Abstract Proper management and inspection are essential to ensure the safety and structural integrity of bridges. In this research, bridge management systems implemented around the world have been studied with a focus on their inspection methods. Based on the results, the authors propose a methodology that integrates the most relevant aspects of many existing approaches, targeting a Brazilian context. It covers six types of inspections, including three levels of depth and an emergency inspection. The aim is to obtain a methodology that can be adapted to the specificities and local conditions of Brazilian bridges. The three levels of inspection depth allow for a comprehensive analysis, from a basic to a detailed assessment, ensuring an accurate understanding of the condition of the bridges.

Abstract Lattice structures have a wide range of applications in real structures. For example, concrete buildings can be modeled as flat or spatial frames, while lattice or ribbed slabs can be modeled as grids. Computer programs frequently used for the design of buildings in Brazil allow the design to be carried out in spatial gantry and grid. Also, some include the possibility of applying calculated support settlements or manually introducing an elastic spring to simulate the behavior of the foundation. However, it is not possible to insert geotechnical data together with the structure for the geotechnical evaluation of soil deformation in an integrated way to obtain an analysis of the interaction between the stresses in the structure and the soil deformations, as well as to take into account the overlapping of stresses applied in the soil mass to evaluate settlements. In this context, classical solutions to analyze these domains together have been proposed with the use of the Finite Element Method (FEM) and by the coupling between the Boundary Element Method (SEM) and FEM. Despite being robust, these techniques are not yet commonly used in calculation offices, due to the high computational cost. In this sense, alternative formulations with lower computational cost, such as the one proposed herein, can be a viable alternative for the analysis of the effects of soil-structure interaction in conventional structures without significantly impairing computational performance. Thus, to approximate the computational analysis to the real behavior of structures, this article proposes an efficient and low-cost computational matrix analysis solution for the integration between structural and geotechnical models, considering the soil-structure interaction. Thus, the integrated model considers the compatibility between the forces calculated in the structure and the settlement prediction, carried out, considering the soil deformation caused by the global contribution of stresses, in such a way as to consider in the analysis of the soil, both the tensions arising from the support itself and those transmitted by the other foundation elements. The proposed alternative formulation was verified for isolated structural analyses, geotechnical isolates and finally considering the coupled form with equilibrium in the deformed condition of the soil, paying attention to the robustness of the implementation.

Abstract This study investigated the feasibility of recovering carbonaceous material from fine coal waste through the bench flotation process. The goal was to find an alternative for the disposal of these waste materials in tailings dams, which cause negative environmental impacts. The possibility of recovering carbonaceous material from fine coal waste through bench flotation was demonstrated. Tested were several combinations of reagents, the collectors Diesel, kerosene and Lilaflot, with concentrations ranging from 1000 to 6000g/t, and the frothers pine oil and MIBC, ranging from 100 to 600 g/t. The target of 40% mass recovery and ash content below 35% was achieved by three tested combinations, being the better result Diesel+MIBC, with concentrations of 6000 g/t + 400 g/t, and mass recovery of 42.2% and ash content of 33.5%. The desliming stage significantly contributed to improving the mass and carbonic recoveries, but it did not significantly improve the ash content results. The study showed potential to reduce the environmental impacts of the coal industry by decreasing the volume of waste disposed in tailings dams and minimizing the exposure of chemical elements that could lead to Acid Mine Drainage (AMD). Additionally, the recovery of carbonaceous material can produce a valuable product for use as fuel or in other applications.

Abstract This article describes the development and validation of a linear viscoelastic model 2S2P1D for silty sand mixed with 16% asphalt emulsion. Experimental data from creep tests were employed to propose and validate the model. The methodology involved soil collection and characterization, after which it was mixed with asphalt emulsion, and exposed to air for 24 hours, followed by the Superpave rotary compaction of the soil-emulsion mixture. Test samples were then exposed to air until a constant density loss was detected, followed by conducting complex modulus tests at thirty different temperature-frequency pairs. Based on these results and the smooth construction of the master curve of the mixture, it was confirmed that the material studied is thermorheologically simple, and the parameters of the linear 2S2P1D model were defined. After defining the constitutive model, a creep test was conducted on the material at a temperature of 0°C for 7200 seconds. The model exhibited satisfactory adjustments to the creep test results, even in the nonlinearity domain. The differences between the strains predicted by the model and those defined experimentally were considered within an acceptability limit for geotechnical materials, and the introduction of a modulus decrease coefficient of approximately 65% was sufficient to simulate the nonlinearity effect in the 2S2P1D model.

Abstract The combination of acidizing and hydraulic fracturing, or proppant-acid fracturing, seems to be a very logical approach to achieve the maximum stimulated volume in tight gas reservoirs, since the acid solution can stimulate the deep microfracture network far beyond the main propped fracture. However, this hybrid stimulation method sparks concerns that acidizing can increase proppant embedment and decrease the propped fracture conductivity. To understand how acidizing may be responsible for reducing conductivity, this article initially delves into the analysis of microscopic images of carbonate and siltstone specimens associated with a low permeability or tight gas reservoir in the São Francisco basin, in Minas Gerais, a kind of reservoir which is becoming considerably more important in recent years due to energy transition initiatives. The microscopic analysis revealed that thin, well-defined layers emerged on the acidized surface of some of the studied specimens. Then additional nanoindentation and proppant embedment tests showed that these new layers are weaker compared to the original rock matrix and are ultimately responsible for fracture conductivity decline. The findings in this study serve as an important piece of information for reservoir stimulation professionals that may consider the combination of acid stimulation and hydraulic fracturing in tight gas formations.

