PPG Engenharia Civil

Identificação e análise de riscos à saúde e segurança do trabalhador da construção civil utilizando sensoriamento vestível (wearable)

Wed, 10 Sep 2025 00:00:00 GMT

Identificação e análise de riscos à saúde e segurança do trabalhador da construção civil utilizando sensoriamento vestível (wearable) Travi, Nadine Schorr This research demonstrated that the use of wearable sensing technologies can enhance the way health and safety risks are identified in construction. From the analysis of two distinct construction sites — a retrofit project in Porto Alegre and a conventional building site in Portão — 58 occupational risks were mapped, six of which were classified as critical, mainly in physically demanding activities such as the removal of ceramic coatings and plaster. The workers’ profile revealed young professionals, with low levels of schooling and limited experience, exposed to conditions that go beyond physical effort: 25% showed symptoms of Common Mental Disorder (CMD), associated with psychosocial factors such as productivity pressure, task insecurity, and intense heat. Environmental and physiological monitoring highlighted the direct influence of climate (external temperature) and tasks on vital parameters, with increases in heart rate and blood pressure during critical activities. These findings reinforce the importance of scheduled breaks and task redistribution as effective protective measures. The study also advanced by proposing a predictive model capable of explaining 75% of risk variation, showing that wearable sensors can support real-time decisionmaking and anticipate situations of physical and mental illness. In summary, the results reveal that the integration of technology, environmental indicators, and attention to psychosocial aspects not only broadens the understanding of risks but also points to concrete pathways for creating safer, healthier, and more humane construction sites.

Análise da influência das características do substrato e da ausência de ancoragem no reforço de vigas submetidas ao cisalhamento utilizando manta de fibra de carbono

Mon, 22 Sep 2025 00:00:00 GMT

Análise da influência das características do substrato e da ausência de ancoragem no reforço de vigas submetidas ao cisalhamento utilizando manta de fibra de carbono Betencourt, Josiani Fatima The present study investigates the use of carbon fiber sheets, without anchorage, for the shear strengthening of reinforced concrete beams, thereby assessing the impact caused by potential bonding failures of the sheet. Carbon fiber sheets exhibit characteristics such as high tensile strength, corrosion resistance, durability, and ease of installation, making them an excellent alternative for structural strengthening, especially in cases of architectural constraints. To develop this research, a literature review was conducted in order to deepen the understanding of fiber-reinforced polymers, their properties for use as structural reinforcement, as well as design and detailing techniques. The experimental phase consisted of the fabrication of four batches of reinforced concrete beams, with three beams in each batch, all with the same longitudinal and transverse reinforcement configuration. The first batch was used as a reference, while the others were strengthened: one batch was bonded by the Quartzolit team, and the remaining ones had intentional bonding defects introduced, in order to evaluate their performance in comparison with the others. The test carried out was a three-point bending test with an offset load, designed to induce shear failure. Deformation, displacements, and crack patterns were also analyzed in each tested element. The results showed that beams strengthened with intentional bonding defects achieved values up to 101.55% higher than the average of the reference beams, whereas other elements, despite showing increased strength, yielded lower results. Furthermore, changes in crack patterns and failure modes were observed when compared to the reference beams, where all failures occurred by diagonal tension. Based on the results obtained, the importance of proper preparation of the beam to be strengthened, as well as the use of anchorage devices, became evident, since some failures were caused by sheet debonding along the edges. Nevertheless, this study highlighted the efficiency of carbon fiber sheets as shear reinforcement, confirming their effectiveness among the materials available in civil engineering.

Modelagem numérica de infiltração de água: dois sistemas de cobertura final de aterro sanitário no Vale do Rio dos Sinos

Thu, 31 Jul 2025 00:00:00 GMT

Modelagem numérica de infiltração de água: dois sistemas de cobertura final de aterro sanitário no Vale do Rio dos Sinos Silva, Carlos Alexandre Quadros da Numerical calculation methods have become much more efficient, making their application in problem-solving increasingly widespread. User-friendly interfaces make model configuration much easier and more intuitive, while the increase in computer speed can solve difficult problems in a matter of minutes. A series of computational models for estimating rainfall processes and their impact on the performance of landfill cover systems have become valuable tools in contemporary times, especially for evaluating the final cover layer of compacted soil. Among them, one of the most notable is HYDRUS-1D, a software based on the Finite Element Method that simulates the one-dimensional movement of water, heat and solute in variably saturated porous media for various limit conditions, including precipitation and evaporation. HYDRUS 1D was used to model the water balance in final cover layers of sanitary landfills in the Vale do Rio dos Sinos, using laboratory data on granulometry, Atterberg limits, compaction, permeability and suction of soils collected in São Leopoldo and Esteio (RS), and adjusting meteorological series (1991–2020) of precipitation, temperatures, relative humidity, evapotranspiration, insolation and wind by multiple linear regression (adjusted R² ≈0.895) for the months of highest and lowest rainfall; the performance of conventional and evapotranspiratory cover systems was compared in a one-dimensional regime, finding that the evapotranspiratory cover significantly reduces water percolation by keeping the soil in an unsaturated condition for longer; It is concluded that the integration of characterization tests, statistical analysis and numerical simulation provides precise subsidies for the dimensioning and selection of materials, contributing to the minimization of environmental impacts associated with water inlet the landfill.

Análise das propriedades de pisos de concreto lapidado com diferentes tratamentos superficiais

Mon, 22 Sep 2025 00:00:00 GMT

Análise das propriedades de pisos de concreto lapidado com diferentes tratamentos superficiais Takeda, Nereu Teixeira Rodrigues Grinding and abrasive polishing are essential processes in the treatment of concrete surfaces, as they improve wear resistance, reduce roughness, and increase durability. These techniques have been applied to indoor concrete floors, aiming to meet performance requirements in commercial, corporate, and residential environments. The efficiency of surface treatments is determined by physical, mechanical, and chemical properties that directly influence the service life of the material. The main objective of this study was to analyze the properties of indoor concrete floors subjected to different levels of abrasive polishing, focusing on their resistance, functional performance, and durability. An experimental program was carried out with 12 concrete slabs, of which 10 received surface treatments and 2 were used as references. After 28 days of wet curing, diamond abrasives, latex-based cement, silicate-based surface hardener, sealant, and polishing pads with progressive grit sizes (#200, #400, #800, #1500, and #3000) were applied. The effectiveness of the treatments was assessed through standardized tests, including abrasion resistance, gloss measurement (GU), surface roughness, hardness, chemical resistance, and stain resistance. The results showed significant improvements in abrasion resistance, with wear reduction of up to 24.86%, progressive increases in gloss, reaching 76.86 GU in the high-gloss finish (#3000), and reductions in surface roughness to 0.85 µm. Hardness increased by up to 82.30% compared with the reference samples, while chemical resistance was classified as Class A. In the stain resistance tests, the highest polishing levels achieved the maximum cleaning classification (Class 5). It was concluded that abrasive polishing of indoor concrete floors provided significant physical, mechanical, and chemical performance improvements, directly contributing to increased durability and reinforcing the importance of choosing appropriate surface treatments.

