Résumé : Depuis le début du XXe siècle, la production de bétons secs représente une industrie importante pour le développement des infrastructures en bétons compactés au rouleau notamment pour la construction de barrages, de digues, de pavages, et les bétons moulés à sec pour la pré-fabrication de blocs de maçonnerie, de briques, de pierres de pavé, etc. La durabilité de celles-ci peut être améliorée en réduisant leur consommation de ciment Portland et de granulats naturels en utilisant, respectivement, des ajouts cimentaires et des matériaux granulaires alternatifs. D’ailleurs, beaucoup de sous-produits industriels et autres ajouts cimentaires alternatifs ne respectant pas les exigences pour le béton conventionnel ont été utilisés avec succès dans ce type de béton. Les cendres de biomasse sont des sous-produits prometteurs pour les applications de bétons secs. Ces cendres sont obtenues dans une centrale de cogénération de l’industrie des pâtes et papiers suite à la combustion de leurs boues de traitement des eaux usées, de leurs boues de désencrage, et autres résidus de bois. Les cendres volantes de biomasse (CVB) ont une finesse similaire à celle du ciment et elles possèdent aussi un potentiel de réactivité pouzzolanique. Elles peuvent donc remplacer une partie du ciment utilisé dans la formulation de bétons. Les cendres grossières de biomasse (CGB) ont une granulométrie voisine de celle d’un sable fin. Elles peuvent donc être valorisées en remplaçant une partie des granulats naturels utilisés dans les formulations de bétons. Bien que les propriétés physico-chimiques et les interactions cimentaires de celles-ci soient étudiées depuis le début des années 2000, très peu d’applications commerciales ou industrielles ont été développées. Ce projet de recherche vise l’étude et l'optimisation des CVB comme ajout cimentaire alternatif et des CGB comme granulats fins alternatifs dans la production de bétons compactés au rouleau (BCR) et à la paveuse (BCP) pour des applications de pavages industriels et dans la production de bétons moulés à sec (BMS) pour des applications de préfabrication de pierres de pavé. Pour chacune de ces applications, des formulations incorporant un taux de substitution jusqu'à 30% du ciment par des cendres volantes et jusqu’à 100% du sable par des cendres grossières ont été réalisées. Ces travaux d’optimisation ont été effectués avec des bétons à rap-port eau-liant de 0,32, 0,35 et 0,37. Les propriétés à l’état frais (maniabilité et consistance), à l’état durci (résistance à la compression, à la flexion et à la traction), et de durabilités (absorption à l’eau, vides perméables et résistivité électrique) jusqu'à 91 jours ont été mesurées pour tous les mélanges de béton. Le rapport eau-liant, la teneur en pâte et les taux de remplacement optimaux ont également été combinés et optimisés afin de valoriser un maximum de cendres de biomasse, volantes et grossières, dans une seule formulation. Les résultats des mélanges de BCR fabriqués en laboratoire avec 10% et 20% de CVB et combinés à 50% de CGB ont respectivement montré des maniabilités désirées et des résistances à la flexion supérieures aux limites prescrites par les devis techniques pour une utilisation pratique de 23% et 29%. Ces deux mélanges donc ont été sélectionnés pour évaluer leur comportement in situ à l’aide de la construction d'une dalle de stockage de 792 m² par 300 mm d'épaisseur à l'aide de pratiques courantes. Des carottes ont été prélevées dans la dalle à 28 et 308 jours. La résistance à la compression des noyaux à l'âge de 308 jours a atteint 33 et 30 MPa pour les deux mélanges testés, respectivement. Les BMS fabriqués avec 5%, 10%, ou 15% CVB et 25% de CGB peuvent atteindre un indice de compaction de 99% avec un travail de compaction inférieur à celui spécifié par les fabricants de pierre de pavés. L'utilisation des CVB et CGB entraîne une faible diminution de la résistance à la compression, mais présente des valeurs de perméabilité et d’absorption à l’eau très faibles et inférieures aux exigences requises les normes (près de 5%). Ces travaux de recherche présentent un débouché potentiel à la valorisation des cendres volantes et grossières de biomasse issues de l’industrie des pâtes et papiers dans les bétons secs