Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: A major challenge for our society is the protection of the environment. Some of the important issues are the reduction in the consumption of energy and natural raw materials, as well as the increase in consumption of waste materials. At present these topics are getting considerable attention as part of sustainable development programs. The use of recycled concrete aggregates (RCA) from construction and demolition waste (C&DW) in construction, as alternative to virgin (natural) aggregates, has strong potential. The use of RCA preserves natural resources and reduces the space required for the disposal of RCA in landfill. It is estimated that 16 thousand million (billion) tons of concrete (and 25 billion tons of aggregate) were used in 2010. Of the 2-3 billion tons of C&DW which are produced worldwide every year, South Africa contributes 5-8 million tons. This amount is increasing rapidly every year. Significant amounts of demolished concrete find their way to landfill sites. A solution for excess waste production would be the utilization of RCA together with an improvement in the final quality of RCA. It might be an important breakthrough for our society in our attempt towards sustainable development. Worldwide, infrastructure has developed a great deal since the beginning of the twentieth century. Much of the core infrastructure, including roads, bridges, water systems, and sewers, was put in place during the first half of that century. Aggregates used as construction materials, as for instance in road pavements, or as an ingredient of concrete, are important components of infrastructure. Urbanization involves reduction of natural aggregate (NA) resources, but environmental concern and the rising cost of NA is the reason that recycled materials from different sources (like roads, buildings) are being used more and more with NA in new construction work. Environmental awareness is increasing in every country for many reasons and sustainable development is demanded of all industries, including the building and construction industries. By nature, construction is not environmentally friendly, and sometimes it also changes the behavior of nature in many ways. Recycling is one of the most important ways to minimize the waste that comes from different sources, thereby avoiding repetition of, and additional environmentally hazardous practices. It may create new wealth by diminished transport and production costs and sparing of landfill site space and cost. It has the potential to extend the life of natural resources by adding a source of material, thereby reducing environmental interference and impacting on nearby construction sites, all of which improve sustainability of our natural resources. Much research on the uses of RCA has been performed during the last few decades. In fact, most of them showed that the strength class of recycled aggregate concrete (RAC) is adequate for use as structural concrete although volume changes in and durability performance of RAC in comparison with natural aggregate concrete (NAC) are still being debated and researched. Some researchers found that the durability of concrete produced with RCA is inferior, but others have found it to be sufficient for use in structural concrete. The fact that an insufficient number of studies have been carried out on the durability aspects, has limited the use of RCA as material for road construction. The aim of this study is to determine the suitability of using the RCA in structural concrete based on its strength, stiffness, dimensional stability and durability. Three types of RCA designated RCA1, RCA2 and RCA3 in this study, were taken from three different sources. These materials were tested to establish their mechanical characteristics for use as aggregates in concrete. In the experimental program RCA was used at replacement percentages of 0%, 30% and 100% to (partially) replace NA in order to study its suitability as aggregate in concrete, and to what level of NA replacement its behavior is satisfactory for structural application. A single compressive strength class was studied, due to the limited time. By performing tests of compressive strength, Young’s modulus, creep, shrinkage, and durability performance, it has been found that selected types of RCA show a real possibility for use as aggregate in concrete. When concrete with a RCA replacement of 100% was compared with NAC100% there was a small decline in strength, but when concrete with a RCA replacement of 30% was compared with NAC100% the results showed almost equal strength. A slight reduction in durability performance