Betong är ett av de vanligaste byggnadsmaterialen och har goda egenskaper som hög beständighet, god formbarhet och lång livslängd. Huvudbeståndsdelen cement orsakar däremot en negativ klimatpåverkan där tillverkningen av bindemedlet cement står för cirka 8 procent av världens koldioxidutsläpp. För att minska de stora koldioxidutsläppen finns det alternativa bindemedel där de vanligaste är flygaska och masugnsslagg, vilket är restprodukter från kolkraft- och stålindustrin. Alternativa bindemedel är det mest effektiva sättet på kort sikt att minska klimatpåverkan. Däremot kan inte de alternativa bindemedlen ersätta cement helt utan att tryckhållfastheten försämras, vilket gör att upp till 20 procent vanligtvis ersätts. För att byggbranschen i en större utsträckning ska tillämpa betong med lägre klimatpåverkan är det viktigt att egenskaperna är minst lika bra som hos traditionell betong. Uttorkningsegenskaperna är av stor vikt då uttorkningstiden är styrande för applicering av golvmaterial. När det kommer till hållfasthet tillverkas idag komponenter med överkvalité, vilket gör att en onödigt stor mängd cement används. Ett klimatsmart alternativ skulle vara att ändra nuvarande norm på klassificeringen av hållfastheten. Dagens norm klassificerar hållfastheten vid 28 dygn efter gjutning. Betong fortsätter dock att öka i hållfasthet efter 28 dygn, men ökningen är inte stor hos traditionell betong, medan betong med alternativa bindemedel fortsätter att härda i en högre grad efter 28 dygn. Skulle en klassificering av hållfastheten hos betong med lägre klimatpåverkan bestämmas i ett senare skede som 56 eller 91 dygn, skulle konstruktionens krav fortfarande uppfyllas samtidigt som mängden cement kan reduceras. Idag behöver byggprojekt vänta på uttorkningstiden, vilket medför att ett projekt sällan är färdigt redan vid 28 dygn. Det gör att byggnaden inte belastar betongplattan fullt ut vid 28 dygn och den potentiella hållfastheten behöver inte uppfyllas förrän i ett senare skede. Om hållfasthetsklassen sänks tillkommer dock ett högre vattencementtal, vilket gör att krav på uttorkningsegenskaperna ökar. Tillsammans med Skanska jämfördes i föreliggande arbete betongrecept med lägre klimatpåverkan i tryckhållfasthet och uttorkning. Det var två Portlandkompositcement av typen CEM II/B-M, med cirka 20 procent slagg eller flygaska. De jämfördes även mot en referensbetong av typen CEM II/A-LL. Provkropparna gjöts vid Skanskas betonglabb i Farsta och testades sedan för uttorkning och hållfasthet av auktoriserade företag. Studien tyder på att det inte finns någon anledning att välja bort slagg eller flygaska när det kommer tilltryckhållfasthet och uttorkning. Det går att argumentera för att betong med alternativa bindemedel har högre hållfasthet vid 7 och 28 dygn i jämförelse med traditionell betong i föreliggande arbete, där slaggbaserad betong är cirka 16 procent högre och betong med flygaska är cirka 5 procent högre. Hållfasthetsutvecklingen från 28 till 91 dygn tyder på att betong med alternativa bindemedel ökar med cirka 12 procent medan traditionell betong nästan stannar av, där hållfasthetsutvecklingen är cirka 4 procent. Det går att argumentera för att slaggbaserad betong har cirka 2 och 5 procent snabbare uttorkning vid 35 och 85 dygn i jämförelse med traditionell betong, medan betong med flygaska tenderar att torka ut minst lika bra vid 35 dygn och cirka 3 procent snabbare vid 85 dygn. Resultaten tyder på att vid en minskad hållfasthetsklass skulle betong med lägre klimatpåverkan inte medföra samma förlängda uttorkningstid som en traditionell betong. En klassificering i ett senare skede som 56 eller 91 dygn för betong med lägre klimatpåverkan indikerar på att konstruktionens krav fortfarande skulle uppfyllas, cementanvändningen reduceras och klimatpåverkan minskas. / Concrete is one of the most common building materials and possesses favorable properties such as high durability, good workability, and long lifespan. However, its main component, cement, has a negative climate impact, with cement production accounting for approximately 8 percent of the world's carbon dioxide emissions. To reduce these CO2 emissions alternative binders can be used. The most common being fly ash and blast furnace slag, which are by-products of the coal power and steel industries. Alternative binders are the most effective way to reduce climate impact. Alternative binders cannot completely replace cement without lose strength, which means that up to 20 precent is usually replaced. For the construction industry to more widely adopt concrete with lower climate impact, it is important that the properties are at least as good as those of traditional concrete. Drying properties are crucial since drying time dictates the application of flooring materials. In terms of strength, components are currently manufactured with high qualities, leading to unnecessary large amounts of cement being used. A climate-smart alternative would be to change the current norm for strength classification. Today strength classifies at 28 days after casting. Concrete continues to gain strength beyond 28 days, but the increase is not significant in traditional concrete, whereas