Rozprawy doktorskie na temat „Earth Construction”

Rammed earth is an ancient construction technique which has recently become popular for sustainable building. Soil is compacted in removable formwork to make a homogeneous wall. A lack of experimental evidence and a poor fundamental understanding means that current design guidelines are highly conservative and inappropriate for the analysis of historic rammed earth buildings. This thesis shows that rammed earth can be viewed in a geotechnical engineering framework and that doing so helps to explain many aspects of the material behaviour. Rammed earth walls were built and tested in the laboratory then modelled using techniques available to practising engineers. Unsaturated soil mechanics was considered useful in explaining much of the behaviour of rammed earth. This was investigated through a series of uniaxial compression tests and the results are explained using unsaturated soil mechanics. Visits to Spain and India were made to investigate rammed earth in the field. Historic construction techniques, modes of failure and repair strategies were studied. The unsaturated nature of rammed earth is used to explain modes of failure and to suggest the most appropriate repair strategies

The earth home, in its many varieties and styles, played an important role in the development of the American Great Plains during the mid-nineteenth century. However, the lack of further study into the material culture of these homes has allowed many of these homes to be misrepresented in the historical record as temporary shelters. Not all of the earth homes constructed during this period were temporary. Further study of the materials used, the locations in which they were built, and their construction methods suggest that many of these homes were built to last. The three case studies used in this thesis represent a large number of earth homes still standing today. The findings of this study enhance the history of the region and open up new avenues for further research on earth homes as well as the possibilities and the importance of their preservation.

Building rammed earth structures provides a sustainable alternative to concrete. As a building material, rammed earth exhibits very varied physical and material properties depending on the proportion of constituting soil types. When very sandy soil is used in rammed earth production, the properties are different from when a clayey soil is used. This variability can be seen as a very great advantage in the use of rammed earth as a building material. Builders are able to adjust specific properties by changing mix proportions to obtain a desirable balance in the characteristics of the resulting rammed earth structure. This research work looks at selected mechanical and physical properties of different mixes of rammed earth. It describes typical range of values in density, thermal conductivity, ultrasonic pulse velocity, water ingress and compressive strength. It examines how these factors interrelate in the same soil mixes. Samples were prepared by blending various soil types in specific proportions to ensure that each definition of soil grade is as specific as possible. Unstabilised rammed earth was tested as was cement stabilised rammed earth. Rammed earth was tested at various levels of stabilisation and it was discovered that higher rates of stabilisation was not always beneficial to every material property. The research also looked into the potential disposal of waste materials in rammed earth. As rammed earth is a monolithic material that largely remains undisturbed throughout its life span, it was suggested that waste materials could be stored in an inert form inside of rammed earth rather than dumping it in otherwise agricultural landmass. Pulverised Fuel Ash and Palm Kernel Shells were identified as wastes to be disposed in rammed earth. Pulverised Fuel Ash, a by-product of industrial furnace is found in abundance in developed countries that burn carbonaceous materials in power plants. Disposals have been seen as a problem as only a small proportion of high loss on ignition (LOI) Pulverised Fuel Ash has found application. Palm Kernel Shell is a by-product of the oil palm industry and is currently a menace in many developing countries that need to dispose large quantities of the shell in landfills. At an early stage of the research, experimental trial runs quickly showed that these supposedly waste materials had a positive effect on some of the material properties of the rammed earth walls they were made into. This research effort evolved to look into exploiting these materials to improve the physical and material property of rammed earth and to suggest their effect on stabilised and unstabilised rammed earth. The extent to which these materials could be useful and the level at which diminishing returns set in was also investigated. It was discovered that soil mixes that would otherwise not be considered suitable for use in rammed earth wall production can now be utilised as their characteristics can be improved on simply by adding Pulverised Fuel Ash or Palm Kernel shell in the right proportion. Incorporating Pulverised Fuel Ash in rammed earth resulted in increased compressive strength. Palm Kernel shell improved thermal properties without compromising compressive strength.

L'utilisation de matériaux locaux, naturels et non transformés offre des solutions prometteuses de construction à faible impact environnemental. La grande variabilité spatiale de ces matériaux est cependant un obstacle à une utilisation à plus grande échelle. Les stratégies de construction développées par les anciens bâtisseurs ont été dictées par le climat local et la qualité ainsi que la quantité de matériaux de construction disponibles localement. Ces stratégies de construction peuvent être considérées comme une gestion optimisée des ressources locales, naturelles et variables et sont une source d'inspiration pour la construction durable moderne. Malheureusement, cette connaissance a été perdue dans les pays occidentaux au cours du 20ème siècle. La redécouverte des savoir-faire traditionnels requiert le développement de moyens rationnels d’analyse du patrimoine. Un autre problème concernant l'utilisation de matériaux de construction naturels et variables est leur conformité vis-à-vis de la réglementation du secteur du bâtiment. Le développement de procédures d’essais performantiels est proposé comme solution pour faciliter l'utilisation des techniques de construction en terre. Une approche multidisciplinaire est proposée, combinant micromorphologie, pédologie, géotechnique et étude du patrimoine pour analyser le bâti vernaculaire en terre. Cette approche fournit des outils complémentaires pour évaluer la source des matériaux de construction et identifier les caractéristiques géotechniques de la terre employées dans le patrimoine. Il fournit également une description détaillée des processus vernaculaires de construction. En utilisant ces résultats, il a été possible d'élaborer des cartes de ressources et d’estimer l’ordre de grandeur de la disponibilité des ressources à l'échelle d’une région. Deux procédures d’essais performantiels ont été proposées afin de tenir compte de la variabilité naturelle des terres dans le contexte réglementaire actuel. La construction en terre jouera un rôle important dans la construction durable du 21ème siècle si les acteurs du secteur adoptent des procédés de construction capables de répondre à la demande sociale, avec un faible impact environnemental et à un coût abordable. L'étude du patrimoine en terre a démontré la capacité des anciens bâtisseurs à innover afin de se conformer aux variations de la demande sociale et aux développements techniques. La construction en terre bénéficie d'un passé ancien et riche et il convient de tirer profit de ce retour d’expérience. L'analyse du patrimoine en terre et la redécouverte des techniques de construction vernaculaire est une source d'inspiration précieuse pour la construction contemporaine. La valorisation des connaissances vernaculaires permettra d’économiser du temps, de l'énergie et d'éviter de répéter les erreurs passées. L'avenir de la construction de la terre doit s’inscrire dans la continuité de la construction en terre vernaculaire
The use of local, natural and unprocessed materials offers promising low impact building solutions. The wide spatial variability of these materials is, however, an obstacle to a large-scale use. The construction strategies developed by past builders were dictated by the local climate and the quality and the amount of locally available construction materials. These construction strategies can be regarded as an optimized management of local, natural and variable resources and are a source of inspiration for modern sustainable building. Unfortunately, this knowledge was lost in Western countries during the 20th century. Vernacular earth construction know-how rediscovering requires the development of rational built heritage investigation means. Another issue regarding the use of natural and variable building material is their compliance with modern building regulation. The development of performance based testing procedures is proposed as a solution to facilitate the use of earth as a building material. A multidisciplinary approach is proposed, combining micromorphology, pedology, geotechnics and heritage disciplines to study vernacular earth heritage. It provides complementary tools to assess pedological sources of construction material and geotechnical characteristics of earth employed in vernacular earth heritage. It also provides a detailed description of the construction process of vernacular earth heritage. Using these results, it was possible to draw resource maps and provide a scale of magnitude of resource availability at regional scale. Two performance based testing procedures were proposed in order to take into account the natural variability of earth in a modern building context. Earth construction will play an important role in the modern sustainable building of the 21st century if the actors of the sector adopt earth construction processes able to meet social demand, with low environmental impact and at an affordable cost. The study of earth heritage demonstrated the ability of historical earth builders to innovate in order to comply with social demand variations and technical developments. Earth construction benefits of an old and rich past and it would be a non-sense to leave this past behind. The analysis of earth heritage and the rediscovering of vernacular construction techniques is a valuable source of inspiration for modern earth construction. The valorisation of vernacular knowledge will save time, energy and avoid repeating past mistakes. The future of earth construction should be a continuation of past vernacular earth construction

Thesis (M.S.C.E.)--University of Toledo, 2006.
Typescript. "Submitted as partial fulfillment of the requirements for the degree Master of Science in Civil Engineering." Bibliography: leaves 53-55.

This paper discusses earth as a building material and the extent to which earth building technology has evolved over the years. In particular it addresses the adobe, compressed and rammed earth techniques of earth building as suitable techniques for Liberia consumption. In addition, the paper investigates the suitability of the Latosols soils of Liberia for earth building construction purposes using standardized earth building principles and requirements. A local Johnson City, Tennessee, earth sample found to have the same physical characteristics of the Latosols of Liberia was used to simulate Liberia soils to produce specimen blocks at different configurations of moisture content and stabilizers (Bentonite and cement). Following 14 days of cure, the blocks were tested for compressive strength. It was found that blocks produced from the natural soil with no stabilizer added were structurally adequate for building construction purposes. A cost-benefit analysis involving blocks with and without stabilizer (cement) added was also performed.

Magmatism is a dominant process on Earth and Mars that has significantly modified and evolved the lithospheres of each planet by delivering magma to shallow depths and to the surface. Two common modes of volcanism are present on both Earth and Mars: central-vent dominated volcanism that creates large edifices from concentrating magma in chambers before eruptions and distributed volcanism that creates many smaller edifices on the surface through the independent ascent of individual magmatic dikes. In regions of distributed volcanism, clusters of volcanoes develop over thousands to millions of years. This dissertation explores the geology of distributed volcanism on Earth and Mars from shallow depths (~1 km) to the surface. On long time scales, distributed volcanism emplaces magmatic sills below the surface and feeds volcanoes at the surface. The change in spatial distribution and formation rate of volcanoes over time is used to infer the evolution of the source region of magma generation. At short time scales, the emplacement of lava flows in these fields present an urgent hazard for nearby people and infrastructure. I present software that can be used to simulate lava flow inundation and show that individual computer codes can be validated using real-world flows. On Mars, distributed volcanism occurs in the Tharsis Volcanic Province, sometimes associated with larger, central-vent shield volcanoes. Two volcanic fields in this province are mapped here. The Syria Planum field is composed three major volcanic units, two of which are clusters of 10s to >100 shield volcanoes. This area had volcanic activity that spanned 900 million years, from 3.5-2.6 Ga. The Arsia Mons Caldera field is associated with a large shield volcano. Using crater age-dating and mapping stratigraphy between lava flows, activity in this field peaked at ~150 Ma and monotonically waned until 10-90 Ma, when volcanism likely ceased.

Includes abstract.
Includes bibliographical references.
The purpose of this thesis was to explore the suitability for Rammed Earth construction in the Cape Town metropolitan area. This would ultimately lead to drawing up a guideline for building of Rammed Earth housing and structures. The research involved collecting sixteen soil samples from strategically selected sites in Cape Town. The suitability of a soil was established through a variety of tests, varying between relatively simple field tests and rigorous laboratory analysis. These tests were undertaken to assess soil grading, organic matter content, plasticity and Optimum Moisture Content (OMC). Grading gave an indication of fines present and plasticity indicated the cohesive nature of the fines. More detailed tests were undertaken to determine type and level of soluble salts and mineralogical composition.

Modern building procedures and requirements demand that the selection and stabilisation of soils for the purposes of rammed earth construction be better quantified. This study examines the relationships between soil properties, stabiliser treatments, and stabilised strength and density for 111 soil samples taken from sites in New South Wales (Australia), and develops new quantitative criteria for soil assessment, selection, and stabilisation. Laboratory measurements of soil particle size distribution, plasticity, and shrinkage were made for each soil. Various quantities from 0-6 % of lime, cement, and asphalt were added to the soil samples, and the resulting 230 specimens were compacted, and cured for 28 days. Determinations were made of the optimum moisture content, maximum dry density, and compressive strength of the stabilised material. The samples showed stabilised strengths ranging from 1.0-5.4 MPa, with a mean of 2.62 MPa, and densities from 1.44-2.21 t/m3, with a mean of 1.86 t/m3. The results show that over 90 % of the variation in stabilised strength and density of the samples is due to variation in soil properties, with differences in stabiliser type or stabiliser quantity being relatively minor. The most important soil properties explaining stabilised strength are linear shrinkage and plasticity index. These properties have been used to categorise the soils into three groups on the basis of their suitability for stabilisation as measured against a compressive strength criterion of 2 MPa. Favourable soils have shrinkages of < 7.1 % and plasticities of < 16 %, and 90 % of these samples passed the 2 MPa criterion. Satisfactory soils have shrinkages of 7.1-13.0 % and plasticities of 16-30 %, and 65 % of these samples had strengths in excess of 2 MPa. Unfavourable soils have shrinkages of > 13 % and plasticities of > 30 %, and only 10 % of these samples exceeded the 2 MPa value. Soils in the favourable and satisfactory categories can be further discriminated using textural information. On that basis, all soils classified as favourable, and those classified as satisfactory and which also have sand contents < 60 %, are recommended as being suitable for stabilisation. Soils not fulfilling these criteria are unlikely to be successfully stabilised and should be rejected. These results stress the importance of selecting a soil favourably predisposed to stabilisation. Field techniques to search for such soils could be refined on the basis of the new soil criteria presented. Use of the criteria should also minimise unnecessary laboratory testing of the density and strength of soils that subsequently prove unsuitable for stabilisation. A flow chart is presented to guide practitioners through the different stages of soil testing, assessment, and rammed earth stabilisation.

