Dans un bâtiment, les déperditions thermiques proviennent de diverses parties opaques (mur, toit et plancher) qui peuvent contenir du béton. Il est donc intéressant d'envisager des formulations de béton de structure avec des propriétés d'isolation thermique améliorées. L'utilisation de granulats légers, qui possèdent de bonnes propriétés thermiques grâce à leur structure poreuse, peut être une solution pour améliorer la capacité d'isolation des éléments en béton. Cette technique d'isolation répartie peut permettre d'éviter des dispositifs constructifs lourds tout en répondant aux exigences de la RT 2012. La présente étude a pour objectif d'optimiser le couple performance mécanique - capacité isolante des bétons de granulats légers. Elle repose sur une double approche expérimentale et numérique.Les bétons de granulats légers ciblés ont une masse volumique inférieure à 1500 kg/m3 et une résistance en compression supérieure à 25 MPa. L'influence de la nature des granulats légers, du taux de substitution du sable alluvionnaire par du sable léger, du rapport E/C et de l'ajout de fumée de silice sur les performances mécaniques et thermiques des bétons est étudiée afin de proposer des formulations adéquates pour une large gamme d'usage structurel. Le module d'Young, la résistance en compression, la conductivité thermique et la diffusivité sont mesurées sur 25 formulations de bétons de granulats légers. Le comportement thermique de ces différents bétons en fonction de facteurs climatiques, comme la température et le degré d'humidité est aussi examiné afin d'optimiser leurs propriétés d'isolation thermique. L'ensemble des résultats expérimentaux permet une meilleure compréhension de la relation entre la formulation des bétons de granulats légers et leur rapport performance mécanique / pouvoir isolant. En s'appuyant sur certaines mesures expérimentales, des modélisations numériques reposant sur des techniques d'homogénéisation permettent d'identifier des propriétés thermiques (conductivité thermique, chaleur spécifique) et mécaniques (module d'Young, résistance à la rupture) des granulats légers (gravillons et sables) difficilement mesurables expérimentalement. Connaissant les propriétés thermiques et mécaniques des différents constituants, des modélisations prédictives des comportements macroscopiques des bétons légers sont développées à partir de schémas d'homogénéisation pour des matériaux multi-phases polydisperses. Les outils développés sont comparés et validés par confrontation aux mesures expérimentales pour les différentes familles de bétons de granulats légers étudiés. Ils permettront par la suite d'alléger les coûts et délais des campagnes expérimentales de mise au point des formulations. La modélisation, sur une année, des transferts thermiques à travers une enveloppe de bâtiment en béton de granulats légers permet de quantifier l'amélioration des performances thermiques des bétons de granulats légers par rapport à un béton classique. / In a building, heat is lost through a variety of surfaces (wall, roof and floor) that may contain concrete. It is therefore useful to consider alternative concrete structures with improved thermal insulation properties. The use of lightweight aggregates, which have good thermal properties due to their porous structure, can present a solution for improving the insulation capacity of the concrete elements. This embedded insulation technique allows lighter construction systems while satisfying the requirements of the RT 2012. This study aims to optimize the mechanical performance/insulating capacity coupling of lightweight aggregate concrete. It is based on a double approach of experimental and numerical analysis.The targeted lightweight aggregate concretes have a density lower than 1500 kg/m3 and a compressive strength higher than 25 MPa. The influence of the lightweight aggregate nature, the rate of substitution of alluvial sand by lightweight sand, W/C ratio and the addition of silica fume on the mechanical and thermal performances of concrete is studied. This allows to identify formulations suitable for a wide range of structural applications. Young's modulus, compressive strength, thermal conductivity and diffusivity are measured on 25 formulations of lightweight aggregate concrete. The thermal behavior of these concretes, including sensible and latent heat transfer, is also examined in order to optimize their thermal insulation properties. The experimental results provide a better understanding of the relationship between the formulation of lightweight aggregate concrete and the mechanical performance to insulating capacity ratio. Based on some experimental measurements, numerical modeling is carried out in order to identify the thermal properties (thermal conductivity, specific heat) and mechanical properties (Young's modulus, fracture strength) of lightweight aggregates (gravel and sand) which are difficult to measure experimentally. Homogenization methods for two phase materials are used for this purpose. By knowing the thermal and mechanical properties of different components, the predictive modeling of the macroscopic behavior of lightweight concrete can be developed from homogenization schemes for multi-phase polydisperse materials. The analytical methods developed are validated by comparison with experimental measurements for the different families of lightweight aggregate concrete studied. They will eventually alleviate the costs and delays of the experimental analysis. The heat transfer over a year through the building envelope made of lightweight concrete is modeled in order to quantify the improvement in thermal performance of lightweight aggregate concrete compared to normal concrete.

