No âmbito da Arquitetura e Construção com terra, a produção de habitação social rural, nos últimos 30 anos, tem começado a se posicionar como uma solução contemporânea e viável ao problema da necessidade habitacional no mundo. O adobe, apesar de ser uma das técnicas e tecnologias mais antigas, tem sido pouco praticado no Brasil para a construção de obras novas, em contextos como o da habitação social rural. No entanto, dentre outras iniciativas destacam-se as do Grupo de Pesquisa em Habitação e Sustentabilidade HABIS, vinculado ao Instituto de Arquitetura da Universidade de São Paulo IAU-USP, o qual promoveu a implementação do adobe para a produção de três habitações em dois Assentamentos Rurais, ambos localizados no estado de São Paulo. Este trabalho teve como objetivo investigar o processo construtivo em adobe de três habitações, sendo um no Assentamento Rural Pirituba II e dois construídos no Assentamento Rural Sepé Tiaraju, buscando identificar condições possivelmente relacionadas à conservação de duas destas casas e ao colapso da outra. O trabalho se desenvolveu por meio da pesquisa ação e o estudo de múltiplos casos, tendo como principais resultados a definição de etapas, variáveis e características do processo construtivo dos três casos, a partir de: a) um estudo independente, encontrando razões que levaram ao colapso de uma casa e aspectos das etapas construtivas que possibilitaram às outras duas ficarem em pé, em função do Assentamento Rural de que fazem parte; b) um estudo grupal, encontrando, por meio da criação de uma ferramenta de categorização, semelhanças, diferenças, problemas e avanços das etapas construtivas das habitações estudadas; c) uma análise integral considerando os seguintes aspectos do processo construtivo das habitações estudadas: projeto geral no âmbito do qual foram desenvolvidos, atores, tradição construtiva e o meio natural e climático. Com o estudo desenvolvido foi possível realizar um breve panorama, sobretudo internacional, de 16 exemplos similares ao objeto empírico desta pesquisa. / The production of rural housing with earthen construction techniques, in the last 30 years, has represented a modern and viable solution to the problem of housing need in the world. The adobe, despite being one of the oldest earthen techniques, has been little used in Brazil for the construction of new houses, especially as rural social housing. However, among other initiatives, stands out the experience of the Research Group on Housing and Sustainability - HABIS, linked to the Institute of Architecture and Urbanism at the University of São Paulo (IAU-USP São Carlos), which promoted the implementation of adobe on the production of three houses in two rural settlements, both located in the state of São Paulo. This work aimed to investigate the construction process of these three adobe houses, one in the Rural Settlement Pirituba II and two built in Rural Settlement Sepé Tiaraju, and the conditions possibly related to the conservation of two houses and the collapse of another. The work was developed through the action research methodology and the study of multiple cases, and the main results was the definition of the steps, variables and characteristics of the construction process of the three cases, achieved from: a) an independent study, finding reasons that led to the collapse of a house and aspects of constructive steps that enabled the other two to be concluded, according to each Rural Settlement; b) a group of studies, which showed similarities, differences, problems and progress of the construction stages of the studied houses, through the creation of a tool for categorization; c) a comprehensive analysis considering the following aspects of the construction process of the studied houses: general project under which they were developed, actors, building tradition and the natural environment and climate. With this study it was also possible to conduct a brief overview, especially international, of 16 examples, similar to the empirical object of this research.

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.