A construção em terra é um processo milenar, e a sua transmissão enquanto tal tem sido feita entre gerações, de país para filhos, e quase sempre de forma operativa. A utilização da terra pauta-se por uma qualidade que consiste na sua reciclabilidade. Esta característica assume especial importância quando se aborda cada vez mais a sustentabilidade ou desenvolvimento sustentável. A reciclabilidade da terra como material construtivo, enquanto processo natural ou artificial, dificulta o seu estudo uma vez que os testemunhos mais antigos não podem ser avaliados devido à sua perda total. Pretende este trabalho criar uma ferramenta aglutinadora de processos construtivos, classificação da terra enquanto material de construção e por ultimo, ferramenta analítica das geometrias utilizáveis na construção com esse material, atendendo às suas propriedades. Trata-se de uma análise comparativa dos processos construtivos em terra crua, suas geometrias e estereotomias, dentro do conceito de obra global, analisando-a no todo e na parte. Esse trabalho redefine o processo de classificação das técnicas construtivas em terra crua em função dos processos auxiliares de construção, e não pelo estado físico do material utilizado ou mesmo pela família de sistema construtivo. ***/Abstract - The construction with earth is a millenary building process and its transmission as such has been passed down from generation into generation i.e. from parents to children and almost always by operative process. The utilization of earth is regulated by its recyclable quality. This characteristic gains special importance when again and again sustainability or sustainable development is approached. The recyclability of earth as a building material, considered as a natural process, makes its study difficult once the more ancient testimonials cannot be evaluated due to their total loss. This work aims at creating an agglutinating tool of constructing processes, classification of earth as a construction material and ultimately an analytical tool of the usable geometries in construction with this material, having in mind its properties. This is a comparative analysis of the constructive processes with crude earth, its geometries and stereotomies, within the concept of global work, analyzing it as a whole or in parts. This work redefines the process of classification of the techniques of construction with earth in function of the auxiliary processes of construction and not by the physical state of the material being used or even by the family of the constructive system. ***/Resumen - La construcción en tierra es un proceso melenar y la suya transmisión en cuanto tal ha sido hecha desde generaciones pasando de padres a hijos y casi siempre de forma operativa. La utilización de la tierra se regula por una cualidad que es la suya reciclabilidad. Esta característica toma una importancia especial cuando, más y más, se aborda la sustentabilidad ó el desarrollo sustentable. La reciclabilidad de la tierra como material de construcción, en cuanto proceso natural ó artificial, se vuelve difícil una vez que los testimonios más antiguos no pueden ser avaluados debido a su pierda total. Con esta obra se pretende criar una herramienta aglutinadora de los procesos de construcción y de clasificación de la tierra en cuanto material de construcción y por último, una herramienta analítica de las geometrías utilizables en la construcción con este material, considerando sus propiedades. Tratase de un análisis comparativo de los procesos de construcción con tierra cruda, sus geometrías y estereotomías, dentro de lo concepto de obra global, analizándola en el todo y en la parte. Esta obra redefine el proceso de clasificación de las técnicas con tierra cruda en función de los procesos auxiliares de construcción y no por el estado físico del material utilizado o mismo por la familia del sistema de construcción.

La construction en terre est considérée comme une construction verte en utilisant des matériaux disponibles localement avec un faible impact environnemental et une performance thermique supérieure. Malgré les avantages de ce matériau de construction, le processus de coulage est très consommateur de temps et d'énergie à cause de l’application de la compaction dynamique. Cette étude a pour but d'évaluer la faisabilité de formuler un béton de terre autoplaçant (BTAP) tout en étudiant ses performances rhéo-thermomécaniques et en identifiant les différents défis. Le premier défi est la présence de particules fines dans la terre, en particulier les particules argileuses, qui peuvent entraver la fluidité du BTAP. L’augmentation du temps de prise est le deuxième défi en raison de la faible teneur en ciment. Le dernier défi vient de la diversité des terres avec des comportements différents, ce qui rend difficile la proposition d'une ligne directrice complète pour la conception des BTAP.Des solutions potentielles ont été introduites pour réaliser le BTAP afin de remédier à l'inefficacité des matériaux en terre. Il s’agit essentiellement de comprendre l'efficacité de différents adjuvants chimiques en présence des systèmes de poudre ternaire (c'est-à-dire l'argile, le limon et le ciment). Une nouvelle approche de mortier du béton équivalent (MBE) a été introduite à la Phase 3. En conséquence, le MBE et les formulations de béton ont été étudiés pour vérifier la faisabilité du BTAP. Les caractéristiques hygrothermiques et microstructurales des BTAP optimisés ont été étudiées. Ce nouveau matériau offre une microstructure conduisant à une performance hygrothermique différente de celle des matériaux en terre conventionnels
The earth construction is identified as a green construction by using locally available materials with low environmental impacts and superior thermal performance. Besides all the advantages of this construction material, the casting process can be very time and energy consuming due to the nature of dynamic compaction. This study aimed to evaluate the feasibility of achieving self-consolidating earth concrete (SCEC) with introduction of its potential challenges and investigating its rheo-thermomechanical performance. As the first challenge, the presence of fine particles in earth, especially clay, can hinder the flowability of SCEC. Promoting the setting time is the second challenge due to the low cement content. The last challenge comes from the diversity of earth with different behaviors which makes it difficult to propose a comprehensive guideline to design SCEC.Potential solutions were introduced to achieve SCEC and address the inefficiency of earth materials. The main objective was to understand the efficiency of different chemical admixtures in presence of various ternary powder systems (i.e., clay, silt, and cement). A new concrete-equivalent mortar (CEM) approach was introduced in the Phase 3. Accordingly, the CEM and concrete mixtures were investigated to verify the feasibility of SCEC. The hygrothermal and microstructural characteristics of the selected SCEC mixtures were investigated. This novel material offers a new microstructural system, hence leading to a different hygrothermal performance compared to conventional earthen materials

The residual flow procedure (RFP) is used to conjunction with finite element method for solution of steady state free surface seepage in dams containing open cracks. The cracks are simulated using the thin-layer element concept. A comprehensive parametric study is performed to analyze the applicability of the numerical procedure with the thin layer element. Here, vertically trending as well as horizontally trending open cracks are considered with variable lengths, widths, and conductivities. It is found that the numerical results involve oscillatory, unstable, and physically unreasonable behavior beyond critical values of the geometry and conductivities. Here, the vertically trending configurations are found to be relatively more sensitive than the horizontally trending configurations. Although additional research will be needed to analyze other factors such as different crack geometries, transient flow, and different ratios of crack conductivities to surrounding soil conductivities, the results presented here suggest that the procedure can be applied for seepage analysis in dams containing open cracks.

The United States government created America's third coastal defense system during the early-to-mid nineteenth century based upon the recommendations of the Board of Engineers of 1816. The engineers of 1816 believed the most economical means of protecting America was the construction of large, permanent forts along key areas of America's coast. Union forces under Brigadier General Quincy Gillmore seized Fort Pulaski in April of 1862. Pulaski was one of the most formidable forts built under the third system. Gillmore required two months to install the weapons used against Pulaski; most of the time was spent installing smoothbore Columbiads, the standard breaching weapon of the day. Yet the weapons that destroyed Pulaski were lighter, rifled guns. Gillmore attributed the fort's destruction to rifled weapons, and found the smoothbore guns practically worthless during the engagement. All forts built by Southern engineers prior to the fall of Pulaski, prior to the proof of the superiority of rifled weapons over permanent works, were earthen forts. Masonry's obsolescence was not a factor in the decision to build earthen works. The South needed forts immediately, for it faced an enemy that had invaded its soil and established a base on its shores. The change in construction material from masonry to earth was not in response to the recognition of a new threat, the rifled weapon, but because the Confederacy lacked the time and resources to build forts like Pulaski. Earthen forts like Fort McAllister, Georgia, were able to withstand repeated attacks by the United States Navy and emerged unscathed. The largest guns in Federal service, 15" Columbiads, were used on several occasions against McAllister. The fort did not fall until assaulted by a greatly superior land force. Although the lessons provided by earthen forts did not change the immediate future of coastal defenses, they did have an impact later in the nineteenth century. Under the Endicott system of the 1880s, engineers constructed coastal forts as one-tier works with dispersed batteries. The materials used were earth and reinforced concrete. By the tum of the century the impressive forts of the third system were abandoned in favor of the Endicott forts.

Cette étude se concentre sur les performances hygro-mécaniques de la terre crue compactée comme matériau de construction alternatif aux matériaux de construction classiques à forte empreinte énergétique. Les briques en terre ont été fabriquées en appliquant des pressions de compactage élevées (jusqu’à 100 MPa, d’où la dénomination d’hyper-compactage) pour augmenter la densité du matériau et ainsi obtenir des propriétés mécaniques similaires à celles des matériaux de construction traditionnels tels que les briques cuites, les blocs de béton et la terre stabilisée. Une vaste campagne expérimentale a été menée sur des échantillons constitués de différents mélanges hyper-compactés de terres à leur teneur en eau optimale respective. La rigidité et la résistance mécanique ont été mesurées par des essais de compression non confinés et triaxiaux, tandis que l’adsorption/désorption de vapeur a été évaluée par la valeur de MBV (Moisture Buffering Value). La durabilité à l'érosion hydrique a été étudiée en effectuant des tests de adsorption capillaire, d'immersion et de goutte-à-goutte conformément aux normes DIN 18945 (2013) et NZS 4298 (1998). Les résultats ont confirmé que l'hyper-compactage améliore les performances mécaniques de la terre crue compactée, mais qu'une augmentation sensible de l'humidité ambiante pouvait entraîner une réduction considérable de la résistance. Néanmoins, les tests de durabilité ont révélé que la terre compactée non stabilisée ne pouvait pas être utilisée pour la construction des parties de structures exposées aux intempéries naturelles en raison de sa sensibilité vis-à-vis de l’eau liquide. Les expériences ont démontré la dépendance de la résistance, de la rigidité, du comportement hydrique, de la sensibilité à l’eau liquide et de la durabilité à la taille des particules. En particulier, il a été observé qu'un mélange de terre à faible granulométrie et calibrées présentait des caractéristiques pour les propriétés susmentionnées supérieures à celle d’un sol à la granulométrie grossière et non maîtrisée. Un défi important a été l'amélioration de la durabilité de la terre crue à l'érosion hydrique en adoptant de techniques de stabilisation à faibles impacts environnementaux, ce qui a conduit à la mise au point d’une méthode originale de stabilisation basée sur l’utilisation d’extraits de plantes. Cette méthode était conforme à la précipitation de calcite induite par voie enzymatique via l'action de l'enzyme uréase pour catalyser l'hydrolyse de l'urée. Cette réaction produit des ions carbonates, qui réagissent ensuite avec les ions calcium du sol dissout dans l’eau interstitielle pour précipiter sous forme de carbonate de calcium, liant ainsi les particules du sol
The present work investigates the hygro-mechanical performance of compacted earth as an alternative to conventional energy-intensive building materials. Earth bricks were manufactured by applying high compaction pressures up to 100 MPa (hyper-compaction) to increase the density of the earth and hence to obtain mechanical properties that are similar to those of traditional construction materials such as fired bricks, concrete blocks and stabilised earth. A wide campaign of laboratory tests was performed on samples made of different earth mixes that were hyper-compacted at their respective optimum water contents. Stiffness and strength were measured by unconfined and triaxial compression tests while vapour adsorption/desorption was assessed by measuring moisture buffering value (MBV). Durability to water erosion was also evaluated by performing suction, immersion and drip tests according to the norms DIN 18945 (2013) and NZS 4298 (1998), respectively. Results showed that hyper-compaction largely improved the mechanical performance of compacted earth but that a marked increase in ambient humidity could produce a considerable reduction of strength. Durability tests highlighted that the unstabilised compacted earth could not be employed for the construction of structures exposed to natural weathering. The experiments also demonstrated the dependency of strength, stiffness, moisture buffering capacity and water durability on particle grading. In particular, it was shown that a fine and well-graded earth mix exhibited higher levels of strength, stiffness, moisture buffering capacity and durability than a coarse and poorly-graded one. One important challenge lied in the improvement of the earth durability against water erosion by adopting novel stabilisation techniques, which led to the development of an original stabilisation method based on the utilisation of plant extracts. The method was consistent with the principles of Enzymatic Induced Calcite Precipitation (EICP), which utilises the action of the urease enzyme to catalyse the hydrolysis of urea. This reaction produces carbonate ions, which then react with the calcium ions dissolved in the pore water to produce the precipitation of calcium carbonate (i.e. calcite), thus binding the soil together. The novelty of the present work resides in the utilisation of crude plant-derived urease enzyme instead of pure reagent-grade products available from chemical suppliers, which reduces environmental and financial costs. In particular, the urease enzyme was obtained from a liquid soybeans extract, inside which the urea and calcium chloride were subsequently dissolved to induce the precipitation of calcite. Measurements of pH, electrical conductivity and precipitation ratio indicated that the optimum equimolar concentration of urea and calcium chloride (leading to the largest precipitation of calcite) was 2.5 mol/L. An experimental campaign was finally undertaken to implement the proposed bio-stabilisation method into the manufacture of compressed earth bricks. The most promising versions of the proposed bio-stabilisation method were also the object of further investigation to assess the hygro-mechanical behaviour of the stabilised earth by means of unconfined compression and moisture buffering value tests. The findings, although preliminary, suggested that a noticeable improvement of strength and water durability could be achieved by the proposed stabilisation protocol, in spite of the difficulty in replicating exactly quantitative results

