction in testing timesmay be achieved.Surface-active substances in coatings have a negative effecton the coatings ability to prevent water ingress, which mostprobably is due to the hydrophilic character of thesesubstances. The presence of these substances, which are commonin waterborne coatings, alters the moisture sorptioncharacteristics of wood. Considering that these substancesoccur in waterborne coatings, may be mobilised during and afterfilm formation and accumulate at the coating/substrateinterface, there is a great probability that these substanceschange the moisture sorption characteristics of the woodsubstrate in an unfavourable way and create unexpected dynamicmoisture conditions at the coating/wood interface.Computerized tomography has been found to be a valuable,non-destructive tool for visualising the spatial moisturedistribution of water and moisture in coated wood panels. Themethod is suitable for recurrent testing of a specimen exposedto a series of processes of wetting, drying. This thesis showsthat high moisture contents occur locally at and around cracks.In these areas there is an increased risk of internal tensionand stress resulting in crack initiation and propagation andthat high moisture contents may occur in the first fewmillimetres under waterborne coatings despite intact coatingfilms. Even with good barrier properties of the coating,moisture may accumulate by water-vapour absorption in air gapsbehind the cladding thus causing favourable conditions formicrobiological colonization.The work that has been carried out regarding assessment ofthe water protection efficiency shows promising resultsregarding the possibility to use reliability-based service lifeprediction methodology for the assessment. The aim of futurework will be to establish more reliable techniques andprotocols for assessing service life expectancy and durability,especially for waterborne coatings with special focus ontendencies to early failure and robustness of the coatingsystems.Keywords:Coatings, surfactants, water absorption value,EN 927, paint, additives, moisture dynamics, absorption,desorption, artificial weathering, artificial exposure,computerized tomography, MRI.
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| 8. |
- Erlandsson, Martin, 1966-
(författare)
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A blueprint for sustainable consumption and design including performance requirements
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A Sustainable Consumption Evaluation(SCE) system framework is developed which is based on anextension of current LCA methodology. The SCE system results inEnvironmental Performance Requirements(EPR's) as the key means for its implementation insustainable design that can be used for product orproduct-service system benchmarking, monitoring and evaluation.The use of EPR's follows an already well-known managementsystem, which means that they will, when applied in design, behandled together with other functional aspects. The SCE systemalso makes it possible to determine whether an individual'slifestyle is sustainable, in the respect that it meets theperformance defined in a so-calledreal-vision, while however being conscious of itsrestrictions.A holistic way to describe the burden of the environmentalimpact is to focus on the consumption from an individual'sperspective. This way of analysing the problem provides theopportunity to evaluate the improvements that can be achievedby changing our lifestyle and our consumption patterns withinthe socially, economically and technically feasiblealternatives. Therefore, in this thesis, it was foundappropriate to divide the consumption into a number of superiorso-calledlife-supporting services(LSSs). Since these LSSs are analysed in a life cycleperspective, they cover all environmental impacts caused bymankind.To illustrate a sustainable development, a holistic,realisable, future scenario - a real-vision -is elaboratedaccording to the SCE system framework. From this real-vision itis then possible to define acceptable impact permits dividedinto a number of LSSs. The real-vision takes part in aprocedure performed in order to define the EPR's that includethe aimed LSSs in terms of being ecologically sustainable,economically as well as technically realistic, and sociallyacceptable (including ethical impacts).To make an assessment of what is ecological sustainabilitypossible, anEnvironmental Quality Objective(EQO) normalisation procedure is introduced. The developednormalisation procedure facilitates the reporting of differentimpact categories in a common unit that is achieved withoutincluding direct value choices. When the EQO normalisation isutilised, no limitation concerning public communication of theresult and its applications exists, according to the ISO 14 042regulation.The result of the developed framework composes a proactivedesign tool, as well as a concurrentclassification system, if verified by the EPR. The real-vision defines the EPRsaccording to environmental class A - Sustainable. In additionto class A, it is possible to define an environmental class C -Acceptable, which means that the EPRs agree with today's praxisor comply with some regulation or standard. The environmentalclass B - Environmentally Sound is between class A and C, butstill represents a relatively ambitious performance.Further, the outlined SCE system framework is specified andput into practice by an implementation of theLSS Living. Already accomplished consensus work that is accepted inSweden is utilised as a basis to define operationalmarket-based EPRs. The EPR category included and elaborated isImpact EPRs, which demonstrate the most innovative part of theSCE system. Impact EPR corresponds to what is often referred toas an environmental profile according to the LCA methodology.If the EPR for LSS Living according to environmental Class A -Sustainable is applied, this should result in a reduction ofabout 50 % of the current environmental impact.Key words:Classification system, Environmental QualityObjective (EQO); EQO normalisation, Environmental PerformanceRequirement (EPR); Life Cycle Assessment (LCA); Life-SupportingService (LSS); living; real-vision; sustainable consumption;Sustainable Consumption Evaluation (SCE); sustainableconsumption; sustainable design.
