O objetivo desta tese foi o estudo da influência do aditivo redutor de retração (SRA) e o aditivo compensador de retração (SCA) em argamassas e pastas de cimento de escória ativada com silicato de sódio. A metodologia foi centrada na análise da retração por secagem e autógena, com o estudo de outras características que influenciam no fenômeno da retração, como as propriedades mecânicas. Para o avanço no conhecimento do efeito dos aditivos no comportamento do cimento de escória, foi caracterizada a microestrutura com a determinação da análise por termogravimetria, porosimetria e difração de raios X. Neste estudo foram empregados os seguintes teores de aditivo, porcentagem relativa à massa de aglomerante: 0,5%, 1%, 1,5% e 2% do aditivo SRA e 5%, 10% e 15% do aditivo SCA. Para a análise da influência da relação a/agl foram empregadas três teores: 0,40, 0,48 e 0,56. No estudo das amostras de referência, sem a utilização de aditivo, observou-se que o aumento da relação a/agl causa o aumento da retração por secagem e da retração autógena do cimento de escória ativada. A diminuição da resistência mecânica com o aumento da relação a/agl, o que torna o esqueleto sólido mais susceptível à deformações, e o aumento das tensões capilares, em razão do aumento da quantidade de água livre para ser evaporada, são os principais fatores para o aumento da retração por secagem. No caso da retração autógena, seu aumento é atribuído ao aumento da auto-secagem com o aumento do volume de poros com diâmetro na faixa de mesoporos, além da diminuição da resistência mecânica. O aditivo redutor de retração (SRA) conseguiu reduzir a retração por secagem em percentuais de 40% até 74% aos 28 dias, no entanto, este tipo de aditivo não obteve êxito no combate a retração autógena. Com relação à resistência mecânica, o aditivo SRA causou a redução de até 40%, efeito atribuído à diminuição do grau de hidratação e retardo do refinamento da porosidade. O aditivo compensador de retração (SCA) amenizou a retração por secagem e a retração autógena, reduzindo em até 64% e 70%, respectivamente, porém reduziu em até 60% a resistência mecânica do cimento de escória ativada. Com relação à microestrutura, o aditivo SCA diminuiu o grau de hidratação e aumentou a porosidade total, com o aumento da proporção do volume de macroporos. / The aim of this research was the study of the influence of shrinkage reducing admixture (SRA) and shrinkage compensating admixture (SCA) in mortars and pastes of blast furnace slag activated with sodium silicate. The method was centered in the analysis of free drying and autogenous shrinkage, with other characteristics that affect the shrinkage, as the mechanical properties. The microstructure behavior was accomplished with thermogravimetry (TG), mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD). The samples were prepared with 0,5%, 1%, 1,5% and 2% of SRA admixture and 5%, 10% and 15% of SCA admixture, by binder mass. The effect of water/binder ratio was accomplished in three contents: 0,40, 0,48 and 0,56. In the reference mixtures, without admixtures, it was observed that an increase of water/binder ratio incurs in an increase of drying and autogenous shrinkage of alkali activated slag. The explanations for drying shrinkage behavior are the decrease of mechanical strength as consequence of water/binder increase, that turns the porous structure more susceptible to deformations, and the increase of the capillary tensions, attributed to the increase of free water to be evaporated. The increase of autogenous shrinkage with water/binder ratio is attributed to the increase of pore volume with diameter in the mesopores range, besides the decrease of the mechanical strength. The shrinkage reducing admixture (SRA) diminish drying shrinkage of 40% up to 74% at 28 days, however, this type of admixture was not capable to combat the autogenous shrinkage. About mechanical strength, the SRA admixture incurs in a decrease up to 40% of compression strength that it was attributed to the decrease of the hydration degree and retard of pore size refinement. The shrinkage compensating admixture (SCA) softened drying and autogenous shrinkage, reducing in up to 64% and 70%, respectively. However, the SCA admixture decreases in up to 60% mechanical strength of alkali activated slag. About microstructure, SCA admixture reduced the hydration degree and it increased the total porosity, with the increase of macropores volume.