Les reticences que rencontre l'utilisation de la terre comme materiau de construction se fondent notamment sur sa sensibilite a l'eau consideree comme responsable de sa faible durabilite. L'objectif de ce travail est d'etudier comparativement aux autres materiaux; le comportement a l'eau d'un silt argileux a structure continue et d'un sable argileux a structure particulaire. Le gonflement-retrait des blocs mesure a l'aide d'un capteur de deplacement ainsi que leur erodabilite sous une pluie simulee sont les parametres utilises. Nous proposons alors une classification des terres basee sur leur gonflement et sur leur erodabilite. Nous situons a 1. 77 la densite de compactage du sable argileux necessaire a l'obtention d'une erodabilite de 0. 2 alors qu'elle n'est que de 1. 55 pour une erodabilite 20 fois moindre dans les blocs de silt argileux. Nous dressons aussi le bilan du comportement de plusieurs protections superficielles sur supports en terre apres plusieurs annees d'exposition. Les enduits pelliculaires (badigeons de chaux ou de ciment) ne peuvent pretendre a une durabilite de plusieurs annees; par contre les mortiers batards ainsi que les impregnations de produits chimiques; sous reserve d'une bonne protection contre les infiltrations a l'interface offrent des possibilites interessantes en climat tempere

This Thesis examines the effect of soil characteristics, cement content and fibers on the strength and durability of compressed earth blocks (CEBs). This work expands on the available information regarding the constituent properties which affect the compressive and tensile strengths and durability of CEBs. Additionally, little research on the subject of synthetic fibers and their effect on strength and durability of CEBs is available and this work provides an initial study in this area. To study the effects of fibers, as well as confirm the trends of previous research regarding the effects of clay and cement, 27 unique batches of CEBs were pressed and tested using a Vermeer BP 714 block press. Three different soil types and two fiber types were utilized. The compressive strength, modulus of rupture (MOR), absorption, and durability were measured on over 185 specimens. The strength and absorption tests were adapted from common ASTM International test methods for similar materials, while the durability test was a uniquely developed method to quantify durability by measuring mass loss during drying and wetting cycles. After the testing regimen was completed, a trend between clay content and strength could not be determined. Durability testing suggested that as clay content decreases, durability increases. A linear relationship was found between cement content and strength, which was confirmed during durability testing. The addition of different fibers did not have an effect on the peak strength of CEBs, although it appears they may decrease the durability. The gross versus net unit strengths of CEBs were examined due to the unique shape of the CEBs utilized. Additionally, a mathematical expression relating the MOR to the compressive strength was developed.

This thesis is concerned with an experimental and theoretical study of the behaviour of a reinforced earth retaining wall built on a rigid foundation, during and after construction with special attention paid to the effect of the compaction process. The theory and development of reinforced earth, four case histories, and tests on full scale models and small scale models related to the effects of compaction and current design methods have been reviewed with comments. The research work is tackled on two fronts: - Experimental model study. - Theoretical studies. 1) Experimental model study The model study, a three dimensional model, simulates a vertical reinforced earth retaining wall of height 6.0m with a model scale `10'. The model comprises an open fronted wooden box 1300mm long, 900mm wide and 700mm high, and the box contains the wall retaining 1200Kg of sand reinforced with aluminium foil strips 0.1mm thick attached to perspex facing panels of 150 x 150 x 18mm each. The sand bed in the model was formed using a sand spreader, dust extractor machine and a vibratory compaction device simulating the compaction plant in the field. Sixty six strain gauges, sixteen miniature pressure cells, which were developed and calibrated completely in the laboratory, and eight LVDTs were used to monitor the behaviour of the wall before, during and after compaction, under various uniform and variable compaction lengths and different methods of construction. Two methods of calibrating the density in the models were established, viz. temporary metal metal cylinders and permanent perspex cylinders. 2) Theoretical studies These were divided into two sections as follows: a - Theoretical study of compaction. b - Finite element method.

Thesis (MEng)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The suitability of local construction materials for construction purposes is governed by several rock mechanical properties. Strength, durability, performance and petrography of aggregates all influence the decisions engineers make in deciding if the aggregate is suitable and sustainable throughout the lifetime of a structure. This thesis investigates these properties by combining engineering, chemistry and geological disciplines to make informed decisions. The pertaining project for which the research was conducted is the construction of the gravimeter vault at the Matjiesfontein Geodesy and Earth Observation Observatory (MGO) although the research acquired can be used for other projects of a similar nature and other outbuildings at the MGO. Material at and around the site were tested for strength and durability according to certain South African National Standards (SANS). Slake durability was tested as certain rock types tend to slake when exposed to the atmosphere such as tillite of the Dwyka formation and shale of the Karoo Supergroup. Concrete cube strength was determined on cubes containing crushed rock from Matjiesfontein as well as river sand. Cube strength was conducted to analyse performance and to establish a mix design that would be sustainable throughout the lifetime of the project. Petrographic examination using Powder X-ray diffraction (PXRD), X-ray fluorescence (XRF), Scanning Electron Microscopy (SEM) and inspection under a petrographic microscope were conducted. These methods were used to determine if a risk exists for alkali-silica reactivity (ASR) in concrete when the rock types are used as aggregate, particularly if high quartz-bearing rock types such as quartzite of the Table Mountain group were to be used as coarse aggregate. Inspection of thin sections for strained quartz under a petrographic microscope and SEM imaging were important in determining if ASR may occur. The gravimeter vault was constructed using materials sourced mainly from Laingsburg. Tillite satisfied all tests and analyses conducted during the research, making it more suitable for construction than the other materials from Matjiesfontein. The slake durability test indicates that tillite is nearly as durable as quartzite, which is considered the most durable rock type at Matjiesfontein. This is due to atmospheric conditions in the Karoo being very dry with low humidity in comparison to the coast where slaking is known to occur. Slaking properties were most prominent for shale at Matjiesfontein and if excavated, it is recommended to cover the exposed shale with a layer of asphalt or cement to prevent slaking. The 10% fines aggregate crushing test (10%FACT) value for tillite was over the 210 kN prerequisite and the wet-to-dry ratio over 75% making it suitable for road construction according to the 10%FACT. All cube tests reached the desired 40 MPa prerequisite although the mixtures containing local river sand were unworkable. Unlike quartzite and quartzitic sandstone from Matjiesfontein, tillite is low in quartz and has minimal strained quartz. Therefore, no risk exists for ASR if tillite were to be used as aggregate in concrete.
AFRIKAANSE OPSOMMING: Die geskiktheid van plaaslike konstruksiemateriale vir konstruksiedoeleindes word deur sekere rots meganiese eienskappe beïnvloed. Sterkte, duursaamheid, volhoubaarheid en petrografie van aggregaat beïnvloed die besluite wat ingenieurs moet neem sodat die aggregaat aan standaarde voldoen en gedurende die leeftyd van ‘n struktuur volhoubaar is. Hierdie tesis ondersoek die genoemde eienskappe deur ingenieurs-, chemiese- en geologiese dissiplines te kombineer. Die voorgenome projek, waarvoor die navorsing ter sprake is, is vir die konstruksie van die gravimeterkluis by die “Matjiesfontein Geodesy and Earth Observation Observatory (MGO)”, alhoewel die navorsing ook gebruik kan word vir soortgelyke projekte, sowel as die konstruksie van die res van die geboue by die MGO. Materiale van die terrein en die omgewing is volgens sekere Suid-Afrikaanse kodes vir sterkte en duursaamheid getoets. Die blusbaarheid van materiale is getoets omdat sekere materiale, soos tilliet van die Dwyka-formasie en skalie van die Karoo Supergroep blus wanneer dit aan die atmosfeer blootgestel word. Die betonsterkte van kubusse, waarin plaaslike gesteentes en riviersand van Matjiesfontein vir aggregaat gebruik is, is bepaal. Die kubusse is getoets om die sterkte daarvan te analiseer en om ‘n betonmengsel, wat tydens die leeftyd van die projek volhoubaar is, daar te stel. Petrografiese eksaminering deur X-straal difraksie (XRD), X-straal fluoressensie (XRF), Skandeerelektronmikroskopie (SEM) en inspeksie onder ‘n petrografiese mikroskoop is gedoen. Met die doel om die petrografiese samestelling van materiale van Matjiesfontein te bepaal, is hierdie metodes gevolg om te uit te vind of daar ‘n risiko vir alkalie-silikaat reaksies (ASR) bestaan, as die gesteentes in beton gebruik word. Veral gesteentes met ‘n hoë hoeveelheid kwarts, soos kwartsiet van die Tafelberg-groep, is hier ter sprake. Inspeksie van dunsnitte vir gespanne kwarts onder ‘n petrografiese mikroskoop en SEM was belangrik om die risiko vir ASR te bepaal. Die gravimeterkluis is hoofsaaklik met materiale afkomstig van Laingsburg gebou. In vergelyking met die ander gesteentes by Matjiesfontein is tilliet, volgens alle toetsparameters, die mees geskikte gesteente vir konstruksiedoeleindes. Die blusbaarheid van tilliet vergelyk goed met kwartsiet, wat as die sterkste en duursaamste gesteente by Matjiesfontein, beskou word. Die rede hiervoor is die atmosferiese toestande wat baie droër is, asook die laer humiditeit in die Karoo, in vergelyking met gebiede nader aan die kus waar blusting meer algemeen voorkom. Die blusbaarheid van skalie by Matjiesfontein kom algemeen voor. As daar dus uitgrawing in hierdie gebied plaasvind, word dit aanbeveel dat ‘n laag sement of asfalt oorgegooi word om die blusting te verhoed. Die 10%FACT waarde vir tilliet was bo die vereiste 210 kN, asook bo die 75% nat-teenoor-droog-verhouding en daarom is dit volgens die 10%FACT-toets as padboumateriaal geskik. Alhoewel mengsels, wat plaaslike riviersand bevat het, onwerkbaar was, het alle toetsmonsters (kubusse) die vereiste 40 MPa- sterkte bereik. In vergelyking met kwartsiet en kwarsitiese sandsteen, bevat tilliet min kwarts en ook minimale gespanne kwarts. Daar bestaan dus geen risiko vir ASR indien tilliet van Matjiesfontien in die beton gebruik word nie.