No âmbito da Arquitetura e Construção com terra, a produção de habitação social rural, nos últimos 30 anos, tem começado a se posicionar como uma solução contemporânea e viável ao problema da necessidade habitacional no mundo. O adobe, apesar de ser uma das técnicas e tecnologias mais antigas, tem sido pouco praticado no Brasil para a construção de obras novas, em contextos como o da habitação social rural. No entanto, dentre outras iniciativas destacam-se as do Grupo de Pesquisa em Habitação e Sustentabilidade HABIS, vinculado ao Instituto de Arquitetura da Universidade de São Paulo IAU-USP, o qual promoveu a implementação do adobe para a produção de três habitações em dois Assentamentos Rurais, ambos localizados no estado de São Paulo. Este trabalho teve como objetivo investigar o processo construtivo em adobe de três habitações, sendo um no Assentamento Rural Pirituba II e dois construídos no Assentamento Rural Sepé Tiaraju, buscando identificar condições possivelmente relacionadas à conservação de duas destas casas e ao colapso da outra. O trabalho se desenvolveu por meio da pesquisa ação e o estudo de múltiplos casos, tendo como principais resultados a definição de etapas, variáveis e características do processo construtivo dos três casos, a partir de: a) um estudo independente, encontrando razões que levaram ao colapso de uma casa e aspectos das etapas construtivas que possibilitaram às outras duas ficarem em pé, em função do Assentamento Rural de que fazem parte; b) um estudo grupal, encontrando, por meio da criação de uma ferramenta de categorização, semelhanças, diferenças, problemas e avanços das etapas construtivas das habitações estudadas; c) uma análise integral considerando os seguintes aspectos do processo construtivo das habitações estudadas: projeto geral no âmbito do qual foram desenvolvidos, atores, tradição construtiva e o meio natural e climático. Com o estudo desenvolvido foi possível realizar um breve panorama, sobretudo internacional, de 16 exemplos similares ao objeto empírico desta pesquisa. / The production of rural housing with earthen construction techniques, in the last 30 years, has represented a modern and viable solution to the problem of housing need in the world. The adobe, despite being one of the oldest earthen techniques, has been little used in Brazil for the construction of new houses, especially as rural social housing. However, among other initiatives, stands out the experience of the Research Group on Housing and Sustainability - HABIS, linked to the Institute of Architecture and Urbanism at the University of São Paulo (IAU-USP São Carlos), which promoted the implementation of adobe on the production of three houses in two rural settlements, both located in the state of São Paulo. This work aimed to investigate the construction process of these three adobe houses, one in the Rural Settlement Pirituba II and two built in Rural Settlement Sepé Tiaraju, and the conditions possibly related to the conservation of two houses and the collapse of another. The work was developed through the action research methodology and the study of multiple cases, and the main results was the definition of the steps, variables and characteristics of the construction process of the three cases, achieved from: a) an independent study, finding reasons that led to the collapse of a house and aspects of constructive steps that enabled the other two to be concluded, according to each Rural Settlement; b) a group of studies, which showed similarities, differences, problems and progress of the construction stages of the studied houses, through the creation of a tool for categorization; c) a comprehensive analysis considering the following aspects of the construction process of the studied houses: general project under which they were developed, actors, building tradition and the natural environment and climate. With this study it was also possible to conduct a brief overview, especially international, of 16 examples, similar to the empirical object of this research.

No meio da Arquitetura e Construção com Terra, aspectos positivos relacionados à diminuição da degradação ao meio ambiente e à promoção de resultados benéficos ao desempenho das edificações são bastante difundidos entre seus simpatizantes e especialistas. No entanto, um tema que parece ser pouco explorado é o canteiro de produção desta arquitetura e as condições de atuação dos trabalhadores. O trabalho frequentemente é pesado, a quantidade de esforço físico necessária para a execução das diversas tarefas é alta, podendo ser excessiva e até degradante se as condições de operação no canteiro não estiverem devidamente equacionadas. Dada a altíssima frequência das situações de intensa exploração no setor da construção civil no Brasil e considerando o caráter fortemente artesanal da construção com terra, faz-se necessário conhecer como ocorre a produção desta arquitetura e se a mecanização parcial destes canteiros repercute em melhores condições de trabalho aos operários envolvidos. A partir de informações coletadas em entrevistas com trabalhadores, engenheiros e arquitetos envolvidos nos canteiros de produção da arquitetura e construção com terra, visitas a canteiros de produção desta arquitetura, além de informação complementar apresentada sobre estes canteiros na bibliografia especializada, é construída uma avaliação estruturada por uma análise qualitativa e crítica fundamentada na teoria crítica da arquitetura. A evolução do canteiro de obras passa pelo remanejamento e pela eliminação de algumas tarefas. A mecanização parcial permite que operários possam se deslocar, ou ser deslocados, a ocupações menos degradantes. No entanto, a inclusão de máquinas não ocorre primordialmente por este motivo, ela passa a ser considerada pois, ao confrontar o custo da mão de obra com o investimento em maquinário, este último começa a se revelar como financeiramente viável no Brasil. Portanto, a mecanização parcial que ocorre até agora não pretende ir além de um aumento na produtividade. Mesmo com a incorporação de algumas máquinas, parte dos trabalhadores seguem realizando outras tarefas bastante pesadas, muitas delas exaustivamente repetitivas. / Among Earthen Architectures supporters and experts, positive aspects related to low environmental degradation and to the promotion of better results to the building performance are well known. However, a subject that seems to be little explored is the construction site of this architecture and the conditions of operation of workers. The labor is often heavy and a high amount of physical exertion is required. If operating conditions at the construction site are not adequately addressed, the demands may be excessive and even degrading. Given the high frequency of intense exploration in the construction sector in Brazil, also considering the strong artisanal character of earthen construction, it is necessary to know how production takes place in this architecture and if the partial mechanization of these sites improves working conditions. Based on information collected in interviews with workers, engineers and architects involved in earth construction production sites, visits to these architecture building sites, in addition to supplementary information provided by the relevant literature, this paper will present an evaluation structured by a critical and qualitative analysis. This review will be based on the Critical Theory of Architecture. The evolution of the construction site occurs by the relocation and the elimination of some tasks. The partial mechanization allows workers to move, or to be moved, to less degrading jobs. However, in Brazil this is not the reason of the inclusion of machines in the processes, the major purpose is to increase productivity. Even with the incorporation of some machinery, the workers continue performing degrading jobs caused by high physical exertion required or exhaustively repetitive tasks.