concrete with alternative binders continues to cure to a greater extent after 28 days. If the strength classification were determined at a later stage, such as 56 or 91 days, the construction's requirements would still be met while reducing the amount of cement used. Today construction projects need to wait for the drying time, meaning a project is rarely completed at 28 days. This means the building does not fully load the concrete slab at 28 days, and the potential strength does not need to be achieved until a later stage. However, if the strength class is lowered the demands on drying increases. In collaboration with Skanska, concrete with lower climate impact was compered in terms of strength and drying. Two Portland composite cements of the type CEM II/B-M, around 20 percent of slag or fly ash, were compared to a reference concrete of the type CEM II/A-LL. The test specimens were cast at Skanska's concrete lab in Farsta and tested for strength and drying by authorized companies. The study suggests that there is no reason to avoid slag or fly ash concerning compressive strength and drying. It can be argued that concrete with alternative binders has higher strength at 7 and 28 days compared to traditional concrete, with slag-based concrete being approximately 16 percent stronger and fly ash concrete about 5 percent stronger. The strength development from 28 to 91 days indicates that concrete with alternative binders increases by about 12 percent, while traditional concrete almost levels off, with a strength development of about 4 percent. It can also be argued that slag-based concrete has about 2 and 5 percent faster drying at 35 and 85 days compared to traditional concrete, while fly ash concrete tends to dry at least as well at 35 days and about 3 percent faster at 85 days compared to traditional concrete. The results indicate that with a reduced strength class, concrete with lower climate impact would not entail the same extended drying time as traditional concrete. Classification at a later stage, such as 56 or 91 days, for concrete with lower climate impact indicates that the construction's requirements would still be met, cement usage would be reduced, and climate impact minimized.

La Tierra es uno de los recursos constructivos más empleados globalmente. Sin embargo, su aplicación en áreas propensas a terremotos y su susceptibilidad a la erosión por agua son aspectos que generan inquietud entre los ingenieros. La investigación se enfocó en integrar estiércol de Equus asinus en la producción de unidades de tierra reforzada con el fin de aumentar su resistencia a la compresión y tracción, además de explorar el efecto de aplicar estearato de calcio en su superficie para disminuir su permeabilidad. Se llevaron a cabo pruebas tanto en campo como en laboratorio para elegir la cantera de suelo y el agua a emplear. Se analizaron las características mecánicas (compresión y tracción) de los bloques de tierra reforzada según lo estipulado en la norma E.080. Además, se sugirieron pruebas de absorción e inundación simulada para evaluar la permeabilidad. Los resultados indicaron un aumento del 19% en la resistencia a la compresión y un 50% en la resistencia a la tracción a nivel de unidades, y del 20% y 22% respectivamente a nivel de muros. El uso de estearato de calcio como recubrimiento permitió que las muestras absorbieran temporalmente agua sin desintegrarse, retrasando su deterioro. Por último, se determinó un aumento del 19.20% del precio de asentamiento con unidades de tierra reforzada y recubrimiento con estearato de calcio. En conclusión, la adición de estiércol de Equus asinus al 6% y el recubrimiento de estearato de calcio mejoran tanto las propiedades mecánicas como las hidrofóbicas de las unidades de tierra reforzada, con un pequeño aumento en su costo de producción. / Earth is one of the most commonly used construction materials. However, its application in earthquake-prone areas and susceptibility to water erosion are concerns for engineers. This research aimed to enhance the compression and traction resistance of earth units by integrating Equus asinus manure into their production. Additionally, it explored the effectiveness of applying calcium stearate to the surface to reduce permeability. Field and laboratory tests were conducted to select the soil quarry and water source. Mechanical properties (compression and traction) of the reinforced earth blocks were analyzed according to the E.080 standard. Furthermore, absorption and simulated flooding tests were suggested to evaluate permeability. Results indicated a 19% increase in compression resistance and a 50% increase in traction resistance at the unit level, and 20% and 22%, respectively, at the wall level. Coating with calcium stearate allowed samples to temporarily absorb water without disintegration, thus delaying deterioration. Lastly, a 19.20% increase in settlement price was observed with reinforced earth units and calcium stearate coating. In conclusion, the addition of 6% Equus asinus manure and calcium stearate coating improve both the mechanical and hydrophobic properties of reinforced earth units, albeit with a slight increase in production cost.