O objetivo desta tese foi o estudo da influência do aditivo redutor de retração (SRA) e o aditivo compensador de retração (SCA) em argamassas e pastas de cimento de escória ativada com silicato de sódio. A metodologia foi centrada na análise da retração por secagem e autógena, com o estudo de outras características que influenciam no fenômeno da retração, como as propriedades mecânicas. Para o avanço no conhecimento do efeito dos aditivos no comportamento do cimento de escória, foi caracterizada a microestrutura com a determinação da análise por termogravimetria, porosimetria e difração de raios X. Neste estudo foram empregados os seguintes teores de aditivo, porcentagem relativa à massa de aglomerante: 0,5%, 1%, 1,5% e 2% do aditivo SRA e 5%, 10% e 15% do aditivo SCA. Para a análise da influência da relação a/agl foram empregadas três teores: 0,40, 0,48 e 0,56. No estudo das amostras de referência, sem a utilização de aditivo, observou-se que o aumento da relação a/agl causa o aumento da retração por secagem e da retração autógena do cimento de escória ativada. A diminuição da resistência mecânica com o aumento da relação a/agl, o que torna o esqueleto sólido mais susceptível à deformações, e o aumento das tensões capilares, em razão do aumento da quantidade de água livre para ser evaporada, são os principais fatores para o aumento da retração por secagem. No caso da retração autógena, seu aumento é atribuído ao aumento da auto-secagem com o aumento do volume de poros com diâmetro na faixa de mesoporos, além da diminuição da resistência mecânica. O aditivo redutor de retração (SRA) conseguiu reduzir a retração por secagem em percentuais de 40% até 74% aos 28 dias, no entanto, este tipo de aditivo não obteve êxito no combate a retração autógena. Com relação à resistência mecânica, o aditivo SRA causou a redução de até 40%, efeito atribuído à diminuição do grau de hidratação e retardo do refinamento da porosidade. O aditivo compensador de retração (SCA) amenizou a retração por secagem e a retração autógena, reduzindo em até 64% e 70%, respectivamente, porém reduziu em até 60% a resistência mecânica do cimento de escória ativada. Com relação à microestrutura, o aditivo SCA diminuiu o grau de hidratação e aumentou a porosidade total, com o aumento da proporção do volume de macroporos. / The aim of this research was the study of the influence of shrinkage reducing admixture (SRA) and shrinkage compensating admixture (SCA) in mortars and pastes of blast furnace slag activated with sodium silicate. The method was centered in the analysis of free drying and autogenous shrinkage, with other characteristics that affect the shrinkage, as the mechanical properties. The microstructure behavior was accomplished with thermogravimetry (TG), mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD). The samples were prepared with 0,5%, 1%, 1,5% and 2% of SRA admixture and 5%, 10% and 15% of SCA admixture, by binder mass. The effect of water/binder ratio was accomplished in three contents: 0,40, 0,48 and 0,56. In the reference mixtures, without admixtures, it was observed that an increase of water/binder ratio incurs in an increase of drying and autogenous shrinkage of alkali activated slag. The explanations for drying shrinkage behavior are the decrease of mechanical strength as consequence of water/binder increase, that turns the porous structure more susceptible to deformations, and the increase of the capillary tensions, attributed to the increase of free water to be evaporated. The increase of autogenous shrinkage with water/binder ratio is attributed to the increase of pore volume with diameter in the mesopores range, besides the decrease of the mechanical strength. The shrinkage reducing admixture (SRA) diminish drying shrinkage of 40% up to 74% at 28 days, however, this type of admixture was not capable to combat the autogenous shrinkage. About mechanical strength, the SRA admixture incurs in a decrease up to 40% of compression strength that it was attributed to the decrease of the hydration degree and retard of pore size refinement. The shrinkage compensating admixture (SCA) softened drying and autogenous shrinkage, reducing in up to 64% and 70%, respectively. However, the SCA admixture decreases in up to 60% mechanical strength of alkali activated slag. About microstructure, SCA admixture reduced the hydration degree and it increased the total porosity, with the increase of macropores volume.

