Thesis (M.S.)--University of Michigan, 1948.

Thesis (Ph. D.)--University of California, Berkeley, 1990. / Includes bibliographical references (leaves 264-271).

Techn. Universiẗat, Diss., 2004--Clausthal.

This thesis aims identifying the sources of competitive advantage of the Turkish clothing and cement industries with respect to the European Union following the methodology of the Diamond Framework, introduced by Porter (1990), which is based on the theory of competitive advantage. The methodology is modified in order to include the effects of Turkey&#039 / s integration process to the European Union on the industries. Using this methodology, this study assesses the sources of competitive advantage of the Turkish clothing and cement industries by evaluating the industries&#039 / factor conditions, demand conditions, related and supporting industries, firms structure, strategy and rivalry and the role of the government and European integration process. The main idea of this study is that both industries take their advantage form basic factor conditions. While the role of Turkey&#039 / s integration process to the EU is more effective on the clothing industry, it stays limited on the cement industry.

Στην παρούσα διατριβή εξετάστηκε η δυνατότητα χρήσης της σιδηραλούμινας, του προϊόντος που προέρχεται από την επεξεργασία της ερυθράς ιλύος, ως πρώτη ύλη και ως πρόσθετο στη διεργασία παραγωγής τσιμέντου. Η ερυθρά ιλύς αποτελεί το παραπροϊόν της επεξεργασίας του βωξίτη για την παραγωγή αλούμινας μέσω της διεργασίας Bayer. Αποτελείται από το τμήμα του βωξίτη που δεν αντιδρά, το τμήμα του βωξίτη που έχει αντιδράσει προς το σχηματισμό άλλων ενώσεων, από συστατικά που εισάγονται στη διεργασία και από τα υδροξείδια του αργιλίου που δεν ανακτώνται. Η απομάκρυνση του νερού από την ερυθρά ιλύ έχει ως αποτέλεσμα την παραγωγή ενός στερεού υπολείμματος, της σιδηραλούμινας. Αν και υπάρχουν αρκετές διαθέσιμες τεχνολογίες για απομάκρυνση του νερού, η χρήση πρέσας φίλτρων υψηλής πίεσης συγκεντρώνει πολλά προτερήματα. Η μελέτη απομάκρυνσης του νερού πραγματοποιήθηκε σε μια εργαστηριακής κλίμακας πρέσα φίλτρων, όπου και διαπιστώθηκε ότι είναι δυνατή η παραγωγή στερεού υπολείμματος (κέικ) με περιεκτικότητα ~35% σε νερό. Η έρευνα επεκτάθηκε σε πιλοτικής κλίμακας πρέσα φίλτρων όπου εξετάστηκαν περισσότερες παράμετροι, όπως ο τύπος του φίλτρου και το υλικό από το οποίο είναι φτιαγμένο. Τα αποτελέσματα έδειξαν ότι είναι δυνατή η παραγωγή στερεού υπολείμματος με σταθερό ποσοστό υγρασίας μεταξύ 27% και 32% και πυκνότητα περίπου 2g/cm3, οδηγώντας στην εγκατάσταση μιας βιομηχανικής πρέσας φίλτρων υψηλής πίεσης, η οποία λειτουργεί από την αρχή του 2006 με επιτυχία στο «Αλουμίνιο της Ελλάδας». Η χημική ανάλυση της σιδηραλούμινας καταδεικνύει ότι πρόκειται για ένα υλικό που μπορεί να χρησιμοποιηθεί σαν δευτερεύουσα πρώτη ύλη στην βιομηχανία τσιμέντου ως φορέας σιδήρου. Η μελέτη της καταλληλότητάς της πραγματοποιήθηκε με το σχεδιασμό μιγμάτων πρώτων υλών για την παραγωγή τσιμέντου τύπου Portland στα οποία η σιδηραλούμινα συμμετείχε σε ποσοστά έως 5%κ.β. Τα αποτελέσματα έδειξαν ότι τα παραγόμενα με σιδηραλούμινα τσιμέντα παρουσιάζουν ίδια ποιοτικά ορυκτολογική σύσταση με το αντίστοιχο αναφοράς ενώ οι φυσικές τους ιδιότητες όπως η απαίτηση σε νερό και ο χρόνος πήξης βρίσκονται στα ίδια επίπεδα. Όσον αφορά στις μηχανικές τους ιδιότητες, οι τιμές που ελήφθησαν κατατάσσουν όλα τα τσιμέντα στην κατηγορία των 42.5N. Ειδικότερα τα τσιμέντα με σιδηραλούμινα κατατάσσονται σε υψηλότερη κατηγορία (52.5N) λόγω των αυξημένων πρώιμων αντοχών (2 ημερών). Τέλος, τα παραγόμενα με σιδηραλούμινα τσιμέντα έδειξαν ότι απελευθερώνουν μεγαλύτερη ποσότητα υδατοδιαλυτού χρωμίου από το τσιμέντο αναφοράς, απόρροια του υψηλότερου αρχικού φορτίου ολικού χρωμίου που περιέχουν. Οι βιομηχανικές δοκιμές που ακολούθησαν στις βιομηχανίες ΤΙΤΑΝ και ΑΓΕΤ ΗΡΑΚΛΗΣ έδειξαν ότι η προσθήκη σιδηραλούμινας σε επίπεδα 2.7%κ.