Due to high rates of emissions of carbon dioxide released in cement production, an alternative to minimize this pollution is the use of rice husk ash in concrete as partial cement replacement. This research aims to investigate the technical feasibility, and the mechanical properties of the use of rice husk ash in concrete for structural purposes. Rice husk ash content to 15% by mass replacement of cement CPII-Z and CPIV were used in natural state and ground in a ball mill and compared with the reference concrete, with three water/binder relationships: 0.45; 0.55 and 0.65. Mechanical strength tests by axial compression and diametral compression at ages 28 and 91 days and elasticity modulus at 28 days were performed. The 28 days results indicated axial compression strength, modulus of elasticity and diametrical compression strength below the reference at 91 days and the concrete results with mineral admixtures were similar to the reference concrete. The mixtures containing CPII-Z, presented higher axial compressive strength than CPIV, because the higher cement consumption compared with the CPII-Z with the same w/b relationship. This fact coupled with the presence of high levels of fly ash, classifies cement CPIV with resistance to higher environmental aggressiveness, which represents more durability and useful life. It was found that mixtures containing CCAN reduced axial compressive and diametral strength compared with CCAM, because of the smaller chemical reactivity and bigger particles of CCAN compared with ground rice husk ash. These differences between the mixtures were not relevant, being about 10% and consumption of about 20 kg/m³ in relation to the same w/b compared with mixtures of CCAM for the two cement types. In conclusion, the results of the tests show that there is technical feasibility for the use of natural rice husk ash in structural concrete due to the differences observed with the ground mixtures were negligible. The values obtained in the tests were satisfactory for natural rice husk ash and ground rice husk ash with sligth advantage for the latter compared to first one, because both developed axial compressive and diametral strength and elasticity modulus similar to the reference concretes. These results reveal the greater sustainability to the concrete utilizing agriculture by-products, contributing to reducing the pollutants emissions and the global warming, due to decreased use of clinker in the mixtures. / Devido às altas taxas de emissão de dióxido de carbono liberado na produção do cimento, uma alternativa para minimizar esta poluição é o uso parcial de cinza de casca de arroz no concreto em substituição ao cimento. Esta pesquisa teve o objetivo de investigar a viabilidade técnica, quanto às propriedades mecânicas do emprego de cinza de casca de arroz natural (sem moagem) e moída, em concretos para fins estruturais. Foram utilizadas cinza de casca de arroz com teor de 15% em substituição em massa de cimento CPII-Z e CPIV, nas formas moída em moinho de bolas e natural (sem beneficiamento), e comparadas com o concreto de referência, com três relações água/aglomerante: 0,45; 0,55; e 0,65. Foram executados os ensaios de resistência por compressão axial e compressão diametral nas idades de 28 e 91 dias e módulo de elasticidade aos 28 dias. Os resultados aos 28 dias indicaram resistências axiais, módulo de elasticidade e resistência por compressão diametral inferiores ao de referência; aos 91 dias, os resultados dos concretos com adições minerais foram semelhantes ao concreto de referência. As misturas com cimento CPII-Z apresentaram resistências à compressão axial superiores com CPIV, este com consumo de cimento maior nas relações a/ag do que o anterior. Tal fato, aliado com a presença de altos teores de cinza volante, classifica o cimento CPIV com maior resistência à agressividade ambiental de agentes deletérios como cloretos e carbonatação, o que representa maior durabilidade frente aos agentes agressivos. Também foi constatado que as misturas com CCAN tiveram menores resistências mecânicas comparadas com CCAM, em razão de a CCAN possuir partículas maiores e reatividade química menor do que a cinza moída. Estas diferenças entre os dois tipos de misturas não se revelaram significativas, ficando em aproximadamente 10%, e consumo, em torno de 20 kg/m³ em igualdade de relação a/ag se comparadas com as misturas de CCAM para os dois tipos de cimentos. Como conclusão, os resultados obtidos nos ensaios revelam que existe viabilidade técnica para o emprego de cinza de casca de arroz natural no emprego em concreto estrutural, em razão de as diferenças constatadas com as misturas com CCA moída terem sido pouco significativas. Os valores obtidos nos ensaios foram bastante próximos, tanto para cinza de casca de arroz natural como moída, com vantagem para esta última, pois ambas desenvolveram resistências à compressão axial, módulos de elasticidade e resistências por compressão diametral similares ao concreto de referência. Estes resultados contribuem para conferir maior sustentabilidade ao concreto pelo aproveitamento de subprodutos da agricultura, contribuindo para diminuir a emissão de poluentes na atmosfera e o efeito estufa, devido à diminuição do uso de clínquer nas misturas.

