Ladrillos elaborados con plástico reciclado (PET), para mampostería no portante

En el presente trabajo se investigó el uso de plástico reciclado para la fabricación de ladrillos para construcción de mampostería no portante. En primer lugar se realiza la caracterización de los residuos sólidos que se generan en la ciudad de Cuenca, donde el 22,7% del total recolectado es material plástico, que se desechan libremente sin un tratamiento previo. De la misma manera se investigan las características del plástico, Polientilen Tereftalato (PET) para descartar efectos nocivos al momento de incluirlos en la mezcla con los materiales tradicionales como son el cemento y agua, agregado fino. Se elaboraron ladrillos con dimensiones de 20x10x6cm con adición de PET al 10, 25, 40, 55, 65 y 70% en sustitución del árido fino. Luego se efectuó diversos ensayoscon la finalidad de compararlos con los ladrillos de arcilla cocida de uso común en la región y analizar el material para mampostería no portante según los lineamientos establecidos por las Normas Ecuatorianas. Una vez realizados los ensayos y analizada la información se obtuvo como resultado un ladrillo óptimo con 25% de adición de PET. El cual fue sometido a un análisis térmico mediante una simulación en el programa Desingnbuilder, obteniendo como resultado niveles de confort término de mejor calidad en viviendas.

Biologia alimentar e morfohistologia do tubo digestório do mussum, synbranchus marmoratus, bloch (osteichthyes: synbranchidae) no açude Marechal Dutra Gargalheiras , localizado no semi-árido brasileiro

Food habits and morpho-histology of the digestive tract of marbled swamp eel, Synbranchus marmoratus (Block, 1917) were investigated. The fish samples were captured during August, 2007 to July, 2008 in the Marechal Dutra reservoir, Acari, Rio Grande do Norte. The rain fall data was obtained from EMPARN. The fish captured, were measured, weighed, dissected, eviscerated and individual stomach weights were registered. The stomach contents analyses were carried out based on volumetric method, points, frequency of occurrence and applying the Index of Relative Importance. The degrees of repletion of the stomachs were determined besides the Index of Repletion relating to feeding activity variations and frequency of ingestion during the rainy and dry seasons. The rainfall varied from 0 mm a 335 mm with a mean value of 71.62 mm. Highest rainfall of 335.5 mm was registered in March, 2008 and August to December was the dry period. During the dry period the study species presented high degrees of repletion of the stomachs, with a peak value in the month of September (mean = 4.54; ± SD = 0.56). The minimum mean value of = 3.99 ± SD = 0.25 was registered in the month of May during the rainy period. The stomach contents of S. marmoratus registered show that this fish prefers animals, 78.22% of crustaceans 2.85% of mollusks, 3.25% of fish, 1.4% of insects and 13.5% of semi-digested organic matter, thus characterizing the study species as a carnivore with a preference for crustaceans. The morpho-histological aspects of the digestive tract of S. marmoratus indicate that the mouth is terminal adapted to open widely, thin lips with taste buds, small villiform teeth forming a single series on maxillas, four pairs of branchial arches with short and widely spaced branchial rays. The oesophagus is short and cylindrical with a small diameter. The oesophagus wall is thick with mucas surface and internal parallel folds. The stomach is retilinical in form, presenting cardiac, caecal and pyloric portions. The caecal portion is long and is intermediary in position between the cardiac and pyloric portions. The cardiac portion of the stomach is short and cylindrical formed of simple epithelial cylindrical mucus cells. The caecal portion is long with narrow walls, a big cavity and smaller folds which give rise to gastric glands. The phyloric portion has no glands and primary or secondary mucas folds. The morphohistological aspects of the digestive tract of S. marmoratus indicate its adaptation to a carnivorous feeding habit