Metal oxide thin films are dynamic materials that have revolutionised the nature of semiconductor and electronic thin film devices. Recently, progress has stagnated in some aspects due to the increasingly complex deposition apparatus required, and the dearth of suitable precursor complexes of certain ???difficult??? metals. This thesis seeks to address both of these issues. The application of a precursor complex, Mg6(O2CNEt2)12 to the SSCVD of MgO thin films delivered the highest quality films ever reported with this technique. The resultant films were found to be of purely (111) orientation. Due to the nature of the precursor, the chemical reactions occurring at the surface during SSCVD growth result in a high growth rate, low flux environment and films of (111) orientation have been achieved without the amorphous underlayer. This finding has important implications for buffer layers in perovskite thin film devices. The unprecedented precursor chemistry has been used as a basis for the extremely high quality material produced, along with the unusual, yet beneficial structural morphology it possesses. A new range of barium complexes with single encapsulating ligands have been prepared for use in chemical vapour deposition (CVD) of BaTiO3 thin films. A novel pathway to an unprecedented class of barium carbamates is reported, and also new dianionic bis ??-ketoesterates and their barium, strontium, and calcium analogues were synthesised. High resolution mass spectrometry showed the barium bis ??-ketoesterate derivatives to be monomeric, and preliminary testing indicated some volatility in these species. Insights were gained into the likely successful pathways to building a volatile heterobimetallic precursor complex containing an alkaline earth metal. The knowledge of intimate mixing in heterobimetallic precursor complexes was extended by some novel chemistry to develop the first mixed Zn/Mg carbamato cluster complexes. These complexes were found to be excellent SSCVD precursors for ZnxMg1-xO thin films. Thin films were deposited with these precursors and exhibited a single preferred orientation, with a constant amount of magnesium throughout the bulk of the films. Investigation of the light emission properties of the films revealed significant improvements in the structural order commensurate with the incorporation of magnesium, and the formation of the ZnxMg1-xO alloy.

Lateritic soils which have been described as highly weathered tropical or sub-tropical residual soils with varying proportions of particle sizes ranging from clay size to gravel, were studied in an attempt to establish its suitability or otherwise as sustainable material in building bricks and housing developments that will meet the present challenge of sustaining the environment without costing too much and maintaining a high standard of strength, durability and aesthetics. Index properties of the lateritic soils tested revealed them as mostly well-graded, comprising both cohesive (silt and clay) and cohesionless (sand and gravel) soil fraction. The mineralogical analysis shows the presence of sesquioxides in the clay portion which were found to be very useful in the natural binding process as well as in the presence of a stabiliser (cement). The geotechnical analysis on the lateritic soil revealed a strong compressive strength with a relatively sound dry density which could guarantee a good durability in resulting bricks made from these soil materials. Further test on the strength and durability of compressed earth bricks (CEBs) made from these lateritic soils revealed a brick with compressive strength ranging between 6.33 and 15.57 MPa which are considered to be of very good strength coupled with its sound durability strength established over a period more than one year under different kinds of severe weather and seasonal conditions. In conclusion, sesquioxides presence and mineralogy of lateritic soils were found to be largely responsible for their good compressive and durability strength which made them good and sustainable materials for CEBs.
Thesis (PhD)--University of Pretoria, 2017.
Geology
PhD
Unrestricted

It is estimated that 3,700 major dams are either planned or under construction, notably in developing countries. Dams can pose a threat to fish diversity, as one of the biggest impacts of damming is habitat fragmentation. Damming causes the isolation of small fish habitats, which reduces genetic diversity and expose fish species to vulnerability of local extinction, hence habitat fragmentation is one of the causes of biological loss. There are tools, which are used to balance between development and biodiversity conservation. One of the tools, which is commonly used, is environmental impact assessment (EIA). EIA uses both science and political knowledge. Science knowledge is important in EIA process as it is required to generate reliable baseline information, impact prediction and effective proposed mitigation. However, no studies have investigated the extent of the use of science knowledge in EIA for hydropower dams in Southern Africa. The purpose of this study is to examine the usage of scientific knowledge in environmental impact statements (EIS), focusing on EISs of dam construction on the impact of habitat fragmentation in fish. Ten EISs were collected from Lesotho, Malawi, Mozambique, Zambia, Zimbabwe. These countries were chosen because they are the hotspots for hydropower planning. I conducted EIS quality   review to answer the research purpose. I adopted and used EIS quality review package, which was developed by Lee and Colley (1991), to assess the content and quality of EISs. The results show that the use of science knowledge varies from one EIS to the other, and from one area of review to the other. The baseline and mitigation areas of EISs aligned with the scientific consensus the best, while the identification, prediction and evaluation of impacts area is generally unsatisfactory. Overall, six EISs out of ten EISs use science in a satisfactory way, and four EISs are unsatisfactory, meaning they attempted or completely omitted methods for assessing the ecological concept of fragmentation. I recommend a comprehensive study to review the use biodiversity concepts and methods in EISs for all the dams in southern Africa.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
A história do solo como material de construção tem cerca de 10.000 anos. Grandes civilizações como a persa e a egípcia, construíram cidade inteiras com terra crua. As construções apresentam como principais vantagens a baixa geração e emissão de poluentes, o reduzido consumo energético e consequentemente o baixo custo, contudo, o principal inconveniente é sua baixa resistência na presença de água, que conduz para a maioria das patologias encontradas. Neste trabalho, a durabilidade de uma matriz de solo estabilizada com acetato de polivinila (PVA) e resina poliuretana derivada do óleo de mamona (RPM) foi avaliada, e ensaios mecânicos foram executados para aferição das resistências. O PVA, diluído em água nas proporções de 50 por cento e 70 por cento, e a RPM foram adicionados ao solo na proporção de 26 por cento, em peso de solo seco. Fibras de Pupunha (Bactris gasipaes K.) e Sisal (Agave sisalana), com comprimento de 25 mm e fração de 0,5 por cento, em peso de solo seco, foram inseridas no solo/RPM e sua resistência à compressão simples, tração por compressão diametral e absorção de água por imersão foram avaliados. A resistência à compressão simples dos corpos de prova de PVA se manteve abaixo do mínimo exigido por norma, e a absorção de água por imersão foi superior ao máximo recomendado, por sua vez, os ensaios de durabilidade para as misturas solo/RPM demonstraram, em todos os casos, a superioridade do aglomerante em comparação ao cimento e PVA. A absorção de umidade, após 24 horas imerso em água, foi de 5 por cento em contraste com os 23 por cento de absorção da matriz solo/cimento. A absorção por capilaridade se manteve abaixo dos demais compósitos. Nos ciclos de molhagem e secagem observou-se uma menor perda de massa e uma maior resistência à abrasão. A adição de fibras vegetais aumentou sua resistência mecânica não influenciando na absorção d água.
The history of earth construction has about 10,000 years. Great civilizations, Egyptian and Persian, built cities with soil. The main advantages of this construction material are a low cost, low energy consumption and emission of pollutants, however, the disadvantage is its low water resistance, which leads to most structural pathologies. In this work, the durability of a matrix of soil stabilized with polyvinyl acetate (PVA) and castor oil resin (RPM) was assessed, and mechanical strength was measured. The PVA (50 per cent and 70 per cent solutions), and RPM were added to the soil in a proportion of 26 per cent in relation to soil dry weight. The performance of two types of vegetable fibers as reinforcement of soil/RPM matrix, Pupunha and Sisal, were investigated. The considered fibers were of 25 mm length, with weight fractions of 0,5 per cent in relation to soil dry weight. The compressive strength of the specimens stabilized with PVA remained below the minimum required by the standard, and water absorption by immersion was higher than the recommended maximum. The results demonstrate the potentiality of the use of castor oil resin. A significant decrease of the mechanical properties (results of unconfined compression and Brazilian test) compared to the mixture soil/cement was not observed. The durability tests showed, in all cases, the superior performance of resin compared to cement and PVA. Moisture absorption rate of soil/resin was 5 per cent in contrast to 23 per cent of the soil/cement matrix. The capillary absorption was lower when compared to other composites studied. There was less weight loss and a higher abrasion resistance after wetting and drying cycles. It was found that the vegetable fibers improved the post-cracking behavior of the composites.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A common problem of the Brazilian semiarid regions is water scarcity. An alternative to attenuate this severe regional problem consists in storing water during the rainy season, in dams with small storage volumes, usually built with inefficiently compacted embankments, which can contribute to the collapse during the first filling. The main goal of this work is to evaluate a construction methodology for earth dams in semiarid regions, taking into account the problems of inadequate compaction and water shortages. To achieve this, a study was done on a theoretical and experimental basis, in order to better understand the mechanical behavior of small dams that collapse during the first filling. An experimental dam was built in QuixadÃ-CE, following the proposition of Miranda (1988), which suggests a zoned cross section, built with low water content, with a better compacted core and side slopes with less efficient compaction. The embankment of this experimental dam was instrumented with piezometers (standpipes) and limnimetric rules, to monitor the filling and operation stages. Another developed study in this research refers to the avant-garde evaluation of suction in earth dams, using a device developed by researchers from the Department of Agricultural Engineering, at the Federal University of CearÃ, a capacitive sensor. To obtain the geotechnical parameters for the embankment soil, some laboratory tests were performed, such as characterization tests, compaction, consolidation and permeability tests, as well as shear strength and triaxial compression (saturated and unsaturated) ones, and also tests to determine the soil-water characteristic curve (using the filter paper method). The results were used in a numerical modeling of transient flow, using the software Slide, associated with UNSTRUCT, to predict the stress-strain behavior of the experimental dam. The results pointed to the occurrence of collapse in the soil structure of the slopes, which indeed happened after the first filling, since large longitudinal cracks were found in loco. The dam stability was also evaluated, by reducing the shear strength parameters, noting its stability, and thus proving efficient what Miranda (1988) proposed: a zoned embankment built with reduced costs of earthworks and low water consumption, contributing to the development of a low-cost methodology for the construction of small dams in the Brazilian semiarid.
Uma das problemÃticas do semiÃrido nordestino à a escassez de recursos hÃdricos. Para atenuar este forte problema regional, à comum realizar o armazenamento da Ãgua, durante o inverno, em barramentos com pequeno volume de acumulaÃÃo, construÃdos geralmente com maciÃos ineficientemente compactados, o que pode contribuir para a ruptura da obra durante o enchimento. O objetivo principal deste trabalho à avaliar uma metodologia de construÃÃo de barragens de terra em regiÃes semiÃridas, levando em consideraÃÃo os problemas de compactaÃÃo inadequada e escassez de Ãgua. Para tanto, foi empreendido um estudo, a partir de bases teÃricas e experimentais, a fim de melhor entender o comportamento mecÃnico de pequenas barragens que entram em colapso durante seu primeiro enchimento. Para tanto, foi construÃda uma barragem experimental no MunicÃpio de QuixadÃ-CE, seguindo a proposta de Miranda (1988), que sugere uma seÃÃo-tipo zoneada, construÃda com baixa umidade, tendo o nÃcleo melhor compactado e os espaldares executados com compactaÃÃo menos eficiente. O maciÃo desta barragem experimental foi, entÃo, instrumentado, com piezÃmetros e rÃguas linimÃtricas, para monitorar o enchimento e a operaÃÃo. Outro estudo desenvolvido nesta pesquisa foi o emprego vanguardista, na avaliaÃÃo da sucÃÃo em barragens de terra, de um equipamento desenvolvido por pesquisadores da Engenharia AgrÃcola da Universidade Federal do Cearà (UFC), para a determinaÃÃo da umidade do solo, um sensor capacitivo. Para a obtenÃÃo dos parÃmetros geotÃcnicos do maciÃo, foram realizados ensaios de caracterizaÃÃo, compactaÃÃo, adensamento duplo, permeabilidade e cisalhamento direto e de compressÃo triaxial (saturado e nÃo saturado), alÃm de ensaios para a determinaÃÃo da curva de retenÃÃo do solo (mÃtodo do papel de filtro). Os resultados foram utilizados em uma modelagem numÃrica de fluxo em regime transiente, com o auxÃlio do programa Slide, associados ao UNSTRUCT, para a previsÃo do comportamento tensÃo x deformaÃÃo do solo da barragem experimental. As anÃlises indicaram a ocorrÃncia de colapso da estrutura do solo dos taludes, fenÃmeno observado in loco apÃs o enchimento, jà que a obra apresentou grandes trincas longitudinais em seus taludes. A estabilidade da barragem tambÃm foi avaliada, atravÃs da reduÃÃo dos parÃmetros de resistÃncia ao cisalhamento, constatando sua estabilidade, e comprovando, assim, a eficiÃncia da proposta de Miranda (1988), de um maciÃo zoneado construÃdo com reduÃÃo de custos de terraplenagem e do consumo de Ãgua, contribuindo para o desenvolvimento de uma metodologia de baixo custo para a construÃÃo de pequenas barragens no semiÃrido brasileiro.