<p>Uvođenje nanočestica u stomatolo&scaron;ke kompozitne materijale predstavlja poku&scaron;aj da se odgovori univerzalnim zahtevima za kvalitetom direktnog zubnog ispuna, i da se stvori materijal koji kombinuje visoku mehaničku otpornost sa dobrim estetskim karakteristikama i zadovoljavajućim kvalitetom poliranja. Cilj sprovedene studije je bio da se ispita uticaj nanočestica, i soft-start metode svetlosne indukcije polimerizacije na mehanička i povr&scaron;inska svojstva savremenih stomatolo&scaron;kih nanokompozita, dostupnih na trži&scaron;tu. Ispitana su četiri stomatolo&scaron;ka nanostrukturisana kompozitna materijala na bazi smola i jedan univerzalni mikrohibridni kompozit, kao referentni materijal (Filtek Z250, 3M ESPE). Kori&scaron;ćena su po dva reprezentativna materijala iz dve podgrupe nanokompozita: nanopunjenih (Filtek Ultimate Body, 3M ESPE i Filtek Ultimate Translucent, 3M ESPE) i nanohibridnih kompozita (Filtek Z550, 3M ESPE i Tetric EvoCeram, Ivoclar Vivadent - TEC). Uzorci su polimerizovani nakon svetlosne aktivacije polimerizacije, uz kori&scaron;ćenje dva svetlosna režima: konvencionalnog i soft start režima. Pritisna i zatezna čvrstoća (dobijena poprečnim sabijanjem valjka, engl. diametral tensile strength) testirane su na Univerzalnoj ma&scaron;ini, kidalici. Tvrdoća uzoraka merena je testom za određivanje tvrdoće po Vickersu. Povr&scaron;inska tekstura i parametri hrapavosti određeni su skeniranjem povr&scaron;ine mikroskopom atomskih sila. Uop&scaron;teno, TEC je pokazao najniže vrednosti pritisne i zatezne čvrstoće, i tvrdoće, i statistićki je značajno bio slabiji od drugih testiranih materijala kroz sve mehaničke testove. Suprotno, TEC je imao najniže vrednosti parametara hrapavosti među testiranim materijalima. Spoj prepolimerizovanog punioca i polimerne baze u ovom materijalu pokazao se kao njegova slaba tačka. Navedeni materijal je iz tog razloga pokazao značajno slabiju otpornost od ostalih na razvijene napone izazvane dejstvom mehaničkih sila. Čestice nanodimenzija u sastavu stomatolo&scaron;kih polimernih kompozita, samostalno, nisu imale značajan uticaj na pobolj&scaron;anje mehaničkih i povr&scaron;inskih svojstava testiranih kompozita. Zaključeno je i da se procentualna zastupljenost neorganskih čestica u polimernoj bazi ne može smatrati apsolutnim kriterijumom kvaliteta kompozita, u pogledu njihovih mehaničkih svojstava. Samo srodni materijali, izrađeni istim tehnolo&scaron;kim postupkom, koji imaju veoma sličan ili isti hemijski sastav, pokazali su se kao mehanički superiorniji ukoliko su sadržali veći procenat neorganske komponente u svom sastavu. Nano prefiks u nazivu klase materijala ne garantuje sigurnu prednost stomatolo&scaron;kih nanokompozita nad univerzalnim mikrohibridnim kompozitima.</p> / <p>The introduction of nanoparticles in dental composite materials was an attempt to respond to the universal quality requirements for a direct dental restoration, and to create a material that meets the needs of high mechanical resistance, good aesthetic characteristics and surface properties of tooth restoratives. The aim of this study was to investigate the effect of nanoparticles in materials composition, and the soft start photoactivation method on the mechanical and surface properties of contemporary dental nanocomposites, available in the market. Four dental resin based nanostructured composites were tested along with a universal microhybrid one, as reference material (Filtek Z250, 3M ESPE). Two representative materials from the two classification subgroups were tested, nanofilled (Filtek Ultimate Body, 3M ESPE and Filtek Ultimate Translucent, 3M ESPE) and nanohybrid composites (Filtek Z550, 3M ESPE and Tetric EvoCeram, Ivoclar Vivadent, TEC). Polymerization of the samples was light activated using two light modes: conventional and soft start. Compressive and diametral tensile strength were tested on the Universal testing machine. The Vickers hardness was also determined. Surface texture and roughness parameters were examined by atomic force microscopy. Generally, TEC showed