Les bétons auto-plaçants (BAP) sont des bétons spéciaux, très maniables, homogènes et stables qui se mettent en place sous le seul effet de la gravité. Grâce à leurs nombreux avantages, les bétons auto-plaçants (BAP) sont aujourd'hui considérés comme étant l'une des innovations les plus marquantes des deux dernières décennies dans le domaine du béton. Plus de 50 % des produits à démoulage différé sont réalisés en BAP. Parallèlement, les bétons légers sont maintenant intégrés dans le contexte normatif et leur utilisation dans l'industrie est croissante du fait notamment de la nouvelle réglementation thermique pour les bâtiments. Ce contexte ouvre la voie aux bétons auto-plaçants légers (BAPL) dont l'utilisation constitue une solution innovante pour répondre encore mieux, aux problématiques de légèreté, d'efficacité énergétique des bâtiments et de productivité. Cependant, la différence de densité entre les granulats légers et la pâte d'une part et le pouvoir absorbant des granulats légers d'autre part, compliquent davantage la formulation et la production des bétons auto-plaçants légers. De plus, les méthodes existantes qui sont pour la plupart empruntées aux méthodes de formulation de BAP traditionnels restent empiriques.Cette thèse vise donc la mise au point d'une méthode de formulation plus rationnelle pour composer des bétons auto-plaçants légers et durables. Cette approche de formation des BAPL est construite autour d'un ensemble de données cohérent dont l'indice de serrage de l'empilement et sur la quantification expérimentale des phénomènes tels que l'absorption dans la pâte de ciment et la ségrégation. A partir de cette méthode, différentes gammes de BAPL sont proposées pour répondent aux critères du cahier des charges en termes de masse volumique réelle sèche et de résistance à la compression. Sa mise en œuvre a permis de simuler et de réaliser des formules de bétons auto-plaçants légers de sable normal (BAPLSN) de classes d'étalement allant de SF1 à SF3, de classes de masse volumique D1.8 et D2.0 et de classes de résistance allant de LC35/38 à LC50/55. Elle a également permis d'explorer les bétons auto-plaçants légers de sable léger (BAPLSL) qui peuvent constituer une solution innovante pour l'industrie du béton dans le contexte de la nouvelle réglementation thermique pour les bâtiments. / Self compacting concrete (SCC) is generally known as the concrete capable of filling up the given structure only using its self weight without any need for vibration and compaction during pouring process. On the other hand, the structural lightweight concrete (LWC) has emerged due to its lightness and all the advantages related to lower thermal insulating characteristics. The two materials open way to the lightweight self compacting concrete (LWSCC) in order to combine the favorable properties of LWC with those of SCC.However, the difference in density between the lightweight aggregate and cement paste complicate the mix design and production of LWSCC. Furthermore, existing mix design methods which are mostly borrowed from SCC design methods are empirical. Therefore, this thesis aims to develop a rational mix design method for suitable lightweight self-compacting concrete. This approach is built around a set of coherent data whose compaction index of granular skeleton and on the experimental data such as water absorption in the cement paste and segregation. From this method, different ranges of LWSCC are proposed to meet the requirements of the specification in terms of dry density and compressive strength. Its implementation was used to simulate and formulate LWSCC of workability classes from SF1 to SF3, density class from D1.8 to D2.0 and resistance class from LC35/38 to LC50/55. The mix design method also explored the total lightweight self compacting concrete (TLWSCC) that may constitute an innovative solution for the concrete industry in the context of the new thermal regulations for buildings

The objectives of this research were to 1) monitor in-situ moisture and diffusivity for both conventional concrete and concrete containing pre-wetted lightweight fine aggregate (LWFA), 2) compare deck performance in terms of early-age cracking, compressive strength, and chloride ingress, and 3) compare concrete properties in terms of compressive strength, chloride permeability, elastic modulus, and water content in the laboratory using cylinders cast in the field at the time of deck construction. The research involved field and laboratory evaluations of four newly constructed bridge decks located in northern Utah, two constructed using conventional concrete and two constructed using pre-wetted LWFA to promote