Abstract : Wastepaper sludge ash (WSA) is generated by a cogeneration station by burning wastepaper sludge. It mainly consists of amorphous aluminosilicate phase, anhydrite, gehlenite, calcite, lime, C2S, C3A, quartz, anorthite, traces of mayenite. Because of its free lime content (~10%), WSA suspension has a high pH (13). Previous researchers have found that the WSA composition has poor robustness and the variations lead to some unsoundness for Portland cement (PC) blended WSA concrete. This thesis focused on the use of WSA in different types of concrete mixes to avoid the deleterious effect of the expansion due to the WSA hydration. As a result, WSA were used in making alkali-activated materials (AAMs) as a precursor source and as a potential activator in consideration of its amorphous content and the high alkaline nature. Moreover, the autogenous shrinkage behavior of PC concrete at low w/b ratio was used in order to compensate the expansion effect due to WSA. The concrete properties as well as the volume change were investigated for the modified WSA blended concrete. The reaction mechanism and microstructure of newly formed binder were evaluated by X-ray diffraction (XRD), calorimetry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). When WSA was used as precursor, the results showed incompatible reaction between WSA and alkaline solution. The mixtures were not workable and provided very low compressive strength no matter what kinds of chemical activators were used. This was due to the metallic aluminum in WSA, which releases abundant hydrogen gas when WSA reacts with strong alkaline solution. Besides, the results of this thesis showed that WSA can activate the glassy phase contained in slag, glass powder (GP) and class F fly ash (FFA) with an optimum blended ratio of 50:50. The WSA/slag (mass ratio of 50:50) mortar (w/b of 0.47) attained 46 MPa at 28 days without heat curing assistance. A significant fast setting was noticed for the WSA-activated binder due to the C3A phase, free lime and metallic aluminum contained in the WSA. Adding 5% of gypsum can delay the fast setting, but this greatly increased the potential risk of intern sulfate attack. The XRD, TGA and calorimetry analyses demonstrated the formation of ettringite, C-S-H, portlandite, hydrogarnet and calcium carboaluminate in the hydrated binder. The mechanical performance of different binder was closely related to the microstructure of corresponding binder which was proved by the SEM observation. The hydrated WSA/slag and WSA/FFA binder formed a C-A-S-H type of gel with lower Ca/Si ratio (0.47~1.6). A hybrid gel (i.e. C-N-A-S-H) was observed for the WSA/GP binder with a very low Ca/Si ratio (0.26) and Na/Si ratio (0.03). The SEM/EDX analyses displayed the formation of expansive gel (ettringite and thaumasite) in the gypsum added WSA/slag concrete. The gradual emission of hydrogen gas due to the reaction of WSA with alkaline environment significantly increased the porosity and degraded the microstructure of hydrated matrix after the setting. In the last phase of this research WSA-PC blended binder was tailored to form a high autogenous shrinkage concrete in order to compensate the initial expansion. Different binders were proportioned with PC, WSA, silica fume or slag. The microstructure and mechanical properties of concrete can be improved by decreasing w/b ratios and by incorporating silica fume or slag. The 28-day compressive strength of WSA-blended concrete was above 22 MPa and reached 45 MPa when silica fume was added. The PC concrete incorporating silica fume or slag tended to develop higher autogenous shrinkage at low w/b ratios, and thus the ternary binder with the addition of WSA inhibited the long term shrinkage due to the initial expansion property to WSA. In the restrained shrinkage test, the concrete ring incorporating the ternary binder (PC/WSA/slag) revealed negligible potential to cracking up to 96 days as a result of the offset effect by WSA expansion. The WSA blended regular concrete could be produced for potential applications with reduced expansion, good mechanical property and lower permeability. / Résumé : Les cendres de boues de désencrage (CBD) sont générées par une centrale de cogénération par combustion boues de désencrage. Ils se composent principalement de phase amorphe d'aluminosilicate, anhydrite, gehlenite, calcite, chaux, C2S, C3A, quartz, anorthite, des traces de mayénite. En raison de leur teneur en chaux libre (~ 10%), CBD ont un