the lowest values of compression, tensile strength and hardness, and was statistically different from the other tested materials throughout all mechanical tests. In contrast, TEC had the lowest values of roughness parameters among the tested materials. In this material, contact zone of prepolimeryzed filler and polymer matrix appeared to be a weak point. For this reason, this material showed significantly lower resistance than the others on mechanically developed stresses. Nanosized particles within the dental polymer composites, individually, did not have a significant influence on improving the mechanical and surface properties of tested composites. It is concluded that the inorganic volume fraction in composites cannot be considered as an absolute criterion of their quality, regarding their mechanical properties. Only similar materials, made using the same technological process, which have very similar or the same chemical composition, and similar technological method of synthesis and optimization of organic and inorganic components, showed improved mechanical strength, if they contained a higher percentage of inorganic components in their composition. Nano prefix in the name of material&rsquo;s class does not guarantee the pure advantage of dental nanocomposites in comparison with the universal microhybrid composites.</p>

<p>U disertaciji su prikazani rezultati sopstvenog eksperimentalnog istraživanja<br />izvr&scaron;enog na uzorcima pripremljenim sa različitim uče&scaron;ćem struganog asfalta (RAP)<br />i dodatnog - &quot;novog&quot; drobljenog kamenog agregata. Variranjem uče&scaron;ća struganog<br />asfalta i dodatnog drobljenog kamenog agregata i variranjem uče&scaron;ća oba veziva<br />omogućeno je praćenje uticaja sastava na mehaničke karakteristike me&scaron;avine.<br />Uticaj vrste i količine upotrebljenog veziva na mehaničke karakteristike nosećeg<br />sloja kolovoza sagledano je kroz variranje sadržaja cementa i bitumenske emulzije.<br />Predmet istraživanja je definisanje međusobne zavisnosti odnosno korelacije,<br />određenih mehaničkih karakteristika me&scaron;avine u funkciji vrste i količine<br />komponentnih materijala i veziva i ocena njihovih fundamentalnih mehaničkih<br />karakteristika.</p> / <p>In dissertation are resented results of own experimental research on<br />samples that have been prepared with different amount of reclaimed<br />asphalt (RAP) and the additional - &quot;new&quot; crushed stone aggregate. By<br />varying participation of reclaimed asphalt and additional crushed stone<br />and varying participation of both binders monitoring of the impact of the<br />composition on the mechanical properties of the mixture was enabled.<br />The influence of type and amount of binder on the mechanical properties<br />of the pavement base layer is seen through variation in the content of<br />cement and bitumen emulsion. The subject of the research is to define the<br />mutual dependence and correlation of certain mechanical characteristics<br />of the mixture as a function of the types and quantities of component<br />materials and binders and evaluation of their fundamental mechanical<br />properties.</p>

Calcium phosphate cements (CPCs) are used as bone void fillers and as complements to hardware in fracture fixation. The aim of this thesis was to investigate the possibilities and limitations of the CPCs’ mechanical properties, and find out if these ceramic bone cements can carry application-specific loads, alone or as part of a construct. Recently developed experimental brushite and apatite cements were found to have a significantly higher strength in compression, tension and flexion compared to the commercially available CPCs chronOS™ Inject and Norian® SRS®. By using a high-resolution measurement technique the elastic moduli of the CPCs were determined and found to be at least twice as high compared to earlier measurements, and closer to cortical bone than trabecular bone. Using the same method, Poisson's ratio for pure CPCs was determined for the first time. A non-destructive