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.

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.

Rammed earth is one of the earliest building materials used for structural walls. Stabilised rammed earth is a variant of traditional or pure rammed earth that involves addition of a small amount of cement to improve strength and durability. Rammed earth buildings experience in-plane shear forces as well as flexural stresses due to out-of-plane bending especially during earthquakes. The thesis attempts to examine the behaviour of cement stabilised rammed earth wall elements and building models subjected to lateral loads. A brief introduction to rammed earth construction followed by a review of literature on rammed earth and details of the existing codes of practice on rammed earth is provided in Chapter 1. Chapter 2 deals with the flexural strength, modulus of rupture, stress-strain relationships and free vibration characteristics of cement stabilised rammed earth (CSRE) in greater detail. Properties of raw materials used in the experimental investigations followed by a detailed description of the experimental programme, method of preparation of various types of specimens and their testing procedures are provided. Flexure strength and modulus of rupture were determined in both the orthogonal directions. Influence of (a) thickness of the specimen, (b) direction of compacted layers with respect to the flexural tension developed and (c) effect of cement slurry coating between the compacted layers on the flexural strength of CSRE were examined. The investigations show that flexure strength increases with the increase in the specimen thickness and a coat cement slurry on the compacted layers leads to improvement in flexure strength. The flexural strength parallel to compacted layers is higher when compared to flexure strength perpendicular to compacted layers. Stress-strain relationships show that the initial tangent modulus of CSRE in saturated condition is about 60% of that in dry condition. Damping ratio as obtained from the free vibration studies is found to be 0.022 in the two orthogonal directions. Dynamic characteristics of CSRE building models are presented in Chapter 3. A simple alternative to shake table called as “Shock Table” was used in the present investigation for providing base motion to the building model. A half-scale CSRE building model with R.C lintels only above door and window openings (with no earthquake resistant features) was constructed on the Shock Table. The wall thickness of the building model was 100 mm. Procedure for construction, instrumentation and testing of the CSRE building model is presented. Responses measured and damages observed are discussed in detail. Finite element (FE) analyses were performed on six different building models with different earthquake resistant features using commercially available FE software (NISA V17). Both free vibration and forced vibration analyses were performed. Natural frequencies and forced vibration responses (acceleration) of building model (BM1) obtained from experiment and FE analysis were compared. Responses (free vibration and forced vibration) of other five building models were predicted using FE analysis. Crack patterns of the building models with roof and without roof are compared. The thesis ends with a summary of the results and concluding remarks in Chapter 4.