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| 9. |
- Ghafoori Roozbahany, Ehsan, 1982-
(författare)
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Flow behavior of asphalt mixtures under compaction
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Asphalt compaction is one of the most important phases of road construction, being the decisive phase when the structure of the asphalt pavement layer is formed. In spite of its importance, the knowledge about this construction phase is still based on empirical and technological background and therefore surprisingly limited. This lack of knowledge is also due to the fact that the existing laboratory scale compaction devices for mix design are not fully capable of simulating the field compaction. The simulation of asphalt compaction in the laboratory is normally focused on the vertical rearrangements of asphalt particles whereas the flow behavior of these particles in other directions is mostly neglected. However, existing literature suggests that the neglected flow is one of the most important factors for the quality of the road construction, particularly in special cases such as asphalt joints. Therefore, building up a better understanding of the flow behavior of asphalt mixtures subjected to compaction loads is needed for improving the quality of the pavements.In this study, a new test setup, the so called Compaction Flow Test (CFT), was developed to simulate the flow behavior of asphalt mixtures at early stages of compaction. In the first step, feasibility tests were performed, substituting asphalt mixtures by model materials with simple geometries and less complex properties. X-ray Computed Tomography (CT) was utilized for capturing 2D radiography images of the flow patterns in the model material during the test. Results of the CFT showed the capability of the new test setup to clearly distinguish between model mixtures with different characteristics. Hence, in the next step, the CFT was applied to real asphalt mixtures and the obtained results were found to support the findings of the feasibility tests with the model materials.The results from the feasibility tests encouraged examining the possible use of an ultrasonic sensor as alternative to the complex and costly X-ray imaging for flow measurements during the CFT. Hence, the CFT was used along with a distance measuring ultrasonic sensor for testing asphalt mixtures with different characteristics. The test results confirmed that an ultrasonic sensor could be effective for capturing the differences of the flow behavior of asphalt mixtures tested by the CFT. In addition, a parametric study with the X-ray setup was carried out to examine the capability of the CFT in reflecting the possible changes of the flow behavior in asphalt mixtures due to the change of construction parameters such as lift thickness, bottom roughness and compaction modes. The results obtained also confirmed the capability of the CFT in showing the possible differences in the flow behavior of the mixtures under the chosen conditions.The encouraging results suggested that the CFT may have potential to become a simple but effective tool for assessing compactability of the mixtures on-site, right after production in an asphalt plant or before placing the mixture on the road. Hence, discrete element method (DEM) was utilized to understand both the influence of selected boundaries of the CFT and the effect of its design on the results.As one specific example of application, an investigation was carried out using the CFT to find the most suitable tracking method for flow measurements in the field. Based on the literature review and feasibility tests, a tracking method with the highest potential for conducting flow measurements during field compaction was introduced. X-ray radiography confirmed the validity of the results obtained with the suggested method.The overall results obtained from this study suggest that the recommended CFT along with the suggested field tracking method may be helpful in building up a comprehensive basis of knowledge on the flow and compaction behavior of asphalt mixtures thus helping to close the gap between the field and laboratory.
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| 10. |
- Ghafoori Roozbahany, Ehsan, 1982-
(författare)
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Investigation of asphalt compaction in vision of improving asphalt pavements
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Asphalt joints are potentially weakest parts of every pavement. Despite of their importance, reliable tools for measuring their mechanical properties for design and performance assessments are still scarce. This is particularly true for cold joints when attaching a new hot pavement to a cold existing one as in case of large patches for pavement repair. In this study, three static fracture testing methods, i.e. indirect tensile test (IDT), direct tension test (DTT) and 4 point bending (4PB), were adapted and used for evaluating different laboratory made joints. The results suggested that joints with inclined interfaces and also the ones with combined interface treatments (preheated and sealed) seemed to show more promising behaviors than the vertical and untreated joints. It was also confirmed that compacting from the hot side towards the joint improved the joint properties due to imposing a different flow pattern as compared to the frequent compaction methods. The latter finding highlighted the importance of asphalt particle rearrangements and flow during the compaction phase as a very little known subject in asphalt industry. Studies on compaction are of special practical importance since they may also contribute to reducing the possibility of over-compaction and aggregate crushing.Therefore, in this study, a new test method, i.e. Flow Test (FT), was developed to simulate the material flow during compaction. Initially, asphalt materials were substituted by geometrically simple model materials to lower the level of complexity for checking the feasibility of the test method as well as modeling purposes. X-ray radiography images were also used for capturing the flow patterns during the test. Results of the FT on model materials showed the capability of the test method to clearly distinguish between specimens with different characteristics. In addition, a simple discrete element model was applied for a better understanding of the test results as a basis for further improvements when studying real mixtures. Then, real mixtures were prepared and tested under the same FT configuration and the results were found to support the findings from the feasibility tests. The test method also showed its potential for capturing flow pattern differences among different mixtures even without using the X-ray. Therefore, the FT was improved as an attempt towards developing a systematic workability test method focusing on the flow of particles at early stages of compaction and was called the Compaction Flow Test (CFT).The CFT was used for testing mixtures with different characteristics to identify the parameters with highest impact on the asphalt particle movements under compaction forces. X-ray investigations during the CFT underlined the reliability of the CFT results. In addition, simple discrete element models were successfully generated to justify some of the CFT results.
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| 11. |
- Hailesilassie, Biruk
(författare)
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Morphology Characterization of Foam Bitumen and Modeling for Low Temperature Asphalt Concrete
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Development of new asphalt technologies to reduce both energy consumption and CO2 production has attracted great interest in recent years. The use of foam bitumen, as one of them, is attractive due to the low investment and production cost. Formation and decay of foam bitumen is a highly dynamic temperature dependent process which makes characterization difficult. In this thesis, new experimental tools were developed and applied for characterizing the foam bitumen during the hot foaming process. One of the main goals of this study was to improve understanding and characterization of the foam bitumen formation and decay. X-ray radiography was used to study the formation and decay of foam bitumen in 2D representation. The results demonstrate that the morphology of bubble formation depends on the types of bitumen used. Moreover, theoretical investigation based on the 3D X-ray computed tomography scan dataset of bubble merging showed that the disjoining pressure increased as the gap between the bubbles in the surface layer (foam film) decreased with time and finally was ruptured. Examining the foam bitumen stream right at the nozzle revealed that foam bitumen at a very early stage contains fragmented pieces of irregular size rather resembling a liquid than foam. The result from thermogravimetric analysis demonstrated that residual water content depends on the initial water content, and was found to be between 38 wt% and 48 wt% of the initial water content of 4 wt% to 6 wt%.Moreover the influence of viscosity and surface tension on bubble shape and rise velocity of the bubbles using level-set method was implemented in finite element method. The modeling results were compared with bubble shape correlation map from literature. The results indicated that the bubble shapes are more dependent on the surface tension parameters than to the viscosity of the bitumen, whereas the bitumen viscosity is dominant for bubble rising velocity.