comme ajout cimentaires ou granulats fins. Cette approche peut offrir une contribution significative pour la réduction des émissions de gaz à effet de serre associés à la production de ce type de béton et dans les gestions des matières résiduelles de l’industrie des pâtes et papiers. / Abstract : Since the early twentieth century, the production of dry concrete is an important industry for infrastructure development including the construction of dams, core dikes, and pavements using roller-compacted concrete, and precast masonry blocks, bricks, pavers using dry-cast concrete. The sustainability thereof can be improved by reducing its consumption of Portland cement and natural aggregates using cementitious supplementary cementitious materials and alternative granular materials, respectively. Moreover, many industrial by-products and other mineral additions not meeting the requirements for conventional concrete have been success-fully used in such concrete. The biomass ashes are promising supplementary materials for dry concrete applications. These ashes are produced in a cogeneration plant of the pulp and paper industry following the burn-ing of their wastewater treatment sludge, their de-inking sludge, and other wood residues. The biomass fly ash (BFA) have a similar finesse in the cement and they also have a potential poz-zolanic reactivity. They may therefore replace part of the cement used in concrete formula-tions. The biomass bottom ashes (BBA) have a particle size close to that of a fine sand. They can be use to replace a portion of the natural aggregates. Although the physicochemical proper-ties and interactions with cement have been studied since the early 2000s, very few commer-cial or industrial applications have been developed. This research project aims at studying and optimizing the BFA content as an alternative sup-plementary cementitious materials and the BBA content as an alternative fine aggregates in the production of roller-(RCC) and paver-compacted concrete (PCC) for industrial pavements and dry-cast concrete (DCC) for the manufacture of pavers. Formulations incorporating substitu-tion rates of cement up to 30% by BFA and of the sand up to 100% by BBA were evaluated for each of the mentioned applications. This optimization work was carried out with concrete water-to-binder ratio (w/b) of 0.32, 0.35 and 0.37. The fresh properties (workability and com-pactness), hardened properties (compressive strength, flexural strength and splitting-tensile strength) and transport properties (water absorption, permeable voids and electrical resistivity) up to 91 days were measured for all concrete mixtures. The optimal w/b, paste content and replacement rates were also combined and optimized in order to maximize the biomass fly and bottom ashes content, in a single formulation. The results of concrete mixtures made with 10% and 20% BFA with 50% BBA showed 23% and 29% higher flexural strength than the limits required for practical use of RCC, respective-ly. These two RCC mixtures were selected for the assessment of in situ behaviors through the construction of a storage slab of 792 m² per 300 mm thick using standard practices. Core sam-ples were cut from the slabs at age of 28 and 308 days for follow-up of the concrete behavior with time. The compressive strength of the cores at an age of 308 days reached 33 and 30 MPa for the two tested mixtures, respectively. The DCC mixtures made with 5%, 10%, or 15% BFA and 25% of BBA can reach a compact-ness index of 99% with a compaction work lower than specified by the Standards. The use of the BFA and BBA lead to small decrease of the compressive strength, however they can result in very low permeability and water absorption values lower than required by the specifications (close to 5%). This research presents a potential market for recycling biomass fly and bottom ashes from the pulp and paper industry in dry concrete as alternative supplementary cementitious materials or fine aggregates. This approach can provide a significant contribution to reduce greenhouse gas emissions associated with the production of this type of concrete and with the managements of by-products from the pulp and paper industry.

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.