Scotland’s vernacular earth-built heritage has received inadequate recognition over a number of decades, being the reserve of a small group of academic, architectural and conservation practitioners, with negative perceptions of the structures and their inhabitants having been developed over the long-term. This has ultimately contributed to the loss of a wide number of earth building traditions previously widespread across Scotland. Heritage custodians have invested in the restoration and maintenance of a select few sites, but wider recognition of the significance of extant structures, including the intangible aspects of inherited traditions, remains limited. This thesis therefore seeks in the first instance to promote improved understandings of Scotland’s earth-built heritage through historical appraisals that underline its wider heritage value within global, regional and local contexts, whilst demonstrating the limitations of survey evidence hitherto relied upon. Heritage policies and management procedures are increasingly driven in response to the climate changes projected for the remainder of the twenty-first century, partly informed by the impacts of changes that have already been observed. As a result of this, new fields of research such as heritage climatology have developed with a view to offering bases from which to develop longer term mitigation and management strategies that recognise potential changes to the causes and processes of deterioration in the historic environment. Alongside the development of academic interest in climate and heritage has been an ever-increasing accessibility to advanced analysis methods through technical apparatus (often portable) that can be used to create improved evidence repositories based on processes-led approaches to investigation. Scotland’s earth-built heritage is susceptible to a range of climate-related phenomena that are likely to manifest in different ways over coming decades. Conservation strategies have continued to rely, however, upon the empirical observations and the experience of very few individuals since the latter-twentieth century. Consequently, the ad hoc approaches to the management of Scotland’s earth-built heritage and lack of strategic planning that have been typical to this point require amendment. This interdisciplinary thesis therefore seeks to contribute to addressing the issues outlined above through the exploration and application of portable scientific sampling apparatus that allow for in situ, rapid and non-intrusive insights to be gained at various scales of interest. These, together with other minimally intrusive approaches to assessing performance in earth building materials, allow for the development of processes-led strategies to extending the evidence base beyond that presently relied upon. Amongst the key outcomes of this are the generation of a locally-focused dataset of climate projections that are used to develop understandings of future climate conditions in the Carse of Gowrie, Perthshire, and in turn garner insights as to how these will impact in relation to the earth-built heritage for which this region is noted. Temperature and humidity monitoring evidence gathered from within the walls of extant structures over the course of fourteen months from March 2012 to April 2013 are set against contemporary external weather conditions and alongside measurements of moisture ingress. These serve to highlight both aspects of inherent resilience and points of particular risk to the future integrity of earth-built structures. An extended benefit of this work is the demonstration that the novel procedures used are easily replicated and could be employed in a variety of local contexts to develop suites of intra-site data across Scotland, with the potential for offering evidence-based inferences relevant to management procedures and policy discussion. The utility of the understandings and methods of investigation long established in the field of soil science but conspicuously overlooked in earth buildings research is also addressed, with insights into micro-scale processes offered using micromorphological and micromorphometric methods and the results being directly related to macro-scale observations.

A newly proposed F-class mission by the European Space Agency (ESA) in 2019,Comet Interceptor, aims to dynamically intercept a New Solar System Objectsuch as a Dynamically New Comet (DNC). The Spacecraft will be placed in aperiodic (Halo) orbit around the Sun-Earth L2 Lagrangian point, waiting for furtherinstructions about the passage of a comet or an asteroid, which could well bereached within the stipulated mission constraints.A major part of the detection of these bodies will be owed to the Large SynopticSurvey Telescope (Currently under construction in Chile), which hopes to vastlyincrease the ability to discover a possible target using the catalogue of LongPeriod Comets and a set of its orbits. It is suggested that, in a mission length of<5 years, discoveries and warnings are possible so that optimization of thetrajectory and characterisation of the object are done within the set windows.This thesis is aimed at facilitating a transfer to a Potentially Hazardous Asteroid(PHA), a subset of the Near-Earth Objects (NEO), as a secondary choice on theoff-chance that the discovered comet could not be reached from the L2 Librationpoint within the mission constraints.The first section of this thesis deals with the selection of a Potentially HazardousAsteroid for our mission from the larger database of the Near-Earth Objects,based on a measure of impact hazard called the Palermo Scale, while the secondsection of the thesis aims to obtain a suitable Halo orbit around L2 through ananalytical construction method. After a desired orbit is found, the invariantmanifolds around the Halo orbit are constructed and analysed in an attempt toreduce the ΔV, where from the spacecraft can intercept the Potentially Hazardous Asteroid through the trajectory demanding the least energy.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O presente trabalho, desdobramento da pesquisa desenvolvida entre 2007 e 2009, relatada na dissertação de mestrado intitulada Design de estruturas reticuladas de bambu geradas a partir de superfícies mínimas, tem como objetivo principal a aplicação de alguns dos modelos de estruturas de cobertura desenvolvidos pelo LILD (Laboratório de Investigação em Livre Desenho), em escala e contexto real para uso comunitário. Isso ocorre através do ensino de técnicas simples e de baixo impacto ambiental, em processos de construção coletiva utilizando materiais e mão de obra locais. Por meio da elaboração de desenhos, modelos físicos reduzidos e da prática construtiva coletiva em si, obtém-se uma dinâmica de troca de saberes entre mestres e aprendizes, onde o conhecimento flui de maneira multidirecional, se retroalimenta. O aprendizado obtido fica evidente em dois momentos: no desenvolvimento das estruturas em laboratório, pois ampliam o repertório de unidades estruturais do LILD, e na construção das mesmas fora dos muros da universidade, pois trazem resultados reais tanto sobre os saberes trocados entre os envolvidos quanto à ação do meio físico e social sobre o experimento.
The present work, unfolding of the research developed between 2007 and 2009, reported in the master dissertation entitled Design of bamboo frame structures generated from minimal surfaces, has as main objective the implementation of models of roof structures developed by LILD (Laboratory Research in Free Design) on a scale and real context for community use. It happens by teaching simple and low environmental impact techniques in processes of collective construction using local materials and labor. Through the development of drawings, reduced physical models and collective constructive practice itself, we can get a dynamic exchange of knowledge between teachers and learners in which knowledge flows multidirectional way, feeds itself. The knowledge gained is evident in two phases: in the development of structures in the laboratory, it expands the repertoire of structural units of the LILD, and building them outside the walls of the university, because they bring real results both on the knowledge exchanged between those involved as the action of the physical and social environment on them.

Pas de résumé en français disponible
Locally available building materials are proven energy efficient and eco-friendly, making them a sustainable building material. In the last two decades, use of raw earth as building material is augmented, owing to the environmental concerns construction industry is also reconsidering the use of raw earth, researchers on the other hand are working to understand the mechanical and dynamic behaviour of earthen buildings, yet the study of mechanical parameters possess multiple challenges due to material inert properties exposing the need of new experimental approaches to extract accurate mechanical parameters. Building techniques such as adobe, compressed earth blocks, rammed earth, and laterite building stones are on a verge of reclaiming elite position in construction industry. In this study, experimental investigation on two naturally available building materials, unstabilised rammed earth (USRE) and laterite building stones (LBS) are carried out. The work focuses on the parameters that need to be considered in the experimental procedures, which influences the mechanical properties of USRE and LBS are seen. The locally available soils in the region of Rhone-alps, France and laterite building stones from Burkina Faso are used in this experimental campaign. Rammed earth walls are constructed by compacting moist soil in layers, due to manufacturing technique there is a density gradient within the layer that leads to heterogeneity. On the other hand, the manufacturing parameters of the USRE such as compaction energy and manufacturing water content have a direct influence on the dry density of the material and therefore the strength. The manufacturing parameters and specimens replicating the in-situ condition are very important to understand the behaviour of USRE wall. Hence an experimental procedure to study the unconfined compressive strength, considering the influence of manufacturing parameters and specimens replicating in-situ conditions are performed along with the cyclic loading and unloading to study the elasto-plastic property of the USRE. The test procedure is performed on two different soils that are used to build USRE structures. Along with the compressive strength of USRE, the tensile strength and flexural strength are also presented by subjecting specimens under split tensile test and four point bending test. Another important parameter is the mechanical strength properties of USRE layer interface under lateral loads. A novel experimental procedure to study the interface strength properties are discussed in this study. The experimental procedure is simple and xii compact that can be performed using a simple uniaxial press using inclined metallic wedges that allows rectangular prism to undergo bi-axial loading. With the help of inclined metallic wedges, shear stress and normal stress can be induced on the specimen interface allowing to obtain coulomb’s failure criteria and hence the strength properties of the interface. Laterite building stones (LBS) which are mainly used in tropical countries are porous in nature. The moisture retention capacity of porous building material will bring indoor comfort, but the presence of water molecules within the material and their variation to the outdoor environment is responsible for complex mechanical behaviour. Hence an experimental investigation to analyse the moisture ingress of LBS and their influence on mechanical strength is designed. The moisture ingress is studied by subjecting LBS for moisture sorption and desorption test and moisture buffering test. Then the influence of moisture ingress on mechanical strength (flexure and compression) are investigated using three point bending test and unconfined compression test with loading and unloading cycles. This experimental investigation allows studying the moisture ingress and their influence on strength along with elasto-plastic behaviour of LBS