was found for RAC30% compared with NAC100%, but similar dimensional stability performance in terms of specific creep and drying shrinkage was measured for RAC30% and NAC100%. Based on detailed experimental results obtained from this thesis project, a number of recommendations have therefore been made for RCA characteristics that will be used in concrete mixes also taking into account the quality of RCA. Some suggestions are proposed based on the mechanical properties and durability of the concrete. In the final conclusions, future studies on RCA properties are suggested, which would help us in increasing our knowledge in the application of RCA, and which may lead to the optimal production of structural concrete in a sustainable way. In general the use of RCA in concrete is feasible and good quality RCA at 30% replacement of NA may be suitable for any kind of structural concrete. / AFRIKAANSE OPSOMMING: ‘n Groot uitdaging vir ons samelewing is die beskerming van die omgewing. Van die belangrike sake is die vermindering in die verbruik van energie en van natuurlike, onverwerkte materiale asook die groter verbruik van afvalmateriaal. Hierdie onderwerpe kry tans aanienlike aandag as deel van volhoubare ontwikkelingsprogramme. Die gebruik van betonaggregate, herwin vanaf konstruksie-en slopingsafval, en gebruik in konstruksie as alternatief vir ongebruikte natuurlike aggregate, het goeie potensiaal. Die gebruik van herwonne aggregaat beskerm natuurlike hulpbronne en verminder die oppervlakte en volume wat nodig is vir die weggooi daarvan op stortingsterreine. Dit is beraam dat 16 duisend miljoen (biljoen) ton beton (en ongeveer 25 biljoen ton aggregaat) gedurende 2010 gebruik is. Van die 2-3 biljoen ton konstruksie-en slopingsafval wat jaarliks wêreldwyd gegenereer word, dra Suid Afrika 5-8 miljoen ton by. Hierdie hoeveelheid word elke jaar vinnig meer. Beduidende hoeveelhede gesloopte beton beland elke jaar op stortingsterreine. ‘n Oplossing vir die probleem van te veel atval generering sou wees die gebruik daarvan as herwonne beton-aggregaat, sou saamval met ‘n verbetering in die uiteindelike kwaliteit van herwonne aggregaat beton. Dit kan dalk ‘n belangrike deurbraak wees vir ons samelewing in ons strewe na volhoubare ontwikkeling. Infrastruktuur het wêreldwyd baie ontwikkel sedert die begin van die twintigste eeu. Baie van die kerninfrastruktuur insluitende paaie, brue, waterstelsels en riole is gebou tydens die eerste helfte van daardie eeu. Aggregaat gebruik as konstruksiemateriaal, byvoorbeeld in padplaveisels of as’n bestanddeel van beton, is ‘n belangrike deel van infrastruktuur. Verstedeliking veroorsaak vermindering van natuurlike aggregaat hulpbronne maar besorgdheid oor die omgewing en die stygende koste van nataurlike aggregaat veroorsaak dat herwonne materiale vanaf verskillende bronne (soos paaie en geboue) meer en meer aanvullend tot natuurlike aggregaat in nuwe konstruksiewerke gebruik word. Omgewingsbewustheid is om baie redes aan die toeneem in elke land en volhoubare ontwikkeling word vereis van alle industrieë. Herwinning is een van die hoofmaniere om afval vanaf verskillende bronne tot ‘n minimum te beperk. Dit skep nuwe rykdom, verminder vervoeren vervaardigingskoste en benut afval wat anders op stortingsterreine verlore sou gegaan het. Dit het die potensiaal om die lewensduur van natuurlike hulpbronne te verleng deur ‘n materiaalbron by te voeg, deur inmenging in die omgewing te verminder, wat almal bevorderlik is om volhoubare benutting van ons hulpbronne te verbeter. Baie navorsing is gedurende die laaste paar dekades gedoen aangaande die gebruik van herwonne aggregaat. Die meeste van die navorsing het inderdaad getoon dat die sterkte van beton met herwonne aggregaat genoegsaam is vir gebruik as struktuurbeton alhoewel daar wel debatte gevoer word oor die volumeveranderings en duursaamheid prestasie van herwonne aggregaat beton vergeleke met dié van natuurlike aggregaat beton. Sommige navorsers het bevind dat die duursaamheid van beton wat met herwonne aggregaat gemaak is, minderwaardig is maar andere het bevind dat dit voldoen aan die vereistes van struktuurbeton. Slegs die feit dat daar onvoldoende toetse rakende duursaamheid gedoen is, het die gebruik van herwonne beton aggregaat beperk tot padboumateriaal. Die doel van hierdie navorsing is om te bepaal wat die geskiktheid van herwonne betonaggregaat is vir gebruik in struktuurbeton, gegrond op sterkte en duursaamheid. Drie soorte herwonne betonaggregaat wat in hierdie studie as RCA1, RCA2 and RCA3 aangedui word, is elk vanaf ‘n ander bron geneem. Hierdie materiale is getoets om hulle meganiese kenmerke vas