This study investigates the carbonation process in concrete, where carbon dioxide is naturally absorbed by the concrete over time. Crushing the concrete into smaller fractions has the potential to accelerate this process. The study aims to evaluate the carbon dioxide reduction through the method of carbonation of crushed concrete, in collaboration with Bjerking and Castellum for their project in Främre Boländerna, Uppsala. Calculation models based on the Swedish standard EN 16757 are used to assess carbon dioxide uptake, which is compared with data obtained from concrete samples taken from buildings scheduled for demolition. These models are used to estimate carbon dioxide uptake during the usage phase of concrete as well as after demolition and crushing. Results indicate that carbonation of crushed concrete has the potential to effectively capture about a maximum of 75 % of the carbon dioxide emissions during calcination. It is found that the carbon dioxide uptake for a concrete wall after 74 years of usage is at 13 %, but this value can increase to 62 % within 4 months after crushing, given optimal waste management practices. These results highlight the impact of crushing and optimal waste management system on achieving carbon dioxide reduction through carbonation. Moreover, the result demonstrates that fractions smaller than 4 millimeters exhibit rapid carbonation, occurring within a few days, while larger fractions in the range of 16–32 millimeters undergo carbonation over a span of several years to a century. The size of the fractions and their proportion in the crushed concrete greatly influence carbon dioxide uptake. Under different fraction conditions, carbon dioxide uptake varies between 59 % and 84 %, emphasizing the impact of fraction composition on carbon dioxide uptake.  The conclusions of this study indicate that crushing concrete for the purpose of carbonation can reduce carbon dioxide emissions from calcination in cement manufacturing. By implementing an optimal waste management system, the carbonation process can be accelerated and utilized within a shorter time frame. Furthermore, the results demonstrate that the ratio of fractions of the crushed concrete has a significant influence on carbon dioxide uptake. However, further research specifically focused on concrete crushing is required to provide a definitive answer. / I denna studie undersöks karbonatiseringsprocessen i betong, en naturlig process där koldioxid från omgivningen absorberas av betongen under dess livslängd. Syftet med undersökningen är att utvärdera möjligheterna för att skapa koldioxidsänka genom karbonatisering av riven betong. Detta görs i samarbete med Bjerking och Castellum inom ramen för deras projekt i Främre Boländerna i Uppsala. För att utvärdera koldioxidupptaget används kalkyleringsmodeller baserade på svensk standard EN 16757 som sedan jämföras med data från betongprover från byggnader som ska rivas. Dessa modeller används för att uppskatta koldioxidupptaget av betong under användarfas och efter rivning och krossning. Studien visar att karbonatisering av riven betong har en potential till att vara en effektiv metod för att maximalt ta upp 75 % av koldioxidutsläppen från kalcinering. Det visar sig även att koldioxidupptaget för en betongvägg efter 74 år i användarfas ligger på 13 %, detta kan öka till 62 % endast 4 månader efter krossning vid optimal avfallshantering. Detta resultat visar effekten av krossning och ett optimalt avfallssystem för att skapa en koldioxidsänka genom karbonatisering. Vidare framgår det att fraktioner på mindre än 4 millimeter kan karbonatiseras på några dagar medan fraktioner som 16–32 millimeter karbonatiseras inom några år till 100 år. Storleken på fraktioner och fraktionsandel av den krossade betongen påverkar koldioxidupptaget avsevärt. Vid två olika förhållanden mellan fraktionerna varierar koldioxidupptaget mellan 59 % och 84 % vilket visar effekten av fraktionsandelen på koldioxidupptaget.  Slutsatserna i denna studie tyder på att krossning av  betong för ändamålet karbonatisering kan minska koldioxidutsläpp från kalcinering vid cementtillverkning. Genom att implementera ett optimalt avfallssystem kan karbonatiseringsprocessen accelereras och utnyttjas inom en kortare tidsram. Vidare visar resultatet att förhållandet mellan fraktioner av den krossade betongen har en betydande inverkan på koldioxidupptaget. Det behövs dock fler undersökningar specifikt inom krossning av betong för att ge ett definitivt svar.