[EN] Over time, the construction potentialities and traditional architecture of Saudi Arabia have declined substantially. The modern generation in Saudi Arabia has neglected the traditional structural and architectural designs for building towns, cities and homes. The materials used in the construction of traditional structures has been replaced by more westernized building materials such as concrete, cement and glass. Westernized methods of design and architecture often fail to last long due to the climatic and topographical conditions of the country, such as extreme heat and fast sand-blowing winds. Reviving traditional architectural and structural building married with westernized building technologies will yield strong structures that are capable of withstanding the harsh conditions of the country. This research seeks to identify the most applicable methods of structural procedures that can be used in historical earthen buildings in Saudi Arabia for conservation purposes. This dissertation addresses the important structural and architectural perspectives of traditional Saudi Arabian buildings. It also examines the perspectives of the Saudi population that affect the selection of building materials and architectural styles that are widely used. An examination of the old techniques employed in traditional Saudi Arabian buildings, how they can help in the formulation of a new approach for contemporary architecture and how this can be implemented in Saudi Arabia are also discussed in this dissertation. In the preparation of this dissertation, conforming processes were performed in order to fulfil the set objectives of the study. The first step was configured to examine different earthen architectural structures in Saudi Arabia. This stage involved travelling to different locations, observing the structures and also conducting interviews with older contractors. To collect more information on the topic, visits to Yemen and South Morocco were made, as these are two countries that have already married earthen architecture with modern architecture. The traditional architecture of Morocco and Yemen is similar to that of Saudi Arabia, but it has taken longer for these countries to shift to modern architecture. A laboratory examination was carried out to examine the relationship between the soil composition, stability, and strength of the structures that are built. Empirical studies were also conducted to examine the compactness, solidity, dimensional steadiness and permeability of the materials used in the constructions. These factors influence the choice of building materials for the conservation of traditional architecture and to solve the current need for cheap housing in the urban fabric. The results of this study indicate that the Adobe and Cob traditional architectural styles are two of the leading architectural styles in Saudi Arabia, with each style symbolizing the perspective of the people living in a particular locality. This dissertation also found that different architectural patterns were influenced by functionality, convenience, efficiency and availability of the construction materials needed. This explains the reason for different structural and architectural patterns in different parts of Saudi Arabia. This study concludes that mixing traditional architectural methods with modern technologies would serve to construct stronger and longer-lasting houses in Saudi Arabia. The new houses would not only serve to conserve the magnificent architecture of the country but would also help in building cheap houses, hence solving the rising demand for housing in urban areas. This study will add to the literature available on architectures in Saudi Arabia.
[ES] Con el tiempo, las posibilidades de construcción con técnicas tradicionales en Arabia Saudita han disminuido considerablemente. La nueva generación de Arabia Saudita ha dejado caer en el olvido los diseños arquitectónicos y estructurales tradicionales a la hora de construir pueblos, ciudades y viviendas. Los materiales utilizados en la construcción de las estructuras tradicionales han sido sustituidos por materiales de construcción más occidentalizados, tales como el hormigón, el cemento y el vidrio. Los métodos arquitectónicos y de diseño occidentalizados no suelen perdurar mucho tiempo debido a las condiciones climáticas y topográficas del país, tales como el calor extremo y las fuertes tormentas de arena. La revitalización de la construcción de estructuras y arquitecturas tradicionales, unida a las tecnologías de construcción occidentalizadas, dará como resultado unas estructuras sólidas capaces de soportar las duras condiciones del país. Esta investigación busca identificar los métodos de construcción de estructuras más aplicables que puedan ser utilizados en edificios históricos de tierra en Arabia Saudita para fines de conservación. Esta tesis aborda la importancia de las perspectivas estructurales y arquitectónicas para los edificios tradicionales de Arabia Saudita. La tesis también analiza el punto de vista de la población saudí frente a la selección de materiales de construcción y a los estilos arquitectónicos utilizados frecuentemente. En esta investigación también se examinan las antiguas técnicas empleadas en los edificios tradicionales de Arabia Saudita, cómo éstas pueden ayudar en la formulación de un nuevo enfoque para la arquitectura contemporánea y cómo pueden introducirse en la construcción actual en Arabia Saudita. En la preparación de esta tesis se ha trabajado con una metodología que permite cumplir con los objetivos establecidos al inicio del estudio. El primer paso fue examinar las diferentes estructuras arquitectónicas de tierra de Arabia Saudita. Esta etapa consistió en viajar a diferentes lugares para observar las estructuras así como para realizar entrevistas a los antiguos constructores. Para recopilar más información sobre el tema se hicieron también visitas a Yemen y al sur de Marruecos, dado que en estos dos países ya se ha unido la arquitectura de tierra con la arquitectura contemporánea. La arquitectura tradicional de Marruecos y Yemen es similar a la de Arabia Saudita, pero en estos países la nueva arquitectura contemporánea se ha desarrollado más tarde. Se han realizado ensayos de laboratorio para determinar la relación entre la composición del suelo y la estabilidad y solidez de las estructuras construidas. También se realizaron estudios empíricos para determinar la compactación, solidez, estabilidad dimensional y la permeabilidad de los materiales utilizados en las construcciones. Estos factores influyen en la elección de materiales de construcción para la conservación de la arquitectura tradicional y para resolver la necesidad actual de construir viviendas económicas en el tejido urbano actual. Los resultados de este estudio indican que las técnicas constructivas tradicionales del adobe y el cob (pared de mano) son dos de las principales técnicas de Arabia Saudita, y cada una de ellas tiene relación con las particularidades de las poblaciones que viven en un determinado lugar. Con esta tesis también se ha determinado que los diferentes patrones arquitectónicos estaban influenciados por la funcionalidad, la comodidad, la eficiencia y la disponibilidad de los materiales de construcción necesarios. Esto explica la razón por la que existen diferentes tipologías estructurales y arquitectónicas en distintas partes de Arabia Saudita. Este estudio concluye que la unión de los métodos arquitectónicos tradicionales con las nuevas tecnologías puede servir para construir viviendas más sólidas y de larga duración en Arabi
[CAT] Amb el temps, les possibilitats de construcció amb tècniques tradicionals a l'Aràbia Saudita han disminuït considerablement. La nova generació d'Aràbia Saudita ha deixat caure en l'oblit els dissenys arquitectònics i estructurals tradicionals a l'hora de construir pobles, ciutats i habitatges. Els materials utilitzats en la construcció de les estructures tradicionals s'han substituït per materials de construcció més occidentalitzats, com ara formigó, ciment i vidre. Els mètodes arquitectònics y de disseny occidentalitzats no solen perdurar molt de temps degut a les condicions climàtiques i topogràfiques del país, com ara la calor extrema i les fortes tempestes d'arena. La revitalització de la construcció d'estructures i arquitectures tradicionals, unida a les tecnologies de construcció occidentalitzades, donarà com resultat unes estructures sòlides capaces de suportar les dures condicions del país. Esta investigació pretén identificar quins són els mètodes de construcció d'estructures més aplicables que es poden utilitzar en els edificis històrics de terra d'Aràbia Saudita amb fins de conservació. Esta tesi aborda la importància de les perspectives estructurals i arquitectòniques per als edificis tradicionals d'Aràbia Saudita. La tesi també analitza el punt de vista de la població saudita front a la selecció de materials de construcció y als estils arquitectònics més àmpliament utilitzats. En esta investigació també s'examinen les antigues tècniques emprades en els edificis tradicionals d'Aràbia Saudita, com estes poden ajudar en la formulació d'un nou enfocament per a l'arquitectura contemporània i com poden introduir-se en la construcció actual a Aràbia Saudita. En la preparació d'esta tesi s'ha treballat amb una metodologia que permet complir amb els objectius establerts a l'inici de l'estudi. El primer pas va ser examinar les diferents estructures arquitectòniques de terra d'Aràbia Saudita. Esta etapa va consistir en viatjar a diferents llocs per a observar les estructures així com per a realitzar entrevistes als antics constructors. Per a recopilar més informació sobre el tema es van fer també visites al Iemen i al sud del Marroc, ja que en aquests dos països ja s'ha unit l'arquitectura de terra amb l'arquitectura contemporània. L'arquitectura tradicional del Marroc i del Iemen és semblant a la d'Aràbia Saudita, però en estos països la nova arquitectura contemporània s'ha desenvolupat més tard. S'han realitzat assajos de laboratori per a determinar la relació entre la composició del sòl i l'estabilitat i solidesa de les estructures construïdes. També es van realitzar estudis empírics per a determinar la compactació, solidesa, estabilitat dimensional i la permeabilitat dels materials emprats en les construccions. Estos factors influeixen en l'elecció de materials de construcció per a la conservació de l'arquitectura tradicional i per a resoldre la necessitat actual de construir cases econòmiques en el teixit urbà actual. Els resultats d'este estudi indiquen que les tècniques constructives tradicionals de l'adob i el cob (paret de mà) són dos de les principals tècniques d'Aràbia Saudita, i cada una d'elles té relació amb les particularitats de les poblacions que viuen en una lloc determinat. Amb esta tesi també s'ha determinat que els diferents patrons arquitectònics estaven influenciats per la funcionalitat, la comoditat, l'eficiència i la disponibilitat dels materials de construcció necessaris. Açò explica la raó per la qual hi ha diferents tipologies estructurals i arquitectòniques en distintes parts d'Aràbia Saudita. Este estudi conclou que la unió dels mètodes arquitectònics tradicionals amb les noves tecnologies modernes pot servir per a construir habitatges més sòlids i de llarga duració a Aràbia Saudita.
Alaidarous, AAH. (2016). Investigating the best methods for structural stabilization procedures for Historical earthen building conservation in Saudi Arabia: a technology-led construction analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68476
TESIS

Le matériau terre peut apporter une réponse face aux problèmes que les constructions modernes rencontrent en termes d’enjeux sociétaux, économiques et écologiques. Cependant, les difficultés à comprendre et à prédire son comportement représente un obstacle au développement de cette technique dans les pays développés. Cette thèse s’insère dans un projet de recherche appelé « Primaterre » et financé par l’Agence Nationale de la Recherche française (ANR). Il vise à apporter les connaissances scientifiques nécessaires afin de pallier ce manque et aider à établir des règlementations adaptées. Ce travail s’intéresse plus particulièrement à l’impact de l’eau sur le comportement mécanique de la matrice fine du matériau, qui a un impact essentiel sur le comportement du matériau dans son ensemble. Cette matrice est constituée de sables, de limons, et d’argiles, et ce sur trois types de terres prélevées sur d’anciennes constructions en pisé. Afin de réaliser des échantillons les plus identiques et homogènes possible, un moule a tout d’abord été conçu, ce qui a permis de travailler avec des échantillons cylindriques de 3,5cm de diamètre et 7cm de hauteur. Une cellule triaxiale a été utilisée et, la seconde étape a été de concevoir les dispositifs permettant la mesure des déformations axiales et radiales, le conditionnement à température contrôlée et l’imposition d’un flux d’air humide variable de part et d’autre de l’échantillon. Différents types d’essais ont alors pu être réalisés : des essais triaxiaux à différent taux d’humidité relative ainsi que des essais de gonflement. Les paramètres mécaniques obtenus ont pu être analysés à la lumière des caractéristiques matériaux mesurées en parallèle. Enfin, l’analyse des essais de gonflement a été menée à bien à l’aide d’un modèle numérique, et ce afin de pouvoir évaluer des paramètres caractéristiques plus complexes. Ce travail de thèse se conclut par une étude supplémentaire, visant à évaluer l’impact du changement de taille d’échantillon sur les paramètres mécaniques mesurés précédemment. Ces essais ont été effectués sur des échantillons approximativement deux fois plus grands, et grâce à un dispositif expérimental plus simple, utilisant la mesure par corrélation d’images
Earthen buildings can provide an answer to face difficulties in modern constructions in both terms of sociology, economics as well as ecology. However, the difficulty to understand and to predict their behavior prevent the spreading of this technique in developed countries. This PhD is part of a research program called “Primaterre” and founded by the French National Agency for Research. It aims at providing the necessary scientific knowledge to overcome this lack and at helping the creation of appropriate standards. This work is more precisely focusing on the impact of water on the mechanical behavior of the fine proportion of the material, including sand, silt and clay, and on three different earths coming from existing rammed earth constructions. In order to be able to produce samples as identical and homogeneous as possible, a mold has first been designed, which enable to manufacture cylindrical samples with diameter of 3.5cm and height of 7cm. A triaxial cell was used and, the second step was to design different devices allowing the measurement of axial and radial deformations, the conditioning at constant temperature, and the command of a variable moist air flux at both sides of the sample. Different types of tests have thus been realized : triaxial tests at different relative humidity, as well as swelling tests. The mechanical parameters thus obtained have been analyzed in comparison with material characteristics measured in parallel. Finally, results of swelling tests have been analysed using numerical modelling, in order to assess more complex material characteristics. This thesis work ends with an additional study, aiming at evaluating the impact of scale change on the mechanical parameters previously measured. Tests have been conducted on sample approximatively twice larger, and thanks to a simpler experimental device using measurement through image correlation

Construction machines, also referred to as engineering vehicles or earth movers, are used in a variety of tasks related to infrastructure development and material handling. While modern construction machines represent a high level of sophistication in several areas, their suspension systems are generally rudimentary or even nonexistent. This leads to unacceptably high vibration levels for the operator, particularly when considering front loaders and dump trucks, which regularly traverse longer distances at reasonably high velocities. To meet future demands on operator comfort and high speed capacity, more refined wheel suspensions will have to be developed. The aim of this thesis is therefore to investigate which factors need to be considered in the fundamental design of suspension systems for wheeled construction machines. The ride dynamics of wheeled construction machines are affected by a number of particular properties specific to this type of vehicle. The pitch inertia is typically high in relation to the mass and wheelbase, which leads to pronounced pitching. The axle loads differ considerably between the loaded and the unloaded condition, necessitating ride height control, and hence the suspension properties may be altered as the vehicle is loaded. Furthermore, the low vertical stiffness of off-road tyres means that changes in the tyre properties will have a large impact on the dynamics of the suspended mass. The impact of these factors has been investigated using analytical models and parameters for a typical wheel loader. Multibody dynamic simulations have also been used to study the effects of suspended axles on the vehicle ride vibrations in more detail. The simulation model has also been compared to measurements performed on a prototype wheel loader with suspended axles. For reasons of manoeuvrability and robustness, many construction machines use articulated frame steering. The dynamic behaviour of articulated vehicles has therefore been examined here, focusing on lateral instabilities in the form of “snaking” and “folding”. A multibody dynamics model has been used to investigate how suspended axles influence the snaking stability of an articulated wheel loader. A remote-controlled, articulated test vehicle in model-scale has also been developed to enable safe and inexpensive practical experiments. The test vehicle is used to study the influence of several vehicle parameters on snaking stability, including suspension, drive configuration and mass distribution. Comparisons are also made with predictions using a simplified linear model. Off-road tyres represent a further complication of construction machine dynamics, since the tyres’ behaviour is typically highly nonlinear and difficult to evaluate in testing due to the size of the tyres. A rolling test rig for large tyres has here been evaluated, showing that the test rig is capable of producing useful data for validating tyre simulation models of varying complexity. The theoretical and experimental studies presented in this thesis contribute to the deeper understanding of a number of aspects of the dynamic behaviour of construction machines. This work therefore provides a basis for the continued development of wheel suspensions for such vehicles.
QC 20110531