Certain types of waste, e.g. bottom ash originating from municipal solid waste incineration (MSWI bottom ash) can be used as road construction materials. A potential problem is the possibility of substances leaching out of the road and spreading in the surrounding groundwater. The aim of this master’s thesis is to conclude whether hydrogeological type settings can be employed to, based on local conditions, provide an estimate of the probable spreading of these substances in the surrounding groundwater, and whether certain types of soils can be identified as being less suitable for the localization of a MSWI bottom ash road. A hydrogeological type setting is defined as a mappable unit with similar hydrogeological properties. An advantage of this approach would be that mainly existing maps and surveys could form the basis for the assessment. The work has been performed by placing a hypothetical road construction in different hydrogeological type settings. The expected patterns of spreading has then been evaluated using theoretical reasoning and analytical and numerical models. The method can be used. In the report various type settings are defined. In several cases further information will be required to render possible a more exact estimate of the spreading. By locating the road on less permeable soils to reduce the local spreading of substances in groundwater, a greater proportion of the water will be drained as surface water. Thus it becomes important to take into account surface water transport aswell. In the report a procedure to estimate the maximum concentrations in groundwater at locations situated downstream the road is presented. This estimate could be used as basis for a more balanced valuation of appropriateness, e.g. by relating the estimated concentrations to background values. / Vissa typer av avfall, exempelvis slaggrus (sorterad bottenaska från avfallsförbränning), kan användas som vägbyggnadsmaterial. Ett potentiellt problem är möjligheten att ämnen lakas ut ur vägen och sprids i omgivande grundvatten. Syftet med detta examensarbete är att avgöra om hydrogeologiska typmiljöer kan användas för att, utifrån omgivningens förutsättningar, ge en bild av hur den vidare spridningen av dessa ämnen i omgivande grundvatten sannolikt ser ut, och om vissa typer av mark kan pekas ut som mindre lämpade för lokalisering av en slaggrusväg. En hydrogeologisk typmiljö definieras som ett område möjligt att avgränsa med avseende på karakteristiska hydrogeologiska förhållanden. En fördel med angreppssättet skulle vara att underlagsmaterialet till bedömningen då kan utgöras av i huvudsak befintligt kartmaterial. Studien har utförts genom att en hypotetisk vägkonstruktion placerats in i olika hydrogeologiska typmiljöer. De troliga spridningsscenarierna har sedan utvärderats genom teoretiska resonemang, samt genom användande av analytiska och numeriska modeller. Metodiken går att använda och i rapporten definieras olika typmiljöer. I flera fall kommer platsspecifik kunskap behöva inhämtas för en närmare beskrivning av spridningsbilden. Genom placering av vägen på tätare mark för att minska lokal spridning av ämnen i grundvatten kommer en större andel av vattnet att avledas som ytvatten. Därmed blir det viktigt att även inhämta kunskap om transport med ytvatten. I rapporten presenteras också en metod för uppskattning av maximala halter i grundvatten nedströms en väg. Denna metod kan användas som underlag för en mer nyanserad värdering av lämplighet, genom att de uppskattade halterna relateras till bakgrundsvärden eller lämpliga riktvärden.

Incineration is a mainstream strategy for solid waste management in Sweden and all over the world. Improved knowledge and understanding about the distribution of trace elements (in ashes) during incineration, and how trace element partitioning respond to the changes in waste composition, are important in terms of combustion process optimization and plant efficiency. Moreover, determination of chemical association of trace elements in ashes are vital for avoiding environmental concerns and to promote possible reuse. In this study, partitioning of trace elements in ashes during incineration as function of input waste fuel and incineration technology was investigated. Further, chemical association of trace elements in resulting ashes was studied. An evaluation was also performed about feasibility of metal extraction from sulfidic mining waste and flotation tailings. Moreover, green liquor dreg (GLD) was tested with respect to stabilization of metals within the sulfidic mining waste. Findings showed that the total input of trace elements and chlorine affects the partitioning and increasing chlorine in the input waste caused increase in transfer of trace elements to fly ash especially for lead and zinc. Vaporization, condensation on fly ash particles and adsorption mechanisms play an important role for metal distribution. Firing mixed waste, especially biofuel mix, in grate or fluidized (CFB) boilers caused increased transfer into fly ash for almost all trace elements particularly lead and zinc. Possible reasons might be either an increased input concentration of respective element in the waste fuel, or a change in volatilization behavior due to the addition of certain waste fractions. Chemical association study for fly ashes indicated that overall, Cd, Pb, Zn, Cu and Sb are presenting major risk in most of the fly ashes, while in bottom ashes, most of elements are associated with stable fraction. Further, fuel type affects the association of elements in ashes. Chemical leaching of mining waste materials showed that sulfuric acid (under different conditions) is the best reagent to recover zinc and copper from sulfidic mining waste and also copper from flotation tailings. GLD indicates potential for metal stabilization in mining waste by reducing the metal mobility. Extraction methods could be applied to treat mining waste in order to meet the regulatory level at a specific mining site.Similarly stabilization/solidification  methods might be applied after leaching for recovery of metals.