The structural optimization of trusses is a complex problem that can be affected by many different factors. In this research, the authors investigated the optimization of trusses performing a geometric nonlinear analysis under dynamic loading, using two different metaheuristic algorithms: the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). The objective function was to minimize the weight of the structure. A number of benchmark test problems for spatial trusses considering a geometric nonlinear analysis, and dynamic loading are analyzed to verify the performance of the optimization algorithms. The results showed that both algorithms were able to find efficient solutions to the optimization problem and suggest that the choice of the optimization algorithm can have a significant impact on the performance of the optimization process.

Abstract This study aimed to characterize kaolin residues originating from the pegmatitic region of northeastern Brazil, an area that annually produces and disposes of thousands of tons of kaolin residue into the environment without any control. The research focused on the industrial potential of these residues through chemical composition analysis by X-ray fluorescence (XRF), mineralogical characterization by X-ray diffraction (XRD), and morphological characterization by scanning electron microscopy (SEM) across different granulometric fractions. The results, supported by the literature, revealed that both siri and sarrabulho residues exhibited chemical, mineralogical, and textural compositions dominated by silica (SiO2) and aluminum oxide (Al2O3), which varied according to particle size. The fine fractions (< 74 µm) showed higher Al2O3 contents (42%), corresponding to kaolinite and muscovite minerals, which confer favorable properties to produce ceramic coatings, cement, and paints. Conversely, the coarse fractions (> 150 µm) contained 83% SiO2, attributed to quartz mineral, contributes to improved mechanical strength and thermal stability in aggregates for the construction industry. Additionally, 8.10% potassium oxide (K2O) and 3.22% phosphorus pentoxide (P2O5) were identified, suggesting potential agricultural applications as soil conditioners. Based on the results, it is concluded that the Siri and Sarrabulho residues, according to literature, exhibit physicochemical and mineralogical characteristics that support their reuse in various industrial sectors, particularly in ceramics, civil construction, and agriculture. The valorization of these residues represents a strategic approach to mitigating environmental impacts and promotes the integration of these materials into production chains aligned with the principles of economic, environmental, and social sustainability.

Abstract Oil exploration is complex and very expensive, presenting long-term returns and considerable risks of accidents. Saving time is the guideline of any optimization method to reduce drilling costs and CO2 emissions. Highly variable performances are found in any oilfield, even in similar depth ranges, due to multiple interactions between the many factors involved in the drilling operations. Understanding such gaps is complex, as different technologies and levels of energy are used in each bit run along an exploration campaign, affecting in different ways their performances. The objective of the methodology presented in this article is to provide tools to identify which are the factors and how they affect the productive time used to drill oilwells, allowing to measure the contributions of each factor in increasing the efficiency of the drilling operations. A case study analyzes a 35-year exploratory campaign offshore Brazil, where data of the 109 wells drilled in an oilfield is used to benchmark different performances, demonstrating the advantages of the methodology in oilwell planning and in finding the paths for reducing drilling costs and CO2 emissions. As drilling for O&G, CCUS and geothermal wells is expected to continue yet for decades, the learnings and the economic benefits for the operators will extended in the long terms to the whole society.

Abstract The global commercial drone market is experiencing rapid growth, particularly in precision agriculture applications such as crop spraying. This market is projected to expand at an 8.3% compound annual growth rate (CAGR), contributing to an overall drone market value of approximately $55.8 billion by 2030. Agricultural drones are made of various materials including electronic waste components such as circuit boards, connectors, and pins, containing significant amounts of gold. While gold cyanidation is the primary method for gold extraction, there is a growing interest in more environmentally friendly alternatives. This study focuses on extracting gold from pins using thiourea-based leaching with temperature variation and ultrasound agitation, comparing it to conventional cyanide processes. The process begins with the X-ray fluorescence analysis of drone components to detect gold. The gold concentration in pins is measured through aqua regia digestion (1:25 ratio, 70°C, 2 h). Cyanide leaching is conducted at 25°C for 2 h at pH 14, with a 1:25 mass ratio, while Thiourea leaching is performed at a 1:10 ratio for 2 h and pH 1, under different conditions: varying temperature and ultrasonic agitation. Cyanide digestion shows about 83 ppm of gold, setting a standard recovery benchmark of 100%. In contrast, aqua regia yields 66.8%. The thiourea leaching's efficiency, influenced by temperature and agitation, sees its highest gold recovery at 43.19% of the cyanide standard, with ultrasonic agitation, although overall performance is below cyanide yields. Further research is needed to enhance gold recovery through thiourea based leaching, focusing on optimizing the temperature parameters and leaching conditions.