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| 12. |
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| 13. |
- Hameury, Stéphane, 1979-
(författare)
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The hygrothermal inertia of massive timber connstructions
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work presented in this Doctoral dissertation concerns the ability of heavy timber structures to passively reduce the fluctuations of the indoor temperature and of the indoor relative humidity, through the dynamic process of heat and moisture storage in wood. We make the hypothesis that the potential offered by the hygrothermal inertia of heavy timber structures is significant, and that it could provide a passive way of regulating the indoor climate. This ultimately could results in a decrease of the energy demand from the Heating, Ventilating and Air Conditioning systems. In this Thesis, the author tries to characterise and quantify the significance of the hygrothermal inertia providing by the heavy timber constructions. The experimental studies contain an in-situ measurement campaign carried out at the Vetenskapsstaden building located in Stockholm and erected in 2001. The results from the test campaign show that a heavy timber construction may contribute to buffer the indoor temperature. A direct quantification of the moisture stored in the wood structure is measured regarding the year-to-year indoor humidity fluctuations. It was however hardly possible to directly quantify the moisture storage potential offered by the structure regarding the day-to-day indoor relative humidity fluctuations because of the low sensitivity of the measuring technique used. In regard to the limitations noticed during the in-situ measurements, laboratory measurements were launched to develop new methods to determine the day-to-day hygric performances of wood exposed indoor. A new method based on the Magnetic Resonance Imaging technology was developed and is intended to provide information about the Moisture Buffer Value measured according to a NORDTEST protocol, and about the moisture distribution in wood with high spatial resolution. The Moisture Buffer Value of untreated Scots pine measured with this method is in accordance with the gravimetric method provided by the NORDTEST protocol. The Moisture Buffer Value of coated Scots pine was also investigated and it is normally assumed that any coatings will decrease the Moisture Buffering Capacity of the structure. The results show however that for specific coating such as waterborne alkali silicate coating, the Moisture Buffering Capacity of the structure may on the contrary be improved. At last, numerical simulations were carried out. They were based upon the extension of a modular simulation environment IDA ICE 3.0, with the implementation of a specific model for heat and moisture transport in a wood. The results obtained pinpoint the highly synergetic effects between the indoor moisture loads, the ventilation rate, the outdoor climate and the moisture interactions with the structure. The outcomes also show that the Moisture Buffering Capacity of a heavy timber structure is appreciable. The structure is able to even out substantially the day-to-day indoor relative humidity fluctuations for a certain range of ventilation rate.
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| 14. |
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| 15. |
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| 16. |
- Namutebi, May
(författare)
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An investigation into some aspects for foamed bitumen technology
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite applications of foamed bitumen technology in pavement construction in various places around the world, there are still several aspects about this technology that are not clear. In addition, knowledge on foamed bitumen technology is mainly empirical and lacks scientific basis. This study addresses some of the aspects for foamed bitumen technology such as: Investigation of any effects in binder composition during the production process for foamed bitumen; assessment of the effect of bitumen source on foamed bitumen characteristics; development of a rational method to optimise foamed bitumen characteristics and conditions; evaluation of aggregate particle coating within foamed bitumen mixes; further improvements in the mix design procedure specifically the method of compaction and optimum bitumen content determination stages are suggested. Fourier transform infrared spectroscopy techniques were used to investigate any changes in bitumen composition after the production process of foamed bitumen. Fourier transform infrared tests were done on foamed bitumen and neat bitumen specimens for two bitumens with similar penetration grades. Foamed bitumen characteristics of three bitumens were established by producing foamed bitumen at temperatures of 150ºC up to 180ºC and foamant water contents of 1, 2, 3, 4 and 5%. From the analysis of variation of foamed bitumen characteristics (maximum expansion ratio and half-life) at different temperatures a new method based on the equi-viscous bitumen temperature to optimize foamed bitumen conditions and characteristics was proposed. Rice density and surface energy concepts were used to evaluate aggregate particle coating with foamed bitumen. A granite aggregate divided into three different size fractions and three sets of foamed bitumen produced from three bitumen penetration grades were used. A gyratory laboratory compaction procedure for laterite gravels treated with foamed bitumen was established using the modified locking concept. Three laterite gravels with different chemical composition were mixed with foamed bitumen produced from one penetration bitumen grade. The resulting mixes were compacted up to 200 gyrations and the corresponding compaction curve defined in terms of height versus number of gyrations noted. In addition, the optimum moisture content requirements at the modified locking point were determined. 