The cement and concrete industry stand for approximately 8% of the global CO2 emissions. The demand of concrete and cement is expected to increase rapidly with the growing world population and increased urbanization. This makes it of the utmost importance for the industry to try to mitigate its emissions. One way to reduce the industry’s environmental impact is by mineral carbonation curing through which CO2 can be sequestered in the concrete. This investigation studied the CO2 uptake of wollastonite (CaSiO3) which can be used for mineral carbonation. The CO2 uptake of different brands of wollastonite powders for different temperatures, pressures and water to solid ratios were tested through carbonation, and the samples were then analyzed through XRD, SEM and particle size analysis. The results showed large differences in CO2 uptake between the brands of wollastonite powders. They also indicate that lower temperatures lead to higher CO2 uptake but also possibly slow down the reaction rate and that higher CO2 pressures seem to increase CO2 uptake though the effect is small. There was significant variation of the effects of the water to solid ratios on CO2 uptake between the tested brands. The morphology of the powders also seemed to be of little relevance as an amorphous and crystalline powder were the two best performing powders, similarly particle size is not indicated by the result to have a large effect on CO2 uptake, though further studies are required to fully determine the effect of the morphology and particle size. / Cement- och betongindustrin står för cirka 8% av de globala koldioxidutsläppen. Efterfrågan på betong och cement förväntas öka snabbt med den växande världsbefolkningen och ökad urbanisering. Detta tyder på hur viktigt det är för industrin att minska sina utsläpp. Ett sätt att minska industrins miljöpåverkan är genom härdning av betongen via mineral karbonatisering, en process som binder in koldioxid i betong. I detta arbete studerades koldioxidupptagningen av mineralen wollastonit (CaSiO3) som kan användas för mineral karbonatisering. Olika märken av wollastonitpulvers koldioxidupptag vid olika temperaturer, koldioxidtryck och vattenhalter testades genom karbonatisering och proverna analyserades därefter genom XRD-analys, SEM-analys och partikelstorleksanalys. Resultaten visade stora skillnader i koldioxidupptagning mellan varumärkena av wollastonitpulver. De visar även att lägre temperaturer leder till högre upptag av koldioxid, men att reaktionshastigheten potentiellt saktar ner vid låga temperaturer. Högre koldioxidtryck verkar öka koldioxidupptagningen men effekten är liten. Det fanns signifikant variation av effekterna av vattenhalterna på koldioxidupptagning mellan de testade varumärkena. Pulvrens morfologi verkade inte ha en stor effekt då ett av de två bäst presterande pulvren var amorft och det andra kristallint. På samma sett verkade partikelstorleken inte ha en stor påverkan på koldioxidupptaget men ytterligare studier krävs för att fullständigt kunna bestämma effekten av morfologin och partikelstorleken.