Submitted by Nadir Basilio (nadirsb@uninove.br) on 2016-06-20T14:26:30Z No. of bitstreams: 1 Mario Roberto Dos Santos.pdf: 2805393 bytes, checksum: 05385968aee97107c3fb2c3af54f225c (MD5) / Made available in DSpace on 2016-06-20T14:26:30Z (GMT). No. of bitstreams: 1 Mario Roberto Dos Santos.pdf: 2805393 bytes, checksum: 05385968aee97107c3fb2c3af54f225c (MD5) Previous issue date: 2015-08-21 / The aim of this study was to evaluate the eco-efficiency of the transformation of industrial waste in potential profitable co-products, as a business approach to reducing environmental impacts within the supply chain. The paper was based on to the following research question: How to measure the eco-efficiency of companies that value their industrial waste to allocate or offer them as alternative raw material for other industries? In this context, bottom ash resulting from the coal combustion in power plants was evaluated as a alternative raw material replacing sand in the production of ceramic materials and clinker in Portland cement industry, as an approach to eco-efficiency in power plants. The methodological procedures have been carried out in three phases: data collection through interviews; secondary data collection in thesis and periodical articles for the Life Cycle Assessment [LCA] preparation and the data evaluation. Pollutant emissions to atmosphere, water and soil were measured in numerical terms, relating to the production process of electric power and its waste, focused on bottom ash. All pollutants emissions to atmosphere, water and soil in numerical terms relating to the production process of sand and clinker were also measured. The evaluation has been carried out following the ABNT NBR ISO 14045 standard. The inventory calculation was based on primary data collected directly in the studied company and secondary data collected from the literature and regulatory agencies and analyzed by the software SimaPro. Within the limits of this research, it can be inferred that the eco-efficiency measure is carried out in two steps: 1) assessment of environmental impacts through research of the environmental aspects involved in the production process from the extraction of raw materials to the final disposal of waste and compare them to the production process to include the use of such waste. For this evaluation it was essential to measure LCA of waste (or wastes) to be evaluate and to compare the two processes (using and without using residue) so you can check what the major impacts are. Calculate the eco-efficiency of the process; 2) survey the probable cost’s uses of this waste in other production processes so that you can check for a monetary threshold that can afford possible valuation resulting from the new operations additions to the delivery of waste to another industrial sector. Based on these two phases it was possible to established eco-efficiency of the project, from both environmentally and economic perspectives. This research used the ReCiPe endpoint score method that presented the following results: a) Eco-efficiency of the generation of bottom ash for use in the ceramic industry compared with the generation of bottom ash by thermal plant and replacing the sand by the bottom ash in the production of ceramic tiles, thermal plant eco-efficiency spend 0.2% lower to 0.97% higher; b) Eco-efficiency of generation of bottom ash for use in cement industry compared with the generation of bottom ash by thermal plant and replacing the clinker by between 15-50%, have eco-efficiency values ranging from 2.4% to 11.5%. The use of bottom ash total replacement scenario of industrial sand in the production of ceramic tiles can use 91% of the amount spent on the acquisition of sand to buy the bottom ash. The use of bottom ash in the partial replacement scenario clinker in Portland cement production is that 91.4% of the clinker value can be used in the purchase of bottom ash. We can infer that it is possible to measure the eco-efficiency by measuring the environmental impacts through the ACV of the waste