3D packing theory concepts, primary aggregate structure porosity and an indirect tensile strength criteria were employed to determine optimum bitumen content for foamed bitumen mixes. Fourier infrared techniques revealed that foaming did not cause any changes in the bitumen chemistry, implying that the foamed bitumen production process may possibly be a physical process. Characterisation of foamed bitumen produced from three bitumen penetration grades showed that foamed bitumen characteristics (maximum expansion ratio and half-life) were mainly influenced by binder viscosity rather than the source. The equi-viscous temperature seemed to provide a suitable criterion at which foamed bitumen with optimum characteristics could be produced. Rice density results showed that aggregate size fraction, binder expansion ratio and viscosity influenced aggregate particle coating. For the coarser aggregate fraction, results revealed that binder coating seemed to be mainly influenced by temperature. Whilst for fine aggregate fraction the coating was mainly influenced by surface area. Surface energy results revealed that foamed bitumen exhibited better coating attributes than neat bitumen. A new laboratory compaction procedure for laterite gravels treated with foamed bitumen based on the modified locking point was developed. The modified locking point represents the state at which maximum aggregate particle interlock occurs when mixes are compacted in the field. It is based on the iii analysis of the rate of change for the gyratory compaction curve. The compaction curve in this case is defined in terms of compaction height versus number of gyrations. Gradation analysis beyond the modified locking point showed that aggregate particle breakdown occurred. Analysis of the optimum moisture at the modified locking point revealed that the moisture conditions were less than the aggregate optimum moisture conditions. It is recommended that this point be used to determine the optimal compaction characteristics of foamed bitumen mixes. Aggregate structure porosity and an indirect tensile strength criteria can be used to determine the bitumen content that could be used in design of foamed bitumen mixes. This would reduce the amount of resources required since the bitumen content could be estimated prior to carrying out the actual laboratory work given that the aggregate grading is known. The aggregate structure can be divided (based on 3D packing theory) into oversize, primary, and secondary structures. The primary structure is mostly responsible for carrying loads whilst the secondary structure fills the voids within the primary structure and provides support to the primary structure. The aggregate size particles constituting the primary structure are deduced as a function of standard sieve sizes using the packing theory concepts. The minimum sieve size for the primary structure is proposed as 1 mm. The oversize structure consists of aggregate particles whose size is greater than the maximum size for the primary structure. The secondary structure consists of aggregate particles whose size is below the minimum size for the primary structure. The primary aggregate structure porosity can be used to establish the starting bitumen content; the bitumen content at which this porosity is 50% is chosen as the initial bitumen content. Indirect tensile strength values corresponding to 50% primary porosity are determined as well as the bitumen contents and compared against the recommended minimum values.
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| 17. |
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| 18. |
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| 19. |
- Peñaloza, Diego, 1981-
(författare)
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Exploring climate impacts of timber buildings : The effects from including non-traditional aspects in life cycle impact assessment
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is an urgency within the building sector to reduce its greenhouse gas emissions and mitigate climate change. An increased proportion of biobased building materials in construction is a potential measure to reduce these emissions. Life cycle assessment (LCA) has often been applied to compare the climate impact from biobased materials with that from e.g. mineral based materials, mostly favouring biobased materials. Contradicting results have however been reported due to differences in methodology, as there is not yet consensus regarding certain aspects. The aim of this thesis is to study the implications from non-traditional practices in climate impact assessment of timber buildings, and to discuss the shortcomings of current practices when assessing such products and comparing them with non-renewable alternatives.The traditional practices for climate impact assessment of biobased materials have been identified, and then applied to a case study of a building with different timber frame designs and an alternative building with a concrete frame. Then, non-traditional practices were explored by calculating climate impact results using alternative methods to handle certain methodological aspects, which have been found relevant for forest products in previous research such as the timing of emissions, biogenic emissions, carbon storage in the products, end-of-life substitution credits, soil carbon disturbances and change in albedo. These alternative practices and their implications were also studied for low-carbon buildings.The use of non-traditional practices can affect the climate impact assessment results of timber buildings, and to some extent the comparison with buildings with lower content of biobased building materials. This effect is especially evident for energy-efficient buildings. Current normal practices tend to account separately for forest-related carbon flows and aspects such as biogenic carbon emissions and sequestration or effects from carbon storage in the products, missing to capture the forest carbon cycle as a whole. Climate neutrality of wood-based construction materials seems like a valid assumption for studies which require methodological simplification, while other aspects such as end-of-life substitution credits, soil carbon disturbances or changes in albedo should be studied carefully due to their potentially high implications and the uncertainties around the methods used to account for them. If forest phenomena are to be included in LCA studies, a robust and complete model of the forest carbon cycle should be used. Another shortcoming is the lack of clear communication of the way some important aspects were handled.