porosity measurement method for wet brushite cements was developed, and subsequently used to study the porosity increase during in vitro degradation. The compressive strength of the experimental brushite cement was still higher than that of trabecular bone after 25 weeks of degradation, showing that the cement can carry high loads over a time span sufficiently long for a fracture to heal. This thesis also presents the first ever fatigue results for acidic CPCs, and confirms the importance of testing the materials under cyclic loading as the cements may fail at stress levels much lower than the material’s quasi-static compressive strength. A decrease in fatigue life was found for brushite cements containing higher amounts of monetite. Increasing porosity and testing in a physiological buffer solution (PBS), rather than air, also decreased the fatigue life. However, the experimental brushite cement had a high probability of surviving loads found in the spine when tested in PBS, which has previously never been accomplished for acidic CPCs. In conclusion, available brushite cements may be able to carry the load alone in scenarios where the cortical shell is intact, the loading is mainly compressive, and the expected maximum stress is below 10 MPa. Under such circumstances this CPC may be the preferred choice over less biocompatible and non-degradable materials.

Cette étude concerne l’ajout de billes de verre de dimension variant de 1 à 50 m dans des matrices cimentaires. Les travaux ont comme objectif dans un premier temps la caractérisation des propriétés physiques et rhéologiques à l’état frais des suspensions cimentaires à deux échelles : la pâte de ciment et le mortier. Puis dans un deuxième temps l’étude de l’influence des microbilles de verre sur les propriétés physiques, mécaniques et durabilité du mortier durci. Des séries d’expériences normalisées ont été faites pour caractériser l’influence des billes de verre sur les indicateurs à l’état frais : la consistance et la prise des pâtes de ciment. Les propriétés mécaniques et de durabilité sont quantifiées au jeune âge (de 3 à 28 jours) et à long terme (de 28 jours à 112 jours). L’étude sur les gels d’hydratation et sur la microstructure du mortier durci a été faite à l’aide de la technique de la microscopie électronique à balayage. Des méthodes de caractérisation complémentaires pour examiner la propagation d’onde, la ségrégation et l’étalement ont également été employées. Les résultats obtenus par l’ensemble des essais évaluent le rôle des microbilles de verre sur les comportements des suspensions de pâtes de ciment et du mortier à l’état frais, et du mortier à l’état durci. Ceci met en évidence l’intérêt rhéologique, mécanique et l’effet sur la durabilité des microbilles de verre dans un matériau cimentaire. / The aim of this work is the valorisation of recycled waste materials in cement paste and mortar in order to reuse these resources for replacing natural aggregates in concrete. Our study concerns the use of a microsphere glass powder (MGP) with a particle size from 1 to 50 m into the cement matrix. This experimental work first focuses on the effect of the MGP on the workability properties of fresh cement paste and fresh mortar and on the physical, mechanical and durability properties of mortar. Many standard tests have been conducted for the characterisation of the behavior of the fresh cement paste i.e the consistency and the setting of fresh cement paste. The durability properties at early age (from 3 to 28 days) and at long time (from 28 days to 112 days) have been also quantified. We employed the scanning electron microscopy for the mortar microstructure analysis. Some supplementary tests like the ultrasonic wave propagation, the segregation and the flow properties on the vibrated table have been also used. The primary results have proved the effect of the MGP on the behaviour of the fresh cement paste, fresh mortar and mortar. The presence of MGP showed interesting modifications on the rheology, mechanical and durability properties of the cement system.