BENEFICIAL REUSE OF LOCALLY-AVAILABLE WASTE MATERIALS AS LIGHTWEIGHT AGGREGATE IN LIGHTWEIGHT CONCRETE

This study investigated the physical characteristics of lightweight concrete produced using waste materials as coarse aggregate. The study was inspired by the author’s Peace Corps service in Kilwa, Tanzania. Coconut shell, sisal fiber, and PET plastic were chosen as the test waste products due to their abundance in the area. Two mixes were produced for each waste product and the mix proportions designed for resulting compressive strengths of 3000 and 5000 psi. The proportions were selected based on guidelines for lightweight concrete from the American Concrete Institute. In preparation for mixing, coconut shells were crushed into aggregate no larger than 3/4 inch, sisal fiber was cut into pieces no longer than 3/8 inch, and PET plastic was shredded into 1/4 inch-wide strips no longer than 6 inches. Replicate samples were mixed and then cured for 28 days before they were tested for compressive strength, unit weight, and absorption. The resulting data were compared to ASTM Standards for lightweight concrete masonry units to determine their adequacy. Based on these results, there is potential for coconut shell to be used as coarse aggregate in lightweight concrete. Sisal fiber was unsuccessful in producing the appropriate compressive strength. However, the reduction in spalling of the hardened concrete and the induction of air in the mixes incorporating sisal fiber suggests that it has the potential to improve other characteristics of lightweight concrete. Concrete mixes using PET plastic as aggregate resulted in adequate compressive strengths, but were too dense to be considered ‘lightweight’ concrete. With some adjustments to slightly decrease absorption and unit weight, the PET plastic concrete mixes could be classified as medium weight concrete and, therefore, achieve many of the same benefits as would be seen with lightweight concrete.

Performance sismique sous charge axiale nulle des murs en maçonnerie armée entièrement remplis de coulis

Résumé : Cette juxtaposition de matériaux solides -blocs, pierres ou briques,...- liés ou non entre eux que nous appelons maçonnerie ne se comporte pas très bien vis-à-vis des forces latérales, surtout si elle n’a pas été réalisée suivant les normes parasismiques ou de façon adéquate. Cette vulnérabilité (glissement, cisaillement, déchirure en flexion, ou tout autre) vient souvent du fait même de ce processus d’empilement, des problèmes d’interaction avec le reste de la structure et aussi à cause des caractéristiques mécaniques peu fiables de certains éléments utilisés. Malgré cette défaillance structurale, la maçonnerie est encore utilisée aujourd’hui grâce à son côté traditionnel, sa facilité de mise en œuvre et son coût d’utilisation peu élevé. Depuis quelques années, la maçonnerie s’est enrichie de documents qui ont été publiés par divers chercheurs dans le but d’une meilleure compréhension des caractéristiques mécaniques des éléments et aussi, et surtout, des mécanismes de rupture des murs de maçonnerie pour une meilleure réponse face aux sollicitations sismiques. Beaucoup de programmes expérimentaux ont alors été effectués et tant d’autres sont encore nécessaires. Et c’est dans ce contexte que cette recherche a été conduite. Elle présentera, entre autres, le comportement sous charges latérales d’un mur en maçonnerie armée entièrement rempli de coulis. Ce projet de recherche fait partie d’un programme plus large visant à une meilleure connaissance du comportement sismique de la maçonnerie pour une amélioration des techniques de construction et de réparation des ouvrages en maçonnerie.

Mode-I fracture parameters of quasi-brittle materials: direct evaluation using DIC and relationship with Mode-II interfacial parameters