Avaliação do desempenho da estação de tratamento de esgotos sanitários da Unisinos no decréscimo de ibuprofeno, diclofenaco sódio e metoprolol

Thu, 26 Jun 2025 00:00:00 GMT

Avaliação do desempenho da estação de tratamento de esgotos sanitários da Unisinos no decréscimo de ibuprofeno, diclofenaco sódio e metoprolol Santos, Leonardo Zanoelo dos In addition to conventional pollutants, emerging contaminants (ECs) such as pharmaceuticals—detected at trace levels (µg/L to ng/L) and not yet regulated by Brazilian environmental legislation—have received increasing scientific and regulatory attention. Due to their persistence and pharmacological specificity, they pose significant challenges to Water and Wastewater Treatment Plants (WTPs and WWTPs), which were not originally designed for their removal. In this context, the present study evaluated, over six sampling campaigns and four monitoring points at the Unisinos WWTP (São Leopoldo Campus, RS, Brazil), the treatment efficiency in reducing the concentrations of pharmaceuticals such as Diclofenac Sodium, Metoprolol, and Ibuprofen. The study also assessed parameters such as COD, TOC, pH, and residual ozone, and compared two analytical techniques for micropollutant detection: UV254 absorbance and Liquid Chromatography. The Unisinos WWTP showed good performance in meeting the standards established by CONSEMA Resolution No. 355 (2017) for pH and COD, with the latter presenting an average removal efficiency above 75%. Regarding pharmaceuticals, influent concentrations of Ibuprofen and Diclofenac Sodium ranged from 21.10 to 987.46 ng/L and 24.58 to 4464.99 ng/L, respectively. Ibuprofen was more susceptible to the applied treatments, with 51.43% removal in the UASB reactor and 65.03% after ozonation. Diclofenac Sodium, on the other hand, showed greater persistence, with only 4.83% removal in the UASB reactor and 35.47% following the ozonation step. Metoprolol was detected in only one sampling event, indicating a low concentration of this compound in the wastewater at the Unisinos WWTP. These findings indicate that the biological processes employed at the University's WWTP are effective in reducing Ibuprofen concentrations, likely due to its higher biodegradability, but appear to be less effective in treating Diclofenac Sodium. The ozonation step showed low efficiency in pharmaceutical removal, suggesting that the current ozone dosage is insufficient. Statistical analyses revealed a strong negative correlation between Diclofenac and TOC, indicating that the pharmaceutical's removal is associated with the reduction of organic load. TOC also showed a positive correlation with COD and UV254 absorbance, reinforcing its role as an indicator of organic matter. Ibuprofen exhibited a moderate correlation with UV254, suggesting that its presence influences absorbance in this spectral range. In contrast, Diclofenac had a weak correlation with UV254, which may be related to its higher resistance to degradation. These results suggest that UV254 monitoring can be useful for the indirect assessment of certain micropollutants, such as Ibuprofen. Overall, the study indicates that while the Unisinos WWTP meets conventional treatment standards, it presents limitations in the removal of persistent pharmaceuticals. The findings highlight the importance of continuous monitoring and the adoption of advanced technologies in the context of environmental sanitation.

Avaliação da autocicatrização em concretos contendo cimentos ternários do tipo LC³: desenvolvimento e impacto na durabilidade

Tue, 10 Jun 2025 00:00:00 GMT

Avaliação da autocicatrização em concretos contendo cimentos ternários do tipo LC³: desenvolvimento e impacto na durabilidade Gil, Leonardo Masiero The objective of this study was to evaluate the self-healing phenomenon and its impact on the durability of concretes containing ternary cements of the LC³ type. For this purpose, concrete mixes with three different water/cement ratios were developed, using, in addition to the LC³ cement, the CPV ARI cement, in order to provide a comparison between both. The cracking of the samples was made by the diametrical compression test, with an opening limiter device, at the age of 7 days, and the curing procedure adopted was submerged in water for a period of 42 days. Self-healing was evaluated through the analysis of crack images by microscopy, the ultrasonic wave propagation velocity test and the low-pressure water penetration test. All concrete mixes also had molded specimens intended for the compressive strength test. For the durability analysis, in addition to the study of water penetration, the amount of material present in the crack was identified, before and after the test, in order to understand its permanence capacity. The material formed on the surface of the cracks was collected and characterized in terms of its mineralogy through the X-ray diffraction (XRD) test. Ternary cement of the LC³ type has self-healing capacity, although at a lower level when compared to CPV ARI cement, under the conditions of this study. The maximum healing achieved by mixtures with LC³ was 64.5% and for CPV ARI cement it was 76.9%. Much of the material formed in the healed cracks remained after the action of water, for both cements analyzed, indicating its probable contribution to durability. The presence of C-S-H, Ca(OH)2 and CaCO3 was identified in the healing products for CPV ARI cement, and the same crystalline phases for LC³, however with the presence also of C-A-S-H and AFm. Regarding compressive strength, a superior performance of LC³ cement was observed. Such behaviors found in the study are probably linked to the fact that ternary cement of the LC³ type culminates in the formation of more stable hydration products and a denser cementitious matrix, which hinders the migration and percolation of this material to the cracks analyzed, and benefits the development of compressive strength.

Estudo da durabilidade do concreto frente à degradação com ataque de sulfatos em Estações de Tratamento de Esgoto (ETE)

Fri, 02 May 2025 00:00:00 GMT

Estudo da durabilidade do concreto frente à degradação com ataque de sulfatos em Estações de Tratamento de Esgoto (ETE) Bender, Samantha Fernanda The recurrence time established in NBR 8681:2003 for the durability of concrete structures is 50 years. It is expected that concrete structures will not present problems or pathologies within this interval. In this research, the durability and degradation of concrete are addressed due to their relevance and the need for special care in aggressive environments such as Sewage Treatment Plants (ETEs), which have difficulties in developing treatments for concrete with pathologies resulting from sulfate attack. The objective of this study is to evaluate the durability of sewage treatment plants, carrying out inspections, diagnosing anomalies and reporting on their treatment. Within this context, for the analysis and methodology applied in this study, “on-site” inspections were carried out in ten ETEs and samples were collected in one ETE for the sewage and concrete inside the tank in which the tests were subsequently carried out followed The test out followed the produce of NBR 16937 – Aggressive Waters – Durability of Concrete Part 6 with the collection of sewage and the X-ray Fluorescence Test (FRX) to verify degradation with the presence of sulfate with the collection of a sample from the internal wall of a tank in ETE sewage. In addition to the samples collected, to determine the data analysis, it was necessary to carry out a comparison with other researched standards regarding the chemical characteristics of the ETE sewage. The result of the sewage sample collected in June 2024 was SO₄⁻² = 181.10 mg/l. And the result of the collection in October 2024 presented the value found for the study SO₄⁻² = 211.97 mg/l. Regarding the analysis, concrete samples, collected on the inner wall of the treatment tank, were analyzed through FRX, resulting in that the five samples are basically formed by two components, SiO2 = 41.517% and CaO = 10.712% at the depth point at 3.00 cm and alkaline earth metals 6.357% (MgO) during sample collection. It also presented at the point 3.00 centimeters a low concentration of metal oxides (Na2O and K2O) and aluminum (Al2O3). After analyzing the results, it was possible to verify the intensity of the concrete degradation action in ETE in the face of sulfate attack

Reforço à flexão de vigas em concreto armado com a utilização de chapas pré-fabricadas em UHPC

Wed, 30 Apr 2025 00:00:00 GMT

Reforço à flexão de vigas em concreto armado com a utilização de chapas pré-fabricadas em UHPC Grings, Guilherme Gregio This study investigates the use of prefabricated Ultra-High Performance Concrete (UHPC) panels as a solution for flexural strengthening of reinforced concrete beams. UHPC is an advanced cementitious material that exhibits high compressive strength, elevated toughness, and superior durability in aggressive environments, making it a viable alternative for structural repair and strengthening. The research was developed through experimental approaches, beginning with an in-depth literature review on conventional strengthening techniques, such as reinforced concrete jacketing, application of steel plates, and carbon fiber reinforcement. This review enabled a direct comparison between these traditional methods and the potential of UHPC. The experimental phase involved the fabrication of reinforced concrete beams and UHPC panels, with variations in the presence of internal reinforcement within the panels. Chemical and mechanical anchoring methods were employed to bond the strengthening elements to the beams, aiming to ensure material adhesion and evaluate the influence of bonding on the efficiency of the reinforcement. Structural testing was conducted using four-point bending tests, allowing for the assessment of the load-bearing capacity of the strengthened elements, their deformations, and the crack patterns observed throughout loading. The results demonstrated that beams strengthened with reinforced UHPC panels exhibited a performance increase of 224% compared to unstrengthened reference beams, particularly showing reduced crack widths and higher flexural resistance under serviceability limit states (SLS). Based on the analysis of the results, it was concluded that the use of prefabricated UHPC panels as structural reinforcement represents a promising solution, combining high mechanical performance, minimal architectural impact, and enhanced durability when compared to traditional systems. Furthermore, the study highlights that the proposed method enables the practical application of UHPC in structural rehabilitation projects, optimizing costs and facilitating on-site execution. Thus, this research contributes to the advancement of structural strengthening techniques and paves the way for new UHPC applications in the civil engineering field.