pH élevé (13). Les chercheurs précédents ont montré que la composition des CDB a une mauvaise robustesse et les variations conduisent à une certaine inconsistance pour le béton avec un mélange de ciment Portland (CP) et des CBD. Cette thèse a porté sur l'utilisation des CBD dans différents types de mélanges de béton pour éviter l'effet délétère de l'expansion due à l'hydratation des CBD. Par conséquent, les CBD ont été utilisées dans la fabrication des matériaux à activation alcaline (MAA), en tant que source précurseur et comme activateur potentiel en tenant compte de sa teneur en matière amorphe et la nature très alcaline des CBD. De plus, le retrait endogène du béton avec CP à faible rapport E/L a été utilisé afin de compenser l'effet d'expansion en raison des CBD. Les propriétés du béton ainsi que le changement de volume ont été étudiés pour le béton mélangé avec des CBD modifiés. Le mécanisme réactionnel et la microstructure du liant nouvellement formé a été évaluée par la diffraction aux rayons X diffraction (DRX), calorimétrie, l'analyse thermogravimétrique (ATG), microscopie électronique à balayage (MEB) et spectroscopie à dispersion d'énergie aux rayons X (DEX). Quand les CBD ont été utilisés comme précurseur, les résultats ont montré des réactions incompatibles entre CBD et une solution alcaline. Les mélanges ne sont pas maniables et donnent de très faibles résistances en compression, peu importe le type d'activateurs chimiques utilisés. Cela est dû à l'aluminium métallique dans les CBD, qui permet de libérer de l'hydrogène gazeux en abondance quand les CBD réagissent avec une solution alcaline forte. D'ailleurs, les résultats de ces recherches ont montré que les CBD peuvent activer la phase amorphe contenue dans le laitier, poudre de verre (PV) et les cendres volantes de classe F (CVF) avec un rapport de mélange optimal de 50:50. Un mortier avec un rapport massique 50:50 de CBD et de laitier (E/L de 0,47) atteint 46 MPa à 28 jours sans l’aide d’un murissement à chaud. Une prise rapide significative a été notée pour le liant CBD activé en raison de la phase C3A, chaux libre et l’aluminium métallique impliqué dans les CBD. L’ajout de 5% de gypse peut retarder la prise rapide, mais augmente grandement le risque potentiel de l’attaque au sulfate interne. Le DRX, ATG et l’analyse calorimétrique ont démontré la formation d'ettringite, C-S-H, la portlandite, hydrogrenat et carboaluminate de calcium dans le liant hydraté. Les différentes performances mécaniques du liant ont été étroitement liées à la microstructure correspondante qui a été prouvée par le MEB. Les liants hydratés CBD/laitier et CBD/CVF ont formé un type de gel C-A-S-H avec un faible rapport Ca/Si (0,47 ~ 1,6). On a observé un gel hybride (à savoir C-N-A-S-H) pour le liant CBD/PV avec un des très faibles rapports Ca/Si (0,26) et Na/Si (0,03). Les analyses MEB/DRX ont montré une formation de gel expansive (d’ettringite et de thaumasite) dans le gypse ajouté au béton avec les CBD et le laitier. L'émission progressive de l'hydrogène gazeux en raison de la réaction des CBD dans un environnement alcaline a augmenté la porosité et la dégradation de la microstructure de matrice hydratée après la prise. Dans la dernière phase de cette recherche, le liant avec un mélange de CBD et de CP a été développé pour former un retrait autogène élevé, afin de compenser l'expansion initiale. Différents liants ont été préparés avec le CP, CBD, la fumée de silice ou du laitier. La microstructure et les propriétés mécaniques du béton peuvent être améliorées en diminuant les rapports E/L et en incorporant la fumée de silice ou du laitier. La résistance en compression à 28 jours du béton aux CBD était supérieure à 22 MPa et atteint 45MPa lorsqu'on a ajouté de la fumée de silice. Le béton avec du CP incorporant de la fumée de silice ou du laitier ont tendance à développer un retrait endogène plus élevée à de faibles rapports E/L, et donc le liant ternaire avec l'ajout des CBD réduit le retrait à long terme en raison de la propriété d’expansion initiale des CBD. Dans l'essai de retrait empêché, l'anneau en béton incorporant le liant ternaire (CP/CBD/laitier) a révélé un potentiel négligeable à la fissuration jusqu'à 96 jours en raison de l'effet de décalage de l'expansion des CBD. Des liants modifiés avec des CBD peuvent être utilisés dans des mélanges de béton ordinaire pour des applications potentielles avec des expansions réduites, des bonnes propriétés mécaniques et une faible perméabilité.