β οδηγεί σε βελτίωση της εψησιμότητας του μίγματος λόγω της μείωσης του πυριτικού δείκτη. Επίσης η προσθήκη σιδηραλούμινας προς αντικατάσταση του χρησιμοποιούμενου πυρίτη στο μίγμα οδήγησε στη μείωση των ιχνοστοιχείων Mn, Pb, Zn και Cu στο μίγμα ενώ αύξησε το ποσοστό του Cr. Τα αποτελέσματα για το παραγόμενο κλίνκερ έδειξαν ότι η προσθήκη δεν επηρέασε ποιοτικά τις σχηματιζόμενες ορυκτολογικές φάσεις ενώ οι αντοχές που παρουσίασαν τα παραγόμενα τσιμέντα φτάνουν τα 27.7MPa για τις πρώτες 2 ημέρες και τα 51.6MPa μετά από 28 ημέρες. Η επίδραση της προσθήκης στους αέριους ρύπους των εργοστασίων ήταν μηδενική, καθώς οι τιμές αυτών παρέμειναν στα ίδια επίπεδα κατά τη διεργασία παραγωγής. Προκειμένου να αξιολογηθεί η περιβαλλοντική συμπεριφορά των παραγόμενων με σιδηραλούμινα τσιμέντων, πραγματοποιήθηκαν δοκιμές εκπλυσιμότητας. Για τις δοκιμές χρησιμοποιήθηκαν δύο δείγματα τσιμέντου, ένα χωρίς σιδηραλούμινα (αναφορά) και ένα 2%κ.β σιδηραλούμινα. Οι ανωτέρω δοκιμές πραγματοποιήθηκαν υπό το πρίσμα δύο προτύπων, του NEN 7345-tank test που αναφέρεται σε μονολιθικά υλικά (service life scenario) και του prEN 14429-pH dependence test που αναφέρεται σε κοκκώδη υλικά (“second life” scenario). Σύμφωνα με τη χημική ανάλυση των δύο τσιμέντων, το τσιμέντο με σιδηραλούμινα παρουσιάζει μεγαλύτερο αρχικό φορτίο σε Cr, Ni και V από το αντίστοιχο αναφοράς. Το παραπάνω γεγονός δεν επηρεάζει την απελευθέρωση στην περίπτωση του μονολιθικού υλικού, όπου τόσο για την περίπτωση του Cr όσο και για αυτές των Ni και V παρατηρούνται ίδια επίπεδα απελευθέρωσης τόσο για το δοκίμιο αναφοράς όσο και για το δοκίμιο με σιδηραλούμινα. Στην περίπτωση του κοκκώδους (θραυσμένου) υλικού η απελευθέρωση των ιχνοστοιχείων στο περιβάλλον είναι ανάλογη του αρχικού τους φορτίου και εντείνεται καθώς η ισορροπία μετατοπίζεται προς χαμηλότερα pH. Οι σύγχρονες τάσεις που αφορούν την εξοικονόμηση ενέργειας και την προστασία του περιβάλλοντος έστρεψαν την έρευνα στη δυνατότητα προσθήκης σιδηραλούμινας ως πρώτη ύλη για την παραγωγή τσιμέντων μπελιτικού τύπου. Η διαφορά των ανωτέρω τσιμέντων με τα τσιμέντα τύπου Portland είναι τα μειωμένα επίπεδα της φάσης του πυριτικού τριασβεστίου (C3S) απόρροια της χαμηλότερης θερμοκρασίας έψησης (~1350οC) γεγονός που τα κατατάσσει στην κατηγορία των φιλικών προς το περιβάλλον τσιμέντων. Τα αποτελέσματα έδειξαν ότι η χρήση σιδηραλούμινας για την παραγωγή μπελιτικών τσιμέντων είναι εφικτή αλλά και ότι τα τσιμέντα αυτού του τύπου έχουν ένα σαφές μειονέκτημα έναντι των Portland, τις χαμηλές πρώιμες αντοχές τους. Το μειονέκτημα αυτό αντιμετωπίστηκε με την εισαγωγή γύψου στο μίγμα των πρώτων υλών που είχε ως επακόλουθο τη δημιουργία της υδραυλικής ένωσης 4CaO.3Al2O3.SO3 κατά τη διαδικασία έψησης. Τέλος εξετάστηκε η δυνατότητα της σιδηραλούμινας να δράσει ως υπόστρωμα για την ρόφηση του εξασθενούς χρωμίου (Cr(VI)) σε υδατικά διαλύματα προκειμένου να χρησιμοποιηθεί ως πρόσθετο στο τελευταίο στάδιο της παραγωγής τσιμέντου. Η μελέτη πραγματοποιήθηκε λαμβάνοντας υπ’ όψιν παραμέτρους όπως το pH του διαλύματος, ο χρόνος επαφής και η αναλογία υγρού προς στερεό (l:s ratio). Τα αποτελέσματα