In Sweden, there are about 64,000 shelters in different places in the country. There is a shortage of shelters, and they arenot enough for the entire country's population, but only about 7 million civilians can be accommodated. Shelters havebecome a highly topical topic lately, but the maintenance of these shelters is still neglected. Many of the existing sheltersneed to be renovated or modernized. This thesis has been carried out in collaboration with Ramboll AB in Uppsala withthe aim of developing possible proposals for future upgrades of a population shelter in Katarinaberget in Stockholm andstudying the construction and its associated problems. The work was based on the following questions; what damage isthere in the concrete structures? and what technical solutions are required to ensure the strength of the concrete structures?  The result of the work was based on the empirical material consisting of previously completed concrete inspections andtechnical documentations, as well as interviews with some experts in the subject. The results showed that there are severaldifferent types of concrete damage in Katarinaberget's population shelter. It also showed several repair methods to ensurethe construction, the method that is most suitable to use to fix the established concrete damage is the dry spraying method. / I Sverige finns cirka 64 000 skyddsrum på olika platser i landet. Det råder brist på skyddsrum och de räcker ej till hela landets befolkning, utan endast cirka 7 miljoner civila får plats. Skyddsrum har blivit ett högst aktuellt ämne på senaste, men underhållet av dessa skyddsrum är fortfarande eftersatt.  Många av de befintliga skyddsrummen behöver renoveras eller moderniseras. Detta examensarbete har utförts i samarbete med Ramboll AB i Uppsala med syftet att ta fram möjliga förslag för framtida uppgraderingar av ett befolkningsskyddsrum insprängt i Katarinaberget i Stockholm och studera konstruktionen samt dess tillhörande problem. Arbetet utgick från följande frågor; vilka skador finns det i betongkonstruktionerna? och vilka tekniska lösningar krävs för att säkerställa hållfastheten hos betongkonstruktionerna?  Resultatet av arbetet baserades på det empiriska materialet som utgörs av tidigare genomförda betongbesiktningar och tekniska dokumentationer, samt intervjuer med några experter inom ämnet. Resultatet visade att det finns flera olika typer av betongskador i Katarinabergets befolkningsskyddsrum. Det visade även flera reparationsmetoder för att säkerställa konstruktionen, den metoden som mest lämplig att använda för att åtgärda de fastställde betongskadorna är torrsprutnings metod.

Numera sker all industriell torkning av virke i sågverken i virkestorkar, som värms upp och därmed torkar virket till den optimala slutfuktkvot som tillönskas. Virkestorkar byggda i betong har länge varit ett stort problem för sågverksindustrin. Problematiken går tillbaka till 80-talet då man tvingades riva ett flertal torkar på grund av att betongtorkarna höll på att vittra sönder. Detta gällde för alla betongtorkar byggda fram till 70-talet. Det genomfördes i slutet på 90-talet en stor rapportundersökningen som behandlade de flesta typer av skador i betongtorkar. Fram tills idag har en närmare undersökning ej gjorts och det har fortfarande inte hittats standarder för reparation och underhåll som förlänger livslängden på betongtorkar. Sågverksindustrin förlorar varje år 10-tals miljoner kronor på reparationer och underhåll som i de flesta fall inte verkar fungera. Därför finns det en stor efterfrågan av tydliga instruktioner för val av material och hur dessa reparationer skall gå till. Rapporten behandlar den allmänna problematiken av skador som uppstår p.g.a. bland annat väldigt högt temperaturbelastade virkestorkar som är konstruerade i betong. Arbetet är uppdelat i två faser den ena fasen består av en teoridel som bland annat förklarar skadorna och dess uppkomst i betongtorkar. Den andra fasen behandlar en fältundersökning som genomfördes under rapportskrivningen samt de förslag till åtgärder som tagits fram. Denna rapport är en liten del av ett stort pågående projekt, där CBI Betonginstitutet och SP trä är projektutförare och samverkar med deltagande sågverk i Sverige och Norge samt leverantörer. Projektet ska mynna ut i en Guideline till sågverksindustrin, för att kunna utföra rätt reparationer med rätt materialval och därmed förlänga betongtorkarnas livslängd. Detta med utgångspunkt från fältundersökningens provtagningar. / Nowadays, all the process of industrial drying of lumber in sawmills are done in kilns, which the wood is heated and dried for the desired optimal moisture content. Timber drying kilns built in concrete has for a long time been a major issues for the sawmill industry. The problems goes as far back to the 80s when several wood kilns was forced to be demolished due to concrete kilns were about to crumble. This was mainly for all the concrete dries built up until the 70s. In the late 90's a report survey was carried out to investigate the damages that were inflicted in concrete dries. No other survey has been done since then and the report didn’t give tangible standards for repairs and maintenance that extends the service life in wood kilns. The sawmill industry loses each year tens of millions on repairs and maintenance that hasn’t shown any results of working. Therefore, there is a great demand of clear instructions for the selection of materials and how these repairs need to be done. The report deals with the general issues of very high temperature-loaded kilns constructed in concrete. The work is divided into two phases; one phase consists of a theoretical part including explaining of the damages and its emergence in the concrete kilns. The second phase deals with a field survey conducted during the report writing as well as the proposed measures have been developed. This report is one small part of a large ongoing project, where CBI and SP wood are the project implementers and interact with participating sawmills in Sweden and Norway and the suppliers. The project will culminate in a Guideline for the sawmill industry, to be able to perform the correct repair with proper materials and thereby extend the life of concrete kilns. This is based on field survey sampling. The project will culminate in a Guideline for the sawmill industry, to be able to perform the correct repair with proper materials and thereby extend the life of concrete drying. This is based on field survey sampling.