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| 20. |
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| 21. |
- Rimsjö, Åsa
(författare)
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Environmental Assessment of Building Products and Components in a Service Life Perspective
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a survey of different tools, used byenvironmental consultants in Sweden, for their recommendationsof building products and components in different constructionprojects. The goal was to identify possible improvements of thetools so that life cycle methodology could be used to a largerextent than today. This thesis also presents a general methodfor multi-criteria assessment. The purpose of this generalmethod was to show how assessment of environmental impacts,cost and prediction of service life have to be combined for acomprehensive view over all the criteria that influencedecision-making in different construction projects.The evaluation of the present role of environmentalconsultants in the building process in Sweden and their toolsis based on a literature study together with interviews.Advantages and disadvantages of the different tools fordecision-making have been identified. It was found that thereare many improvements to be made, for example, concerningbuilding product declarations. The declarations have to containmore quantitative data and the guidelines have to be furtherdeveloped to secure equivalence in product comparisons. Thestudy showed that an environmental consultant seldom makes anelaborate assessment of aspects other than environmentalimpacts. Others, for example, the client or contractor,consider aspects of economy and technical functionality.However, there is a need of a more comprehensive view wherecosts and technical functionality are included in theassessment together with environmental concerns. If differentaspects are treated separately there is a risk ofsuboptimisations. This need has been identified by for exampleconsultants and the commission of the Swedish government and isoften emphasised by the building material industry.In Life Cycle Assessment (LCA) the functionality, as well asthe time of use should be reflected in the definition thefunctional unit of the study. Calculations of Life Cycle Cost(LCC) also include the time aspect and compared systems shouldfulfil the same requirements of functionality. Therefore, it isof obvious interest to find a method that brings together LCA,LCC and service life planning (with estimations of servicelives). The presented method of multi-criteria assessment is toa large extent considered to be of practical use for practisingconsultants in their recommendations of the preferable choice,as soon as a pedagogical interface has been developed. Inaddition, a simplified LCA technique has to be used, where somesystemlimits and assumptions are pre-defined. A multi-criteriaassessment approach is one step ahead to fulfil therequirements of the authorities and the society. Themulti-criteria approach also helps the building sector to worktowards the goal of increased environmental concern in thesector and the overarching goal of an environmental sustainablesociety.Key words:life cycle assessment, LCA, environmentaldeclarations, building product declarations, environmentalconsultants, tool for decision-making, service life planning,estimation of service life, the factor method, multi-criteriaassessment
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| 22. |
- Rosenkilde, Anders, 1960-
(författare)
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Moisture content profiles and surface phenomena during drying of wood
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Timber drying is one of the most important processes whenmanufacturing sawn timber products. The drying processinfluences deformations, surface checking, discoloration andhence, the product quality and the manufacturing costs.Research in this field is of great importance for the woodindustry since the industrial drying process always needs to beimproved as market demands increases and new wood products aredeveloped.The aim of the present thesis was to investigate themoisture transport behaviour in wood based on measurementsduring drying from fresh condition down to end use moisturecontent. The behaviour near the surface interface has beenspecifically investigated since it is of great importance forthe theoretical description of the drying process. Furthermore,studies based on measurements in the wood surface layer duringdrying are not easy to find in the literature. The reason forthat is probably that it is very difficult to make accuratemoisture measurements with high spatial or temporal resolutionwithout disturbing the drying process.Measurements of moisture content profiles in Scots pineheartwood and sapwood during drying have been performed byusing three different methods. The first was a destructivemethod where the wood samples are sliced with a knife intoseveral smaller pieces. The moisture content in each piece wasdetermined with the dry weight method. The second method usedis non-destructive and it utilises a medical CT-scanner thathas been adapted for drying experiments. The samples are driedin-situ the scanner through the whole experiment. TheCT-scanner measures density and the moisture content arecalculated according to existing methods developed by otherscientists. The third method was also non-destructive and itutilises a Magnetic Resonance Imaging, MRI, technique. Withthis technique the amount of water in the wood sample ismeasured directly even though it has to be calibrated tomoisture content.The surface emission factor, S, or surface resistance, 1/S,has been studied by performing sorption experiments with MDF ina narrow moisture content range. The experiment was evaluatedusing a simple diffusion model that includes a surface emissionfactor S. The experimental result was compared with resultscalculated using well established boundary layer theories.Measurements of moisture content profiles in the wood bulkshowed an expected Fickian behaviour at moisture contents belowthe fibre saturation point. Above the fibre saturation pointalmost flat moisture profiles were observed. This behaviour wasnot expected and it is not possible to simulate this behaviourwith the existing drying models since they usually assume thatthere is a gradient in the moisture profile over the wholemoisture content range. From the moisture profiles thediffusion coefficients were determined over a moisture contentranging from 8 to 30%. The values for heartwood and sapwood areapproximately equal in radial and tangential direction tograin. Furthermore, the diffusion values in longitudinaldirection are much higher as expected.The sorption experiments with MDF gave a greater surfaceresistance compared with the calculation that was based onboundary layer theory. The ratio was three or higher. Thisimplied that there was a greater resistance in the surfacelayer. In addition, this was not well described in theliterature even though a few recent published studiesexist.High resolution measurements in the surface layer of woodshowed behaviour similar to that observed in the bulk wood. Theresults showed the very early development of a dry zone closeto the surface interface. In that zone or shell the moisturecontent was below the FSP even though the bulk moisture contentwas far above the FSP. At the end of the experiments themoisture content in the surface layer (0–300 µm)nearly reached the equilibrium moisture content even though thebulk moisture content still was much higher.Keywords:Computer tomography, Diffusion, Magneticresonance, Moisture measurements, Moisture profiles, Surfaceemission, Wood drying
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| 23. |
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| 24. |
- Segerholm, Kristoffer, 1979-
(författare)
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Characteristics of wood plastic composites based on modified wood : Moisture properties, biological performance and micromorphology