κατέδειξαν ότι η σιδηραλούμινα εμφανίζει ροφητικές ιδιότητες οι οποίες αυξάνονται εάν προηγηθεί ένα στάδιο χημικής και θερμικής επεξεργασίας αυτής. Αυτό οφείλεται στην αύξηση της ειδικής επιφάνειας της σιδηραλούμινας από τα 10m2 g-1 στα 70m2 g-1 λόγω της αύξησης του μικροπορώδους της. Τα επίπεδα ρόφησης χρωμίου για την επεξεργασμένη σιδηραλούμινα έφτασαν σε ιδανικές συνθήκες στα 0.82mg g-1. Ο μηχανισμός της ρόφησης περιγράφεται από την ισόθερμη Langmuir ενώ περιορίζεται σε μια στενή περιοχή τιμών του pH ανάμεσα στο 5 και στο 6. / In the present thesis the potential utilization of ferroalumina, a by-product that derives from the dewatering of red mud, as a raw material as well as an additive material in the cement production route is examined. Red mud is the main by-product that derives from the digestion of bauxite ores during Bayer process in order to produce alumina. It comprises from the ore part that has not reacted, the part that has reacted and has formed other than the desired compounds, from supplementary materials that were introduced during the procedure and from aluminium hydroxides that were not recovered. The removal of red mud’s water content leads to the production of ferroalumina. Although there are many ways of removing the water, the use of a filter press has many advantages. The laboratory study of the water removal from red mud by means of a filter press led to the formation of a cake with ~35%wt of water. Parameters, such as the filter type and the material that it comprises were examined with the further use of a pilot scale filter press. The results indicated that the filter press can produce a cake with constant water amount between 27% and 32%wt and density 2g/cm3. The latter results, led to the installation of an industrial high pressure filter press, which is in operation since the beginning of 2006, in the Aluminium Hellas industry. Ferroalumina’s chemical analysis indicates that it can be used as a secondary material in the cement industry, mainly as an iron oxide carrier. The study for its suitability was performed by preparing Portland cement raw mixtures introducing ferroalumina up to 5%wt are a raw material. Consequently, the raw mixtures were fired up to 1550oC in order to produce clinker and co-grounded with gypsum in order to produce Portland cement. The results indicate that the produced ferroalumina cements presents similar mineralogical composition with the cements without ferroalumina whilst their physical properties such as the water demand and the setting time are at the same levels. Regarding their mechanical properties, the obtained compressive strength values are ranking all the cements in the 42.5N category. Especially the ferroalumina cements are falling into a higher category and more specifically in the 52.5N category due to their high early day strengths. Finally, the study indicate that the ferroalumina cements presents higher amounts of water soluble chromium than the cement without ferroalumina (reference), most probably due to their higher initial amount of total chromium. The industrial trials that were performed by the Greek cement industries TITAN and AGET Heracles showed that the addition of ferroalumina up to 2.7%wt improves the burnability of the mixture due to the silica modulus reduction. The substitution of the raw material pyrite from the ferroalumina, led to the reduction of Mn, Pb, Zn and Cu on the raw mixture whilst it increased the Cr percentage. The results for the produced clinker