te stel vir gebruik as aggregaat in beton. In die eksperimentele program is 0%, 30% en 100% herwonne betonaggregaat gebruik om natuurlike aggregaat gedeeltelik be vervang om sodoende die geskiktheid as betonaggregaat te bestudeer. Deur toetse uit te voer op ‘n beperkte sterkte-klas beton, soos toetse vir die bepaling van druksterkte, Young’s modulus, kruip, krimp en duursaamheid, is daar bevind dat sekere soorte herwonne betonaggregaat heel moontlik gebruik kan word in struktuurbeton. Toe beton met 100% herwonne betonaggregaat vergelyk is met beton met 100% natuurlike aggregaat, is bevind dat daar ‘n klein vermindering in sterkte was, maar waar beton met 30% herwonne betonaggregaat vergelyk is met beton met 100% natuurlike aggregaat, het die resultate byna dieselfde sterkte getoon. Dus op grond van gedetaileerde eksperimentele resultate is ‘n aantal aanbevelings gemaak vir kenmerke van herwonne betonaggregaat wat in betonmengsels gebruik sal word met inagneming van die gehalte van herwonne betonaggregaat. Die resultate vir beton met 30% en 100% herwonne betonaggregaat word vergelyk met beton wat slegs natuurlike aggregaat bevat. Sekere voorstelle gegrond op meganiese eienskappe en duursaamheid van die beton word gemaak, asook aanbevelings vir toekomstige studies van herwonne betonaggregaat wat ons sal help om ons kennis vir die toepassing van herwonne betonaggregaat uit te brei.

Ground Improvement using vibro stone columns is gaining increasing acceptance on marginal soft clay sites as a sustainable foundation solution, particularly for lightly loaded low-rise structures supported by shallow, narrow footings. Most experience in this context however has been with widespread loads and use of the wet top-feed stone column technique, which has now been largely superseded, on environmental grounds, by the dry bottom-feed technique, and for which no significant published field trial data currently exists in deep soft clay deposits in the context of shallow, narrow footings. This research is therefore principally concerned with evaluating both the ground response to installation of partial depth vibro stone columns using the dry bottom-feed method in a deep moderately sensitive soft clay soil, together with the influence of parameters such as stone column spacing and length, founding depth within a thin surface 'crust', and also foundation shape on the performance of narrow footings subsequently constructed and subjected to incremental loading, over the installed stone columns, at the Bothkennar soft clay research site in Scotland. Comparisons are made with footings constructed within the surface 'crust' at Bothkennar without stone columns. Whilst stone columns were satisfactorily constructed with the dry bottom-feed technique at Bothkennar, it was evident that the vibroflot should not remain in the ground for longer than is necessary, in order to avoid excessive soil disturbance. For this reason construction of partial depth stone columns to a more uniform diameter, without construction of an 'end bulb', is advocated. Stress ratio was found to increase significantly with increasing length of stone column and also applied load, up to a maximum value of around 4.0. Moreover, for a trial footing founded at the base of the 'crust', stresses attracted by the columns were higher than all other columns where founding depth (level) was at shallower depth in the crust. A significant stress transfer was also measured beneath the toe of columns intentionally installed shorter than the minimum design length predicted by the Hughes and Withers (1974) approach at all iii applied loads, but not for columns equal to, or longer than minimum design length, confirming the predictions of this laboratory-based approach at the field scale. The stress measurements recorded by the field instrumentation demonstrate that the behaviour of the composite stone column-soil-foundation system is complex, with simultaneous and interdependent changes in pore pressures, soil stress ratios and resulting stiffness of both soil and columns. Whilst observed settlements exceeded those predicted, with larger foundation settlements observed at low applied loads over stone columns than at the same loading level in untreated ground, principally due to soil disturbance and accelerated consolidation effects during initial loading, at higher applied loadings however the stone columns significantly reduced the rate and magnitude of settlement compared to a foundation in the untreated 'crust'. It is therefore clear that the stone columns 'reinforced' the weak soil, providing a significantly increased factor of safety against bearing failure.