and, together, economically test the feasibility of their use. / O objetivo desta pesquisa foi avaliar a ecoeficiência da transformação de resíduos industriais em potenciais coprodutos rentáveis, como uma abordagem empresarial para a redução dos impactos ambientais dentro de uma cadeia de suprimentos. Este trabalho teve como referência a seguinte questão de pesquisa: Como medir a ecoeficiência das empresas que valorizam seus resíduos sólidos industriais ao destiná-los como matéria-prima alternativa para outros setores industriais? Nesse contexto, foi avaliada a valorização de cinzas pesadas, provenientes da combustão de carvão mineral em usinas termelétricas, como matéria-prima alternativa em substituição da areia na produção de materiais cerâmicos e também na substituição do clínquer na indústria de cimento Portland, como uma abordagem de ecoeficiência em termelétricas. Os procedimentos metodológicos foram realizados em três fases: levantamento dos dados por meio de questionários e entrevistas; levantamento de dados secundários em teses e artigos de periódicos para elaboração da Avaliação do Ciclo de Vida [ACV]; e a avaliação dos dados. Foram dimensionadas as emissões de poluentes para atmosfera, água e solo em termos numéricos relativos ao processo produtivo de energia elétrica e seus resíduos, com o foco nas cinzas pesadas. Foram dimensionadas também todas as emissões de poluentes para atmosfera, água e solo em termos numéricos relativos ao processo produtivo da areia e do clínquer. A avaliação foi realizada segundo a norma ABNT NBR ISO 14045. O cálculo do inventário foi baseado em dados primários levantados diretamente na empresa estudada e os dados secundários coletados na literatura e nas agências reguladoras e analisados pelo software SimaPro. No limite desta pesquisa, pode-se inferir que a medida de ecoeficiência seja realizada em duas etapas: 1) avaliação dos impactos ambientais por meio da pesquisa dos aspectos ambientais envolvidos no processo produtivo desde a extração das matérias-primas até a disposição final dos resíduos e sua comparação com o processo produtivo com a inclusão do uso desses resíduos. Para essa avaliação, é fundamental dimensionar a ACV do resíduo (ou dos resíduos) a ser valorizado e comparar os dois processos (sem uso e com do resíduo) para que se possa verificar quais são os maiores impactos. Calcular o valor da ecoeficiência do processo; 2) levantamento dos prováveis custos do uso desses resíduos em outros processos produtivos para que se possa verificar se há uma margem monetária que possa arcar com possíveis valores decorrentes do acréscimo de novas operações até a entrega do resíduo para outro setor industrial. Baseado nessas duas etapas, foi possível estabelecer a ecoeficiência, tanto ambiental quanto econômica do projeto. Esta pesquisa utilizou o método ReCiPe endpoint H pontuação única, que apresentou os seguintes resultados: a) Ecoeficiência da geração de cinzas pesadas para uso na indústria de revestimentos cerâmicos comparada com a geração de cinzas pela termelétrica e a substituição da areia pelas cinzas pesadas na produção de revestimentos cerâmicos, a ecoeficiência da termelétrica passaria de 0,2% inferior para 0,97% superior; b) Ecoeficiência da geração de cinzas pesadas para uso na indústria de cimento comparada com a geração de cinzas pela termelétrica e a substituição do clínquer por cinzas pesadas em quantidades de massa entre 15-50%, têm-se valores de ecoeficiência variando de 2,4% a 11,5%. O uso das cinzas pesadas no cenário de substituição total da areia industrial na produção de revestimentos cerâmicos poderá usar 91% do valor gasto na aquisição de areia para comprar as cinzas pesadas. No uso das cinzas pesadas no cenário de substituição parcial do clínquer na produção de cimento Portland tem-se que 91,4% do valor do clínquer poderá ser utilizado na compra das cinzas pesadas. Pode-se inferir que é possível medir a ecoeficiência medindo-se os impactos ambientais, por meio da ACV do resíduo e, em conjunto, verificar economicamente a viabilidade do seu uso.