indicate that the ferroalumina addition did not affect the formatted mineralogical phases. The compressive strength values of the obtained cements, was 27.7MPa after the first 2 days and 51.6MPa after 28 days of curing. The flue gas emissions were at the same levels during the cement production indicating that the ferroalumina addition does not affect that part of production either. In order to evaluate the environmental behaviour of the ferroalumina cements, two types of leaching tests, which refer to different field scenarios, were employed. The NEN 7345-tank test which refers to monolithic materials (“service life” scenario) and the prEN 14429-pH dependence test, which concerns granular materials (“second life” scenario). Two different cement samples were used for the above mentioned tests. The first one was produced without ferroalumina (reference sample) whilst the second one was produced with a 2%wt ferroalumina addition. The chemical analysis of the cement with ferroalumina showed that it presents greater content of Cr, Ni and V than the reference cement. The latter does not affect leaching in the service life scenario. More specifically in the case of Cr the reference cement presents the same leaching amount with the ferroalumina cement whilst in the case of Ni and V no leaching is observed for any of the two cement samples. During the “second life” scenario the leaching is greater in the case of the ferroalumina cement. The latter is related to the greater initial content of the above mentioned cement in Cr, Ni and V. The leaching behaviour is for both cements pH sensitive as higher leaching values for Cr and Ni are observed while the pH shifts to lower values. The new trends concerning the sustainable development through energy conversion and environmental protection have led the current study in the utilization of ferroalumina in the field of belite cements. The main difference of the above mentioned cements from the Portland cements is the low content in calcium silicate (C3S) mainly due to the lower firing temperature (~1350οC). The latter ranks the above mentioned cements in the environmental friendly cements category (green cements). The obtained results indicate that the use of ferroalumina as a raw material for the production of belite cements is possible as well as that the produced cements have a certain drawback when compared with the OPC. The lack of C3S leads to low early day strength. This drawback was confronted with the introduction of gypsum in the raw mixture which led to the formation of the hydraulic compound 4CaO.3Al2O3.SO3 (Klein’s compound) during the firing procedure. The last chapter deals with the possibility of utilize ferroalumina as a substrate for the absorption of hexavalent chromium in order to use it as an additive material in the last stage of cement production. The study examined parameters such as the pH of the solution, the contact time and the liquid to solid ratio (l:s ratio). The results indicate that the ferroalumina is able to absorb chromium and that this ability increases if a stage of chemical and thermal treatment is employed before. The treatment enhances ferroalumina’s absorption ability due to an increase of specific surface from 10m2 g-1 to 70m2 g-1. The absorbance mechanism is described with the Langmuir model and the best results are obtained for pH 5 and contact time 1h. The amount of chromium that is absorbed from each grammar of ferroalumina in the above mentioned conditions is 0.82mg.