Alkali activated materials (AAMs) represent construction materials with a huge potential especially because of environmental and economic aspects but sufficient mechanical properties as well. A fibre or fabric reinforcement of the AAMs could support more widespread application potential due to the mechanical properties, fracture toughness or composite durability improvement. Various alkaline activators were used for a blast furnace slag (BFS) activation to produce a suitable matrix for basalt fibres (BF) implementation in this thesis. The BFs represent applicable reinforcing material because of its favourable mechanical and thermal properties. Still, the utilization of BFs in the AAMs is quite limited due to the fibres low chemical stability under the alkaline conditions. Accelerated leaching tests with a determination of basalt fibres chemical composition same as tensile strength change using various analytical techniques (XRD, XPS, SEM-EDX, ICP-OES) have confirmed these assumptions. An influence of basalt fabric reinforcement in one or more layers on the mechanical properties was determined with the meaning of the compressive and flexural strengths. The fibre/matrix adhesion and transition zone properties were studied using SEM-EDX and pull-out tests as well because they are crucial parameters for the composite material reinforcement efficiency.

V mnoha oborech jsou stále využívána anorganická filtrační media založená na materiálech, jejichž výroba využívá primární suroviny. Jejich výroba je tedy energeticky náročná a v důsledku nákladná a neohleduplná k životnímu prostředí. Cílem této práce je ověřit možnost využití alkalicky aktivovaných materiálů na bázi sekundárních surovin, především vysokopecních strusek (BFS) a popílků z uhelných elektráren (FA), pro výrobu porézních médií schopných v budoucnosti nahradit keramické a jiné anorganické filtry. Výzkum je rozvinut skrze experimentální design založený na výpočetním schématu samostatně vyvinutém s pomocí programu MATLAB. Toto schéma počítá vhodná složení směsí na základě poměrů obsahu nejdůležitějších oxidů ve vstupních surovinách. Tak je zajištěno zohlednění proměnlivého složení vstupních surovin a práce je tím hodnotnější, že její výsledky jsou skrze početní nástroj zohledňující základní oxidové složení surovin zobecnitelné. Zároveň byly však pro srovnání a lepší názornost závislostí vlastností na složení navrhnuty a připraveny i série vzorků založené vždy pouze na jedné ze surovin. Z výsledků vyplývá, že pevnost vzorků z těchto směsí (vytvrzených 24 hodin při 70 °C) ve čtyřbodové ohybové zkoušce dle ČSN EN 12390 5 může přesáhnout 7,6 MPa. Dosažením co možná nejvyšší porozity však zákonitě negativně ovlivňuje pevnost materiálu a výsledný materiál tedy dosahuje pevnosti těsně nad hranicí 6,3 MPa. Výsledky obecně dokazují, že nejvíce je pevnost materiálů ovlivněna poměrem SiO2/Al2O3 a množstvím alkalického aktivátoru. Z výsledků vyplývá, že alkalicky aktivované materiály (AAM) na bázi strusky dosahují i více než dvojnásobné pevnosti analogických materiálů na bázi elektrárenského popílku. Velikost pórů materiálů připravených z tříděných surovin s velikostí zrna od desítek po lehce přes sto mikronů se ve většině případů pohybuje v rozmezí desetin ž jednotek mikronů, v případě výsledného materiálu je to pak přibližně 0,2 mikronu. Celková porozita lisovaných těles se pohybuje těsně pod 40 %, což je v tomto případě téměř dvojnásobek ve srovnání s totožnými materiály na bázi netříděných surovin. Výsledky rovněž ukazují, že materiály na bázi strusky vykazují nižší porozitu než ty na bázi popílku, což je patrně způsobeno rozdílnou morfologií částic obou materiálů – částice strusky jsou nepravidelně hranaté a částice popílku kulaté. V průběhu experimentální činnosti byla pozorována tvorba výkvětů u materiálů na bázi elektrárenských popílků. Pomocí Energo-disperzní spektroskopické analýzy (EDS) byly výkvěty identifikovány jako hydroxid sodný procházející karbonatací za účasti vzdušného CO2. Test permeability vyžadoval, kvůli velmi jemné povaze porézní struktury, přípravu asymetrických filtračních přepážek. Tyto přepážky dosáhli propustnosti 138 L/h.m2.bar pro vodu a 1320 L/h.m2.bar pro vzduch.