Integração de sistemas de produção de biogás em estações de tratamento de esgotos com estratégia para a resiliência urbana em face às mudanças climáticas

Mon, 14 Apr 2025 00:00:00 GMT

Integração de sistemas de produção de biogás em estações de tratamento de esgotos com estratégia para a resiliência urbana em face às mudanças climáticas Pereira, Brenda Natália Population projections for 2054 estimate a total of 9.9 billion people worldwide, with more than half living in urban areas. This scenario poses challenges for urban infrastructure, requiring innovative and sustainable solutions to meet increasing demand in limited spaces. Wastewater Treatment Plants (WWTPs) play a key role in this context and, when using anaerobic processes, generate methane as a by-product. Methane has a global warming potential approximately 28 times greater than carbon dioxide, but it can be converted into thermal, electrical, mechanical energy, or vehicular fuel. The use of methane in WWTPs presents an opportunity for decentralized renewable energy generation, contributing to the reduction of greenhouse gas emissions, circular economy strategies, odor control, and the environmental and financial viability of these facilities. This study aimed to estimate the biogas generation potential of four WWTPs located in the state of Rio Grande do Sul, Brazil — Morada dos Eucaliptos (Novo Hamburgo), Vicentina (São Leopoldo), Tega (Caxias do Sul), and Serraria (Porto Alegre) — as well as to calculate the avoided emissions of greenhouse gases and the potential for electricity generation from methane. The results showed differences among the plants, with Serraria standing out for its highest specific methane production per kilogram of COD removed (0.232 m³ CH₄/kg COD) and the greatest energy generation potential (17,057.14 kWh/day). The Tega plant showed negative methane values due to the dilution of wastewater by the stormwater drainage system. The estimated avoided emissions revealed considerable reductions, especially at the Serraria plant, which could achieve a net reduction of over 51,000 tons of CO₂ equivalent per year. It is concluded that the energy recovery from methane can make WWTPs less dependent on the power grid and more capable of responding to extreme events and system instabilities, contributing to urban resilience and aligning with sustainability and climate adaptation goals.

Avaliação do beneficiamento e recuperação de materiais críticos de ímãs de NdFeB pós-consumo

Wed, 26 Mar 2025 00:00:00 GMT

Avaliação do beneficiamento e recuperação de materiais críticos de ímãs de NdFeB pós-consumo Kich, Agnes Mitzi The increase in Waste Electrical and Electronic Equipment (WEEE) generation has become a global concern, driven by rapid technological advancement and the growing consumption of electronic devices. The improper disposal of this waste not only has the potential to cause negative environmental impacts but also results in the loss of valuable resources, including rare earth elements (REEs), which are essential for the production of modern technologies. In this context, this study evaluated the feasibility of recycling NdFeB magnets from post-consumer hard disk drives (HDDs) through the recovery of these materials. The hydrogen decrepitation (HD) method was employed as an initial step for the extraction and separation of the magnets. This process was applied with the goal of recovering materials for the subsequent production of recycled magnets using the conventional powder metallurgy route. The powder preparation stage, prior to compacting the test specimens, was adapted to reduce environmental impact and occupational risks by eliminating the use of solvents during milling. This modification aimed to minimize the generation of hazardous liquid effluents and workers’ exposure to toxic substances, while also simplifying the process. NdFeB magnets from WEEE were characterized using ICP-OES, XRD, XRF, and SEM techniques. The use of HD demonstrated a significant increase in the grinding efficiency of the magnets, rising from 25.33% to 73.33%. This percentage refers to the amount of material effectively ground within the same milling time. However, the sintering stage yielded unsatisfactory results, as the absence of solvents during milling affected particle size distribution and specimen compaction, promoting oxidation and compromising the cohesion of the resulting magnets. The research highlights the need for strict control of processing conditions to minimize these effects. The SEM micrographs indicate that HD is a promising approach for NdFeB magnet recycling. Nevertheless, adjustments are required to enable the effective production of recycled magnets, emphasizing WEEE recovery as a key strategy for reducing the extraction of critical raw materials and promoting material circularity.

Análise de viabilidade da reciclagem de lama do beneficiamento de rochas ornamentais em argamassas colantes

Sat, 24 Aug 2024 00:00:00 GMT

Análise de viabilidade da reciclagem de lama do beneficiamento de rochas ornamentais em argamassas colantes Cadore, Bianca Carlin

Avaliação do potencial de captura de CO2 em pastas de cimento com adição de cal hidratada e da resistência à corrosão da armadura com aços CA-50 e microcompósito

Mon, 04 Nov 2024 00:00:00 GMT

Avaliação do potencial de captura de CO2 em pastas de cimento com adição de cal hidratada e da resistência à corrosão da armadura com aços CA-50 e microcompósito Menegussi, Giovanna Costella The cement industry is responsible for approximately 25% of industrial carbon dioxide emissions into the atmosphere, equivalent to, approximately, 7% of global CO2 emissions. Given the need to contain the increase in Earth's temperature, collective involvement in minimizing CO2 emissions into the atmosphere is essential. Given this, the capture and storage of carbon in concrete structures through carbonation has been gaining significant prominence. However, the advance of CO2 in cementitious compounds containing metal bars culminates in the corrosion process of the reinforcements. Thus, this research evaluated the potential for CO2 capture in cementitious masses by adding hydrated heat by X-ray diffraction and thermogravimetry tests. Furthermore, the physical and mechanical properties of the masses were studied by specificity resistance and porosity tests by nitrogen adsorption. To enable carbon sequestration, the resistance to carbonation corrosion of the steel microcomposite was investigated using corrosion potential and linear polarization resistance tests. The results indicated strong carbonation of C-S-H in the REF paste, which resulted in greater carbon capture, but with significant losses in mechanical strength. Adding hydrated lime increased the CO2 capture potential and minimized the carbonation of C-S-H in the masses, thus avoiding losses in mechanical strength – especially in the 2CH paste, which obtained an increase of approximately 23% in resistance to variations after carbonation. However, the masses with lime did not reach the CO2 capture potential in the investigated time, due to the decrease in the carbonation rate due to the increase in the alkaline reserve and densification of the cementitious matrix. In the corrosion analysis, the microcomposite steel (MC) was more resistant than the conventional carbon steel (CA-50), remaining passivated in all the investigated scenarios, especially after carbonation. Therefore, it was concluded that the hydrated lime publications preserved the C-S-H of the carbonation and that the use of MC steel avoided the corrosion process of the reinforcements, to enable the capture and storage of CO2 in structures, including reinforced concrete, without compromising durability and service life.