Rammed earth is a technique of forming in-situ structural wall elements using rigid formwork. Advantages of rammed earth walls include flexibility in plan form, scope for adjusting strength and wall thickness, variety of textural finishes, lower embodied carbon and energy, etc. There is a growing interest in the construction of rammed earth buildings in the recent past. Well focused comprehensive studies in understanding the structural performance of rammed earth structures are scanty. Clear-cut guidelines on selecting soil grading and soil characteristics, assessing strength of rammed earth walls, density strength relationships, limits on shrinkage, standardised testing procedures, behaviour of rammed earth walls under in-plane and out of plane loads, etc are the areas needing attention. The thesis attempts to address some of these aspects of cement stabilized rammed earth for structural walls. Brief history and developments in rammed earth construction with illustrations of rammed earth buildings are presented. A review of the literature on rammed earth has been provided under two categories: (a) Unstabilised or pure rammed earth and (b) stabilised rammed earth. Review of the existing codes of practice on rammed earth has also been included. Summary of the literature on rammed earth along with points requiring attention for further R&D are discussed. Objectives and scope of the thesis are listed. The thesis deals with an extensive experimentation on cement stabilised rammed earth (CSRE) specimens and walls. Four varieties of specimens (cylindrical, prisms, wallettes and full scale walls) were used in the experiments. A natural soil and its reconstituted variants were used in the experimental work. Details of the experimental programme, characteristics of raw materials used in the experimental investigations, methods of preparing different types of specimens and their testing procedures are discussed in detail. Influence of soil grading, cement content, moulding water content, density and delayed compaction on compaction characteristics and strength of cement stabilised soil mixes were examined. Five different soil gradings with clay content ranging between 9 and 31.6% and three cement contents (5%, 8% and 12%) were considered. Effect of delayed compaction (time lag) on compaction characteristics and compressive strength of cement stabilised soils was examined by monitoring the results up to 10 hours of time lag. Influence of moulding water content and density on compressive strength and water absorption of cement stabilised soils was examined considering for a range of densities and water contents. The results indicate that (a) there is a considerable difference between dry and wet compressive strength of CSRE prisms, and the strength decreases as the moisture content at the time of testing increases, (b) wet strength is less than that of dry strength and the ratio between wet to dry strength depends upon the clay fraction of soil mix and cement content, (c) saturated moisture content depends upon the cement content and the clay content of the soil mix, (d) optimum clay percentage yielding maximum compressive strength is about 16%, (e) compressive strength of compacted cement stabilised soil increases with increase in density irrespective of cement content and moulding moisture content, and the strength increases by 300% for 20% increase in density from 15.70 kN/m3, (f) compressive strength of rammed earth is one - third higher than that of rammed earth brick masonry and (g) density decreases with increase in time lag and there is 50% decrease in strength with 10 hour time lag. Stress-strain relationships and elastic properties of cement stabilised rammed earth are essential for the analysis of CSRE structural elements and understanding the structural behaviour of CSRE walls. Influence of soil composition, density, cement content and moisture on stress-strain relationships of CSRE was studied. Three different densities (15.7 – 19.62 kN/m3) and three cement percentages (5%, 8% and 12% by weight) were considered for CSRE. Stress-strain characteristics of CSRE and rammed earth brick masonry were compared. The results reveal that (a) in dry condition the post peak response shows considerable deformation (strain hardening type behaviour) beyond the peak stress and ultimate strain values at failure (dry state) are as high as 3.5%, which is unusual for brittle materials, (b) modulus for CSRE increases with increase in density as well as cement content and there is 1 to 3 times increase as the cement content changes from 5% to 12%. Similarly the modulus increases by 2.5 to 5 times as the dry density increases from 15.7 to 19.62 kN/m3 and (c) the modulus of CSRE and masonry in dry state are nearly equal, whereas in wet state masonry has 20% less modulus. Compressive strength and behavior of storey height CSRE walls subjected to concentric compression was studied. The results of the wall strength were compared with those of wallette and prism strengths. The wall strength decreases with increase in slenderness ratio. There is nearly 30% reduction in strength as the height to thickness ratio increases from 4.65 to 19.74. It was attempted to calculate the ultimate compressive strength of CSRE walls using the tangent modulus theory. At higher slenderness ratios, there is a close agreement between the experimental and predicted values. The storey height walls show lateral deflections as the load approaches failure. The walls did not show visible buckling and the shear failure patterns indicate material failure. The shear failures noticed in the storey height walls resemble the shear failures of short height wallette specimens. The thesis ends with a summary of the results with concluding remarks in the last chapter.

The theme of this thesis are surfaces made of unburned earth and used in architecture. The thesis focuses mainly on detailed mapping and analysis of the present state. However, it does not omit the historical roots of earthen surfaces in the area of today`s Czech Republic. In these roots it looks for connections with contemporary practice. The thesis deduces conclusions from thorough evaluation of the present situation – it shows perspectives and possible drift of the future development of earthen surfaces. Both in the field of architecture and in areas broadening this field.