Flue gas desulphurisation (FGD) is a crucial method to minimise the SO2 emissions from industrial processes. The FGD system utilise an alkaline sorbent to remove SO2 from the flue gases. Calcium in form of limestone is a commonly used sorbent where gypsum is produced asa by-product. However, the limestone reactivity, along with impurities within the sorbent, can significantly influence the effectiveness of SO2 removal and the quality of the by-products. At Heidelberg materials Cement Sverige an intermediate product, raw meal (RM) 8, is used assorbent in the FGD and gypsum is used as setting retarder in the cement. The aim with this project is to examine if raw meal 7 or A-sten is a better sorbent than raw meal 8 with respect to consumption rate, gypsum quality and its effect on the cement properties, and economic viability. To accomplish this a theoretical study was performed along with data analysis. RM 7 and A-sten are both purer than RM 8 but the raw material cost for RM 7 is about 1.24 times the raw material cost for RM 8 and the production costs and transportation costs are greater for RM 7 than for RM 8. The raw material cost for A-sten is about 0.45 times the cost for RM 8 but is not produced on site. All sorbents contain magnesium which can react with sulphur and precipitate as epsomite or hexahydrite, which also acts as retarders, where epsomite retard the cement setting time significantly compared to gypsum. To calculate the consumption rate of raw meal and A-sten into the scrubber three different methods were used. The difference between the methods lies in the consideration of how the calcium and magnesium species in the sorbent react with sulphur, with all calcium and magnesium reacting with sulphur in method 1, method 2 take the mass fraction of sulphurcontaining species into consideration, and method 3 incorporating mole fractions of calcium and magnesium species as well as sulphur from the sorbent. The pH and SO2 emissions were analysed for two different time periods where the first analysed period shows a correlation between low pH and high SO2 emissions, while the latter analysed period lacks a clear pH-SO2 correlation. A correlation between a lower pH and a lower percentage of MgSO4⸱6H2O and MgSO4⸱7H2O in the slurry could be made. The calculated rawmeal flow rate for RM 8 is between 520 and 554 kg/h, depending on the method used. To achieve the same desulphurisation efficiency with RM 7 the flow was calculated to 499-538kg/h and 427-464 kg/h for A-sten. Given the comparable mass flow rates of RM 8 and RM 7 it is advisable to retain RM 8 as asorbent in the scrubber regardless of the higher magnesium content due the higher cost associated with RM 7. However, the epsomite content in the slurry should be considered when optimising sulphur in cement production. Using A-sten as sorbent would minimise the rawmaterial costs and result in purer gypsum slurry with a lower epsomite content. Operating with a purer sorbent can also enhance the efficiency of the FGD process, leading to lower SO2 emissions. The calculations in the report assume that calcium and magnesium in the different sorbents react similarly, further analysis of their reactivity is recommended for more accurate results. / Rökgasavsvavling är en avgörande metod för att minimera SO2-utsläppen från industriella processer. Rökgasavsvaling använder en alkalisk sorbent för att avlägsna SO2 från rökgaserna. Kalcium i form av kalksten är en vanligt förekommande sorbent där gips produceras som en biprodukt. Kalkstensreaktiviteten, tillsammans med föroreningar i sorbenten kan emellertid avsevärt påverka avsvavlingseffektiviteten och biproduktens kvalitet. På Heidelberg materials Cement Sverige används en mellanprodukt, råmjöl (RM) 8, somsorbent i avsvavlingsprocessen och gipset används som härdningshämmare i cementet. Syftet med detta projekt är att undersöka om råmjöl 7 eller A-sten är en bättre sorbent än råmjöl 8 med avseende på konsumtionshastighet, gipskvalitet och dess effekt på cementens egenskapersamt ekonomisk bärkraft. För att uppnå syftet genomfördes en teoretisk studie tillsammans med dataanalys. RM 7 och A-sten är båda renare än RM 8 men råvarukostnaden för RM 7 är cirka 1,24 gånger råvarukostnaden för RM8. Dessutom är produktions- och transportkostnaderna högre för RM7 än för RM 8. Råvarukostnaden för A-sten är cirka 0,45 gånger råvarukostnaden för RM 8, dock mals inte A-sten på plats. Alla sorbenter innehåller magnesium som kan reagera med svavel och fälla ut som epsomit eller hexahydrit, vilka också har en härdningshämmande effekt, där epsomit fördröjer cementens härdning signifikant jämfört med gips. För att beräkna konsumtionshastigheten för råmjöl och A-sten i skrubbern användes tre olika metoder. Skillnaden mellan metoderna är hur kalcium- och magnesiumarterna i sorbenten reagerar med svavel, där allt kalcium och magnesium reagerar med svavel i metod 1. Metod 2 tar hänsyn till massfraktionen av svavelhaltiga ämnen och metod 3 innehåller molfraktioner av kalcium- och magnesiumarter samt svavel från sorbenten. pH och SO2-utsläppen analyserades under två olika tidsperioder där den första perioden visar ett samband mellan lågt pH och höga SO2-utsläpp, medan den senare analyserade perioden saknar ett tydligt pH-SO2-samband. En korrelation mellan ett lägre pH och en lägre andel MgSO4⸱6H2O och MgSO4⸱7H2O i gipsslurryn skulle kunna göras. Det beräknade flödet av råmjöl för RM 8 är mellan 520 och 554 kg/h, beroende på vilken metod som används. För att uppnå samma avsvavlingseffektivitet med RM 7 måste flödet vara 499–538 kg/h och 427–464 kg/h för A-sten. Med tanke på de jämförbara massflödena för RM 8 och RM 7 är det lämpligt att behålla RM 8 som sorbent i skrubbern, trots den högre magnesiumhalten, på grund av de högre kostnaderna för RM 7. Epsomithalten i slurryn bör dock tas i beakting vid optimering av svavel i cementproduktionen. Att använda A-sten som sorbent skulle minimera råvarukostnaderna och resultera i en renare gipsslurry med lägre epsomithalt. Att använda med en renare sorbent kan också förbättra avsvavlingseffektiviteten, vilket leder till lägre SO2-utsläpp. Beräkningarna i rapporten förutsätter att kalcium och magnesium i de olika sorbenterna reagerar lika, ytterligare analys av deras reaktivitet rekommenderas för mer exakta resultat.