In order to reduce the use of landfilling within waste management great emphasis is being placed on waste reduction and recycling. Each year in the UK approximately 2.5 Mt of waste glass is produced and approximately half of this waste is not recyclable. Therefore alternative ways need to be found for using waste glass and one possibility is to use it within concrete as a replacement for cement and/ or aggregate. In the research programme concrete mixes were tested which had 0%, 25%, 50% and 100% of the fine aggregate replaced by crushed waste glass. All glass was originally in bottle form and was crushed to produce ‘sand’ which had a grading curve more-orless identical to fine aggregate obtained from a commercial supplier. Three colours of glass were studied, i.e. flint (clear), amber and green. Concretes were also made which contained a mixture of colours (in proportion according to the weight of each type of waste glass produced annually within the UK) and also a mixture of unwashed waste glasses. The overall concrete mix adopted for investigation, i.e. 1:2:4, was selected because of its wide use within industry, and all concrete was made with a water:cement content of 0.6 without the addition of plasticiser or ASR-retarding agents. The suite of laboratory tests included; slump, flow, initial and final setting time, ultrasonic pulse velocity, water absorption by immersion and capillarity rise, ASR measurement (volumetric and linear), compression strength at ages from 7 days to 365 days. Techniques of developed digital imaging and processing have been applied to the glass aggregate to quantify various particle shape factors, i.e. aspect ratio, percentage concavity, Riley inscribed sphericity and surface texture index. Statistical analysis has been used to compare the distribution of particle forms present within the fine aggregate materials used in the experimental work. Dimensional changes (in three orthogonal directions) were measured as concrete cubes hardened over a period up to 365 days. The length changes of concrete prisms were also measured over the same period of time. The resultant data indicated that a fine aggregate which comprised 25% glass and 75% sand would be categorised as “non-expansive”, i.e. the same as the sand on its own. As the proportion of glass in the fine aggregate became greater than the aggregate became more expansive but it did not exceed recommended limits.

This thesis is concerned with developing porous materials from tyre shred residue and polyurethane binder for acoustic absorption and thermal insulation applications. The resultant materials contains a high proportion of open, interconnected cells that are able to absorb incident sound waves through viscous friction, inertia effects and thermal energy exchanges. The materials developed are also able to insulate against heat by suppressing the convection of heat and reduced conductivity of the fluid locked in the large proportion of close-cell pores. The acoustic absorption performance of a porous media is controlled by the number of open cells and pore size distribution. Therefore, this work also investigates the use of catalysts and surfactants to modify the pore structure and studies the influence of the various components in the chemical formulations used to produce these porous materials. An optimum type and amounts of catalyst are selected to obtain a high chemical conversion and a short expanding time for the bubble growth phase. The surfactant is used to reduce the surface tension and achieve a homogenous mixing between the solid particulates tyre shred residue, the water, the catalyst and the binder. It is found that all of the components significantly affect the resultant materials structure and its morphology. The results show that the catalyst has a particularly strong effect on the pore structure and the ensuing thermal and acoustical properties. In this research, the properties of the porous materials developed are characterized using standard experimental techniques and the acoustic and thermal insulation performance underpinned using theoretical models. The important observation from this research is that a new class of recycled materials with pore stratification has been developed. It is shown that the pore stratification can have a positive effect on the acoustic absorption in a broadband frequency range. The control of reaction time in the foaming process is a key function that leads to a gradual change in the pore size distribution, porosity, flow resistivity and tortuosity which vary as a function of sample depth. It is shown that the Pade approximation is a suitable model to study the acoustic behaviour of these materials. A good agreement between the measured data and the model was attained.