Made available in DSpace on 2014-06-11T19:23:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-01-30Bitstream added on 2014-06-13T19:09:19Z : No. of bitstreams: 1 peron_ab_me_bauru.pdf: 1180628 bytes, checksum: fdf98821f4364d3799335a94a181838b (MD5) / As indústrias de processamento de couros, conhecidas como curtumes ou indústrias de acabamento de couro apresentam grandes problemas ambientais. A preocupação com o meio ambiente por parte dos órgãos de controle ambiental fez com que muitas indústrias implantassem sistemas de tratamentos e destinação final dos resíduos gerados por elas. Associados à necessidade de materiais compostos, impulsionada pela crescente necessidade de novas tecnologias, principalmente a que se refere às combinações entre materiais, há alternativa de incorporação do resíduo em materiais já utilizados. Entre as alternativas tem-se a incorporação do resíduo em matrizes de cimento. Neste trabalho, pretende-se encapsular o lodo residual como alternativa de co-disposição do resíduo, em matrizes de cimento, utilizando cimento CPIIIF-32, em substituição parcial do agregado miúdo. O material foi coletado em um curtume na região centro-oeste do estado de São Paulo e caractrização de todos os insumos de concreto. Para os estudos utilizou-se um corpo-de prova referência e diferentes traços de concreto com adições de lodo residual seco a uma temperatura de 150ºC, com variação de 2% a 8% de resíduo em relação a areia utilizada no traço referência. Realizou-se ensaios de resistência mecânica, lixiviação e solubilização. Após a análise dos resultados, constatou-se que o resíduo pode ser considerado um plastificante na trabalhabilidade do concreto, atendendo aos limites de lixiviação e solubilização estipulados pelas normas 10005/2004 e 10006/2004. / The industries of leathers processin, konown as tanneries or industries of leather's finish, present great environmental problems. The concern with environment on the part of the agencies of environmental control made with that a lot of industries implanted systems of treatments and final destination of the residues generated by them. Associates to the necessary of composed materials stimulated by the increasing necessity of new technologies, mainly the one thet if it relates to the combinations between materials, there are the residue incorporation in the used material. Between the alternatives we have the incorporation of the residue in cement head offices. In this work, it intends encapsulate the residual silt as alternative of codisposition of the residue in cement head offices, using cements CPIIIF-32 in partial substitution of the small aggregate. The material was collected in a tannery in the area centerwest of the state of São Paulo and characterization of all the inputs of the concrete. For the studies a test body it was used reference and traces of concret with additions of dry residual silt in a temperature of 150ºC, with variation of 2% to 8% of residue in relation to sand used in the trace reference. One the became fullfilled rehearsals of mechanical resistance, leaching and solubilization. After results of the analysis, it was verified that the residue com be considered plastificate in the management of the concrete, taking care of to the leaching and solubilization limits stipulated by norms 10005/2004 and 10006/2004.