Influência da substituição parcial do cimento Portland por Metacaulim nas propriedades mecânicas e na espessura de pasta do concreto permeável

Mon, 29 Jul 2024 00:00:00 GMT

Influência da substituição parcial do cimento Portland por Metacaulim nas propriedades mecânicas e na espessura de pasta do concreto permeável Ferreira, Ayrton Rodrigues The paved areas of cities mostly use impermeable coatings, which contribute to problems caused by floods and inundations. Permeable concrete coating is a way to mitigate these problems and promote the return to the natural hydrological cycle. Permeable concrete allows water to flow through its physical structure via interconnected macropores. Its physical structure is composed of coarse aggregate coated with cement paste. The paste must have an adequate consistency to avoid defects, failure in the aggregate coating, and clogging of the pores during concrete production. In this regard, the main objective of this research is to verify the influence of the partial replacement of cement by metakaolin on the mechanical and hydraulic properties, as well as the paste thickness of permeable concrete. Thus, the study proposed examining the amount of water to be added to the cement paste that provides the best consistency and allows satisfactory mixing with the aggregate. Four cement pastes were used: a reference paste and replacements of 5%, 10%, and 15% of the cement mass with metakaolin. Water content was tested until each mixture reached a spread of 100±5 mm, measured with the Kantro mini-cone. The uniform rheological behavior in all pastes studied was confirmed through squeeze-flow tests, showing that all pastes with metakaolin exhibited similar behavior when subjected to a force of up to 200 N with a mass displacement of approximately 5 mm. Four (04) permeable concrete mixtures were molded with the same metakaolin contents. Comparing the reference mixture with the replacements, it was observed that the 5% content achieved the best results at 28 days, with the axial compressive strength of 18.09 MPa increasing by about 7.36%, the tensile strength by diametrical compression of 2.73 MPa increasing by about 5.00%, the resistance to degradation by impact and abrasion of 56.18% increasing by about 4.74%, and the permeability coefficient of 0.00507 m/s increasing by about 58.93%. The 10% replacement content showed deterioration in most properties, and the 15% content proved unfeasible.

Fertilizante organomineral a base de resíduos sólidos da indústria de celulose e do beneficiamento de rochas ornamentais

Thu, 26 Sep 2024 00:00:00 GMT

Fertilizante organomineral a base de resíduos sólidos da indústria de celulose e do beneficiamento de rochas ornamentais Borba, Andreza Becker de

Avaliação do desempenho do ozônio na remoção de bisfenol-A : um estudo de caso na ETE UNISINOS– CAMPUS SÃO LEOPOLDO/RS

Tue, 27 Feb 2024 00:00:00 GMT

Avaliação do desempenho do ozônio na remoção de bisfenol-A : um estudo de caso na ETE UNISINOS– CAMPUS SÃO LEOPOLDO/RS Silva, Isabela da In addition to the contaminants traditionally evaluated in sanitary sewers, such as BOD, COD, nitrogen, phosphorus, pH, color, etc., there is great concern about pollutants found in low concentrations, in µg/L or ng/L, that are not yet covered by Brazilian legislation. In this case, these are known as micropollutants or emerging contaminants (EC). Examples of micropollutants include pharmaceuticals, pesticides, endocrine disruptors (ED), hormones, personal care products, cleaning products, among others. Studies addressing these pollutants show that there is an accumulation and increase in concentrations in water resources, since conventional Effluent Treatment Plants (ETPs) do not have the capacity to remove them. Ozone is an effective disinfectant for application in wastewater and for disinfection of drinking water. It is efficient for the removal of a wide range of organic and inorganic compounds. In addition, it meets the requirements for reducing energy usage and reducing the use of chemicals in treatment systems, therefore, this study sought to evaluate the performance of ozone in the removal of Bisphenol-A at the Sewage Treatment Plant (STP) of the University of Vale do Rio dos Sinos (Unisinos) - Campus São Leopoldo/RS. This research identified notable variations in the presence of Bisphenol-A, ranging from 576.93 ng L-1 to 9176.48 ng -1. The evaluation of Bisphenol-A removal efficiency in biological treatment proved to be inefficient, as did the result of ozone-based removal analysis, which was also ineffective. Finally, statistical tests were conducted to assess the correlation between Bisphenol-A, COD, and pH; the tests suggest that there is no measurable linear relationship between these variables. The limitation of effectiveness of a conventional Sewage Treatment Plant in the removal of the investigated micropollutant was evident. It is crucial to emphasize that the results presented in this dissertation serve as a relevant warning regarding the presence of Bisphenol-A in domestic sewage, highlighting the complexity associated with its removal.

Avaliação da sinergia entre aditivo cristalizante e adições ternárias na autocicatrização de concretos

Tue, 20 Jun 2023 00:00:00 GMT

Avaliação da sinergia entre aditivo cristalizante e adições ternárias na autocicatrização de concretos Oliveira, Franciele Rodrigues de Portland cement concrete is the most widely used construction material due to its high compressive strength and durability. To minimize environmental impacts and enhance existing cements, more studies on supplementary cementitious materials are being developed. The durability of concrete structures is an area that lacks understanding regarding the contribution of these materials. Cracks are pathological manifestations that trigger and accelerate other categories of damage. To cease or mitigate the effects of cracks, materials can be employed that, either spontaneously or stimulated, contribute to self-healing. The general objective of this research is to analyze the influence of crystalline admixture on the behavior of concretes produced with different supplementary cementitious materials (SCMs) concerning the selfhealing capacity of cracks. Limestone filler, metakaolin, and fly ash were used as SCMs, composing ternary additions. The experiments adopted three water-to-cement ratios (0.40, 0.50, and 0.60) with the addition of the crystalline admixture at 0% and 1%. Crack formation occurred at 3 days, and to evaluate self-healing, the following aspects were analyzed: the recovery of strength, establishing a mechanical selfhealing index; the ultrasonic pulse velocity; water absorption; optical microscopy images of cracks; and scanning electron microscopy images. The results show that the use of metakaolin is more efficient than reference mixes in terms of durability, and the crystalline admixture contributed to increased strength and reduced water absorption in most mixes. The use of ultrasonic wave propagation velocity could only be taken as a qualitative evaluation of healing. The analysis of images through optical and scanning electron microscopy contributed to justifying the behaviors observed in the other tests, although it was not possible to obtain data that led to an objective assessment. Through the evaluation conducted, it was possible to observe the contribution of SCMs, with emphasis on the combined use of metakaolin and limestone filler, and the effective contribution of the crystalline admixture.

Conceito de economia circular para resíduos de construção e demolição : um estudo de caso em Porto Alegre/RS

Wed, 27 Sep 2023 00:00:00 GMT

Conceito de economia circular para resíduos de construção e demolição : um estudo de caso em Porto Alegre/RS Rinkevicius, Raisa Machado Associated with the three pillars of sustainability, the circular economy (CE) presents itself as an effective tool for reducing the environmental impacts of the construction industry, as it propagates a cyclical concept for construction and demolition materials and waste (CDW). Based on the principle of the 9Rs (refuse, rethink, reduce, reuse, repair, recondition, remanufacture, repurpose, recycle, and recover), the methodology enables a reduction (or non-generation) of these materials and minimizes the extraction of new resources from nature. This study analyzed construction and demolition waste from the perspective of the CE in Porto Alegre, RS, Brazil. Through exploratory analysis, the research examined four distinct phases (waste production, public entities, transportation, and final waste disposal) that encompass the main flows that CDW goes through during its life cycle. Environmental, social, and economic issues were addressed. The results indicate that Porto Alegre construction sector still operates, in most part, in a linear economy model. Although connections between stages were observed, there are still disruptions in the flow, making it difficult to return CDW to the origin of the production chain. The main shortcomings identified in this study include: difficulty in accessing information (generation and transportation); disposal as the primary approach in awareness campaigns, which makes it the primary destination; deficiencies in the control and monitoring process, and inconsistency in legislation. Physical stores selling used materials play an economic and social role but have limited reach, meanwhile digital platforms have a significant reach. Both serve private renovation projects.