A utilização de misturas asfálticas recicladas com alto teor de material fresado (RAP) tem se tornado atrativa nos últimos anos por ser uma opção sustentável e que permite reduções de custo nas obras de pavimentação. No entanto, a produção dessas misturas sem prejuízo ao seu desempenho em campo ainda é um desafio. Diferentemente do que ocorre na reciclagem a frio, nas reciclagens a quente e morna o ligante envelhecido presente no RAP é mobilizado, ou ativado, mas é difícil mensurar em que grau isso ocorre. Dessa forma, a dosagem é feita de forma imprecisa, podendo comprometer o desempenho da mistura reciclada final. O presente trabalho tem como objetivo analisar a aplicabilidade de procedimentos laboratoriais para a avaliação da ativação do ligante presente no material fresado e da interação entre os ligantes (velho do RAP e novo adicionado), em misturas asfálticas recicladas através dos processos a quente e morno. O método de análise da ativação do ligante foi aplicado em diferentes tipos de material fresado, e um procedimento de extração por etapas foi desenvolvido para analisar o grau de interação entre ligantes na reciclagem. Neste processo, a extração do ligante asfáltico presente na mistura é realizada em etapas, de forma a separá-lo em camadas, e os ligantes obtidos em cada etapa são recuperados, sendo avaliada a homogeneidade entre eles por meio de ensaios reológicos. Os resultados mostraram que é possível obter informações relevantes acerca dos mecanismos de ativação e de interação entre ligantes por meio dos métodos analisados, principalmente em relação à presença de polímero no RAP e na identificação do grau de interação entre ligantes. / The production of recycled asphalt mixtures with high contents of reclaimed asphalt pavement (RAP) has become attractive in the past few years, as it is a sustainable solution which allows considerable cost reductions. However, the production of these mixtures without losing performance in the field is still a challenge. Different from what happens on cold recycling, on hot and warm recycling processes the aged asphalt binder present in the RAP is activated, and it is difficult to determine the degree to which this happens. As a result, the mix design is often not done properly, what might compromise mixture performance. The present study aims to analyze the applicability of laboratory procedures to evaluate the RAP binder activation and the blending between fresh and RAP binders, in hot and warm recycled asphalt mixtures. The method for evaluating RAP binder activation was applied to different types of RAP, and a staged extraction method was developed to assess the degree of binder blending in recycled mixtures. In this process, binder extraction is conducted in three steps, dividing the binder in three layers. The binder layers obtained are recovered, and the homogeneity between them is determined through rheological testing. The results obtained showed it is possible to obtain relevant information by applying the studied methods, especially regarding the presence of polymer in the RAP and the degree of blending in recycled mixtures.

Dans le domaine automobile, intégrer de plus en plus de matériaux composites recyclés tout en améliorant les performances initiales et en diminuant les masses emportées devient un compromis auquel il faut répondre. Par ailleurs, les pièces de structures en matériaux composites destinées au crash sont souvent soumises à des conditions environnementales, notamment des températures modérément élevées, pouvant produire une dégradation physico-chimique progressive. Ainsi, pour assurer une meilleure conception et une durabilité des pièces, il est primordial de bien cerner l’influence du vieillissement thermique sur les propriétés dynamiques des matériaux. Dans ce but, ce travail vise à coupler la physique de la cinétique de dégradation par oxydation et le comportement mécanique multi-échelles d’un nouveau matériau composite totalement issu du recyclage à renfort carbone et matrice à base polypropylène. Le premier axe de l’étude est dédié à l’élaboration, la caractérisation physicochimique, microstructurale et mécanique de plusieurs formulations de composites. Une fois le composite optimal sélectionné, une méthodologie hybride, expérimentale et numérique, visant à caractériser les propriétés dynamiques rapides allant jusqu’à des vitesses de déformation de 100 s-1 est développée. Le deuxième axe de ce travail est focalisé sur l’étude de l’influence de la thermo-oxydation sur les propriétés physico-chimique et