Le ciment est le matériau le plus utilisé de nos jours pour plusieurs raisons: de bonnes propriétés mécaniques à la compression, un faible coût et une facilité d'utilisation. Cependant, le ciment est fragile lorsqu'il est soumis à des charges élevées et il est susceptible de se dégrader par des agents externes. Pour cette raison, différents additifs sont utilisés pour modifier le processus de prise et ainsi les propriétés finales du ciment. Parmi ces additifs, il y a un type appelé « accélérateurs de prise » qui permet la prise de la matrice de ciment plus rapidement. Il existe un type d'additifs « accélérateurs » qui constituent des points de germination pour la formation de gel C-S-H autour d'eux. L'objet de ce travail a été de développer une nouvelle voie de synthèse, basée sur la technologie eau supercritique, de deux nanoadditifs d'hydrates de silicate de calcium : la xonotlite et la tobermorite.Dans un premier temps, la synthèse a été effectuée dans des conditions souscritiques. Ensuite, il a été développé un réacteur continu supercritique adapté à la synthèse de ces nanoadditifs. Les synthèses ont été réalisées à 400 ° C et 23,5 MPa. La xonotlite et la tobermorite ont toutes deux été obtenues en réduisant drastiquement les temps de réaction d'heures/semaines (dans des conditions souscritiques) à quelques secondes seulement, dans des conditions supercritiques.Le dernier point étudié a été l'effet d'ensemencement par ces deux additifs de la pâte de ciment. Dans tous les cas, il a été observé, une accélération de la réaction et également une amélioration de la résistance du ciment.En conclusion, ce travail présente une nouvelle méthode ultra-rapide pour synthétiser des hydrates de silicate de calcium très cristallins, et prouve également l'effet « accélérateur » de ces particules lorsqu'elles sont utilisées comme germes dans des pâtes de ciment. Cette recherche propose une nouvelle méthodologie pour la synthèse des additifs pour ciments. / Cement is the most used material nowadays due to several reasons: its good mechanical properties to compression, its low cost, and its easy use. However, cement is fragile when submitted to high charges and it is susceptible to degradation by external agents. For this reason different additions are used modify the setting process or the final properties of the cement paste. Among them there are one type called “setting accelerators” that develop the cementitious matrix faster. There is one type of accelerating additions that act as seeds; these are nucleating points for the formation of C-S-H gel around them. The aim of this work is to develop a new synthesis route, based on supercritical water technology, of two calcium silicate hydrates nanoadditions. These products are xonotlite and tobermorite.The first approach to the synthesis was done under subcritical conditions. After that it was developed the supercritical continuous reactor in order to adapt it to the necessities of the synthesis of the nanoadditions. The syntheses were carried out at 400ºC and 22.5 MPa. Both xonotlite and tobermorite were obtained reducing drastically the reaction times from hours/weeks (under subcritical conditions) to just some seconds under supercritical conditions.The last point studied was the seeding effect of both particles into cement paste. In every case it was observed, an acceleration of the reaction and also an improvement of the strength trough mechanical test.As a conclusion this work presents a new ultrafast method to synthesize highly crystalline calcium silicate hydrates, and also proves the accelerating effect of these particles when they are used as seeds in cement pastes. This research proposes a new methodology for the synthesis of additions to cement.

L’objectif de cette thèse est la caractérisation de la porosité de la pâte de ciment partiellement saturée par des ondes ultrasonores. Les corrélations entre les vitesses ultrasonores et la porosité ont été étudiées en se basant à la fois sur les résultats expérimentaux et la modélisation micromécanique. Des mesures expérimentales de vitesses ultrasonores longitudinales et transversales en fonction du rapport eau/ciment et à différents états de saturation ont été réalisées sur la pâte de ciment avec et sans entraîneur d’air. En modélisation micromécanique, les effets de saturation ont été modélisés en supposant que la structure poreuse est formée d’inclusions ellipsoïdales de facteur de forme variable selon le rapport E/C. Afin d’estimer les modules homogénéisés élastique de la pâte de ciment et de pâte de ciment à entraîneur d’air différents modèles micromécaniques ont été étudiés. Les résultats de la modélisation micromécanique ainsi que les