Alkali activated materials, especially when activated with waterglass, are subjected to substantial drying shrinkage that hinders their broader industrial application. The effect of shrinkage reducing admixtures (SRA), based on poly(propylene glycol), on drying shrinkage of alkali activated blast furnace slag (BFS) mortars was studied. The aim of this thesis is to determine the efficiency of SRA as well as the influence of different type of alkali activator with varying silicate modulus on drying shrinkage characteristics. It was observed that the high amount of alkalis positively influenced the effect of SRA. The higher the amount of alkalis, the lower the drying shrinkage was. It also caused more water to be incorporated in the alkali activated structure and prevent it from evaporation. Thus, the weight change of such mortars was the lowest. Reduced effect of SRA on mechanical strength properties was observed in mortars with low amount of alkalis which was connected with delayed hydration resulting in insufficient amount of created C-S-H gel. The presented thesis further discussed and underlines the role of different kinds of alkali ions as well as their amount on the properties of alkali activated BFS systems.

No description available.

Aujourd'hui, les problèmes environnementaux sont plus graves que jamais. Des mesures urgentes devraient être prises dans tous les domaines de l'activité humaine, y compris la construction. L'un des principaux contributeurs à l'impact négatif de cette industrie sur l'environnement est la fabrication du ciment Portland ordinaire (OPC) nécessaire à la production de béton et d’autres matériaux cimentaire. Malgré son importance, il présente un inconvénient important: sa production est accompagnée par de grandes quantités de gaz à effet de serre. Ils représentent 5 à 8% des émissions mondiales totales de CO2. Des matériaux cimentaires plus écologiques sont maintenant nécessaires.Des réductions significatives de l’impact sur l’environnement ne peuvent être obtenues que par l’utilisation de liants de nouvelle génération dont la fabrication ne nécessite pas beaucoup de processus et de traitements supplémentaires. L'une d'elles consiste à utiliser des déchets industriels comme liants (différentes laitiers, cendres volantes, cendres de biomasse, etc.). De cette manière, il y a non seulement une réduction de l'impact de processus tels que l'extraction minière ou la calcination, mais également le recyclage des déchets (un principe de l'économie circulaire).Une possibilité consiste à utiliser du laitier de haut fourneau (GGBS) comme base pour ce ciment de nouvelle génération. En raison de sa réactivité relativement faible avec l'eau, des suppléments (également appelés activateurs) doivent être utilisés pour favoriser le processus d'hydratation. Le carbonate de sodium (Na2CO3) est l’un des activateurs les plus prometteurs et en même temps les moins étudiés. Un tel ciment alkali-activé présente des propriétés mécaniques et de durabilité élevées, ainsi qu'une empreinte CO2 très faible. Parmi les principaux problèmes qui entravent son utilisation à l'échelle industrielle, on peut mentionner une évolution de la résistance lente à jeune âge et de rhéologie médiocre.L'objectif de la présente thèse est de développer une nouvelle conception du liant à base de laitier activé par Na2CO3, qui répondrait à toutes les exigences modernes du secteur de la construction, en particulier les propriétés rhéologiques et le développement de la résistance à jeune âge. Ce liant doit toujours répondre à au moins trois critères principaux: faible impact environnemental, faibles risques de danger dans les applications sur le terrain et être économiquement compétitif à l'échelle industrielle.Dans le présent travail, l’influence de différents paramètres tels que le rapport eau/liant, la concentration de Na2CO3, la finesse du laitier et les conditions de durcissement sur les propriétés du mélange à jeune âge et à long terme a été étudiée. Sur la base des résultats du processus d’hydratation, les additifs à base de phosphonate qui permettent de contrôler efficacement la rhéologie de tels liants ont été testé avec succès. Ils permettent non seulement de contrôler le temps de prise, mais fournissent également un effet plastifiant.En ce qui concerne l’amélioration des propriétés de résistance au jeune âge, différentes méthodes ont été utilisées. L’utilisation d’un traitement thermique ou d’une augmentation de la finesse du GGBS s’est avérée efficace. L’exploration des causes d’une longue période d’induction a montré que l’accélération pouvait également être obtenue par l’ajout d’une source de calcium à cinétique de dissolution contrôlée. En conséquence, le liant est devenu plus réactif et plus robuste à certains facteurs (concentration d’activateur, rapport eau/liant, conditions de durcissement, etc.). Pour compenser l'empreinte carbone supplémentaire de la source de calcium ajoutée, le liant a été dilué avec succès par le calcaire sans aucune dégradation des propriétés à un certain pourcentage de dilution. / Today, environmental problems are