RESUMO -Este artigo apresenta uma avaliação dos mecanismos de compactação de misturas entre solo arenoso e altos teores de emulsão asfáltica. Para tanto, foram utilizados um solo classificado pelo Sistema Unificado de Classificação dos Solos como SP e uma emulsão asfáltica catiônica de ruptura lenta (RL-1C). As misturas entre solo e emulsão asfáltica foram confeccionadas com teores de emulsão entre 13% e 31%, em peso, e foram submetidas a diferentes condições de compactação, de forma que as informações obtidas permitissem a identificação dos mecanismos que governam a sua compactação, bem como a identificação da metodologia de compactação mais apropriada para este tipo de material. Os resultados mostraram que os mecanismos responsáveis pela compactação das misturas entre solo e altos teores de emulsão asfáltica são significativamente diferentes daqueles que regem a compactação dos solos granulares e finos. A rigidez do filme betuminoso apresentou-se como o parâmetro com maior influência na compactação das misturas estudadas, mostrando que para a obtenção de uma compactação eficiente é necessária a diminuição da viscosidade do ligante asfáltico, que pode ser feita pelo aumento da energia, ou aumento da temperatura do ligante no momento da compactação.ABSTRACT -This paper presents an evaluation of the mechanisms which define the compaction of mixtures between sandy soil and high asphalt emulsion contents. A sandy soil classified according to the Unified Soil Classification System as SP and a cationic asphalt emulsion slow set (RL-1C) were used. The mixtures between soil and asphalt emulsion were manufactures with asphalt emulsion contents varying from 13% to 31%, in weight, and were compacted under different conditions, in order to allow the identification of the mechanisms responsible for their compaction, and compaction methodology suitable for this material. Results show that the mechanisms governing the compaction of mixtures between soil and high asphalt emulsion contents are significantly different from those ones regarding the granular and fine soils. The stiffness of the residual asphalt binder on the soil particles presents itself as the most important factor that has influenced the compaction of the studied mixtures, indicating that to obtain an efficient compaction of the mixtures it is necessary to increase the energy used in the compaction process or decreasing the viscosity of the residual binder by heating during the compaction procedure.Palavras Chave - solo-emulsão, compactação, emulsão asfáltica.

The behavior of asphalt binders modified with recycled crumb rubber depends on several factors, such as: rubber content and type, temperature and time employed during the digestion process. Some of these aspects are investigated in this paper by means of a series of tests performed on asphalt-rubber produced via the wet process. Crumb rubber manufactured by ambient grinding and cryogenic processes were used in this work. Reduction of penetration and sharp increase of viscosity, softening point and resilience were observed for increasing rubber contents. The results show that the Brookfield viscosity limits the crumb rubber content incorporated into straight binder, once it tends to become too high above a certain critical amount of incorporated rubber. The effect of digestion time on the viscosity of the modified binders depended in this research on the rubber content. For high rubber contents, there seems to exist a critical time after which viscosity tends to decrease for continuing digestion process. A rubber-binder interaction model, which could explain such results, is proposed. The influence of rubber type occurred especially in terms of Brookfield viscosity and softening point. It was observed a decrease in these properties for the asphaltrubber binders produced with crumb rubber obtained by cryogenic process in relation to those produced by the grinding process.

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The purpose of this article is to evaluate the shear strength parameters of mixtures of sandy soil with high asphalt emulsion contents for their use in geotechnical structures, such as zoned earth dams, embankments, etc. The methodology adopted consisted of: collecting and characterizing samples of sandy soil to be laboratory tested; compacting the mixtures between soils and asphalt emulsion with contents varying between 13% and 28% in weight by using different compaction methodologies; and performing direct shear tests to evaluate the parameters governing the shear strength behavior of the manufactured mixtures. Results showed that the use of a high asphalt emulsion content contributed to greater homogeneity of the mixtures. It was also found that the presence of residual asphalt gave a bilinear behavior to the sandy soil for the failure envelopes obtained from direct shear tests. At normal stresses usually less than 100 kPa, the mixtures present a cohesive intercept due the existing residual binder, while for normal stresses higher than 200 kPa, the mixtures presented a friction angle equal to the matrix of sandy soil used.