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The need of building new bridges is always existing in relation with the increase of infrastructureand transport needs. Bridge constructions have traditionally been associated with highconsumption of resources and large greenhouse gas emissions. Involved parts (clients, designers,contractors and material suppliers) see the need for sustainable solutions and the respective partsare searching for means to get there.The large emission of carbon dioxide (CO2) comes from the production of concrete/cementand steel reinforcement bars. Studies in 2017 measured climate gas emissions in the constructingand infrastructure sector, which showed that concrete and reinforcement steel stood for 8 % ofthe CO2 emissions each. The large climate emission from these products led to climate goals forsustainable development, both global and local, with purpose to reduce the climate emissionregulated by the United Nations (U.N) and applied by the Swedish transport administration(Trafikverket).The purpose of this master’s thesis was to identify possible measures that will have positiveimpact on the climate goals. The possible measures could contribute to future guidelines forhow a bridge designer should work to reduce the climate emissions.The master’s thesis is divided into two main parts: Literature study and case study. The literaturestudy identifies the different materials and their climate impact with focus on the materialsconcrete, cement and reinforcement. It also identifies how a bridge designer can affect theclimate impact in a positive way. The case study implements the measures from the literaturestudy that are applicable. The literature study is implemented on a real bridge that is locatedover road E4 in Kalix. Calculations is performed during the case study to measure the climateimpact from the bridge construction process, in terms of CO2, which is compared to differentmeasures found in the literature study.The results from the literature study shows that the largest climate savings can be achieved byreplacing as much Portland cement as possible. Portland cement is replaced by mixing thecement with supplementary cementing materials such as fly ash, granulated blast furnace slag orcalcined clay. Smaller climate saving was identified by comparing different reinforcementsuppliers and compare their respective environmental product declarations. Finally, recyclingcrushed concrete as coarse aggregates presented possible climate savings along with reducedamounts of waste disposal.Conclusions and results from the studied research are that the largest climate savings can beachieved from the actions made by the material manufacturers. A bridge designer can affect theenvironment by optimizing the bridge structure with the help of suitable bridge types or crosssections.The most effective optimization is achieved through iterative calculations of thedifferent bridge types and cross-sections.