Avaliação da utilização de polímeros superabsorventes residuais com fibra ceulósica como agente de cura interna em concretos: ensaios laboratoriais e aplicação em escala real

Fri, 15 Sep 2023 00:00:00 GMT

Avaliação da utilização de polímeros superabsorventes residuais com fibra ceulósica como agente de cura interna em concretos: ensaios laboratoriais e aplicação em escala real Cardoso, Bruno Henrique Reinforced concrete can suffer different types of pathological manifestations, including different types of cracks. This type of manifestation is as harmful as the others, and may be the one that most needs observation, because the moment a fissure occurs, a door opens for the appearance of other forms of pathological manifestations. In the fresh state, in order to minimize the occurrence of surface desiccation cracks and drying shrinkage, curing of the concrete must be started immediately after concreting, normally spraying water in order to keep the concrete moist and prevent water from entering the interior. of the same evaporate. . In this work, a residual superabsorbent polymer (PSAR) was used, having its origin in the production of hygiene products. Along with this material there is also the presence of cellulosic fibers, which are part of the original product, and which can help to reduce shrinkage. PSAR has great potential for use as an internal curing agent, as seen in previous studies, where it was applied in pastes and mortars. Having as objective the practical use of the material, this work evaluates its behavior in concrete, evaluating the effects of internal curing both in the fresh state (superficial desiccation), using tests by Girotto, Barbosa and Maciel (2014), where they performed an adaptation of Turcry ( 2004) and by Saliba et al. (2011), as for the hardened (mechanical strength and free retraction), through the NBR 5739:2007 and the American standard the ASTM C157 standard, and finally its porosity verifies through the RILEM TC 116 PCD standard (1999). This research also presents the first real-scale field study carried out, where the behavior of the material on a concrete floor on the outside of a concrete mixer is verified. The results show that the material contributes positively, reaching a reduction of approximately 2.7 times in plastic shrinkage tests. The mechanical strengths, on the other hand, obtained lower values compared to the reference mix for poor mixes, however, in rich mixes. In the porosity tests it is seen that in curing conditions with low humidity the internal curing agent demonstrates a better efficiency. In field tests, this difference in values is also very noticeable, where the trace with the addition of polymeric material almost does not show cracks, however, in the reference trace, it has an average of 9 cm in length spread throughout its area.

Análise mecânica em elevadas temperaturas de barras poliméricas reforçadas com fibra de vidro

Thu, 31 Aug 2023 00:00:00 GMT

Análise mecânica em elevadas temperaturas de barras poliméricas reforçadas com fibra de vidro Trevisan, Rafael One of the main damages in reinforced concrete structures is the corrosion of the steel reinforcements. As an alternative to this scenario, there is the use of polymer bars reinforced with glass fiber (GFRP – Glass Fiber reinforced Polymer), increasing durability. The material also has reduced mass compared to steel bars and also high tensile strength. In order to use these bars, it is necessary to study their behavior in the face of accidents such as fires and the action of high temperatures, objective of this study. Specifically, the study evaluated the elastic modulus and direct tensile strength of the bars during and after exposure to high temperatures. The experimental program characterized the bar at room temperature. Afterward, the bars were tested during and after exposure to temperatures at levels of 150, 200, 250, 300, and 350 ºC. After exposure to high temperatures, the bars were evaluated with scanning electron microscopy (SEM), and the resin consumption was evaluated through the fiber content test. The indicated results indicate that the fiber content was in accordance with the assumptions of the IBRACON/ABECE recommended practices and international standards. Regarding exposure at high temperatures, it was noticed that the damage was more severe in the tests carried out during the high temperatures than in the bars after this exposure. The reduction in direct tensile strength reached 37% at a temperature of 350 °C. The greatest reduction in the modulus of elasticity, however, was 8.3%, indicating that the performance of the fibers was not so compromised even in the face of exposure to heat. For tests after exposure to high temperatures, the greatest reduction in tensile strength occurred at 150 ºC, being less than 1%. For the modulus of elasticity in this condition, the greatest reduction was 7.9%, observed at 200 ºC. The glass transition temperature obtained was 101.75 ºC. Through scanning electron microscopy, it was possible to perceive flaws that result from the consumption of resin due to the action of heat, such as: surface damage, flaws, less thickness of fiber cover, fiber breakage, among others. The fiber content test after high temperatures showed a direct relationship with the reduction of mechanical properties.

Adsorção de bisfenol-a utilizando cinza de casca de arroz e carvão ativado

Mon, 28 Aug 2023 00:00:00 GMT

Adsorção de bisfenol-a utilizando cinza de casca de arroz e carvão ativado Perotti., Nathalia Currently, the focus of studies on contaminants in water and effluent matrices deals with the presence of micropollutants and their effects on the environment and public health. The problem involved is due to evidence that conventional Wastewater Treatment Plants (WWTP) are not efficient in removing these pollutants. Therefore, there is a need to implement advanced technologies to polish the treatment. Among several techniques under study, adsorption processes stand out as a viable alternative for reducing contaminants, such as the endocrine disruptor Bisphenol A (BPA), which is the subject of this work. In this sense, this work aimed to study the efficiency of adsorptive processes to reduce BPA concentrations in aqueous solutions. Rice Husk Ash (RHA) was tested as an alternative adsorbent to Activated Carbon (AC). The AC was characterized through analysis of granulometric distribution, surface area, specific mass, hydration capacity, pH, zero load test, loss on ignition, total carbon, elemental chemical composition, determination of functional groups and image analysis. Kinetic and equilibrium adsorption studies (isotherms) were performed with standard BPA solutions, quantified by Liquid Chromatography coupled to Mass Spectrometry. In the adsorption kinetics, the following variables were evaluated: contact time (15, 30, 45 and 60 minutes); initial adsorbate concentration (50, 500 and 1000 ng L-1) and adsorbent dosage (0.5, 5.0 and 10 g L-1). The kinetic models of Pseudo-first order and Pseudo-second order were fitted to the experimental data, as well as the obtained experimental isotherms were fitted to the Langmuir and Freundlich models. The characteristics of activated carbon showed a uniform microstructure formed by micro and mesopores and the presence of functional groups such as carboxylic acids, alcohols and phenols. Differently, RHA has macroporous structures, which allowed a fast adsorption, tending to equilibrium after 60 minutes, with removal efficiencies above 99.0%. Among the kinetic models, the pseudo-second order linear model fitted better to BPA adsorption, for both adsorbents, reaching k2 up to 0,99 for RHA and AC. The adsorption isotherms were linear, with the Freundlich isotherm as a reference for adjustments for BPA adsorption using RHA, while for the AC, no model showed unanimity. BPA removal values with RHA ranged from 7,5% to 99,7%; and for activated carbon between 16,5% and 99,2%. These results indicate the potential of using rice husk ash as an alternative adsorbent for BPA adsorption.