Le travail de la thèse concerne de l'utilisation des matériaux à mémoire de forme (AMF) pour la précontrainte des structures en béton. L’étude s'est portée sur des composants structuraux composites complexes constitués de béton et de matériaux à mémoire de forme tels que des fils de nickel-titane ou de cuivre-aluminium-béryllium. Les fils ont été placés sur les éprouvettes en forme de cylindres creux ou de poutrelles de section rectangulaire. La réalisation de la précontrainte de ces éléments est effectuée par des fils d’AMF sans prédéformation ou avec la déformation initiale. La thèse montre le processus de préparation en vue de la réalisation de précontrainte en utilisant le courant électrique : vérification expérimentale de la température des phases transformations, les propriétés thermomécaniques des matériaux AMF, les effets de l'intensité de courant électrique dans le fil AMF sur sa température. Ensuite, il décrit le programme de la recherche, sa réalisation et l'analyse des résultats obtenus. Ce travail décline aussi les conditions de l'application de la technologie de précontrainte de cylindres en béton avec chauffage des alliages à mémoire de forme par effet Joule. Enfin, le document présente la procédure pour calculer les contraintes générées dans les fils AMF à chaque étape de la recherche. / This work concerns the application of shape memory materials (SMA) to prestressing the concrete structures. The main aim of the thesis was detailed recognition of behavior of composite elements made of concrete and shape memory materials, ie nickel - titanium and copper - aluminum - beryllium wires. The tests were made on the concrete samples with a tubular cross-section and beam. The prestressed of those elements was carried out using the wire without pre-deformation and with initial deformation. The thesis shows the preparation process for the realization of prestressing using electric current: experimental verification of temperature of the phases transfers, thermo-mechanical and thermo-strength properties of SMA materials, temperature effects on the intensity of the current flowing trough SMA wires. Then it is described the research program, its implementation and analysis of results. This work also assumes the conditions of application of the technology of prestressed concrete cylinders with heating of shape memory alloys by Joule effect. Finally, the paper shows how to calculate the stresses generated in the SMA wires at each stage of research. / Niniejsza praca poświęcona jest tematyce związanej z wykorzystaniem materiałów z pamięcią kształtu do sprężania konstrukcji betonowych. Głównym celem rozprawy było szczegółowe rozpoznaniu pracy elementów kompozytowych złożonych z betonu i materiałów z pamięcią kształtu tj. drutów niklowo – tytanowych oraz miedziano – aluminiowo – berylowych. Badania wykonano na betonowych próbkach o poprzecznym przekroju rurowym i belkowym. Przeprowadzono sprężanie tych elementów za pomocą drutów bez wstępnego odkształcenia oraz ze wstępnym odkształceniem. W rozprawie pokazano proces przygotowania się do realizacji sprężania z wykorzystaniem efektu Joula tj. przeprowadzenia badań materiałowych: weryfikacji doświadczalnej temperatur przemian fazowych, właściwości termo-mechanicznych i termo-wytrzymałościowych materiałów SMA, wpływu natężenie prądu płynącego przez drut SMA na jego temperaturę. Kolejno omówiono przebieg badań oraz analizę otrzymanych wyników. Rozprawa ta zawiera opis uwarunkowań technologicznych przy wykonywaniu sprężania betonowych rur metodą ogrzewania drutów AMF za pomocą prądu elektrycznego. Ponadto, w pracy zaprezentowano opracowaną procedurę pozwalającą na obliczenie naprężeń powstałych w drutach SMA na każdym etapie procedury badawczej.