internal curing. Data from sensors embedded in the concrete decks indicate that the moisture content of the internally cured concrete was consistently 1.5 to 4 percentage points higher than the moisture content of the conventional concrete for the first 6 months following deck construction. By 1 year, however, the internally cured concrete showed little difference in moisture content compared to the conventional concrete. While the internally cured concrete decks had a higher average moisture content, the electrical conductivity values were not consistently higher than those measured on the conventional concrete decks during the first approximately 8 to 10 months. However, after 8 to 10 months, both internally cured concrete decks exhibited higher electrical conductivity values than those measured on the conventional concrete decks. Laboratory compressive strength data indicate that, for the first 6 months following deck construction, the two concrete mixtures exhibited very similar strength gain characteristics. However, at 1 year, the conventional concrete was stronger by an average of 12.9 percent, or nearly 900 psi, than the internally cured concrete. In rapid chloride permeability testing, the internally cured concrete consistently passed between 13.1 and 17.5 percent less current than that passed by the conventional concrete. Laboratory free-free resonant testing at 1 year showed that the modulus of the internally cured concrete was 3.9 percent lower, on average, than that of the conventional concrete. For the tested specimens, the moisture content of the internally cured concrete was 0.5 percentage points higher, on average, than that of the conventional concrete. In the field, Schmidt rebound hammer testing showed that the internally cured concrete was neither consistently stronger nor weaker than the conventional concrete. On average, the internally cured concrete exhibited higher chloride concentrations than the conventional concrete. On average, the conventional concrete bridge decks had 4.6, 21.5, and 2.8 times more cracking than the internally cured concrete decks at 5 months, 8 months, and 1 year, respectively. At 1 year, very distinctive reflection cracks from the joints between the underlying pre-cast half-deck panels were observed on all of the decks.

O concreto leve de alto desempenho (CLAD), com argila expandida nacional, é um material alternativo para as concentrações brasileiras, considerando as características climáticas do país e baixo custo do material. Mas atualmente, existe pouca informação disponível sobre a produção e aplicação deste concreto com agregados leves, adições e aditivos nacionais. O objetivo desta dissertação é analisar o comportamento estrutural, por intermédio de ensaios mecânicos (resistência à compressão, resistência à tração por compressão diametral e módulo de deformação) do CLAD, sob ação de altas temperaturas. Para tanto, realiza-se uma análise comparativa da resistência mecânica do concreto em estudo, constituído por agregados leves de argila expandida, com o concreto convencional CAD (concreto de alto desempenho), composto por agregados de brita basáltica, determinando-se assim as respectivas resistências mecânicas, após terem sido expostos a temperaturas externas de até 800 graus centígrados. Através da análise dos resultados obtidos experimentalmente, pode-se comprovar a viabilidade do CLAD, produzido com argila expandida, comparativamente ao CAD, sob à ação de altas temperaturas. / The high performance lightweight aggregate concrete (HPLC), with national expanded clay, is an alternative material for the Brazilian constructions, considering the climatic characteristics of the country and low cost of the material. But now, little available information exists about the production and application of this concrete with lightweight aggregate, additions and addictive national. The aim of this dissertation is to analyze the structural behavior, by mechanical tests (compressive strength, splitting tensile strength and deformation modulus) of HPLC, under action of high temperatures. For so much, it takes place a comparative analysis of the mechanical resistance of the concrete in study, constituted by lightweight aggregate of expanded clay, with the conventional concrete HPC (high performance concrete), composed by crushed basalt coarse aggregate, determining the respective mechanical strength, after they have been exposed to external temperatures of up to 800°C. Through the analysis of the results obtained experimentally, it can be proven the viability of HPLC, produced with expanded clay, comparatively to HPC, under to the action of high temperatures.