résultats expérimentaux ont montré que les vitesses des ondes longitudinales et transversales de la pâte de ciment à l’état sec sont inférieures à ceux de l’état saturé. Cet effet est tout aussi important pour l’ensemble des rapports E/C. Le modèle de Mori-Tanaka a donné la meilleure estimation des résultats expérimentaux mesurés sur la pâte de ciment. Alors que le modèle auto-cohérent a donné la meilleure estimation des propriétés mécaniques et ultrasonores de la pâte de ciment avec entraîneur d’air.Les résultats de ce travail devraient constituer le fondement d’un processus d’inversion et d’amélioration de la détermination de la porosité de la pâte de ciment par les ultrasons en tant que méthodes non destructives / The objective of this work is the characterization of unsaturated cement paste porosity through the use of ultrasonics. The correlation between ultrasonic velocity and porosity in cement paste material is studied based on both micromechanical modelling and experiments.Experimental measurements of ultrasonic longitudinal and transverse velocities as a function of water to cement ratio and under different saturation states were performed on cement paste with and without air-entrained adjuvant. In the micromechanical modeling, the effects of saturation were modeled by approximating the porous structure as a penny shaped ellipsoidal inclusions of aspect ratio varying with the W/C ratio. Several different micromechanical models for estimating the homogenized elastic moduli of cement paste and air-entrained cement paste were studied.The micromecanical modelling has shown that the longitudinal and transverse wave velocities of the dry cement paste are lower than those of the water saturated cement paste. This effect is equally prominent for all the cement paste W/C ratios. The model of Mori-Tanaka was found to give the best fit with the experimental results for the cement paste modeling. While, the self-consistent model gave the best estimate of the mechanical and ultrasonic air-entrained cement paste properties when compared to the laboratory experimental results.The findings of this work should be most appropriate as a foundation for an inversion process and improved cementitious material porosity determination by nondestructive methods

Made available in DSpace on 2014-06-11T19:27:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-12Bitstream added on 2014-06-13T20:27:39Z : No. of bitstreams: 1 bertolucci_fs_me_ilha.pdf: 2860301 bytes, checksum: 3f3004f9d02861054ffe5fb10b1b2e7d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A indústria estruturas de concretos pré-moldados possui como grande preocupação a ligação entre seus elementos, tendo em vista que a mesma exerce grande influência no comportamento da estrutura, sendo responsável pela transmissão e redistribuição dos esforços na estrutura. A grande diferença entre estruturas pré-moldadas e estruturas de concreto moldadas “in loco” em relação ao seu comportamento estrutural está na ligação entre seus elementos. As ligações apresentam certa deformação quando solicitadas, recebendo na literatura técnica a denominação de ligações semi-rígidas. Dessa forma, buscou-se estudar todos os grautes existentes no mercado e desenvolver um compósito cimentício de fácil preparo e de baixo custo, do tipo calda de cimento e argamassa, que apresentasse características mecânicas similares aos grautes. Foram desenvolvidas duas caldas de cimento e uma argamassa, as quais foram submetidas juntamente com os grautes selecionados a ensaios específicos de propriedades adesão e aderência. Dentre as principais conclusões obtidas podem ser ressaltadas que a grande parte dos grautes possui problemas de fluidez dificultando o preenchimento total das ligações e sua aplicação. Em relação à aderência as duas caldas de cimento e a argamassa apresentaram comportamento semelhante indicando que há uma boa condição de aderência e, os grautes, devido à sua grande diferença de composição, tiveram comportamentos distintos / One of the concerns of the precast concrete industry is the connection among their different types of elements, in order that they strongly influence the behavior of the structural group, being responsible for the transmission and redistribution of the efforts in the structure. Among the differences between precast structures and concrete structures shaped “in loco” we have the concern about the structural behavior of the link between its elements. The links have shown some deformation when tested, receiving in the technical literature the name of semi-rigid connections. For that the concrete’s precast structure has the behavior of a monolithic structure it’s necessary the solidarization