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biobased materials made from renewable resources, such as wood, play an important role in the sustainable development of society. One main challenge of biobased building materials is their inherent moisture sensitivity, a major cause for fungal decay, mold growth and dimensional instability, resulting in decreased service life as well as costly maintenance. A new building material known as wood-plastic composites (WPCs) has emerged. WPCs are a combination of a thermoplastic matrix and a wood component, the former is usually recycled polyethylene or polypropylene, and the latter a wood processing residual, e.g. sawdust and wood shavings.The objective of this thesis was to gain more insight about characteristics of WPCs containing a modified wood component. The hypothesis was that a modified wood component in WPCs would increase the moisture resistance and durability in outdoor applications. The study comprises both injection molded and extruded WPC samples made with an unmodified, acetylated, thermally modified or furfurylated wood component in a polypropylene (PP), high density polyethylene (HDPE), cellulose ester (CAP, a cellulose ester containing both acetate and propionate substituents) or polylactate (PLA) matrix. The WPCs were prepared with 50-70 weight-% wood. The emphasis was on studying the moisture sorption, fungal resistance and micromorphological features of these new types of composites. Water sorption in both liquid and vapor phases was studied, and the biological performance was studied both in laboratory and in long term outdoor field tests. Micromorphological features were assessed by analyzing of the wood component prior to and after processing, and by studying the composite microstructure by means of a new sample preparation technique based on UV excimer laser ablation combined with scanning electron microscopy (SEM).Results showed that the WPCs with a modified wood component had a distinctly lower hygroscopicity than the WPCs with unmodified wood, which resulted in less wood-plastic interfacial cracks when subjected to a moisture soaking-drying cycle. Durability assessments in field and marine tests showed that WPCs with PP or CAP as a matrix and 70 weight-% unmodified wood degraded severely within a few years, whereas the corresponding WPCs with a modified wood component were sound after 7 years in field tests and 6 years in marine tests. Accelerated durability tests of WPCs with PLA as a matrix showed only low mass losses due to decay. However, strength losses due to moisture sorption suggest that the compatibility between the PLA and the different wood components must be improved. The micromorphological studies showed that WPC processing distinctly reduces the size and changes the shape of the wood component. The change was most pronounced in the thermally modified wood component which became significantly reduced in size. The disintegration of the modified wood components during processing also creates a more homogeneous micromorphology of the WPCs, which may be beneficial from a mechanical performance perspective. Future studies are suggested to include analyses of the surface composition, the surface energy and the surface energy heterogeneity of both wood and polymer components in order to tailor new compatible wood-polymer combinations in WPCs and biocomposites.
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| 25. |
- Segerholm, Kristoffer, 1979-
(författare)
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Wood Plastic Composites made from Modified Wood : Aspects on Moisture Sorption, Micromorphology and Durability
- 2007
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wood plastic composite (WPC) materials have seen a continuous market growth worldwide in the last decade. So-called extruded WPC profiles are today mainly used in outdoor applications, e.g. decking, railing and fencing. In outdoor conditions, moisture sorption in the wood component combined with temperature induced movements of the polymer matrix causes deformations of such composites. On the macroscopic scale this may lead to unacceptable warp, cup and bow of the WPC products, but on a microscopic scale, the movements will cause interfacial cracks between the particles and the matrix, resulting in little or no ability to transfer and re-distribute loads throughout the material. Moisture within the composite will also allow fungi and micro organisms to attack the wood particles. The conceptual idea of this work is to use a chemically modified wood component in WPCs to enhance their long term performance. These chemically modified wood particles exhibit reduced susceptibility to moisture, resulting in better dimensional stability and a higher resistance to biological degradation as compared to that of unmodified wood. The objective of this thesis is to study the effects of using modified wood in WPCs on their moisture sorption behaviour, micromorphology and microbiological durability. The modification methods used were acetylation, heat treatment and furfurylation. Equilibrium moisture content (EMC) and sorption behaviour of WPCs were determined by water vapour sorption experiments. The use of thin sections of the composites enabled EMC to be reached within a comparably short time span. The micromorphology was studied by LV-SEM (low vacuum-scanning electron microscope) using a specially designed sample preparation technique based on UV laser. The biological durability was evaluated by laboratory fungal test methods. The moisture sorption experiments showed lower moisture levels for all the composites when modified wood particles were used. This was also reflected in the micromorphological studies where pronounced wood-plastic interfacial cracks were formed due to moisture movement in the composites with unmodified wood particles. The sample preparation technique by UV laser proved to be a powerful tool for preparing surfaces for micromorphological studies without adding mechanical defects caused by the sample preparation technique itself. Results from the durability test showed that WPCs with modified wood particles are highly resistant to decay by fungi.
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| 26. |
- Sterley, Magdalena
(författare)
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Green gluing of wood
- 2004
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)
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| 27. |
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| 28. |
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| 29. |
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| 30. |
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| 31. |
- Trinius, Wolfram
(författare)
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Environmental assessment in building and construction
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Access to tools for environmental assessment is aprecondition for identifying and improving the environmentalperformance of building sector products. With the multitude ofparties involved in that sector, also the context within whichassessment results are implemented varies. Such variations haveto be correctly reflected in the premises under which anassessment is carried out. A wide variety of assessment tools,from simple checklists to Life Cycle Assessment (LCA)approaches, is available. The choice of assessment method hasan evident influence on the character and quality of thegenerated results.Without confronting the ISO framework for LCA, a largevariety of methodology choices can be made by theLCA-practitioner in order to adapt the assessment to hisrequirements. The application context is to be reflected in thegoal and scope definition of the assessment. From thatdefinition, methodology choices are to be made concerning amongothers allocation procedures and the delimitation of theanalysed system. The choice of allocation method has shownsignificant influence on the generated results, when applyingLCA on highly recyclable building materials.Within this publication, a method for deriving a link fromthe goal via the scope into the definition of systemboundaries, and an economic allocation procedure for reuse andrecycling, are proposed. Both are intended to enable a clearlink between methodology choices and the goal and scopedefinition, which was identified as the key point in LCA. Themethods presented in this publication do accord with the ISOstandards.Keywords:Environmental Assessment, Building Sector,Life Cycle Assessment, Goal and Scope Definition, SystemBoundaries, Allocation, Result Variation
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| 32. |
- Tsantaridis, Lazaros
(författare)
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Reaction to fire performance of wood and other building products