Cement-based concrete is one of the main construction materials that is widely used for many construction applications due to its strength, durability, reflectivity, and versatility. However, it is acknowledged that production of cement as a primary material of concrete releases 1.8 Gt carbon dioxide (CO2) into the environment. It is estimated that one ton of cement production releases one ton of CO2 to the atmosphere. That is why, this work aims to create a concrete that could be an alternative to cement-based concrete. Geopolymer concrete (GPC) is an eco-friendly construction material and an alternative to conventional concrete that is produced by reacting aluminate and silicate bearing constituents with a caustic activator (i.e. sodium-based or potassium-based). Both potassium and sodium have been considered as generally safe intergradient by the FDA, based upon the observance of several good manufacturing practice conditions of use. Theses activators are used in various application including concrete, food, as a stabilizer, and as a thickening agent. Moreover, these activators are also used in making soap, as an electrolyte in alkaline batteries and in electroplating, lithography, and paint and varnish removers. Medically, these activators are widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions, Currently, it was determined that these activators solution were found to be a safe and effective treatment of plane warts. Despite the developments in the studies relating to GPC made by various precursors such as fly-ash and slag in the literatures, the use of GPC made by fly-ash and bottom-ash has not been overly researched. In this study, attempts have been made to produce a unique mix proportion for Potassium-based GPC made by fly-ash and bottom-ash and investigate various mechanical properties of this type of GPC including elastic modulus, freeze-thaw resistance, heavy metal leach-ability and corrosion in both laboratory and real environmental conditions using Non-Destructive Tests (NDT)s. / Graduate / 2021-12-15

Dans un contexte accru d’économie circulaire et de valorisation des matières premières recyclées, les mâchefers d’incinération de déchets non dangereux (MIDND) constituent des déchets granulaires minéraux identifiés comme ressources renouvelables potentiellement valorisables dans la filière construction, notamment dans le domaine des matériaux cimentaires (type mortier/béton). Compte tenu de l'origine et de la nature des granulats de mâchefers, dans une finalité de concourir à une meilleure compatibilité mâchefer/ciment, il apparait essentiel en premier lieu de considérer des fractions minérales de mâchefers au mieux épurées par l’optimisation de l’enlèvement des métaux ferreux, non-ferreux et indésirables. En second temps, tenant compte des spécificités physico-chimiques résultantes des mâchefers, le choix de la base cimentaire constitue le second facteur prépondérant en sus de la nécessité de meilleure qualité de la fraction minérale de mâchefer. Le présent travail doctoral traite spécifiquement de l’apport de l’utilisation d’un ciment sulfo-alumineux dans le contexte de valorisation des mâchefers en matrice cimentaire. Des sables de mâchefers améliorés de fraction 0/2 mm ont été élaborés et utilisés pour l’étude. Dans une première partie, les résultats de formulation de mortiers cimentaires (ciment Portland, noté OPC / ciment sulfo-alumineux, noté CSA) à base de mâchefers en substitution volumique partielle du sable naturel (25, 50 et 75 %) et totale (100 %), mettent en évidence l’apport bénéfique du ciment CSA sur les résistances en compression par comparaison aux mortiers OPC. Une analyse expérimentale du réseau poreux des mortiers à 90 jours révèle que la frange de porosité supérieure à 50 nm est nettement plus faible pour les mortiers CSA. La thèse met en évidence un résultat majeur et pionnier : en interaction mâchefer, le niveau de basicité du milieu réactionnel joue un rôle prépondérant sur le potentiel de dégagement gazeux (hydrogène) après la mise en œuvre et avant la prise. Ce gaz impacte le niveau de porosité de la frange la plus grossière des mortiers durcis. La seconde partie concerne l’étude physique et microstructurale des mortiers soumis à l’attaque à l’eau pure ou à attaque sulfatique pour des substitutions volumiques de 50 et 100 %, avec les témoins pour référentiels. Les observations MEB sur les différentes matrices mettent en évidence une nette moindre sensibilité des mortiers mâchefer/CSA que des mortiers mâchefer/OPC, traduit par des porosités, fissurations et épaisseurs dégradées moindres. / In a world where circular economy and the valorization of raw materials is taking a greater importance, municipal solid waste incineration (MSWI) bottom ash is identified as potentially renewable resource in the construction field and more specifically in cementitious materials like mortar and concrete. Given the origin of the bottom ash and in order to have a better cement/MSWI bottom ash compatibility, the fraction used was as refined as possible by removing ferrous, non-ferrous and unwanted materials. The choice of the cement used is a critical factor as well because it affects the quality of the end product since MSWI bottom ash has particular physicochemical properties. The work in this PhD studies the advantages of using a sulfo-aluminate cement to valorize an improved 0/2 mm fraction of bottom ash that has been developed to be used in cementitious matrices. The first part presents the results of