Incipient caries lesions or white spot lesions are one of the most common clinical problems resulting from orthodontic treatment with fixed appliances. Literature has shown that infrared photothermal radiometry and modulated luminescence (PTR-LUM), used by The Canary System for caries detection, is capable of monitoring artificially created carious lesions and their evolution during demineralization. Recently, a water-based calcium aluminate glass ionomer luting cement, Ceramir, has shown bioactive surface apatite formation that may influence local remineralization. This in vitro study’s objective was to evaluate effects of bioactive cement on enamel demineralization around orthodontic brackets compared to composite resin cement. A sample of 32 caries-free extracted human teeth was collected under an IRB-exempt protocol. Orthodontic brackets were cemented to each tooth with either Transbond XT or Ceramir. A 3x3 mm window adjacent to the bracket was created with acid-resistant varnish f / Oral Biology

Three main objectives have been set for this research. The first is to develop an accurate method for measuring the dielectric constant of PCC using a capacitor probe (C-Probe) that has been recently developed at Virginia Tech and validate it for field application to detect internal PCC flaws such as delamination. The C-Probe consists of two flexible conducting plates, connected to a Network Analyzer, with a specific separation between them. The second is to optimize the C-Probe design configuration for different PCC slab thicknesses. The third objective is to develop a predictive model that correlates the bulk dielectric constant of PCC with its critical parameters (cement, aggregate, and air content). Five calibration methods have been developed and evaluated for the C-Probe to measure the dielectric properties of PCC. This evaluation has demonstrated that open, short, Teflon material (OSM) calibration method is the most appropriate one for the C-Probe. The selected calibration method was used to validate the C-Probe fixture for field application by measuring 1.5 x 1.5 m PCC slabs prepared with different mix properties, thicknesses, and induced deterioration. The C-Probe has been proved to detect induced voids in the PCC slabs. In addition, the effect of steel reinforcement on measurements can be mastered by controlling the penetration of electromagnetic (EM) field in the PCC slabs. The effective penetration depth of the EM field for different C-Probe design configuration was optimized by computer simulation. The results have been used to develop a predictive model that correlates the effective penetration depth with the plates' size, separation between them, and the dielectric constant of the PCC under test. Thus, an optimum design for different desired penetration depth was achieved. Two experimental designs were developed to identify the critical parameters that affect the bulk dielectric constant of PCC. A computer simulation was used to identify the significance of each parameter. A predictive model has been developed to correlate the PCC bulk dielectric constant to the critical parameters. The estimated dielectric constant of PCC using the predictive model was correlated to that obtained by other theoretical mixture models; the predictive model has found to correlate well with Looyenga theoretical mixture model. / Ph. D.

In view of the fact that prestressed concrete is extensively used in bridge construction and that it holds potentialities for eventual use in pavement construction, and that methods must be investigated to utilize an otherwise rejected aggregate which cannot be used for its poor performance under natural weathering, it has become of paramount importance that further efforts be made to evaluate the effect of prestressing on the durability of concrete. The purpose of this thesis was twofold: 1) To study the durability of prestressed concrete made of poor-performing aggregate; 2) To compare the freezing and thawing effects on prestressed concrete with those on ordinary concrete. Two mix designs having different proportions of poor performing aggregate were used in this study. Half the number of specimens were post-tensioned after they had been cured for a period of 13 to 18 days in water, and were then replaced in the curing room for 24 hours, Level of prestress was 600 psi. Before transferring the specimens - both prestressed and non-prestressed - into freezing and thawing apparatus, they were tested for fundamental transverse frequency and initial weight and length measurements were recorded. Thereafter, transverse frequency, weight, length change and temperature change measurements were made periodically. The relative dynamic modules of elasticity and durability factor were then calculated for each specimen. On the basis of the results furnished by these tests, it may be concluded that prestressing improves the durability of concrete made of poor performing aggregate and that the magnitude of improvement in the durability ef concrete tends to diminish with increasing proportion of good performing aggregate. / Master of Science