Μεγάλο τμήμα της παραγόμενης ενέργειας στην Ελλάδα προέρχεται από την καύση λιγνίτη στην Βόρεια (Δυτική Μακεδονία) και Νότια (Πελοπόννησος) Ελλάδα. Η καύση του λιγνίτη έχει ως αποτέλεσμα την παραγωγή μεγάλων ποσοτήτων στερεών παραπροϊόντων, όπως η ιπτάμενη τέφρα (ΙΤ) και η τέφρα πυθμένα (ΤΠ), των οποίων η συνολική παραγωγή ανέρχεται σήμερα σε 14Mt ετησίως. Η ποσότητα των παραπροϊόντων αυτών αναμένεται να αυξηθεί τα επόμενα χρόνια εξ’ αιτίας της συνεχώς χαμηλότερης ποιότητας λιγνίτη που χρησιμοποιείται (χαμηλότερη θερμογόνος δύναμη). Ένα τμήμα της παραγόμενης ΙΤ (10-12%) στην Ελλάδα αξιοποιείται ως πρώτη ύλη στη παραγωγή τσιμέντου, ενώ η ΤΠ δεν απορροφάται μέχρι σήμερα από καμία εφαρμογή, κυρίως λόγω του υψηλού ποσοστού άνθρακα που περιέχει. Το αντικείμενο της παρούσας διατριβής είναι η αξιοποίηση, πρωτίστως, της ΤΠ και, μετέπειτα, της ΙΤ ως πρώτες ύλες στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στην παραγωγή ελαφροσκυροδέματος. Για την παραγωγή των τεχνητών ελαφροαδρανών εφαρμόστηκε η διεργασία της πυροσυσσωμάτωσης σε σχάρα (grate sintering) έπειτα από σφαιροποίηση μιγμάτων των δύο τεφρών. Πραγματοποιήθηκε διερεύνηση των φυσικοχημικών χαρακτηριστικών των λιγνιτικών τεφρών (Κεφάλαιο 2) με σκοπό τον προσδιορισμό και την κατανόηση των χαρακτηριστικών τους, τα οποία αναμένεται να έχουν σημαντική επίδραση στην εφαρμογή της διεργασίας και στην ποιότητα του παραγόμενου προϊόντος. Επιπλέον, γίνεται αναλυτική αναφορά στα βασικά χαρακτηριστικά των διεργασιών σφαιροποίησης και πυροσυσσωμάτωσης (Κεφάλαιο 3). Για την εφαρμογή της επιλεγμένης διεργασίας παραγωγής τεχνητών ελαφροαδρανών πραγματοποιήθηκε σχεδιασμός μιγμάτων με διαφορετικές αναλογίες ΤΠ και ΙΤ (Κεφάλαιο 4). Ο περιεχόμενος άνθρακας της ΤΠ αποτελεί το καύσιμο της διεργασίας πυροσυσσωμάτωσης, ενώ η υψηλή περιεχόμενη υγρασία της ΤΠ αξιοποιείται ως το κύριο συνδετικό υλικό κατά την διάρκεια σφαιροποίησης για τον σχηματισμό σφαιριδίων. Οι διαφορετικές αναλογίες ΤΠ και ΙΤ αντιστοιχούν σε διαφορετικό ποσοστό στερεού καυσίμου στο μίγμα (προκύπτει από τις διαφορετικές vi αναλογίες), μία παράμετρος η οποία έχει επίδραση στην ολοκλήρωση της πυροσυσσωμάτωσης και στην ποιότητα του παραγόμενου (ελαφροαδρανούς) προϊόντος. Η πυροσυσσωμάτωση ολοκληρώθηκε με επιτυχία με ελάχιστο ποσοστό στερεού καυσίμου (περιεχόμενο άνθρακα ΤΠ) 6.5%κβ (Κεφάλαιο 5). Πραγματοποιήθηκε φυσικοχημικός χαρακτηρισμός όλων των προϊόντων της πυροσυσσωμάτωσης των μιγμάτων λιγνιτικών τεφρών της Μεγαλόπολης, και διαπιστώθηκε ότι το ποσοστό περιεχόμενου άνθρακα της ΤΠ είναι μια πολύ σημαντική παράμετρος για την παραγωγή ελαφροαδρανών υλικών. Ο σχηματισμός πορώδους δομής στο εσωτερικό των πυροσυσσωματωμένων πελλετών, στην οποία οφείλεται και το χαμηλό βάρος των παραγόμενων αδρανών, προκαλείται από την ταυτόχρονη εξέλιξη δύο διεργασιών: α) την παραγωγή αερίων σε υψηλές θερμοκρασίες και β) τον σχηματισμό ρευστής φάσης στην εξωτερική επιφάνεια της πελλέτας στο ίδιο χρονικό διάστημα (Κεφάλαιο 6). Οι αντοχές των πυροσυσσωματωμένων πελλετών οφείλονται σε αντιδράσεις και στον σχηματισμό νέων φάσεων είτε στερεών μέσω διάχυσης είτε ρευστών που προέρχονται από επιτήξεις στα όρια των κόκκων. Στην συνέχεια τα παραγόμενα ελαφροαδρανή χρησιμοποιήθηκαν για την παραγωγή δοκιμίων θερμομονωτικού και δομικού ελαφροσκυροδέματος και πραγματοποιήθηκε έλεγχος των