of the connection which is made by filling the vertical and horizontal niches with the aid of the grout. In this paper, we aimed to study some grouts of the Brazilian market and, at the same time, develop a cimentitius composite of easy prepare and low cost, of the cement paste and mortar types, with similar mechanical characteristics to industrialized grouts to be used in the filling of the precast structures. It was rheologically and mechanically created and evaluated two kinds of cement grout and one mortar composition that were submitted along with the selected grouts to an evaluation of their rheological behavior, and to specific tests of their mechanical properties of adhesion and bond. This study let us conclude that the cement paste and mortar developed showed a similar rheological behavior to the Herschel-Bulkley, besides to a good condition of bond and a good behavior in the structure link when compared to some industrialized grouts. Not all the evaluated grouts showed appropriate behaviors for joints’ filling

Made available in DSpace on 2014-06-11T19:28:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-26Bitstream added on 2014-06-13T20:18:31Z : No. of bitstreams: 1 almeidajunior_aa_me_arafo.pdf: 459545 bytes, checksum: df0008777c6ad28ca07cacdc0ed332ac (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este estudo avaliou a resistência ao cisalhamento da união entre o titânio comercialmente puro fundido e o cimento resinoso não-adesivo (RelyX ARC – 3M ESPE) após diferentes tratamentos na superfície metálica. Noventa discos de titânio comercialmente puro foram divididos aleatoriamente em nove grupos, os quais receberam um dos seguintes tratamentos, antes da aplicação do RelyX ARC: (n=10): 01) Al2O3 (50 μm); 02) Al2O3 (50 μm) + adesivo; 03) Al2O3 (50 μm) + silano; 04) Cojet Sand (30 μm); 05) Cojet Sand + adesivo; 06) Cojet Sand + silano; 07) Al2O3 (50 μm) + Rocatec (110 μm); 08) Al2O3 (50 μm) + Rocatec + adesivo; 09) Al2O3 (50 μm) + Rocatec + silano. Os espécimes foram termociclados (5.000 ciclos - 5 – 55 oC - 30 segundos de imersão) e então submetidos ao ensaio de cisalhamento As médias de resistência ao cisalhamento da união dos grupos de 1 a 9 foram respectivamente: 4,10 ± 0,79CD; 6,14 ± 0,99B; 4,34 ± 0,71CD; 2,58 ± 0,37EF; 2,31 ± 0,23 F; 5,70 ± 0,93B; 3,65 ± 0,70DE; 5,25 ± 1,08BC e 8,36 ± 1,63A. O teste t de Student apontou igualdade estatística entre os grupos jateados com partículas de Al2O3 e com partículas revestidas por sílica (P=0,630). A análise de 22 variância (ANOVA) a dois critérios seguida pelo teste de Tukey indicaram que: 1) o Rocatec apresentou resistência significativamente maior que o Cojet Sand (P<0,05); 2) o jateamento com partículas de óxido de alumínio apresentou resistência significativamente maior quando associado ao adesivo (P<0,001) enquanto o silano foi o melhor tratamento pós jateamento para as partículas revestidas por sílica (P<0,001) e 3) O jateamento com Rocatec seguido da aplicação do silano proporcionou a maior resistência ao cisalhamento de união entre o titânio comercialmente puro e o RelyX ARC. Todos os grupos apresentaram falha 100% adesiva. / This study evaluated the shear bond strength of a conventional resin cement (RelyX ARC – 3M ESPE) to cast commercially pure titanium (cp Ti) after different treatments on metal surface. Ninety cp Ti disks were randomly divided into 9 groups which received one of the following treatments before the application of RelyX ARC: (n=10): 01) Al2O3 (50 μm); 02) Al2O3 (50 μm) + adhesive; 03) Al2O3 (50 μm) + silane; 04) Cojet Sand (30 μm); 05) Cojet Sand + adhesive; 06) Cojet Sand + silane; 07) Al2O3 (50 μm) + Rocatec (110 μm); 08) Al2O3 (50 μm) + Rocatec + adhesive; 09) Al2O3 (50 μm) + Rocatec + silane. All specimens were thermal cycled (5000 cycles, 5 - 55 oC – 30-second dwell time) before tested in shear mode. The mean bond strength values (Mpa) for all groups were, respectively: 4,10 ± 0,79CD; 6,14 ± 0,99B; 4,34 ± 0,71CD; 2,58 ± 0,37EF; 2,31 ± 0,23 F; 5,70 ± 0,93B; 3,65 ± 0,70DE; 5,25 ± 1,08BC e 8,36 ± 1,63A. The Student t test showed that there was no significant difference between Al2O3 particles and silica-modified Al2O3 particles (P=0.630). Two-way ANOVA and post hoc Tukey test (=.05) showed that: 1) Rocatec demonstrated significantly higher shear bond strength than Cojet Sand (P<0.05); 2) airborne-particle abrasion with Al2O3 particles exhibited the highest shear bond strength with adhesive (P<0.001) while silica-modified Al2O3 particles exhibited the best behavior when associated with silane (P<0.001); 3) Rocatec plus silane provided the highest shear bond strength between cp Ti and RelyX ARC. All groups showed 100% adhesive failure.