mécaniques à différentes vitesses de sollicitation du composite optimal et sa matrice. L’ensemble des données expérimentales issues du vieillissement a permis l’identification d’un modèle cinétique basé sur un schéma mécanistique de l’oxydation des matériaux vieillis. D’autre part, une étude qualitative et quantitative de l’effet du vieillissement sur les mécanismes d’endommagement a été réalisée à l’échelle microscopique visant à mettre en place une loi d’endommagement reliant, pour une déformation imposée donnée, le taux d’endommagement local à la concentration des produits d’oxydation. Les résultats de cette étude mettent en évidence la possibilité de développer des lois de comportement affectés par les paramètres de modèles cinétiques décrivant l’évolution de l’état physico-chimique du composite au cours du vieillissement. / In the automotive sector, integrating more and more recycled composite materials while improving the initial performance and decreasing the carried masses becomes a compromise that needs to be addressed. Moreover, structural parts made of composite materials intended for crash are often subjected to environmental conditions, including moderately high temperatures, capable of causing gradual physico-chemical degradation. Thus, to ensure better design and durability of parts, it is important to understand the influence of thermal aging on the dynamic properties of materials. To this end, this work aims to couple the physics of oxidative degradation kinetics and the multi-scales mechanical behavior of a new fully recycled composite based on a polypropylene matrix and carbon fibers. The first axis of the study is dedicated to the elaboration, the physicochemical, microstructural and mechanical characterization of several formulations of composites. Once the optimal composite is selected, a hybrid experimental and numerical methodology is s is developed in order to characterize the dynamic properties at high strain rates reaching 100 s-1. The second axis of this work is focused on the study of the influence of thermo-oxidation on the physicochemical and mechanical properties at different strain rates of the optimal composite and its matrix. The resulting experimental has allowed the identification of a kinetic model parameters based on a mechanistic scheme. Furthermore, a qualitative and quantitative study of the effect of aging on the damage mechanisms has been carried out at a microscopic scale in order to establish a damage law linking, for a given imposed strain, the local damage density to the concentration of the oxidation products. The results of this study highlight the possibility of developing behavioral laws affected by the parameters of kinetic models describing the evolution of the physicochemical state of the composite during aging.

L'introduction de granulats de béton recyclé (i.e. granulats produits à partir des gravats issus de la démolition d'ouvrages en béton obsolètes) dans les formulations de béton impacte de manière significative le comportement structurel des éléments en béton armé. Ce travail est consacré à l'étude de l'influence des granulats de béton recyclé sur l'adhérence armature-béton. Dans un premier temps, un modèle analytique de l'adhérence armature-béton est développé. L'originalité du modèle proposé réside dans le nombre limité de paramètres physiques sur lesquels il est fondé. Ces paramètres physiques sont ensuite déterminés expérimentalement via la réalisation d'une campagne d'essais d'arrachement. Trois types de bétons, dont deux bétons de granulats de béton recyclé, sont étudiés. Le suivi de l'arrachement de l'armature est complété par des mesures acoustiques permettant d'obtenir des informations provenant du coeur de l'échantillon, où l'armature se trouve. / The use of recycled concrete aggregate (i.e. aggregate produced from concrete demolition rubble) has a significant impact on the mechanical behavior of reinforced concrete members. This work focuses on the influence of recycled concrete aggregate on rebar-concrete bond. First, an analytical madel of the rebar-concrete bond is developed. The original feature of this modellies in the limited number of non-free physically-based parameters on which it is based. These parameters are then experimentally determined through a pull out test campaign. Three types of concrete, including two recycled aggregate concretes, are studied. Pull-out test monitoring is completed by acoustic measurements in order to obtain data from inside the concrete bulk, where the reinforcing bar is located.