A construção civil é, atualmente, apontada como responsável pela extração de grande parte dos recursos naturais do planeta consumidos pela humanidade. Nesse sentido, a utilização de materiais construtivos nãoconvencionais, como a terra, surge como alternativa para construir edificações mais amigáveis com o meioambiente e, assim, também, modos de vida mais saudáveis, mais sustentáveis. Entretanto, a falta de informações, por parte de grande parte da população, inclusive de instituições de ensino e de profissionais atuantes no ramo da construção civil, em relação ao tema, faz com que o preconceito para com esse tipo de bioconstrução seja considerável. Surge, pois, a possibilidade de promoção da utilização da terra enquanto material construtivo, para que esse método de construção amigável com o meio-ambiente possa, aos poucos, recuperar o importante papel que desempenhava no passado, quando tais construções eram tidas como convencionais por nossos ancestrais. Através da investigação das técnicas de construção em terra e dos programas que favorecem esse tipo de iniciativa, o presente estudo tem como meta estabelecer um conjunto de diretrizes para orientar profissionais do ramo da construção civil e entidades interessadas em contribuir com a promoção da arquitetura em terra. Além disso, pretende prover de informação a sociedade em geral, para que haja o resgate da técnica e uma maior conscientização, no sentido de gerar edificações mais saudáveis e, portanto, menos prejudiciais ao meio-ambiente. Como no Uruguai, país que se limita com o Rio Grande do Sul e que tem clima semelhante a este, a utilização da terra enquanto componente construtivo ocupa papel de destaque, o presente estudo fundamenta-se nas edificações desta natureza, construídas no país vizinho. De tal modo, o objetivo principal deste trabalho é formular diretrizes para o desenvolvimento da arquitetura de terra no Rio Grande do Sul, a partir da interpretação de estratégias uruguaias, para bioconstrutores gaúchos e instituições financeiras / administrações municipais. Como objetivos secundários, têm-se: identificar programas de apoio do governo uruguaio e incentivos de instituições financeiras, além de outras iniciativas visando a promoção da arquitetura de terra naquele país; identificar bioconstrutores uruguaios, obras recentemente edificadas em terra naquele país e verificar quais são as técnicas construtivas utilizadas e como as mesmas são executadas; identificar bioconstrutores gaúchos que trabalhem com terra, bem como suas obras recentemente edificadas, além de verificar quais as técnicas utilizadas e como as mesmas são executadas; identificar possíveis programas de incentivo à utilização da terra enquanto material construtivo, bem como eventuais instituições financeiras que aprovem esse tipo de solução no Rio Grande do Sul. Como estratégia de pesquisa, utiliza-se o estudo de casos múltiplos, desenvolvido no Rio Grande do Sul e no Uruguai, sempre apoiado na bibliografia. Por final, as contribuições deste trabalho atingem os objetivos propostos, na medida em que se proporcionam ferramentas de informação à população em geral, auxílio a construtores interessados em desenvolver o tema e orientação a instituições financeiras e administrações municipais que permitam e apóiem esse tipo de solução inovadora e ambientalmente responsável, aplicada ao ramo da construção civil.
Civil construction is identified as the sector of human activities that more extracts natural resources from the Earth´s crust. On this way, the use of non conventional building materials, like earth, comes as an alternative towards the construction of more environmentally friendly buildings and, also, more sustainable and healthy ways of life. However, the lack of information by a large fraction of the population, including Educational Institutions and professionals working in the civil construction area, in relation to the subject, causes considerable prejudice to such type of bioconstruction . It’s therefore necessary to promote the use of earth as a building material. In this way, this building technique, friendly to the environment, can gradually recover the role it played in the past, when such type of construction was considered conventional by our ancestors. Through the investigation of earth building techniques and programs, which encourage this type of initiative, this study aims to establish a set of guidelines to guide professionals in the field of construction and the entities interested in support the promotion of earth architecture. Furthermore, it aims at providing information to society, so that the rescueying of this technology and the increase of the awareness on the subject, can contribute to a healthier environment in buildings. As in Uruguay, a country that borders the Rio Grande do Sul, with a similar climate, the use of earth as a building material, plays a leading role, this study is based on buildings built with such technology in the neighboring country. In this way, the main objective of this study is to formulate guidelines for increasing the use and the awareness on the benefits deriving from the use of earth buildings in the State Rio Grande do Sul, that may arise from the interpretation of Uruguayan strategies. This may be of interest both to builders interested in work with earth as a building material in the State of Rio Grande do Sul and to financial institutions or different levels of local government. The following secondary objectives were aimed at: to identify support programs, offered by the Uruguayan government as well as incentives by financial institutions, in addition to other initiatives aimed at promoting earth architecture in that country; to identify Uruguayan builders that work with earth architecture, their most recent works and also to check what techniques are being used in that country and how they are implemented; to identify builders in Rio Grande do Sul that work with earth architecture,their most recent works and to check what techniques are being used in that country and how they are implemented; to identify possible programs to encourage the use of earth as a building material, and any sort of financial institution that encourage this solution in the State Rio Grande do Sul. The research strategy used is the study of multiple cases and was developed in Rio Grande do Sul and Uruguay, always supported by the literature. Finally, the study intends to verify whether the resulting guidelines can achieve their objectives, to the extent that they may constitute tools of information to the general population, and to aid to builders interested in enrolling with the theme and to guide financial institutions and municipal governances to allow and support this type of innovative and environmentally responsible solution, in its application to the civil construction field.

La terre est le premier matériau de construction par les hommes, disponible et peu consommateur d’énergie. Aujourd’hui encore, environ 30 % des habitants de la planète vit dans des habitats en terre, et pour les pays en développement, ce pourcentage s’élève à 50 % de la population rurale. De plus, les matériaux à base de terre permettent un meilleur équilibre et contrôle du climat thermique et acoustique intérieur par rapport aux matériaux usuels de construction. Cependant, la majorité des constructions en terre ne répondent pas aux exigences actuelles en termes de contraintes mécaniques, thermiques ou architecturales. Afin de répondre à ces exigences, un travail tant au niveau scientifique qu’au niveau des praticiens est à accomplir dans ce domaine.L’objectif de cette étude est de déterminer l’influence des propriétés des matériaux utilisés sur le comportement mécanique et hygrothermique de composites terre-fibres végétales. Pour cela, différents types de sols et de fibre végétales (paille de lin, paille de blé) ont été utilisés. Ensuite, les performances mécaniques (compression, flexion) et hygrothermiques (sorption/désorption, perméabilité à la vapeur d’eau, conductivité thermique) ont été déterminées pour différents composites terre-fibres végétales. Les résultats montrent que l’utilisation de paille de lin permet d’obtenir des performances mécaniques supérieures à celles obtenues pour la paille de blé. Cependant, il est à noter que l’introduction de fibres aux sols diminue les performances mécaniques due à la diminution de la densité du matériau. Aucune influence claire de la longueur des fibres sur les performances mécanique n’a été constatée. L’étude du comportement hygrothermique a permis de montrer que le comportement à la sorption/désorption du matériau terre-fibres végétales peut être approximer à partir des résultats obtenus pour les matériaux de base. De plus, il a été démontré que l’évolution de la conductivité thermique du matériau terre-fibres végétales au cours du séchage est reliée au comportement au retrait
Soil is the first construction material used by man, widely available and low energy consuming. Indeed, about 30% of the current world population lives in earthen structures and, in developing countries, this rate rise to 50%, mostly rural. Moreover, earth-based materials allow an improved balance and control of thermal and acoustic indoor climate compared to industrial construction materials. However, most of earthen structures do not reach current requirements in terms of mechanical, thermal or architectural. To respond to these requirements, a work at scientific and craftsman levels is necessary.The objective of this study is to determine the influence of materials’ properties on the mechanical and hygrothermal behaviour of earth-fiber composites. In order to do this, different types of soil and plant fiber (flax straw, wheat straw) were used. Then, mechanical (compression, bending) and hygrothermal performances (sorption / desorption, water vapor permeability, thermal conductivity) were determined for different soil-fiber composites. Results show that the use of flax straw provides better mechanical performances than use of wheat straw. However, it should be noted that fibers addition to soil decreases mechanical performance due to the decrease of material density. No clear influence of fiber length on mechanical performance was found. The study of hygrothermal behaviour has shown that the sorption / desorption behaviour of earth-fiber material can be approximated from the results obtained from basic materials. In addition, it has been shown that the thermal conductivity evolution of earth-fiber material during drying is related to the shrinkage behaviour

La construction en terre crue constitue une alternative écologique aux bétons de ciment. Afin de promouvoir son usage, la présente étude s’intéresse à la mise au point de bétons de terre coulables permettant une mise en œuvre analogue à celle des bétons usuels. Dans cette optique, il est nécessaire de conférer au matériau une solidification à court terme (24 h) sans attendre son séchage, afin de permettre un débanchage rapide. La voie explorée pour répondre à cette problématique s’inspire de la technique du Gelcasting utilisée dans le domaine des céramiques techniques. Celle-ci s’appuie sur la gélification de polymères préalablement introduits dans une barbotine céramique pour induire une transition liquide-solide rapide et homogène. Une étude bibliographique complétée par des essais préliminaires a mené à la sélection de l’alginate, un polymère biosourcé non toxique et gélifiant à température ambiante sous l’action de cations multivalents tels que le calcium. Ce polymère s’est révélé très prometteur. Il a permis la réalisation d’éprouvettes de mortier démoulables 24 h après coulage et présentant une résistance en compression de l’ordre de 0,1 MPa, théoriquement suffisante à un mur de 3 m de haut pour tenir sous son propre poids. Une preuve de concept à l’échelle du béton a par ailleurs pu être réalisée sous la forme d’un muret de 40 cm de haut coulé et vibré à partir d’une consistance fluide puis décoffrable en 24 h. Les performances mécaniques et hygrothermiques du matériau sec ont été validées, et la présence du polymère gélifié pourrait améliorer la résistance à l’érosion. De premiers essais ont montré que le procédé pouvait être adaptable à des terres moins calcaires que celle utilisée tout au long de l’étude
Developing raw earthen construction is nowadays a major environmental issue, due to its low embodied energy compared to Portland cement. A solution would be to use a similar process as cement-based concrete, by casting into formworks. Nevertheless, this is limited by technical difficulties, owing to the fact that earth is not a hydraulic binder. In that perspective, this work focuses on inducing a liquid-solid transition to an earth suspension without waiting for drying, similar to cement-based materials. The approach explored to meet this challenge is inspired by the technique of Gelcasting used in the field of technical ceramics. This relies on the gelation of polymers previously introduced into a ceramic slurry to induce a rapid and homogeneous liquid-solid transition. A bibliographic study supplemented by preliminary tests led to the selection of alginate, a biosourced polymer that is non-toxic. Its gelation is allowed at ambient temperature, via addition of multivalent cations such as calcium ions. This polymer proved to be very promising. It made it possible to produce mortar specimens which could be unmoulded 24 hours after casting. A wet compressive strength close to 0.1 MPa could be reached, theoretically sufficient for a wall of 3 meters high to stand under its own weight. A proof of concept at the concrete scale was then realized as a low wall of 40 cm high casted and vibrated and then unmoulded in 24 hours. Mechanical and hygrothermal performances of the dry material were validated, and the presence of the gelled polymer could improve the resistance to erosion. Initial trials showed that the process could be adapted to low calcareous soils

The Zimbabwean construction industry is currently facing an enormous challenge to provide affordable housing to the urban dwelling low income earners. The urban population of Zimbabwe rose rapidly from 27% in 1992 to 42% by early 2002, and the urban housing backlog had risen to over 1,000,000 units by 2005. The use and cost of established construction materials, such as, cement, steel and brick are beyond the reach of most Zimbabweans. Thus, there is a pertinent need for a more affordable alternative. This study investigated the use of contemporary stabilised earth construction as an alternative solution to address the urban low cost housing crisis in Zimbabwe. Although experimental stabilised earth construction projects were a great success in Zimbabwe, this technology has not yet been widely adopted. Factors, such as benefits, drawbacks, inhibitors and drivers thus play an influencing role in the adoption of contemporary stabilised earth construction technologies. These factors must be understood as there are limited appropriate alternatives in Zimbabwe. A critical appraisal of the literature revealed that there is sparse structured research to date carried out to identify the factors that affect the widespread use of contemporary stabilised earth construction. Furthermore, the factors identified in the literature review lack empirical evidence and well structured research is essential to substantiate whether the factors are real or mere speculation. Earth construction is still largely representative of ancient architecture and unfortunately is still related to poor and primitive construction. Contemporary stabilised earth construction is still a relatively new technology in Zimbabwe; therefore, construction professionals will play a pivotal and significant role in the widespread adoption of this technology. Therefore, this study developed a holistic understanding of the factors influencing the adoption of stabilised earth by construction professionals in order to address the low cost housing crisis in Zimbabwe. The aim of this study resided in the interpretivism philosophy; the factors found in the literature review are directly and indirectly related to complex social phenomena. A critical review and appraisal of the literature, combined with findings of the Delphi technique produced a list of generic factors which formed an initial conceptual framework. A series of in-depth interviews were subsequently conducted with construction professionals to validate the generic list of factors and refined the conceptual framework in the context of Zimbabwe.