θερμικών και μηχανικών τους ιδιοτήτων, αντίστοιχα (Κεφάλαιο 7). Τα αποτελέσματα δείχνουν ότι τα τεχνητά ελαφροαδρανή μπορούν να χρησιμοποιηθούν για την παραγωγή θερμομονωτικού και δομικού ελαφροσκυροδέματος. Η επιτυχής παραγωγή τεχνητών ελαφροαδρανών από μίγματα λιγνιτικών τεφρών Μεγαλόπολης αποτέλεσε και την βάση για δοκιμές πυροσυσσωμάτωσης των παραπροϊόντων αυτών με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ερυθρά ιλύς (ΕΙ), η οποία παράγεται από την επεξεργασία βωξίτη προς παραγωγή αλουμινίου (Κεφάλαιο 8). Για την διαπίστωση της συνεργασίας των δύο διαφορετικών παραπροϊόντων πραγματοποιήθηκε προσθήκη μέχρι και 30%κβ ΕΙ σε μίγματα λιγνιτικών τεφρών. Πραγματοποιήθηκε φυσικοχημική διερεύνηση των προϊόντων της πυροσυσσωμάτωσης και χρήση τους στην παραγωγή δοκιμίων σκυροδέματος. Τα αποτελέσματα δείχνουν ότι η αύξηση της προστιθέμενης ΕΙ στο μίγμα λιγνιτικών vii τεφρών της Μεγαλόπολης επιφέρει αύξηση στο βάρος των παραγόμενων αδρανών, ενώ μπορούν να χαρακτηριστούν ελαφροαδρανή τα προϊόντα πυροσυσσωμάτωσης μιγμάτων μέχρι και 20%κβ προσθήκης ΕΙ. Τα αποτελέσματα των μετρήσεων των μηχανικών αντοχών των δοκιμίων σκυροδέματος δείχνουν ότι η ΕΙ επιφέρει αύξηση στις αποκτώμενες αντοχές σε ποσοστό προσθήκης μέχρι και 15%κβ. Η εφαρμογή που προτείνεται σε αυτή την διατριβή για την παραγωγή τεχνητών ελαφροαδρανών υλικών από τα στερεά λιγνιτικά παραπροϊόντα του ΑΗΣ Μεγαλόπολης αποτελεί την πρώτη πρόταση για αξιοποίηση της ΤΠ στην Ελλάδα. Η πυροσυσσωμάτωση μιγμάτων των λιγνιτικών τεφρών μπορεί να οδηγήσει στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στο δομικό και θερμομονωτικό ελαφροσκυρόδεμα ενώ ο περιεχόμενος άνθρακας της ΤΠ, ο οποίος αξιοποιείται ως το καύσιμο διεργασίας παραγωγής, αποτελεί σημαντική παράμετρο για την ποιότητα των τεχνητών ελαφροαδρανών. Επιπλέον, οι λιγνιτικές τέφρες της Μεγαλόπολης μπορούν να συνεργαστούν με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ΕΙ για την παραγωγή τεχνητών ελαφροαδρανών διαφορετικής ποιότητας. Επίσης, η συγκεκριμένη πρόταση αφορά στην μαζική αξιοποίηση της ΤΠ και πιθανή εφαρμογή έχει την δυνατότητα να απορροφήσει το μεγαλύτερο τμήμα του παραγόμενου αυτού παραπροϊόντος. / Large part of energy demand in Greece is covered by lignite combustion in West Macedonia and Peloponnesus. Lignite combustion results in production of, approximately, 14Mt/year of solid byproducts, such as fly ash (FA) and bottom ash (BA). The quantity of these byproducts is going to be increased in future because of the low quality of available lignite (lower calorific value). Part of FA (10-12%) produced in Greece is utilized as raw material in cement production while there is no application of BA, mainly because of its high carbon content. This study investigates a new method for utilization of BA, primarily, and FA, afterwards, as raw materials in the production of lightweight aggregates and further utilization of produced aggregates in lightweight aggregate concrete. A two stage process, pelletization and sintering, is applied in BA and FA mixtures. Physical and chemical analyses of Megalopolis lignite ashes are performed (Chapter 2) in purpose of characterization of process raw materials. Furthermore, fundamental theory of pelletization and grate sintering is presented (Chapter 3) in purpose of better understanding of process