The objective of this thesis is the investigation of the Mode-I fracture mechanics parameters of quasi-brittle materials to shed light onto the influence of the width and size of the specimen on the fracture response of notched beams. To further the knowledge on the fracture process, 3D digital image correlation (DIC) was employed. A new method is proposed to determine experimentally the critical value of the crack opening, which is then used to determine the size of the fracture process zone (FPZ). In addition, the Mode-I fracture mechanics parameters are compared with the Mode-II interfacial properties of composites materials that feature as matrices the quasi-brittle materials studied in Mode-I conditions. To investigate the Mode II fracture parameters, single-lap direct shear tests are performed. Notched concrete beams with six cross-sections has been tested using a three-point bending (TPB) test set-up (Mode-I fracture mechanics). Two depths and three widths of the beam are considered. In addition to concrete beams, alkali-activated mortar beams (AAMs) that differ by the type and size of the aggregates have been tested using the same TPB set-up. Two dimensions of AAMs are considered. The load-deflection response obtained from DIC is compared with the load-deflection response obtained from the readings of two linear variable displacement transformers (LVDT). Load responses, peak loads, strain profiles along the ligament from DIC, fracture energy and failure modes of TPB tests are discussed. The Mode-II problem is investigated by testing steel reinforced grout (SRG) composites bonded to masonry and concrete elements under single-lap direct shear tests. Two types of anchorage systems are proposed for SRG reinforced masonry and concrete element to study their effectiveness. An indirect method is proposed to find the interfacial properties, compare them with the Mode-I fracture properties of the matrix and to model the effect of the anchorage.

Movimenti di genti in tempo di peste: studio antropologico e documentale dei deceduti nel Lazzaretto Vecchio di Venezia (xv-xvii secolo).

Fondato nel 1423 per decisione del Maggior Consiglio di Venezia, il Lazzaretto Vecchio, è la prima struttura permanente in Europa destinata al ricovero degli ammalati di peste e alla quarantena preventiva di coloro che erano entrati in contatto con infetti o che provenivano da zone epidemiche. Questo studio si pone come obiettivo quello di analizzare antropologicamente una parte dei resti umani rinvenuti e comparare i risultati ottenuti con le fonti edite riguardanti la composizione dei ricoverati all’interno della struttura. Sono stati selezionati 110 individui provenienti da 9 comuni appartenenti a due diversi archi cronologici, il 1575-1577 e il 1630-1631. Gli individui sono stati sottoposti a diverse analisi antropologiche tradizionali e indagini più dettagliate di stampo biomolecolare. Parallelamente, è stata vagliata la letteratura prodotta da studi popolazionistici editi. Le analisi antropologiche hanno rivelato un quadro popolazionistico con normale presenza di maschi e femmine, e attestazione di tutte le classi di età, dagli 0 agli oltre 50 anni. Le analisi chimico-fisiche hanno rivelato la presenza di sette individui non locali. Con riguardo all’alimentazione non vi sono particolari differenze in termini di periodi cronologici o di sesso degli individui, quanto invece si possono individuare schemi relativi alla qualità del cibo ingerito in relazione all’inserimento nel mondo del lavoro. Per quanto riguarda le indagini di carattere documentale, nonostante alcuni degli studi popolazionistici individuati non siano considerabili recenti, ci forniscono un quadro dell’andamento della popolazione a Venezia a partire dal 1500 fino al 1700, coprendo in questo modo le cronologie d’interesse del progetto, legate agli episodi di maggiore mortalità della peste. Si riscontra una sostanziale coerenza tra i dati riportati nei diversi resoconti e la sex ratio e le fasce di età alla morte riscontrate, anche se non mancano casi specifici di forte discostamento tra i dati.

Plutarch's chemistry of stones and metals: conceptions and explanations. With an appendix on the TheSu XML annotation scheme

This dissertation presents a systematic and analytic overview of most of the information related to stones, minerals, and stone masonry which is found in the corpus of Plutarch of Chaeronea, combined with most of the information on metals and metalworking which is connected to the former. This survey is intended as a first step in the reconstruction of the full landscape of ‘chemical’ ideas occurring in Plutarch’s writings; accordingly, the exposition of the relevant passages, the assessment of their possible interpretations, the discussion on their implications, and their contextualization in the ancient traditions have been conducted with a special interest in the ‘mineralogical’ and ‘metallurgic’ themes developed in the frame of natural philosophy and meteorology. Although in this perspective physical etiology could have come to acquire central prominence, non-etiological information on Plutarch’s ideas on the nature and behaviour of stones and metals has been treated as equally relevant to reach a fuller understanding of how Plutarch conceptualized and visualized them in general, in- and outside the frame of philosophical explanation. Such extensive outline of Plutarch’s ideas on stones and metals is a prerequisite for an accurate inquiry into his use of the two in analogies, metaphors, and symbols: to predispose this kind of research was another aim of the present survey, and this aim has contributed to shape it; moreover, a special attention has been paid to the analysis of analogical and figurative speaking due to the nature itself of a large part of Plutarch’s references to stones and metals, which are either metaphorical, presented in close association with metaphors, or framed in analogies. Much of the information used for the present overview has been extracted —always with supporting argumentation— from the implications of such metaphors and analogies.