Utilização de biossorventes produzidos a partir da casca de banana para a remoção de bisfenol-A presente em efluente sintético

Fri, 25 Aug 2023 00:00:00 GMT

Utilização de biossorventes produzidos a partir da casca de banana para a remoção de bisfenol-A presente em efluente sintético Fonseca, Natália Alice Vargas da Among the contaminants highlighted due to potential risks to the environment and health, bisphenol-A (BPA) is one of the contaminants of great importance as it is present in our daily lives, as it is a plasticizer, and disrupts the endocrine system of beings alive. The detection of this in water sources is a consequence of the fact that national Effluent Treatment Plants are not designed to remove this type of pollutant, and this justifies the study of treatment technologies. In this sense, adsorption is a technique that has been applied for this purpose. Therefore, the objective of the present work is to evaluate the efficiency of the biosorbent made from banana peel (CB) in removing bisphenol-A (BPA) present in synthetic effluent. The CB and activated carbon (CA) adsorbents were characterized regarding moisture content, ash content, granulometric analysis, functional groups, zero charge point, pH, electrical conductivity, real specific mass, hydration capacity, elemental analysis by XRF, SEM and BET surface area. The adsorption tests were carried out by varying the amount of adsorbent, the influence of contact time and the influence of the initial adsorbate concentration. The data obtained were fitted to adsorption kinetic models (pseudo-first order and pseudo-second order) and adsorption isotherm models (Langmuir and Freundlich). The results of bisphenol-A removal at the optimum time for CB in the three adsorption tests were, respectively: 66.23 ± 2.06%, 77.98 ± 2.06% and 75.91 ± 0.86%. The characterization results of the adsorbents were similar, and most were compatible with what was found in the literature for other studies. The results used to evaluate the adsorption kinetics were satisfactorily adjusted to the two models tested, but the best fit was the pseudo-first order model. The kinetic models were adjusted using linear regression and non-linear regression to compare the error functions of these two modes. The results suggest that the non-linear regression had the lowest error function values compared to the linear one. The results used to evaluate the adsorption isotherms were satisfactorily adjusted to the two models tested, but the best fit was the Freundlich model. Finally, it is concluded that the adsorbent made from banana peel has great potential for use as an alternative adsorbent and that there are few studies relating this type of adsorbent to the removal of bisphenol-A. Therefore, it is necessary to continue this study seeking to improve it.

Otimização da eficiência dos ligantes em pastas através do empacotamento de partículas em microescala com substituição parcial de cimento Portland

Thu, 27 Jul 2023 00:00:00 GMT

Otimização da eficiência dos ligantes em pastas através do empacotamento de partículas em microescala com substituição parcial de cimento Portland Kebhard, Jonathan Mello Civil construction consumes a lot of resources ad emits greenhouse gases, and Sustainability becomes one of the main focuses of attention. Among the materials used in the production of cementicious materials, Portland cement has the greatest environmental impact. In this context, the presente work proposes the application of a particle packing method to obtain pastes with greater binder efficiency, using mineral additions such as: sílica fume, limestone filler, granitic filler and pozzolanic ash, these additions being a positive point for Sustainability, which can reduce cement consumption, which has a great impact on CO2 emissions, on the scale of production. In the first stage, the fine materials were characterized. In step 2, the proportion of the fine materials was adjusted, seeking a lower IDE in relation to Alfred’s particle packing model. In the third step, two traits were proposed taking into account the ideal compositon of the paste in terms of stoichiometric calculations. In the fourth stage, the pastes were made, with spreading control in the fresh state. Observing in two types of curing, the pastes were charaterized in the hardened state, in terms of strength, with a photografic survey of the internal part of the test specimens to analyze the dispersion of the particles. In general, in the fresh state, pastes with better packing required more additives and had lower consistency. In the hardened state, the adjusted pastes did not reach the resistance potencial of the reference pastes, but obtained a better Binder efficiency index, with a reduction in the kg/MPa index of 42.5% in the pastes with cement CPII F-40 and 20.7% reduction in the pastes with cement CPIV 32. From na ideal paste contente adopted for concrete, it is calculated that there is the possibility of producing concrete with 3.0 kg/MPa. Evaluating in terms of Sustainability, based on the estimate adopted for concrete, the clinker factor was taken into account, making it passible to produce concrete with 2.4 kg of clinker for each MPa per m³ with cement CPII F-40 and 2.2 kg of clinker for CPIV 32 cement. The method used makes it possible to generate optimized pastes for concrete, with high performance and less environmental impact, due to the maximization of officiency in the use of binders.

Modelo para estimar o consumo de madeira em formas de estrutura de concreto armado em unidades habitacionais unifamiliares

Fri, 12 May 2023 00:00:00 GMT

Modelo para estimar o consumo de madeira em formas de estrutura de concreto armado em unidades habitacionais unifamiliares Furtado, João Henrique Moreira Wood has great relevance in the generation of construction waste because it is an element of temporary use. The knowledge of the wood consumption parameter is of extreme importance to the rational use of the material, both from the constructor's point of view, for financial issues, or from the environmental point of view. This work aims to propose a model to estimate the consumption of wood used as a form of reinforced concrete structures in isolated residential constructions, considering the use of sawn wood boards. It was done from data from architectural and structural projects of residential houses, which were analyzed by linear regression, generating an equation that expresses the amount of wood needed to make forms, using as variables built area, building height and verge length. The proposed model was elaborated in an electronic spreadsheet and expresses the wood consumption for each element, considering different information units (area or boards) and different reuse rates. The results indicate that on average the wood consumption (m²) in relation to the built area (m²) is 2.00m²/m². Of the total, on average, 43% is consumed for column forms, 24% for baldram beams and 33% for beams in general.

Sistema a vácuo para redução da carga orgânica e de nutrientes em esgoto sanitário

Mon, 27 Mar 2023 00:00:00 GMT

Sistema a vácuo para redução da carga orgânica e de nutrientes em esgoto sanitário Oliveira, Rafael de Freitas The use of vacuum technology, applied to the area of sanitary sewage and effluents, is associated with studies of the properties of compaction and settlement of sludge and processes of degassing and/or removal of gases and/or determination of the quantity/quality of gases generated in aerobic and anaerobic treatment processes. However, there is a need for specific studies on the effect of vacuum application on biological treatment processes and their relationship with improvements in the quality of the treated effluent. From this, this research aimed to analyze the influence of the vacuum in the reduction of the organic load and of nutrients in the treatment of raw sanitary sewage. The research began with the study and development of a bench-scale vacuum chamber for system operation and analysis of the experimental configurations adopted through theoretical foundations and preliminary tests. The methodology was based on carrying out three experimental sequences (depending on temperature and pH variables) in two vacuum variations (40 kPA and 80 kPA) under two variations of vacuum exposure time (30 and 60 minutes). The samples were analyzed for potential organic load removal (BOD, COD and TSS) and nutrient removal (NA, NTK and P). The obtained results suggest that the vacuum has influence in the reduction of the organic load and of nutrients in the raw sewage. Regarding the efficiency analysis regarding the removal of organic load, the reductions in BOD, COD and TSS ranged from nonexistent to 36.9%, from 9.3% to 32.1% and from 6.9% to 52.4 %, respectively. Regarding the analyzes regarding the efficiency in the reduction of NA, NTK and P, the removals ranged from 3.9% to 14.1%, 4.1% to 12.9% and from 12.2% to 31%, respectively. For BOD, COD and TSS analyses, the best operating conditions were VAT30 (vacuum of 40 kPa, period of 30 minutes and temperature of 40°C), VA60 (vacuum of 40 kPa for period of 60 minutes) and VBP30 (vacuum of 80 kPa, period of 30 minutes and pH change), respectively. For NA, NTK and P analyses, the best operating conditions were VB30 (80 kPa vacuum for 30 minutes), VB60 (80 kPa vacuum for 60 minutes) and VAP60 (40 kPa vacuum, period 60 minutes and pH change), respectively.