details. Mixtures of different BA/FA ratio are prepared for sintering tests (Chapter 4). Carbon contained in BA is utilized as the fuel of the process, while high water content of BA is utilized as the primary binding material during pelletization in purpose of pellets formation. Different BA/FA ratios represent different solid fuel percentages in sintering mixtures. This is an important parameter, which strongly affects the completion of the process and the quality of product. Successful completion of sintering process is achieved with minimum solid fuel content (BA carbon) 6.5wt% in mixture (Chapter 5). Physical and chemical characterization is performed for products of all different sintering mixtures. The results show that BA carbon content is an important parameter for the production of lightweight aggregates. Porous structure formation inside the sintered pellets, which is responsible for aggregates low weight, is caused by simultaneous development of two different processes: a) production of gases in high temperatures and, b) liquid (glassy) phase formation in the outer part of pellets in the same time period (Chapter 6). ix Formation of either solid state bonds, through diffusion, and/or glassy phase bonds at the points of particles mutual contact are responsible for pellet strength. Lightweight aggregates produced are used in the production of insulating and structural lightweight aggregate concrete specimens and thermal and mechanical tests are performed, respectively. According to tests results artificial lightweight aggregates can be used for insulating and structural purposes. The successful experimental results from the utilization of lignite solid byproducts in the production of LWA offered new opportunities for collaboration of these byproducts with other industrial solid residues, such as red mud (RM) which is produced during bauxite treatment for aluminum production (Chapter 8). In purpose of investigation of collaboration of these different byproducts sintering mixtures are prepared with low RM addition, up to 30wt%, in lignite ashes mixtures. Physical and chemical characterization is performed for products of all sintering mixtures and they are used for production of concrete specimens. Results show that increase of RM addition brings increase in aggregates weight, while aggregates formed by RM addition up to 20wt% can be considered as lightweight ones. The results of mechanical strength tests in concrete specimens show that RM addition up to 15wt% brings increase in aggregates strength. This is the first proposed method for utilization of lignite BA in Greece in the production of lightweight aggregates. Sintering of mixtures of lignite ashes results to the production of lightweight aggregates and the produced aggregates can be used for insulating and structural lightweight aggregate concrete. BA carbon content, which is utilized as the fuel of the process, is an important parameter for lightweight aggregate production and porous structure formation. Furthermore, Megalopolis lignite ashes can be treated in collaboration with other industrial solid byproducts, such as RM for the production of lightweight aggregates of different quality. Finally, the proposed method targets to massive utilization of BA produced in Megalopolis power station.