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The theme of this thesis is the reaction to fire performanceof wood and other building products, andparticularly thematerial fire properties time to ignition, rate of heat releaseand smoke production. These properties have been measured by asmall-scale fire test method, the Cone Calorimeter, andpresented for different types of building products.Uncertainty analysis, included instrument and assumptionuncertainty, has been performed for the case that both O2 andCO2 are measured for calculation of the rate of heat release inthe Cone Calorimeter. The partial derivatives for theuncertainty analysis are given. The relative uncertainty forthe rate of heat release measurements in the Cone Calorimeteris between ±5% to ±10% for rate of heat releasevalues larger than about 50 kW/m2.The time to ignition in the Cone Calorimeter is compatiblewith the time to ignition in the ISO Ignitability test, whichis the main test method for measuring time to ignition. Thetime to ignition is an increasing linear function of density.The rate of heat release in the Cone Calorimeter is dependentof material thickness and of use of retainer frame. Thematerial thickness gives the heat release curve duration andshape. Thin materials have short burning time and two maximumvalues. Thick materials have long burning time and when thematerial is thicker than about 35 mm no second maximum appears.When the retainer frame is used the actual exposed surface isreduced from 0.01 m2 to 0.0088 m2, the rate of heat release isreduced and the burning time is increased. A comparison ofresults with and without use of the retainer frame gives thenequal results when the exposed area is set to 0.0088 m2 in thecase of using the retainer frame.The time to flashover in the full-scale room corner test waspredicted on the basis of Cone Calorimeter data at 50 kW/m2 bya power law of ignition time, the total heat release calculatedover 300 s after ignition and the density of the product. Therelation gives a simple relation to evaluate if a productreaches flashover in the room corner test.The smoke production has also been measured in the ConeCalorimeter. The white light and the laser smoke measurementsystems have shown similar results. There is a correlationbetween Cone Calorimeter and room corner test smoke productionwhen the products are divided into groups: those that reachflashover in the room corner test in less than 10 min and thosethat have more than 10 min to flashover. Temperature profilesin wood have been measured in the Cone Calorimeter by a simpletechnique. The effect of fire protective gypsum plasterboardson the charring of wood frame members has been determined andcompared with fullscale furnace wall tests. The protectiveeffects of twenty different boards have been presented. ConeCalorimeter and furnace tests show similar charring of wooduntil the boards fall down in furnace tests. After that, thecharring of wood is higher in the furnace, because the wood isexposed directly to the fire.Keywords:building products, charring of wood, ConeCalorimeter, fire retardant treated wood, fire tests,ignitability, mass loss, rate of heat release, reaction tofire, smoke production, wood products
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| 33. |
- Twumasi, Ebenezer
(författare)
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Molecular filtration : the study of adsorbents
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adsorbent materials for gas purification have been studied and developed for application in many areas. It is known that a single adsorbent may not adequately control multiple contaminants. Therefore, the development of adsorbent materials has accelerated over the past two decades, and is today an area attracting a lot of attention. In view of the global environmental movement for clean air, the development of improved sorbents will help address new challenges that cannot efficiently be met with the generic sorbents that are presently commercially available. On the other hand, the utilization of these new sorbents for specific applications within the area of molecular filtration remains largely unexplored. This thesis presents a synthesis of new sorbent materials, and the characterization and application of these materials for molecular filtration. Commercial adsorbents have been used for benchmarking for the pore properties, the applicability, and the performance of these new adsorbents. A double metal-silica adsorbent has been synthesized. The preparation procedure is based on the use of sodium silicate coagulated with various ratios of magnesium and calcium salts which yields micro-meso porous structures in the resulting material. The results show that molar ratios of Mg/Ca influence the pore parameters as well as the structure and morphology. The bimodal pore size can be tailored by controlling the Mg/Ca ratio. The effect of thermal treatment on pore parameters of these adsorbents has been investigated. The results show that heat treatment had a notable effect on the pore parameters, and that the pore structure was thermally stable even at 600°C. A synthesis method has also been developed for the preparation of carbon-silica composites. The method involves a number of routes, which can be summarised as addition of activated carbon particles to (I) the paste, (II) the salt solution, or (III) with the sodium silicate solution. In route II and III the activated carbon is present also before coagulation. The routes presented here leads to carbon-silica composites possessing high micro porosity, meso porosity as well as large surface areas. The increase in micro porosity and surface areas was linear with carbon content. The results shows further that pore size distribution may be tailored based on the route of addition of the carbon particles. Following route I and III a wide pore size (1-30nm) was obtained where as by route II a narrow pore size (1-4nm) was observed. KOH or KMnO4 modified MgCa adsorbent varieties were also prepared. The impregnationwas performed by either a direct synthesis or post-synthesis procedure. Potassium hydroxide and potassium permanganate have been chosen as impregnate chemicals. Results revealed that theimpregnate amount significantly affected both the structural and the gas adsorption characteristics of the impregnated MgCa adsorbents. The properties of double- metal adsorbents, impregnated adsorbents and carbon-silica composites were characterized by various methods (X-ray diffraction, scanning electron microscopy, thermo gravimetric analysis, and nitrogen adsorption at 77K) to study the material structure and morphology, thermal stability, ignition temperature and porous parameters with regard to surface area, pore size, pore size distribution and porosity volume, which is important for optimizing their use in many practical application. The up-take performance of adsorbents for dynamic adsorption of SO2, H2S and toluene was performed in a system similar to the setup usedin ASHRAE 145.1. Finally the applicability and performance of the impregnated modified MgCa-silica adsorbents and composites have been evaluated for H2S, SO2 and toluene adsorption and compared to some commercial adsorbent materials. Results revealed that a potassium permanganate modified MgCa-adsorbent has a H2S adsorption capacity in the range of 0.08-3.19 wt % at 50% efficiency, and that the uptake capacity was relative to the amount of potassiumpermanganate loading. Moreover, KOH modified MgCa-adsorbent shows highest SO2 adsorption capacity (1.7 wt %) which is 3.47 times higher than commercial alumina impregnate with potassium permanganate (0.49 wt %). Carbon-silica composites on the other hand shows adsorption of toluene and high adsorption capacity was obtained when carbon content was 45 wt %. The results further shows that a composite with 45 wt % carbon and obtained via route I present the highest toluene adsorption capacity ( 27.6 wt % relative to carbon content) at 0% efficiency. The large uptake capacity of this composite was attributed to the presence of high microporosity volume and a wide (1-30nm) bimodal pore system consisting of extensive mesopore channels (2-30nm) as well as large surface area. These capacity values of carbon-silica composites are competitive to results obtained for commercial coconut based carbon (31 wt %), and better than commercial alumina-carbon composite.