Asphalt cement content is one of the most important requirements for producing high quality hot-mix asphalt. The determination of the asphalt cement content of hot-mix asphalt by traditional methods is time consuming and hazardous. A demand for faster and safer methodes) led to the development of a nondestructive technique using nuclear technology. Measuring asphalt cement content of Marshall specimens by nuclear gauges is a new technique; this study evaluates the feasibility of using the nuclear gauges. Two hundred fifty-six specimens were prepared for this purpose. The study evaluated the effect of different parameters on the measured asphalt cement content by 3241-C Troxler nuclear asphalt content gauge. The following parameters were considered: aggregate type, aggregate gradation, air-void content, moisture content in specimens, asphalt cement content, and total specimen weight. Different calibration models were developed for different bituminous mixtures. / Master of Science

As was stated before, the purpose of this problem was to find out the effect of freezing on mortar at different hours after mixing. This was a continuation of the work done by G.H. Harris in 1945. It was hoped that by using different materials, steel molds, and by molding, freezing and testing the specimens as accurately as was possible to do so with the equipment available the peculiar results obtained by Harris could either be verified or disproved. The results obtained by this problem were very irregular but did show a slight trend and did not show the great difference in strength over a short period of time as was shown by Harris’s results. To get a definite answer a large number of samples should be run for each different time of set before freezing. A large variety of materials should be used and it is also believed that test cylinders 6”x12” would give better results. / Master of Science

Based on the results of this investigation certain conclusions were arrived at relative to Portland cement concrete using Dolomitic limestone sand as the fine aggregate. The most important of these are as follows: 1. Fresh concrete continues to gain strength while in the frozen state. 2. Freezing and then thawing of fresh concrete does not have an appreciable effect on the twenty-eight day ultimate strength, and the concrete, if given time to recover, will compare favorably with concrete cured under normal conditions. 3. Freezing of concrete immediately after pouring has a greater effect on the twenty-eight day ultimate strength of the concrete than has freezing for the same period at a more advanced age within the twenty-eight days. 4. Concrete cured at 65°C. tends to increase its twenty-eight day ultimate strength, providing the water lost through evaporation is replaced. 5. High early strength concrete can be obtained by curing ordinary Portland cement concrete at high temperatures. Based on the results of compression tests performed in this investigation, Dolomitic limestone sand has been found to be satisfactory as the fine aggregate for Portland cement concrete; verifying what Messrs. Broyles and Brown had said in 1936 and 1937 respectively. What has been done in the way of concrete research at Virginia Polytechnic Institute is satisfactory for relatively new concrete using Dolomitic limestone sand as the fine aggregate; but it is wondered how this concrete will stand up over a long period of time. Professor Hartman and Dr. Holden have inaugurated some long time studies at the Institution, but there is still much room for further investigation. Dolomitic limestone rock has proven itself worthy when used as the coarse aggregate for Portland cement concrete. It is up to time and future research to prove the worth of its sand used as the fine aggregate. / Master of Science

During the initial heating of hydraulically bonded castable refractories, dehydration of cement phases causes build-up of high levels of internal steam pressure. If this pressure exceeds material strength, explosive spalling results. A probe capable of measuring internal steam pressures"in-situ" has been developed and tested. Correlation of cement calorimetry and pressure data suggests that castable heating schedules can be modified to reduce explosive spalling. / Master of Science