O concreto leve de alto desempenho (CLAD), com argila expandida nacional, é um material alternativo para as concentrações brasileiras, considerando as características climáticas do país e baixo custo do material. Mas atualmente, existe pouca informação disponível sobre a produção e aplicação deste concreto com agregados leves, adições e aditivos nacionais. O objetivo desta dissertação é analisar o comportamento estrutural, por intermédio de ensaios mecânicos (resistência à compressão, resistência à tração por compressão diametral e módulo de deformação) do CLAD, sob ação de altas temperaturas. Para tanto, realiza-se uma análise comparativa da resistência mecânica do concreto em estudo, constituído por agregados leves de argila expandida, com o concreto convencional CAD (concreto de alto desempenho), composto por agregados de brita basáltica, determinando-se assim as respectivas resistências mecânicas, após terem sido expostos a temperaturas externas de até 800 graus centígrados. Através da análise dos resultados obtidos experimentalmente, pode-se comprovar a viabilidade do CLAD, produzido com argila expandida, comparativamente ao CAD, sob à ação de altas temperaturas. / The high performance lightweight aggregate concrete (HPLC), with national expanded clay, is an alternative material for the Brazilian constructions, considering the climatic characteristics of the country and low cost of the material. But now, little available information exists about the production and application of this concrete with lightweight aggregate, additions and addictive national. The aim of this dissertation is to analyze the structural behavior, by mechanical tests (compressive strength, splitting tensile strength and deformation modulus) of HPLC, under action of high temperatures. For so much, it takes place a comparative analysis of the mechanical resistance of the concrete in study, constituted by lightweight aggregate of expanded clay, with the conventional concrete HPC (high performance concrete), composed by crushed basalt coarse aggregate, determining the respective mechanical strength, after they have been exposed to external temperatures of up to 800°C. Through the analysis of the results obtained experimentally, it can be proven the viability of HPLC, produced with expanded clay, comparatively to HPC, under to the action of high temperatures.