Seismic vulnerability of buildings and non-structural elements: insights from the 2011 Lorca earthquake

This PhD dissertation presents a profound study of the vulnerability of buildings and non-structural elements stemming from the investigation of the Mw 5.2 Lorca 2011 earthquake; which constitutes one of the most significant earthquakes in Spain. It left nine fatalities due to falling debris from reinforced concrete buildings, 394 injured and material damage valued at 800 million euros. Within this framework, the most relevant initiatives concerning the vulnerability of buildings and the exposure of Lorca are studied. This work revealed two lines of research: the elaboration of a rational method to determine the adequacy of a specific fragility curve for the particular seismic risk study of a region; and the relevance of researching the seismic performance of non-structural elements. As a consequence, firstly, a method to assess and select fragility curves for seismic risk studies from the catalogue of those available in the literature is elaborated and calibrated by means of a case study. The said methodology is based on a multidimensional index and provides a ranking that classifies the curves in terms of adequacy. Its results for the case of Lorca led to the elaboration of new fragility curves for unreinforced masonry buildings. Moreover, a simplified method to account for the unpredictable directionality of the seism in the creation of fragility curves is contributed. Secondly, the characterisation of the seismic capacity and demand of the non-structural elements that caused most of the human losses is studied. Concerning the capacity, an analytical approach derived from theoretical considerations to characterise the complete out-of-plane seismic response curve of unreinforced masonry cantilever walls is provided; as well as a simplified and more practical trilinear version of it. Concerning the demand, several methods for characterising the Floor Response Spectra of reinforced concrete buildings are tested through case studies.

Mechanical behaviour and durability assessment of Fibre Reinforced Cementitious Matrix (FRCM) strengthening systems.

In recent years, the seismic vulnerability of existing masonry buildings has been underscored by the destructive impacts of earthquakes. Therefore, Fibre Reinforced Cementitious Matrix (FRCM) retrofitting systems have gained prominence due to their high strength-to-weight ratio, compatibility with substrates, and potential reversibility. However, concerns linger regarding the durability of these systems when subjected to long-term environmental conditions. This doctoral dissertation addressed these concerns by studying the effects of mild temperature variations on three FRCM systems, featuring basalt, glass, and aramid fibre textiles with lime-based mortar matrices. The study subjected various specimens, including mortar triplets, bare textile specimens, FRCM coupons, and single-lap direct shear wallets, to thermal exposure. A novel approach utilizing embedded thermocouple sensors facilitated efficient monitoring and active control of the conditioning process. A shift in the failure modes was obtained in the single lap-direct shear tests, alongside a significant impact on tensile capacity for both textiles and FRCM coupons. Subsequently, bond tests results were used to indirectly calibrate an analytical approach based on mode-II fracture mechanics. A comparison between Cohesive Material Law (CML) functions at various temperatures was conducted for each of the three systems, demonstrating a good agreement between the analytical model and experimental curves. Furthermore, the durability in alkaline environment of two additional FRCM systems, characterized by basalt and glass fibre textiles with lime-based mortars, was studied through an extensive experimental campaign. Tests conducted on single yarn and textile specimens after exposure at different durations and temperatures revealed a significant impact on tensile capacity. Additionally, FRCM coupons manufactured with conditioned textile were tested to understand the influence of aged textile and curing environment on the final tensile behavior. These results contributed significantly to the existing knowledge on FRCM systems and could be used to develop a standardized alkaline testing protocol, still lacking in the scientific literature.