Carbon nanotubes (CNTs) and nanofibers (CNFs) were synthesized on clinker silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an situ chemical vapor deposition (CVD) process using converter dust, industrial byproduct, as iron precursor. use of these materials reduces the cost, with objective application large-scale cement production. resulting products analyzed scanning electron microscopy (SEM), transmission (TEM)...

Nanotechnology can significantly improve the mechanical strength and durability of concrete. At nanoscale, good dispersion constituent materials is an essential factor for improvement concrete properties. In this scenario, objective research was to evaluate properties high performance containing stabilized nano-silica. The incorporation nano-silica polycarboxylate chemical admixture allowed its application in concrete, since evenly dispersed mass. For study, three different concretes were...

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PURPOSE: To assess the intraocular pressure (IOP) and ocular rigidity (E) at 1, 3, 6 24 postoperative months in eyes that underwent LASIK. METHODS: The IOP measured by Goldmann applanation tonometer (GAT) 5.5 10 gm. weights of a standardized Schioetz (ST) E differential tonometry (the ST) were assessed before after LASIK (at month) 23 eyes. volume corneal indentation (Vc) with ST resting on eye (tonometric - Pt) also evaluated. RESULTS: average was lower than 1 3 A statistically significant...

ABSTRACT It is well known that aggregate characteristics can intensively interfere in concrete behavior especially when sulfides are presented the aggregates. The lack of consensus to content limit value these deleterious sulfur compounds structures for dams has motivated several investigations worldwide. Within this scenario, work presents a methodology evaluate presence pyrite and pyrrhotite concretes produced with aggregates containing sulfides. For study, rock samples from Irapé...

The theory is presented for a two‐layered one‐dimensional elastic member acting either as beam or beam‐column, including both connector and geometric nonlinearities. This capable of having slip at the interface two layers displacements perpendicular to longitudinal axis that are on order magnitude depth member. force‐slip relationship interlayer connectors assumed be nonlinear in accordance with accepted constitutive relationships nailed joints. An energy approach employed formulation from...

Cement pastes and mortars were prepared incorporating carbon nanotubes (CNTs) nanofibers (CNFs) synthesized directly on ground clinker silica fume. Setting times of the cement not significantly influenced by presence nanofibers. Mortar mechanical behavior (compressive flexural tensile strength) was evaluated compared with reference having same composition but without The nanostructured showed 5.4–14.1% higher compressive strengths, respectively. values for fume 39.6 9.4%, Gas adsorption...

The results of an experimental investigation on the microcracking high-performance concrete subjected to biaxial tension-compression stresses are presented. Short-term static tests and mapping were performed 12.5 cm square by 1.25 thick plates. Strain controlled executed in a testing machine constructed at University Texas. primary variables studied deformations ultimate stress level each ratio as well patterns total crack lengths. For study, plates, after straining, impregnated epoxy then...

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The use of web has become an attractive option for the development learning environments due to high interactive interfaces which computers have throughout their multimedia resources - graphic, videos, animation and simulation. Here is presented analysis influence ConcWeb online virtual environment on process reinforced concrete design. Data was collected by student's exams longitudinal study employed obtain results. All measurements were obtained during course one semester adjusted...

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<title>Abstract</title> This study intends to develop a new mortar material with improving microstructural properties through the addition of nanomaterials in its composition. Among interesting features, graphitic carbon nitride (g-C₃N₄) stands out for having graphene-like carbon-based structure, exhibiting high chemical/thermal stability, and excellent electronic optical properties. The present evaluated influence exfoliated g-C₃N₄ addition,...

Os grandes avanços tecnológicos ocorridos nas últimas décadas relativos às estruturas de concreto têm conduzido a elementos mais esbeltos e maiores vãos. Nesses casos, o tratamento dos efeitos segunda ordem em pilares cálculo flechas lajes vigas armado demandam quantificação do módulo elasticidade concreto. Esta é usualmente feita através expressões simplificadas estabelecidas normas técnicas pertinentes. Entretanto, incertezas não desprezíveis estão associadas aos modelos normativos para A...

A ABNT NBR 6118 (2023) apresenta expressões que relacionam a resistência à tração do concreto sua característica compressão. Diversas pesquisas têm sido desenvolvidas em todo o Brasil com intuito de aprimorar essas relações, proporcionando previsões mais precisas. Neste contexto, objetivo deste trabalho é contribuir para esse esforço. Para tanto, foi compilado um banco dados abrangente contendo resultados ensaios realizados território nacional. Esses incluem compressão e por diametral...

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A ABNT NBR 8800 (2008) permite dois critérios para avaliação da força cortante longitudinal resistente última em lajes mistas de aço e concreto: método m-k interação parcial. O é o considerado internacionalmente como padrão cálculo dessa resistente. Neste método, a resistência das obtida por regressão linear dos resultados ensaios realizados com fôrma uma mesma espessura. parcial, outro lado, surge alternativa ao m-k, melhor explorar comportamento dúctil perfis disponíveis no mercado, os...

Reinforced concrete codes worldwide establish that the design of slender columns must ensure under most unfavorable load combination, there is neither instability nor material failures. Thus, it mandatory to consider as well geometrical nonlinearities. The consideration second order effects can be done using simplified methods or general method. This work analyses based on approximate shown in NBR 6118 [1]: curvature method and stiffness procedure. Due importance stability buildings...

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