A resistência à compressão uniaxial e o módulo de deformabilidade são parâmetros que descrevem o comportamento de materiais rochosos frente a solicitações por esforços. É prática corriqueira em investigações geológico-geotécnicas para projetos de engenharia estimar a resistência de maneira preliminar com base em propriedades de tenacidade, dureza e friabilidade, aferindo à rocha graus de coerência. Dados laboratoriais referentes a aspectos físicos, texturais e mineralógicos de arenitos da Formação Piramboia, Bacia do Paraná, amostrados via sondagens mistas na região de Anhembi e Santa Maria da Serra, Estado de São Paulo, foram correlacionados entre si e a parâmetros geomecânicos como resistência à compressão uniaxial, módulo de deformabilidade e graus de coerência. As fácies reconhecidas nos arenitos foram agrupadas em associações de dunas e interdunas e suas rochas classificadas como quartzo arenitos e arenitos feldspáticos ou subarcóseos, com cimentação principalmente de esmectita ou material argilo- ferruginoso. Encontraram-se correlações significativas da resistência à compressão uniaxial com tamanho médio dos grãos e densidade, inversa no primeiro caso e direta no segundo. Já o módulo de deformabilidade apresentou correlação significativa inversa com proporção de pelíticos, e direta com tamanho médio dos grãos, desvio padrão da distribuição granulométrica e grau de empacotamento. Arenitos característicos de inundações efêmeras em domínio de interdunas úmidas, com maiores teores de pelíticos, apresentaram módulos de deformabilidade baixos e resistências altas em comparação aos arenitos de demais fácies. Variações da composição mineralógica do arcabouço não se mostraram suficientes para influenciar significativamente o comportamento geomecânico dos arenitos. / The uniaxial compressive strength and the deformability modulus are parameters that describe the behavior of rock materials under stress. It is an everyday practice in geological and geotechnical investigations for engineering projects to estimate strength in a preliminary fashion, based on properties such as tenacity, toughness and friability, attributing to the rock a qualitative term describing its strength. Laboratorial data on physical, textural and mineralogical aspects of sandstones of the Piramboia Formation, Paraná Basin, obtained by core drillings in the region of Anhembi and Santa Maria da Serra, state of São Paulo, were correlated to each other and to geomechanical parameters such as uniaxial compressive strength, deformability modulus and qualitative terms describing their strength. The recognized sandstone facies were grouped in dune and interdune associations and their rocks were classified as quartz arenites and feldspathic arenites or subarkoses, whose cementation is mainly composed of smectite or ferruginous clay material. Significant correlations of uniaxial compressive strength with mean grain size and density were found, inverse in the first case and direct in the second. On the other hand, the deformability modulus showed a significant inverse correlation with the amount of pelitic material, and direct with mean grain size, standard deviation of grain size distribution and packing density. Sandstones characteristic of ephemeral floods in the domain of wet interdunes, with greater amounts of pelitic material, presented low values of deformability modulus and high strength values compared to the other facies. Variations in the mineral composition of the framework were not sufficient to significantly influence the geomechanical behavior of the sandstones.

Este trabalho caracterizou os siltitos do Grupo Itararé, rocha branda proveniente da amostragem de pedreira localizada nas proximidades de futuro empreendimento brasileiro, o Trem de Alta Velocidade. Objetivou entender as causas da pronunciada e rápida alteração da rocha intacta, e simular, em condições controladas de laboratório, a degradação hidromecânica causada pela simples variação da umidade relativa do ar. Para tal, estabeleceu-se técnica de amostragem de testemunhos por meio da extração via seca com ar-comprimido, e processo de intemperismo artificial, composto por 4 ciclos de 2 etapas (secagem e umedecimento). O processo se deu em dessecadores, sendo a variação da umidade ocasionada pela técnica do vapor e sílica gel. O acompanhamento da degradação dos corpos de prova efetuou-se com duas técnicas não-destrutivas de propagação de ondas: o pulso ultrassônico e a excitação por impulso (sistema Sonelastic). Em paralelo, realizou-se a caracterização geotécnica dos siltitos em umidade natural, com ensaios mineralógicos, físicos, físico-mecânicos, físico-químicos e de alteração laboratorial. Por meio desta metodologia, foi possível estimar as minorações do módulo de deformabilidade e da resistência, além das causas físico-químicas da degradação. / This work characterized the siltstones of the Itararé Group, a soft rock sampled in a quarry located near a future Brazilian venture, the High Speed Train. It aims at understanding the causes of the pronounced and fast changes of the intact rock, and simulate in controlled laboratory conditions the hydro degradation process caused by simple variation of relative air humidity. Dry sampling technique with compressed air was used to extract samples from blocks, and the process of artificial weathering consisted on 4 cycles of 2 steps (drying and wetting). The process occurred in desiccators, where moisture variation was caused by the vapor technique and silica gel. The monitoring of the specimens degradation was performed with two non-destructive wave propagation techniques: the ultrasonic pulse and the impulse excitation (Sonelastic system). A geotechnical characterization of the siltstones in natural moisture condition was made in parallel, consisting on mineralogical, physical, physical-mechanical, physical-chemical and durability tests. By this methodology, it was possible to estimate the mitigation of the deformability modulus and strength besides the physical- chemical causes of degradation.