the mortar sample mixes containing bottom ash in a substitution by volume of the standard sand. To better highlight the effect of using a sulfo-aluminate (CSA), CSA mortars containing bottom ash were compared to a Portland cement (OPC) mortars, with substitution rates of 25 %, 50 %, 75 % and 100 % were used. A study of the porosity was then conducted at 90 days ; it shows that the pores larger to 50 nm are remarkably less present for CSA mortars. This thesis brings forward a major and innovative result : the level of alkalinity of the mortar plays an important role in the release of hydrogen gas after mixing and before setting. The presence of these gases creates large porosity in the hardened mortar samples. The second part studies the physical and microstructural aspects of the mortars after being immersed in aggressive environments : pure water and sulfate solution. The substitution rates used in this experiment were 50 % and 100 % by volume as well as the reference mortars with no bottom ash. These samples were then studied in the SEM which showed that CSA/bottom ash mortars were clearly less affected than the OPC/bottom ash mortars. This was highlighted by the porosity, the cracking and the depth of degraded zone.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology / Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution. / Eskom

[pt] A gestão dos Resíduos Sólidos Urbanos (RSU) e seu consequente reaproveitamento ou não é um problema existente no Brasil e no mundo. No Brasil, a produção de energia mediante incineração de RSU ainda está na sua etapa inicial, como por exemplo, com a implantação da Usina Verde no campus da UFRJ, com a consequente produção de subprodutos, como as cinzas volante e de fundo. Este estudo apresenta o comportamento de um solo coluvionar argiloso estabilizado com cinzas de RSU sob carregamento estático, tendo como principal objetivo avaliar a influência destas cinzas misturadas com o solo para possíveis aplicações em obras geotécnicas. Para isso foram realizados ensaios de caracterização física, química e mecânica, como ensaios de compactação Proctor Normal e ensaios triaxiais consolidados isotropicamente drenados (CID), para o solo puro e misturas solo-cinza. Foram avaliadas as influências do teor de cinzas (20 por cento, 30 por cento e 40 por cento de cinza volante e de cinza de fundo), bem como do tempo de cura (30 e 60 dias). Os resultados mostram que todas as misturas solo-cinza apresentam melhores parâmetros de resistência, em comparação do solo puro, onde as misturas solo-cinza volante apresentaram melhores resultados quando comparadas às misturas solo-cinza de fundo. A variação de teor de cinza adicionado ao solo, sem cura, mostra que para maiores teores de cinza volante a coesão diminui e ocorre o contrário com a cinza de fundo. Com relação ao tempo de cura, na maioria dos casos houve melhora do comportamento das misturas solo-cinza em comparação ao obtido sem cura. O teor de cinza (volante ou de fundo), tempo de cura e a tensão de confinamento influenciam na deformação volumétrica das misturas solo-cinza, apresentando menores deformações volumétricas para maiores teores de cinza e maiores tempos de cura. As misturas com 40 por cento de cinza volante e 30 por cento de cinza de fundo apresentaram as melhores características de resistência e poderiam ser utilizadas como estabilizante no solo estudado, cumprindo exigências geotécnicas e ambientais, além de rebaixar os custos de obra e dar um destino mais nobre para as cinzas de RSU. / [en] Management of Municipal Solid Waste (MSW) and its subsequent reuse or not is an existing problem in Brazil and the world. In Brazil, the production of energy through incineration of MSW is still in its initial stage, for example, with the implementation of Usina Verde on campus at UFRJ, with the consequent production of byproducts, such as fly and bottom ashes. This study presents the behavior of a colluvial clayey soil stabilized with ashes from MSW under static load, with the main objective to evaluate the influence of these ashes mixed with the soil for possible applications in geotechnical works. For this characterization were performed physical, chemical and mechanical tests, as Proctor compaction tests Normal isotropically consolidated and drained triaxial (CID) for the pure and soil-ash mixtures. Were evaluated the influence of the ash content (20 per cent, 30 per cent and 40 per cent fly ash and botton ash) and of curing time (30 and 60 days). The results show that all mixtures soil-ash have better shear strength compared to the pure soil, where the soil- fly ash mixtures showed better results compared to mixtures of soil- bottom ash. The variation of the ash content added to the soil, without curing, shows that higher levels of ash the cohesion decrease and the opposite occurs with the bottom ash. Respect to the curing time, in most cases there was as improvement of the behavior of mixtures soil-ash compared to that obtained without curing. The ash content (fly or bottom), curing time and confinement stress influence the volumetric deformation to soil-ash mixtures, showed lower volumetric deformations to higher concentrations of ash and longer curing times. The mixtures with 40 per cent fly ash and 30 per cent bottom ash, showed the best characteristics of strength and could be used as stabilizer in the studied soil, compliance requirements geotechnical and environmental, in addition to lower labor costs and give a nobler destiny for the ashes of MSW.