In Sweden housing shortage is a rising issue. Within a ten year period scientists predict that the Swedish population will increase from 10 to approximately 11 million people. Due to this increase in the Swedish population, the production of multi-dwelling buildings should be expanding, though instead building development is now decreasing. The Swedish government recently stated upon a climate strategy, to have no excessive emissions of greenhouse gases until the year of 2045. Regarding this climate strategy and the increasing need for housing, the need to build time-efficient, low cost buildings that have minimal environmental impact is in a greater demand than ever before. The purpose of this degree project is to elucidate the environmental effects, costs and assembly time for multi-dwelling buildings with prefabricated wooden and concrete frames. The study, based on literature and interviews, displays that prefabricated cross-laminated timber frames are more expensive than prefabricated concrete frames. However, choosing a timber frame does not necessarily result in a higher production cost compared to a concrete frame. Due to the dehydration time with concrete frames, wooden frames are almost 20 % more time efficient to assemble. Although wooden frames take less time to assemble, they often need more post-production work to withhold quality demands in comparison to concrete frames. The difference in environmental effect between the two materials is significant. Wood is an organic and renewable material and therefore has a low environmental impact. Concrete, which is a non-renewable material, has a higher environmental impact because of its cement component. Today 90 % of the newly developed multi-dwelling buildings are constructed with concrete. To reach the climate strategy in 2045, an increase of wooden constructions is one solution to lower the greenhouse gas emissions. Regarding that most of today’s construction building companies are using concrete as their primary frame material, this way of construction will have to change. Due to this future change, a decisionmaking model for selecting framework material has been developed. The model aims to guide clients and construction companies in an early process to get a first indication on what type of material that would be most beneficial to use in a project. The model is based on three different key factors; environmental effect, investment cost and time. When using the model, these key factors will be compared to each other and prioritized in a hierarchy setting. The outcome specifies the most preferable material to use in a project.

Greenhouse gas emissions drive climate change, posing a global challenge with serious consequences ranging from glacial melting to societal disruptions. Sweden has introduced a climate policy framework to achieve climate neutrality by year 2045, with the construction and real estate sector accounting for about 21 percent of total greenhouse gas emissions. Concrete, despite its long history and versatility, significantly contributes to the climate crisis. The problem is serious where a circular construction sector and concrete reuse can reduce the carbon footprint and contribute to Sweden's environmental goals. The study focuses on today's challenges with concrete's extensive climate impact and the insufficient reuse of older concrete buildings and strives to identify solutions for the reuse of concrete walls. Real estate companies Castellum and Vectura, along with consulting firm Bjerking, lead a reuse project for circular construction in Främre Boländerna. The properties of concrete, including its compressive strength, vary depending on the area of use, ranging from general building structures to commercial and industrial buildings. Previous research has shown that there is great potential for reuse, but also many challenges. The report's methodology includes interviews with six respondents, three field visits, compressive strength tests of concrete samples, and an extensive literature review, all to answer the study's purpose and problem. The interview study indicates that there are several challenges with reuse and the concrete samples show suitable compressive strength values for reuse with approved crack creation. The study's conclusions show that the concrete from Främre Boländerna can be used for general structures like homes and parks, but not for commercial buildings that require a load-bearing building frame. The main challenges identified in the study are intermediate storage, economic factors, legal issues, lack of standards and guidelines, reuse depots, and logistical problems. Despite these challenges, future opportunities appear promising.