more acute than ever. Urgent measures should be taken in all spheres of human activity including construction and civil engineering. One of the major contributors of negative environmental impacts from this industry is the manufacturing of ordinary Portland cement (OPC) required for concrete and other cementitious materials production. Although its importance to economical development, it has a significant drawback - its production is accompanied by the emission of large quantities of greenhouse gases. They account for 5-8% of total world CO2 emissions. More environmentally friendly cementitious materials are now required.Significant reductions of the environmental impact can be achieved only through the use of new-generation binders whose manufacture does not require a lot of additional processes and treatments. One route is through the use of industrial wastes as binders (different slags, fly ash, biomass bottom ash, etc.). In this way there is not only a reduction in the impact of processes such as mining or calcination, but also the recycling of waste materials (circular economy principle).One possibility is to use ground granulated blast furnace slag (GGBS) as the basis for such a new generation cement. Due to its rather low reactivity with water, additional supplements (also called activators) should be used to promote the hydration process. One of the most promising, and at the same time least studied, activators is sodium carbonate (Na2CO3). Such alkali-activated cements present high mechanical and durability properties, as well as a very low CO2 footprint. Among the main problems hindering its industrial scale adoption are their poor rheology and too slow strength gain within the first days of hardening.The objective of the present thesis is to develop a new binder based on Na2CO3 activated GGBS that would meet all the modern requirements of the construction industry, in particular regarding the rheological properties and early age strength development. In addition this binder should always respond to at least three main criteria: low environmental impact, low health and safety concerns in field applications, and be economically competitive at industrial scale.In the present work, the influence of different parameters like water/binder ratio, Na2CO3 concentration, slag fineness and curing conditions on both early age and long term properties of the mixture were studied. Based on the results of the hydration process analysis, phosphonate based additives that allow for the effective control of the rheology of such binders were successfully tested. They not only allow control over the setting time, but also provide a plasticizing effect.Regarding the improvement of early age strength properties, various methods have been used. The use of heat treatment or an increase of GGBS fineness turned out to be efficient. Exploring the causes of the long induction period has shown that acceleration can also be achieved by the addition of a calcium source with controlled dissolution kinetics. As a result, the binder became more reactive and robust against certain factors (activator concentration, Water/Binder ratio, curing conditions, etc.). To compensate for the additional carbon footprint from the added calcium source, the binder was successfully diluted by limestone without any degradation of the properties below some dilution percentages.

Production of construction materials requires a large amount of energy. That can be decreased by using of waste materials. This thesis deals with the self-sensing properties of composites. It presents electrical properties of building materials and their measurement. In the experimental part, the influence of conductive fillers on the self-sensing properties of aluminosilicate composites was examined. Test cubes were made of alkali-activated slag with a content of graphite powder, carbon black, carbon fibers, steel fibers or carbon nanotubes. The fractional change in resistence during cyclic compressive loading was monitored.

This study evaluates question of alkali–silica reaction (ASR) in hybrid system, which was designed in the bachelor's thesis, to meet the requirements of EN 197-1 and classified to the Blastfurnace CEM III/C cements. The durability of this system is a great unknown. For this reason, the same methods (ASTM C1260, ASTM C289 and ASTM C856) were used to observer the ASR effects as the ones used to observer the Portland cement based concrete. Supplementary methods include determination of compressive strengths according to EN 196-2 and scanning electron microscopy to observe the microstructure. Hybrid system results were compared to two different types of cements, CEM I and CEM III/B. From the results of the ASR evaluation assays, it was found that the hybrid system (CEM III/C-HB) and CEM III/B showed the lowest tendency to ASR. The results of the supplementary methods showed that CEM III/C-HB compressive strength increases after 14 days within NaOH by 43 % in comparison to 28 days strength. Based on those results, it is sure that the CEM III/C-HB shows little susceptibility to ASR.