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-07-03T14:07:50Z No. of bitstreams: 1 pedrohenriquegarcia.pdf: 7575599 bytes, checksum: 5f088290c1ce19e54a605c6adc84e54f (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-08T12:27:34Z (GMT) No. of bitstreams: 1 pedrohenriquegarcia.pdf: 7575599 bytes, checksum: 5f088290c1ce19e54a605c6adc84e54f (MD5) / Made available in DSpace on 2017-08-08T12:27:34Z (GMT). No. of bitstreams: 1 pedrohenriquegarcia.pdf: 7575599 bytes, checksum: 5f088290c1ce19e54a605c6adc84e54f (MD5) Previous issue date: 2017-03-17 / O concreto de agregado leve é conhecido pelo reduzido peso específico e alta capacidade de isolamento térmico e acústico. Um dos grandes desafios relacionados a esse tipo de concreto é a obtenção de algumas propriedades mecânicas dos agregados leves, tais como o módulo de elasticidade e a resistência à compressão, em função de suas dimensões reduzidas, o que gera dificuldades na realização de ensaios experimentais. É possível encontrar trabalhos na literatura que tentam determinar as propriedades mecânicas dos agregados leves por meio de métodos baseados em formulações matemáticas e deduções empíricas. Uma alternativa a tais métodos é o emprego de modelos de simulação e a resolução de um problema inverso para a previsão de tais propriedades. O objetivo do trabalho é a aplicação de um procedimento inverso para obtenção do módulo de elasticidade e da resistência à compressão de agregados leves presentes em concretos via simulação computacional de ensaios de compressão uniaxiais em corpos de prova. O corpo de prova de concreto é representado por um modelo computacional mecânico bidimensional e bifásico, constituído por argamassa e agregados leves de formato circular, e as simulações foram conduzidas no programa Abaqus R. Os resultados encontrados foram satisfatórios em comparação com outros métodos da literatura, chegando a casos com diferenças menores que 2% para um corpo de prova com 15% de agregados. A abordagem proposta emerge como uma possível solução para análises de propriedades mecânicas de agregados leves em concretos com um reduzido tempo e custo, sendo aplicada para diversos tipos de curvas granulométricas, tipos de argamassa e diferentes porcentagens de agregados no corpo de prova. Além da previsão das propriedades mecânicas dos agregados em concretos leves, a abordagem traz um melhor entendimento da relação dos diversos conjuntos de agregados leves com as argamassas. / The lightweight aggregate concrete is known for its low specific weight and high thermal and acoustic insulation capacity. One of the great challenges related to this type of concrete is to get some mechanical properties of lightweight aggregate, such as the modulus of elasticity and the compressive strength, due to its reduced size, which generates difficulties to carry out experimental tests. It is possible to find works in the literature that try to determine the mechanical properties of the lightweight aggregate through methods based on mathematical formulation and empirical deductions. An alternative to such methods is the use of simulation models and the resolution of an inverse problem for the prediction of lightweight aggregate properties. The objective of this study is the application of an inverse procedure to obtain the modulus of elasticity and the compressive strength of lightweight aggregates present in concrete by computational simulation of uniaxial compression tests in specimens. The concrete specimen is represented by a two-dimensional and biphasic mechanical computational model, constituted by mortar and circular lightweight aggregates, and the simulations were conducted in the Abaqus R program. The results were satisfactory compared to other methods in the literature, reaching cases with differences of less than 2 % for a test specimen with 15 % of aggregates. The proposed approach emerges as a possible solution for the analysis of mechanical properties of lightweight aggregates in concrete with reduced cost and time, being applied for several types of grain sizes, mortar types and different percentages of aggregates in the concrete specimen. In addition, the approach brings a better understanding about the connection between lightweight aggregates and mortars.

The current usage of both classical and fluid combustion ashes is not sufficient and they are deposited in large quantities. The focus of this master´s thesis is to determine and verify some possibilities of their suitable applications in construction industry, specifically as the alternative aggregates for concrete. After the performed analysis several systems based on both classical and fluid combustion ashes have been proposed. Portland cement and hydrated lime were used as admixtures and binding properties of fluid combustion ashes were also tested. The most important properties were compressive strength and bulk density. The aim was to appropriate an optimal ratio between the addition of modifying substance and resulting strength of prepared aggregate in order to correspond to standards for aggregates for concrete.

This thesis addressed the development renders the optimal ratio of thermal insulation and mechanical properties. In developing these materials were used alternative latent hydraulic binders. Research was conducted plasters and renders the requirements of technical standards in the Czech Republic. Work dealt with the general composition of plaster, including the use of secondary raw materials in dry plaster mixtures and thermal insulation properties and remediation plaster. Furthermore, the measured values of physical and mechanical properties of the test formulations. The best recipes were compared with plaster on the Czech market.

This diploma thesis deals with the technology of production of ultralight concretes using direct lighten cementing compound and at the same time indirect lighten using lightweight aggregate. Further work deals with the choice of suitable raw materials for these concretes. The practical part consists of a proposal of several different recipes, experimental verification and by comparing their properties in a fresh or hardened state.