Surgindo da necessidade de criar novos métodos construtivos mais sustentáveis, com a uti-lização de materiais ecológicos, é cada vez mais procurada a construção tradicional em terra. Este método é conhecido como uma das mais antigas técnicas de construção, genero-samente utilizada ao longo da história, até ao decaimento da sua utilização, aquando do aparecimento de técnicas atualmente conhecidas como convencionais. Esta dissertação pretende dar a conhecer outras soluções de construção em terra, onde são elaborados blocos de terra compactada, com a incorporação de diferentes adições, com o objetivo de melhorar as propriedades mecânicas e físicas dos mesmos. Os blocos foram avaliados experimentalmente, permitindo verificar a evolução da resistência mecânica, e a sua capacidade de absorção de água, tornando-se possível compreender o comportamento e adequabilidade da alvenaria de blocos de terra compactada; Abstract: The need to create more sustainable constructive methods with the utilization of ecological materials, made the compressed earth blocks construction more pursued again. This method is known for being one of the eldest and commonly used techniques in construction, however evolution of the construtive technologies caused a decay on the traditional techniques, as the compressed earth blocks. This dissertation intends to show new compositions of compressed earth blocks construction, where are elaborated compressed earth blocks, with the incorporation of different additions with the objective of improving the mechanical and physical properties of the compressed earth blocks. The blocks were evaluated experimentally, allowing to verify the evolution of the mechanical resistance and the capacity of water absorption of the blocks, to understand the behaviour and the masonry suitability of the compressed earth blocks.

Cette étude vise à contribuer au développement d’un produit de construction à faible impact environnemental utilisant la terre crue. Pour cela, le comportement hygro-mécanique de la terre crue compressée à haute pression par une technique novatrice mise au point dans ce projet a été caractérisé. De plus, plusieurs méthodes de stabilisation ont été évaluées afin d’améliorer la durabilité de ce matériau, notamment vis-à-vis de l’érosion induite par l’eau. Une vaste campagne d’essais expérimentaux a été menée sur ces matériaux stabilisés ou non, à deux échelles différentes : les caractérisations des échantillons cylindriques (petite échelle) ont tout d’abord permis de sélectionner la formulation optimale. Par la suite, les tests menés à grande échelle sur les briques de terre compressée ont contribué à développer un produit pour la construction. Une nouvelle technique de fabrication basée sur l’application d’une contrainte de compactage très élevée (hyper-compactage) a été mise au point. Son objectif principal est d’augmenter la densité du matériau afin d’améliorer ses performances mécaniques. Les échantillons compactés par la méthode proposée présentent une densité sèche d’environ 2320 kg/m3, ce qui représente la valeur la plus élevée jamais enregistrée dans la littérature pour une terre non stabilisée. Les effets de la contrainte de compactage sur la microstructure du matériau ont été analysés par intrusion au mercure et adsorption d’azote liquide. Les résultats montrent que l’augmentation de la contrainte de compactage réduit la porosité du matériau, majoritairement les grands pores inter-agrégats. Cependant, le compactage mécanique influence peu les petits pores intra-agrégats. L'approfondissement de la caractérisation des propriétés microstructurales des échantillons stabilisés constitue un développement intéressant de ce travail. La résistance et la rigidité des échantillons non stabilisés et stabilisés ont été mesurées. Ces essais mécaniques confirment que la méthode d'hyper-compactage permet d’améliorer grandement la réponse mécanique du matériau par rapport aux techniques de fabrication existantes. Ainsi, les briques réalisées présentent une résistance en compression comparable à celle-là des matériaux traditionnels de construction (e.g. terre stabilisée et briques en terre cuite). Pour compléter cette étude, des essais mécaniques à l’échelle paroi sont à mener. Le comportement hygroscopique des échantillons stabilisés et non stabilisés a été analysé par la mesure du paramètre MBV (i.e. Moisture Buffering Value), qui traduit la capacité d’échange avec la vapeur d’eau. Il s'avère que la terre non stabilisée possède une excellente capacité à absorber et relarguer l’humidité ambiante. Cette capacité est, par contre, réduite pour les échantillons stabilisés testés dans le cadre de cette étude. La caractérisation du comportement thermique de la terre compressée à haute pression ainsi que l’analyse expérimentale des transferts thermo-hygroscopiques à l’échelle paroi représentent deux compléments d'étude afin de préciser le comportement hygroscopique d'un mur à base de terre crue. Enfin, la durabilité par rapport à l’érosion induite par l’eau des briques stabilisées et non stabilisées a été estimée à travers les essais d’immersion, de succion et de contact qui sont prévus par la norme DIN 18945 (2013). Les briques stabilisées montrent une meilleure résistance à l’eau par rapport aux briques non stabilisées. Toutefois, des études supplémentaires sont nécessaires pour améliorer les méthodes de stabilisation garantissant la durabilité dans le cas d'applications structurelles exposées aux intempéries, tout en maintenant de bonnes performances hygro-mécaniques et un faible impact environnemental
The present work explores the hygro-mechanical behaviour of a raw earth material and investigates different stabilisation techniques to improve the durability of the material against water erosion. An extensive campaign of laboratory tests was performed on both unstabilised and stabilised materials at two different scales: small cylindrical samples and large bricks. An innovative manufacturing method based on the application of very high compaction pressures (hypercompaction) was proposed. Also, the compaction load was maintained constant for a sufficient period of time to allow soil consolidation. The main objective was to increase material density, thus improving mechanical performance. Samples compacted with the proposed method exhibited a dry density of about 2320 kg/m3, which is the highest value registered in the literature for an unstabilised earthen material. The effect of the compaction pressure on the material fabric was assessed by means of mercury intrusion porosimetry and nitrogen adsorption tests. Results showed that the increase of compaction pressure reduced material porosity with major effects on large inter-aggregate pores. On the contrary, small intra-aggregate pores were not affected by the mechanical compaction. Mechanical tests were then performed to measure stiffness and strength of both unstabilised and stabilised samples. These tests demonstrated that hypercompaction can largely improve the mechanical response of the material over conventional manufacturing methods. Hypercompacted bricks showed a compressive strength comparable with that of traditional building materials, such as stabilised compressed earth and fired bricks. The hygroscopic behaviour of both unstabilised and stabilised samples was investigated. The capacity of the samples to absorb/release water vapour was assessed by measuring their moisture buffering value (MBV). Results showed that unstabilised earth has an excellent capacity to buffer ambient humidity. This capacity was significantly reduced by the different stabilisation techniques tested in the present work. Finally, the durability against water erosion of both unstabilised and stabilised bricks was assessed by performing different tests prescribed by the norm DIN 18945 (2013). Stabilised bricks exhibited a higher resistance against water erosion compared to unstabilised bricks. Still, these materials cannot be adopted for structural applications exposed to natural weathering as indicated by the norm DIN 18945 (2013). Therefore, further investigation is required to identify novel stabilisation methods that can balance the needs of sustainability, durability, moisture buffering and mechanical performance

Proposta: o setor da construção civil é responsável por grande parte do consumo de energia e recursos e da geração de resíduos, provocando impactos significativos sobre o meio ambiente. Algumas alternativas para se construir, reduzindo os impactos, envolvem o uso de materiais renováveis, como a palha, e de materiais minimamente processados, como a terra. Contudo, estes materiais pouco são referidos nos sistemas de classificação de edifícios ambientalmente amigáveis. Muitos edifícios, rotulados como sustentáveis, apenas refletem esforços para reduzir a energia incorporada e são, em muitos outros aspectos, convencionais. Objetivo: considerando a lacuna identificada, o objetivo deste trabalho é realizar uma avaliação de sustentabilidade de uma habitação de interesse social, construída no meio rural, com fardos de palha, terra e cobertura verde. Metodologia de pesquisa: a estratégia geral de pesquisa utilizada foi o levantamento de um caso. A definição dos critérios de avaliação foi embasada naqueles tradicionalmente incluídos em métodos existentes, porém as formas de caracterização foram adaptadas a dados e procedimentos acessíveis ao contexto nacional. Além de critérios ambientais, foram incluídos outros, econômicos e sociais, devido à importância de uma abordagem pluridimensional. A apresentação dos resultados dos critérios ambientais em três escalas (da edificação, dos subsistemas e dos materiais) permite identificar os subsistemas e materiais com maior potencial de impactos, explicitando os pontos fracos da habitação, além de facilitar a comparação, total ou parcial, com os resultados obtidos em pesquisas semelhantes. Resultados: verificou-se a incorporação de grande quantidade de materiais que produzem emissões tóxicas, além de apresentarem um alto consumo energético para transporte. Em contrapartida, devido à utilização, predominante, de recursos pouco processados, identificou-se um baixo dispêndio de energia para manufatura de materiais e um potencial de reaproveitamento satisfatório. Os custos iniciais da edificação são baixos, em relação a habitações de interesse social construídas com materiais convencionais, e medianos, em relação àquelas que empregam materiais não convencionais. Em termos sociais, verificou-se que as soluções adotadas são adequadas para a autoconstrução e para o resgate da capacidade de trabalho em mutirão, e que o projeto não atende requisitos mínimos de acessibilidade.
Proposal: the construction industry is responsible for a large consumption of energy and resources, and produces a large amount of wastes, determining considerable environmental impacts. Some alternatives to build in a way to reduce environmental impacts include the use of renewable materials and the use of materials which require minimum amount of processing, such as straw and earth. Nevertheless, these materials are hardly ever referred to in green building classification systems. Many buildings classified as environmentally friendly or green may simply reflect efforts to reduce the embodied energy and are, in most other aspects, conventional. Objective: considering the identified gap, this work’s aim is to evaluate a low-income rural house, built with straw bales, earth and a green roof. Methods: the assessment criteria definition was based on those traditionally included in existent methods, but adapted in accordance to national acessible data and proceedings. Besides environmental criteria, others like social and economics, were included. The results presentation in three analysis scales (of the construction, as a whole, of the subsystems and of the materials) allows the identification of the potencially most impacting materials and subsystems, expliciting the dwelling weak points, and facilitates total or partial comparision with other similar researchs results. Findings: a large number of materials that emit toxic gases, besides having a high energy consumption for materials transport, was identified. However, due to the predominant use of materials with a minimum processing, a low energy consumption for materials production and a sactisfatory reuse potential was identified. The dwelling’s initial costs are low, if compared to low-income houses built with conventional materials, becoming average, in regard to those built with non-convetional materials. In social terms, it was verified that the construction solutions are suitable to self-building and to rescue the ability of working cooperatively, and that the dwelling’s design does not supply the minimum requirement for spatial acessibility.

Society is on an unsustainable course, predicted to reach a tipping point where greenhouse gas emissions cause irreversible consequences. The cement industry is estimated to be responsible for 7% of the global CO2 emissions, but remains an essential part of building safe and affordable infrastructure for an urbanising and growing population. It is imperative that the industry urgently transitions to a more sustainable pathway. As a key stakeholder, the construction industry could play a role in this. This paper looks at the sustainability of the cement production process from a systems perspective and how the construction industry can help leverage change, using the FSSD and Meadows’ (1999) leverage points as a framework. An analysis of the cement production method against the misalignments with the FSSD Sustainability Principles was performed, as well as a document content analysis of the WBCSD 2018 roadmap for the cement industry. We also conducted 9 semi-structured interviews with experts in the cement and construction industry. Results showed that while CO2 emissions are the biggest challenge for the industry, change will not happen fast enough while a number of structural barriers prevent this. These barriers, their potential solutions and leverage points within the construction industry are discussed.