Influência do grau de desidroxilação na reatividade de argilas cauliníticas calcinadas

Wed, 08 Mar 2023 00:00:00 GMT

Influência do grau de desidroxilação na reatividade de argilas cauliníticas calcinadas Pires, Maikon Moreira de The high consumption of Portland cement worldwide brings with it the responsibility for its environmental impacts due to its high carbon dioxide (CO2) emissions originating from the clinker manufacturing process. Thus, a strategy adopted to reduce CO2 emissions is the partial replacement of clinker with supplementary cementitious materials (SCMs). Among the SCMs are calcined clays, especially kaolinitic clays. In order for clays to become active, meaning that silicon and aluminum are available to react with calcium hydroxide and carbonates in the case of LC3 cement, they need to be activated, which occurs through temperatures above 500°C. Kaolinite is one of the main clay minerals that compose kaolin, with a chemical composition of Al2Si2O5(OH)4, being a 1:1 dioctahedral phyllosilicate structure. Dehydroxylation consists of the removal of this hydroxyl, disrupting the crystalline structure and making silica and alumina available for pozzolanic reactions. This research aimed to evaluate the influence of dehydroxylation degree on the reactivity of kaolinitic clays. For this purpose, two kaolinitic clays called white kaolin and pink kaolin were used, with a total sum of ∑SiO2;Al2O3;Fe2O3 of 79% and 77%, respectively, and a sum of ∑SiO2;Al2O3 of 78% for the white clay and 76% for the pink clay. Calcination temperatures of 550, 650, 750, and 850°C were used, with residence times of 15 and 45 minutes. The degree of dehydroxylation was correlated with the physical and chemical characteristics of the clays, as well as with the consumption of Portlandite (CH), combined water, and compressive strength of cement pastes. After analyzing the results, it was possible to infer that although the degree of dehydroxylation positively influenced the consumption of CH and the content of combined water, the most influential factor in the development of reactivity of the evaluated clays was the specific surface area. As the chemical parameters of the clays were similar, as well as particle size, arrangement of hydroxyls, and surface regularity, the higher reactivity of the pink kaolinitic clay can be attributed to its higher specific surface area (twice the SS of the white clay).

Avaliação do comportamento de revestimento de argamassa submetido a envelhecimento acelerado e à carbonatação

Sun, 28 May 2023 00:00:00 GMT

Avaliação do comportamento de revestimento de argamassa submetido a envelhecimento acelerado e à carbonatação Menegotto, Camila Werner The continuous wetting and drying cycles to which mortar coatings are subjected throughout their life, associated with the effect of carbonation and the impacts arising from use, cause traction and shear stresses to the coating that, throughout its useful life, may cause microcracks in the structure of the coating and, therefore, influence the way the material ruptures. Consequently, it is recommended to give mortars a low modulus of elasticity, which is responsible for their ability to deform without cracking when subjected to stress. However, this property is affected by the aging process and carbonation, which can make the mortar more rigid or more elastic. The objective of this research is to evaluate the effect of carbonation and accelerated aging on the behavior of the mortar when subjected to tensile stress, when applied on different substrates, as well as to estimate the modulus of elasticity by digital image correlation (CID). Two ceramic substrates with different capillary absorption and roughness values were used. Mortars were molded in the proportion 1:1:4 (cement:lime:sand), CP II-F 40 and lime CH-I, a/gl ratio 0.80. Samples were cured for 56 days in a controlled environment. The voids index, water absorption by capillarity and tensile strength were determined before and after the aging and carbonation processes. The stress and deformation analysis was carried out applying the CID methodology and later calculating the modulus of elasticity with the aid of specific software. It was concluded that accelerated aging increases capillary water absorption and reduces bond strength and that carbonation is influenced by the type of substrate to which the mortar is applied. The modulus of elasticity calculated from the CID were coherent with the values found in the literature and indicated that there are modulus differences along the thickness of the coating.

Segurança contra incêndio: estudo sobre sistemas de selagem perimetral para compartimentação vertical em fachadas envidraçadas

Thu, 23 Feb 2023 00:00:00 GMT

Segurança contra incêndio: estudo sobre sistemas de selagem perimetral para compartimentação vertical em fachadas envidraçadas Giannakos, Gregório Beck da Silva The densification of urban centers, the verticalization of buildings and the increasingly recurrent use of glazed facades puts fire safety in these buildings on debate. Since the glass facades are composed of non-fire resistant elements, it becomes a fragile system and liable to compromise the overall safety of the building and its users. Propagation through the facade can happen both internally, through the space formed between the facade and the building, and externally through leapfrogging. In this way, compartmentalization must be taken into account even in buildings with glazed facades, based on Brazilian technical instructions, which started to adopt 1,20 meter vertical bulkheads together with fireproof sealing systems and horizontal extensions of 0,90 meters as passive protective measures. Unlike other countries, Brazil does not have a specific technical test standard to evaluate the system proposed by the technical instructions, which raises questions about the areal effectiveness of these systems. The present work presents the evaluation of a vertical partitioning system according to Brazilian technical instruction based on the test methodology of ASTM E2307 (ASTM, 2020) and ASTM E2874 (ASTM, 2019), as well as a discussion of the results based on the behavior of fire. Based on the results obtained, it was found that the perimeter seal was able to resist fire until the moment the glass broke next to it and, after breaking, the measured temperatures exceeded the normative limits. The 1,20 meter vertical bulkhead proved to be effective in preventing flames from entering the upper floor, but the heat flux measured at the top of the bulkhead would be capable of igniting materials commonly used as coatings in commercial rooms. Thus, the constructive system proposed by the technical instruction proved to be efficient until the glass broke along with the perimeter sealing, demonstrating the importance of having an appropriate Brazilian technical standard for the development of specific systems that guarantee the vertical compartmentation in the glazed facades.

Potencial de autocicatrização dos materiais cimentícios promovida pela biomineralização de carbonato de cálcio por diferentes linhagens bacterianas em uma matriz com ar incorporado

Mon, 10 Oct 2022 00:00:00 GMT

Potencial de autocicatrização dos materiais cimentícios promovida pela biomineralização de carbonato de cálcio por diferentes linhagens bacterianas em uma matriz com ar incorporado Mello, Vinicius Muller de Historical data and future projections indicate a growing use of concrete worldwide, while its production and that of other cementitious composites is linked to a large consumption of inputs and energy. Cracking is a constant pathological manifestation in these materials, contributing to the deterioration of buildings and causing various damages. In this scenario, studies seek to provide cementitious materials the ability to self-heal their cracks, with some of them focused on the use of bacteria for this purpose. It is common to encapsulate bacteria for protection against the aggressiveness of the cementitious matrix, and recent publications suggest incorporating air pores into the matrix to serve as protection for bacteria. Thus, this study seeks to evaluate different bacterial strains, collected in the metropolitan region of Porto Alegre - RS, isolated and molecularly identified, regarding their potential for the formation of healing products in a mortar with incorporated air. Optical microscopy was performed to verify the occurrence of self-healing, in addition to scanning electron microscopy (SEM) associated with energy dispersive X-ray spectroscopy (EDS) for morphological and elemental characterization of the crystals, and X-ray diffraction (XRD) for its mineralogical characterization. The influence of different strains on the compressive strength of the mortar was verified. The isolation steps performed resulted in the obtaining of 6 distinct isolates, characterized as belonging to the genera Bacillus, Pseudomonas, Cronobacter and Citrobacter. All isolates provided an increase in compressive strength compared to air-entrained and bacteria-free mortar, with increases between 10 and 108% at 28 days. Regarding the analysis by optical microscopy, 1 of the isolates showed no formation of healing products, while the others showed healing between 7 and 14 days of analysis, but only in the lower regions of the specimens, in addition to an observed loss of part of the crystals formed. XRD and EDS analyzes indicate that the crystals are calcite, being visualized by SEM calcite, but also aragonite. The results indicate that all isolates were able to promote selfhealing and that their encapsulation in incorporated air bubbles was effective.