RESUMO Neste artigo avaliou-se o efeito do processo de cura na resistência ao cisalhamento de um solo arenoso misturado com teores de emulsão superiores a 10% em massa. A metodologia consistiu na coleta e caracterização do solo, caracterização da emulsão, compactação das misturas, cura dos corpos de prova por exposição ao ar por 1, 7 e 28 dias, e realização de ensaios de compressão triaxial em condições saturadas e não saturadas. Evidenciou-se que o aumento do tempo de cura ocasionou uma diminuição da massa específica aparente dos corpos de prova em razão da diminuição do teor de umidade devido à evaporação da água de constituição da emulsão. Os resultados dos ensaios realizados em condições saturadas indicaram não haver influência do tempo de cura na resistência ao cisalhamento. Já nos corpos de prova sem saturação, o aumento do tempo de cura produziu um aumento no valor do intercepto coesivo das misturas, mais pelo incremento da sucção do que pelo aumento da capacidade de ligação entre os grãos minerais. Em todos os casos, a adição de altos teores de emulsão asfáltica provocou um aumento no intercepto coesivo e diminuição do ângulo de atrito nos corpos de prova ensaiados com e sem saturação.

The modeling of seasonal and interannual streamflow forecasting at northeastern Brazil represents a great relevance problem to the use and management of water resources; which demands greater prediction ability models. This is still a difficult task to solve due to the seasonal and interannual climate variability at the semi-arid region. This work presents the artificial neural networks (ANN) as an alternative for modeling the seasonal to interannual climate prediction,. For the development of this task the hydropraphic Oros weir Basin was chosen due to its importance as water resources in the State of Ceara. According to recent studies, the temperatures of the North Atlantic, South Atlantic and equatorial Pacific can be satisfactorily as predictors for the Northeast climate. The proposed model predicts, in July, the next rainy season (January to June) river flow regime. This time frame is of great relevance for the allocation of water resources. Among the studied models, those using the average temperature anomalies of April, May and June preceding the predicted year as input data showed the highest Nash-Suttcliffe efficiency (0.80).

As a result of a number of studies, some analytical models have been developed to predict the shear behavior of unfilled rock joints, but they all present a purely deterministic nature because their input variables are defined without considering the uncertainties inherent in the formation processes of the rock masses and related discontinuities. This work aims to present a model for predict the shear strength of unfilled rock joints by incorporating uncertainties in the variables that govern its shear behavior with a First-Order Takagi-Sugeno fuzzy controller. The model is developed based on the results of 44 direct shear tests carried out on different types of joints. The model input variables are the normal boundary stiffness and initial normal stress acting on the joint, its roughness (expressed by the JRC value), the uniaxial compressive strength, the basic friction angle of the intact rock and the shear displacement imposed to the joint. The results show that the predicted shear strength of unfilled rock joints obtained by the fuzzy model fits satisfactorily the experimental data and allows the shear behavior of the discontinuities to be defined. A practical application of the model in a stability analysis of a rock mass is also presented.

RESUMO -No Brasil, em obras de abastecimento de água e esgoto, a classificação dos materiais das escavações realizadas se dá em função da dificuldade que estes oferecem ao desmonte, como materiais de 1ª, 2ª e 3ª categorias, não havendo critérios de engenharia bem definidos para tal classificação. Este trabalho tem por objetivo apresentar uma proposta para classificação de materiais de escavação com base em critérios de engenharia definidos a partir de resultados de sondagens de simples reconhecimento (sondagens a trado, SPT e rotativa). Para aplicação de tal proposta, foi considerado um estudo de caso, que consistiu na classificação de materiais no Município de Coreaú, Estado do Ceará, na qual havia um conflito referente à quantificação dos materiais obtidos na escavação. Os resultados mostraram que os critérios propostos permitiram a classificação satisfatória dos materiais em função de ensaios geotécnicos correntes. SYNOPSIS -In Brazil, excavation materials in water supply and sanitation works are classified, according to the difficulty offered by their removal, as 1st, 2nd and 3rd category materials, with no well-defined engineering criteria for such classification. This paper aims to present a proposal for excavation material classification based on engineering criteria defined from the results of simple identification surveys (Auger, SPT and rotary surveys). For the purposes of this proposal, a case study was considered that consisted of material classification in the city of Coreaú, State of Ceará, in which there was a conflict about the classification of the materials obtained from excavation. The results have shown that the proposed criteria provide a satisfactory classification of materials in function of current geotechnical tests.