[pt] Este estudo apresenta o comportamento de um solo arenoso estabilizado com cinzas obtidas através da incineração de Resíduo Sólido Urbano (RSU) e cal. Através de um estudo experimental, objetiva-se avaliar a aplicabilidade de misturas solo-cinza e solo-cinza volante-cal em obras geotécnicas como, por exemplo, camadas de aterros sanitários, aterros sobre solos moles e estabilização de taludes. Para isso, foram realizados ensaios de caracterização física, química e mecânica (ensaios triaxiais CID) para os materiais envolvidos. Para as misturas solo-cinza volante-cal, adicionou-se 3 porcento de cal em substituição ao peso seco das cinzas. Foram avaliadas as influências do teor de cinza (30 e 40 porcento) e tipo de cinza (volante - CV e fundo - CF), bem como o tempo de cura (0, 60 e 90 dias) para misturas com cinza volante e cal. Os resultados mostram que tanto as misturas com CV, como CF, apresentam resultados satisfatórios. Para ambas as cinzas, as porcentagens de 30 e 40 porcento apresentaram resultados similares, podendo-se adotar o valor de 40 porcento como teor ótimo, uma vez que proporciona a utilização de uma maior quantidade de resíduo. Comparando-se as cinzas, a CF apresentou resultados mais satisfatórios que a CV. Para as misturas com cura, observou-se que no tempo de 60 dias o material sofreu um maior ganho de resistência. Foram utilizados dois métodos de moldagem de corpo de prova para o ensaio com cura, obtendo-se melhor resultado para o método onde a cura era realizada em um corpo de prova pré-moldado. Portanto o uso das cinzas de RSU em mistura com este tipo de solo se mostra satisfatório, uma vez que apresentou um bom comportamento, contribui com o menor consumo de material natural e proporciona uma destinação ambientalmente correta deste resíduo. / [en] This study presents the behavior of a sandy soil stabilized with municipal solid waste ash, and lime. In order to evaluate the applicability of mixtures soil-ash and soil-fly ash-lime for using in geotechnical projects as layers of landfills, embankment on soft soils and slope stability, an experimental campaign is presented. Thus, physical, chemical and mechanical (isotropically consolidated-drained triaxial test) characterization tests were performed for each material and mixtures. It was used 3 percent of lime in the mixtures soil- fly ash-lime, being added in replacement to the dry weight of fly ash. Were evaluated the influence of ash content (30 and 40 percent), type of ash (fly ash and bottom ash) and curing time (0, 60 and 90 days) for mixtures containing fly ash and lime. The results have shown that mixtures with both kinds of ashes present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure material. For both kinds of ashes the variation of the content has not provided significant changes in the strength parameters, therefore, 40 percent can be considered as best content, once it provides a bigger destination of the residue. Comparing fly and bottom ash, the last has presented better results than fly ash. For mixtures with lime and cure, it has been observed better results for 60 days of cure, with greater gain of strength. Two molding methods have been used for preparing the mixture specimen, being obtained a better result with pre modeled specimen. Therefore, the use of municipal solid waste ash for stabilizing this kind of soil for using in the cited works, could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.