Este trabalho investiga o potencial de utilização do entulho de construção e demolição, C&D, triturado na estação de reciclagem de entulhos de Ribeirão Preto - SP, como agregado graúdo no preparo de concretos de baixa e média resistências. A utilização da fração graúda, compreendida entre 4,8 mm < Dmáx < 19,0 mm, para substituir parcialmente ou totalmente o agregado graúdo graduado como brita 0 e brita 1 (NBR 7211/82), pode resultar em uma significativa economia na execução de componentes urbanos e habitacionais para construções de interesse social. O presente trabalho apresenta as características granulométricas e físicas, dos agregados reciclados, em comparação com as do agregado natural, usado como referência. Os resultados obtidos na substituição, parcial (50%) e total (100%), do agregado natural graduado como brita 1 e brita 0, utilizados na região de Ribeirão Preto, pelo reciclado graúdo da mesma faixa granulométrica, também são apresentados. A influência do agregado reciclado na perda do abatimento do concreto fresco e nas propriedades mecânicas do concreto endurecido, foram investigadas. Finalmente, realizou-se avaliação de desempenho à flexão em painéis leves de vedação, com a finalidade de se obter uma aplicação prática ao estudo desenvolvido. Concluiu-se, assim, pela viabilidade do emprego do agregado graúdo reciclado em substituição, total ou em parte, do equivalente natural em concretos estruturais de baixa resistência. / This dissertation researches the potential of the use of construction and demolition debris (C&D), crushed in the recycling station of Ribeirão Preto-SP, as coarse aggregate to make concrete of low and medium strenght. The use of coarse fraction, 4,8 mm < Dmax < 19,0 mm, substituting, partial or totally the natural aggregate, as recommended in NBR 7211/82, can result in a significant economy on the production of urban components and for social interest constructions. The present work presents the physical and granulometric characteristics of the recycled aggregate, comparing with the natural one, used as reference. Experimental results are showed and compared. The influence of recycled aggregate on the loss of the slump of fresh concrete and on the mechanical properties of harden concrete were analyzed. Finally, the flexural behavior of a model of panels was evaluated.

A crescente quantidade de resíduos sólidos da construção civil gerada em cidades de médio e grande portes tem sido fonte de preocupação em todo o mundo em função de questões ambientais, econômicas e até sociais. Desta forma, a reciclagem dos resíduos de construção para a produção de agregados torna-se uma alternativa interessante, principalmente em função de normas e pesquisas já existentes que podem garantir sua aplicação. A pavimentação com agregados reciclados já vem sendo amplamente realizada em alguns países onde, inclusive, já existe conhecimento consolidado sobre o assunto. No Brasil, as primeiras experiências que remetem ao uso de agregados reciclados em pavimentação datam de meados da década de 80. Desde então, poucas pesquisas sobre o tema vem sendo realizadas, embora haja a necessidade de se procurar novas técnicas e materiais no setor de infra-estrutura rodoviária, uma vez que o país possui somente cerca de 10% de suas vias, muitas vezes urbanas, em condição pavimentada. Este trabalho analisa laboratorialmente aspectos físicos e de comportamento mecânico do agregado reciclado da cidade de São Paulo, a ser utilizado em camadas de base, sub-base ou reforço do subleito de pavimento, em substituição aos materiais convencionais, com enfoque em vias urbanas de baixo volume de tráfego. O estudo envolveu a análise do agregado reciclado in natura, além de sua mistura com 4% de cal ou 4% de cimento Portland, como forma de promover um aumento da resistência do material. Além disso, foram realizados alguns ensaios com brita graduada (material comumente empregado em pavimentos), a fim de comparar resultados. Concluiu-se que o agregado reciclado analisado é de uso promissor em pavimentação, dadas suas propriedades físicas e mecânicas satisfatórias, comparáveis a tradicionais materiais estabilizados granulometricamente ou mesmo a brita graduada simples. Ademais, a adição de cal ou cimento Portland apresenta-se como excelente alternativa quanto ao requisito de aumento de resistência do material reciclado. / The increasing amount of construction and demolition waste generated in medium-sized and large cities has become a source of concern all over the world due to environmental, economic and even social issues. Thus, the recycling of construction and demolition waste to produce aggregates becomes an interesting alternative mainly because of existing specifications and researches that can guarantee its application. Paving with recycled aggregates has already been largely done in some countries where there is even a consolidated knowledge about the subject. In Brazil, preliminary experiences that refer to the use of recycled aggregates in pavement layers date from the mid 80s. Since then, few researches on the subject have been conducted, although it is necessary to look for new techniques and materials in the road infra-structure sector, since the country has only about 10% of its roads, many times urban ones, in paved condition. This work analyses recycled aggregates from São Paulo City as a material to be used in base, subbase or subgrade reinforcement courses in urban roads of low-volume traffic, to replace conventional materials. So, physical and mechanical behaviour aspects of the material were observed by means of laboratory tests. This study involved the analysis of recycled aggregate in natura, as well as its mix with 4% of lime or 4% of Portland cement, to promote a gain in strength. Moreover, some tests were made using graded crushed rock (that is commonly used as a pavement material) so as to compare the results. It was concluded that recycled aggregate is promising for paving, given its satisfactory physical and mechanical properties, comparable to traditional granulometrically stabilized materials or even to simple graded crushed rock. The addition of lime or Portland cement is an excellent alternative concerning the increase in strength of those recycled materials.