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| 34. |
- Vrána, Tomáš, 1978-
(författare)
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Condensation and frost formation in fibrous thermal-insulation materials
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Heavily insulated constructions are at present being used to strike at the vast energy consumption in residential buildings and commercial alike. They introduce a high-thickness layer of thermal insulation in the building envelopes. Such constructions have great moisture capacity and could be at risk due to moisture leakages and other moisture related problems connected to bad design, climate effects, extended construction period to late autumn and winter seasons and mishandle of building materials. Thermal-insulation materials based on stone wool and cellulose are commonly used in a wide range of applications that harness their high thermal-insulation properties. Both these materials could be fault-prone due to their fibrous structure in case of moisture problems – e.g. built-in moisture, annually repeating condensation and frost formation in the cold climates. The aim of this research was to observe the stone-wool and cellulose specimens in various temperature fields under extreme moisture load and to explore the issue of moisture transport and real moisture properties of the tested materials when condensation and frost formation occur. A special testing device, Thermobox, was constructed and the fibrous samples were exposed to temperature gradients simulating real conditions. The climate data as well as the moisture-transport data were registered. They were used in calculations of moisture resistance factor, µ, denoting permeability of the tested samples in the defined moist conditions. Following the laboratory measurements, a mathematical simulation was done to compare total moisture accumulation in the specimens with the practical measurements and to be able to simulate these processes in a longer time interval. Besides, a special outdoor experiment concerning the effect of outdoor climate on the stone-wool structure was executed. Final research findings proved that the phenomenon of frost formation can exist in the fibrous insulation materials. Moisture transport properties of stone wool and cellulose were affected by the extreme water condensation and freezing, but they remained highly permeable. As regards the moisture storage in the samples, this process was continuous during the tested period and it indicated significant growth of the total water accumulation in connection with dry densities of the tested materials. This emphasises the importance of proper handling with the fibrous thermal-insulation materials and keeping them dry.
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| 35. |
- Westberg, Kjell
(författare)
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Användning av tillgängliga klimat- och miljödata vid livslängdsbedömningar av byggnader
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since there is a demand to achieve improved precision ofestimations of the service life of a building and itsmaintenance intervals, in international organisations tasks arerunning to establish methods, models and standards for servicelife estimations. However, exact estimations are not feasibleat a reasonable cost. Accordingly, the estimations have to besimplified. The extent of simplifications being acceptabledepends on the use of the result. A service life estimation maybe intended for research, engineering or needs within thesocial science area. An important issue in service lifeestimations is the degradation of the materials. Thedegradation rate depends on the intensity of the degradationagents. Hence, there is a need of assessing degradation agentson the micro level, i.e. a characterisation of the degradationenvironment at buildings. Data on several degradation agentsare available in databases emanating from measurements on macroand meso levels at climate, meteorological and environmentalstations. Due to lack of data on the micro level, at presentdata from such databases are utilised in spite of the fact thatthese relate to larger surface areas than what is of relevancein service life estimations. This results in a poorer accuracyand, in the worst case, a completely misleading numericalvalue. The concept suggested in this thesis is based on theusage of data in databases that are available for otherpurposes in the society, data being transformed to refer to theimmediate surroundings of the building. In the thesis, examplesof climate and environmental databases obtainable in Europe andabove all in Sweden are given. Furthermore, it is pointed outthat there exist models to be employed for the transformationof data. This implies that the concept should be useful for thepurposes described above. Assessments of local sources of, forinstance, traffic, built-up areas, industries and water courseshave to be included, as well as degradation agents beingproduced in the building. Moreover, own studies are discussed,the results of which demonstrate that, starting from data of aclimate station, indeed it is feasible to develop models thatproduce data on degradation agents on the micro level. However,the models will become increasingly advanced for shorterperiods of time than a half-year. In service life assessmentsof buildings, though, this does not represent any problem asthe time perspective extends over several years or decades. Thehypothesis, set forth in this licentiate's thesis, is thattransformation of data can be brought about by means ofmathematical models, computer simulations and/or index values.The thesis deals with service life assessments in general aswell as degradation agents for the assessment of service livesand maintenance intervals of external building materials, andin particular transformation of data from climate andenvironmental stations. In addition, a few proposals of furtherresearch within the subject area are discussed.Keywords: service life planning, degradation environment,degradation agents, transformation, buildings, structures,maintenance intervals, meteorological data, climate data,environmental data, air pollutions
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