Atualmente, a madeira ainda é o material mais usado nas cruzetas das redes aéreas de distribuição de energia elétrica no Brasil, o que vem causando problemas às companhias distribuidoras de energia elétrica quanto a: (i) degradação devida a defeitos e a ataques de fungos e de insetos, (ii) aumento dos custos operacionais, para a substituição das peças danificadas e (iii) problemas ambientais, uma vez que a matéria-prima está se tornando escassa e apresenta restrições ambientais. Nesse sentido, estudos vêm sendo realizados visando a substituição da madeira por outros materiais, tais como aço, concreto e materiais poliméricos reforçados com fibras. Embora os materiais termoplásticos com função estrutural sejam de uso bastante recente, quando comparados com madeira, concreto ou metais, vários fatores contribuem para sua utilização (e.g., o alto consumo energético na produção do aço e do cimento e a abundância de material plástico com custo competitivo). Diante disso, este trabalho tem por objetivo contribuir para o desenvolvimento de uma cruzeta de polímero reciclado, de modo que ela seja comercialmente competitiva e que apresente vantagens quando comparada com as demais cruzetas existentes no mercado, tais como peso reduzido, facilidade de instalação e possibilidade de retorno de parte do capital investido, uma vez que, quando danificadas, o material pode ser novamente reciclado. Para tanto, realizou-se uma análise das propriedades geométricas de possíveis seções transversais para as cruzetas. Uma vez definidas as seções mais adequadas, foram feitos modelos reduzidos de cruzetas poliméricas e ensaios experimentais, cujos resultados foram validados por análise numérica feita com o programa ANSYS. Constatou-se que os modelos numéricos desenvolvidos representaram de forma satisfatória o comportamento verificado nos ensaios e comprovaram a viabilidade de empregar os polímeros reciclados em cruzetas e em outros elementos estruturais. Entretanto, com era de se esperar, será necessário melhorar algumas de suas características, tais como a resistência e a rigidez. / Nowadays, wood is still the most used material in crossarms of aerial power distribution lines in Brazil. However, it has caused problems to power utilities concerning (i) degradation due to defects and attacks of fungi and insects, (II) higher operational costs to replace damaged pieces and (III) environmental problems, as the raw material has become scarce and presented environmental restrictions. In this sense, studies have been conducted aiming to replace wood by other materials, such as steel, concrete and polymeric materials reinforced with short fibers. Although thermoplastic materials with structural function have a recent use, when compared to wood, concrete or metals, several factors contribute to their application (e.g., high energetic consumption in the production of steel and cement and the abundance of plastic material with competitive cost). Therefore, this work aims contribute to the development of a recycled polymer crossarm, to be commercially competitive, with advantages over the ones existing in the market, such as lower weight, easiness of installation and possibility of recovering part of the invested capital, when damaged, the material can be recycled again. An analysis of the geometric properties of possible transversal sections for the crossarms was conducted. After defining the most adequate sections, reduced models of polymeric crossarms and experimental tests were made. The results were validated by numerical analysis performed by ANSYS. The numerical models developed satisfactorily represented the behavior verified in the tests, proving the viability of using the recycled polymers in crossarms and other structural elements. However, as expected, some of their characteristics, such as resistance and stiffness, must be improved.