Proposição de uma estrutura de planejamento e controle de médio prazo com apoio de BIM

Fri, 21 Oct 2022 00:00:00 GMT

Proposição de uma estrutura de planejamento e controle de médio prazo com apoio de BIM Tonatto, Marciano The inefficiency of traditional construction project management systems has resulted in the dissociation between the stages of Engineering, Procurement and Construction (EPCM), contributing to increase fragmentation between different processes in project management. EPCM projects are characterized by large contracts, high costs, long planning and execution periods with fixed completion dates, specialized technical staff, and the involvement of several stakeholders. In this context, Building Information Modeling (BIM) has been used to facilitate information sharing and support decision making that, associated with the planning approach called Location Based Management (LBMS), allows the stages of a project to be structured as a flow pulled by the construction planning. The objective of this research is to propose an information modeling structure to allow a more systematic planning and control in the medium term through the use of BIM. The 4D model is used to represent and simulate the construction progress, while the look-ahead planning information is related to the creation of the construction-oriented engineering and procurement packages. The model adopted features of the Advanced Work Package (AWP) approach to support the delivery of all detailed work packages. The balance line was used to represent the workflows through the hierarchical structure of locations. As a methodological approach, constructive research (design science research) was chosen, and the model was developed through an exploratory study and an empirical study applied in collaboration with an engineering company specialized in the pharmaceutical and food industry. It was concluded that the integration of preconstruction processes promoted by location-based planning, with the support of BIM, provided a more effective control of the look-ahead planning, allowing the visualization of the variability of production processes in order to eliminate or reduce the uncertainties for the execution of tasks.

Aplicação da análise de valor agregado para o controle de prazos e custos em obras públicas

Tue, 27 Sep 2022 00:00:00 GMT

Aplicação da análise de valor agregado para o controle de prazos e custos em obras públicas Telles, Luís Gustavo Souza Extension of deadlines and costs are common events in civil construction, especially in public works. Studies are carried out at different levels with the aim of developing methods and tools that contribute to the management in relation to compliance with the time and cost previously established. The present study aims to investigate the use of the Earned Value Management (EVM) method in the process that precedes the bidding, as well as in the stages of contracting and execution, offering support for taking preventive and/or corrective actions regarding the need for amendments to deadlines and costs. The work analyzed three infrastructure works already completed, which had extensions of deadlines and costs during their construction processes, applying the EVM method to them. The result of the analyzes obtained in this study indicates that the three works had the need for amendments to deadlines, costs, and contractual readjustments, in different periods of their construction, evidencing that there was not, on the part of the Public Administration, a preliminary analysis of the technical parts and of its feasibility in complying with the signed agreements. In the same way, the company that won the bidding process corroborated such preliminary information to the project management, both in the identification of the projected resources to be disbursed monthly and in the actual physical and financial progress, having in the application of the EVM a support for taking preventive actions, prior to the bidding process, as well as in the physical-financial management, during the execution, aiming at mitigating the need for contractual amendments.

Modelagem termográfica: uso de fotogrametria em imagens termográficas de edificações para visualização tridimensional de manifestações patológicas

Mon, 22 Aug 2022 00:00:00 GMT

Modelagem termográfica: uso de fotogrametria em imagens termográficas de edificações para visualização tridimensional de manifestações patológicas Hemesath, Hubert Braun It has long been known about the existence of buildings defects that cannot be visibly identified early, such as detachment of ceramic cladding on facades, when on the outside of buildings, and infiltrations, when on the inside of them. These manifestations usually interfere with the thermal coefficient of the elements that make up the building, causing a discrepancy in the emission of infrared radiation, which can be measured in a thermogram. In order to better visualize and understand the set of pathological manifestations, with regard to temperature, an orthomosaic composed of several superimposed thermographic images results in a three-dimensional image on a thermal scale, which facilitates the identification and measurement of the analyzed defects. Through it, it is possible to navigate throughout the modeled surface, perceiving the colorimetric variations in an isolated or systemic way. For this purpose, in this study, images were captured through cameras with an infrared sensor, orthogonally to the recorded surface, so that they could be processed in Agisoft Photoscan, a photogrammetry software, allowing the comparison between the data obtained in the field with the model full-scale digital surface of the building to be studied. The capture took place with two thermal imaging cameras, FLIR C5 and FLIR A325 and with two UAVs, DJI Phantom 4 Advanced and DJI Mavic 2 Enterprise Advanced. After processing the images, a three-dimensional model of the building was obtained, keeping the dimensional properties in temperature scale, thus allowing an easy reading and understanding of the data to carry out the search for buildings defects. The results obtained in the comparison between the measurements of the facades of the building in this study, acquired on the project and on the IR and RGB orthomosaics, indicate that photogrammetric processing on thermographic images was possible, resulting in a model with sufficient scale accuracy to perform measurements of distances and areas of defects, with an average accuracy of 97.37% in the center of the orthomosaic IR and 98.46% in the center of the orthomosaic RGB.

Análise da influência do cromo trivalente e hexavalente na formação dos compostos de hidratação de pastas de cimento

Fri, 30 Sep 2022 00:00:00 GMT

Análise da influência do cromo trivalente e hexavalente na formação dos compostos de hidratação de pastas de cimento Savicki, Gabriela The search for more sustainable treatment technologies for industrial waste to avoid their final disposal in landfills is growing, especially for hazardous waste. Chromium (Cr) is a metal that can bring the characteristic of toxicity to residues, depending on its valence and concentration, making it dangerous, and several industrial residues have this metal in their composition. The stabilization by solidification (S/S) is a treatment technology that uses residues containing metals in Portland cement matrix and it is necessary to evaluate the technical and environmental feasibility of the application. There are several studies on the feasibility of S/S for Cr waste, but few have specifically analyzed the Portland cement hydration process. This research aimed to evaluate the influence of water-insoluble Cr(III) compound (Cr2O3) and water-soluble Cr(VI) compound (K2CrO4) in the hydration products formation of Portland cement pastes in the initial ages, through the adding of 0%, 10%, 20% or 30% of these compounds separately. Analyzes of pH, X-ray diffraction (XRD), isothermal calorimetry, thermogravimetry (TG/DTG) and compressive strength were performed on the prepared samples. From the results, it was possible to verify that the incorporation of the water-insoluble Cr(III) compound (Cr2O3) delayed the hydration process of the Portland cement paste, but did not prevent the hydration compounds formation and got higher compressive strength than the reference sample. In addition, it was possible to evidence the formation of the compound called “bentorite”, whose chemical formula is Ca6Cr2(SO4)3(OH)12.26H2O. The incorporation of water-soluble Cr(VI) (K2CrO4) resulted in a more significant delay in the hydration process of the material and it was not possible to verify the formation of hydrated products according to the reference sample, besides the compressive strength was smaller. In these samples, it was also possible to evidence the formation of a hydrated product containing Cr, named hydrated calcium chromate (CaCrO4.H2O). The treatment of Cr(III) containing waste trough S/S could be a viable option with the application of other analysis such as environmental viability, while the S/S for Cr(VI) containing waste is not recommended.

Influência da aplicação de produtos de proteção passiva ao fogo no comportamento acústico de lã de PET

Tue, 31 May 2022 00:00:00 GMT

Influência da aplicação de produtos de proteção passiva ao fogo no comportamento acústico de lã de PET Ott, Maira Janaina The finishing and coating materials for civil construction must meet technical criteria aimed, primarily, at the safety of users. In this context, the materials used to improve the acoustic quality of environments must have, as a basic premise, the compliance with legislation and normative references that define the appropriate classification for fire safety in internal environments. That said, this research aimed to perform an analysis on the influence of the application of passive fire protection surface coatings, on the sound absorption behavior of 100% PET wool, a fibrous material already studied and validated as a good acoustic absorber. The passive fire protective surface coatings were intumescent paint for acoustic foams, applied to PET wool, and flame retardant fabric to 100% polyester fabric. The substrate, the PET wool, was used in two compositions: in the thickness of 60 mm and density of 20 kg/m³ and in the thickness of 60 mm and density of 30 kg/m³. To achieve the proposed objective, experimental research was carried out to obtain the absorption coefficients of materials with and without the application of passive fire protection products, through impedance tube testing, according to the procedure of the ISO 10534-2 standard. In addition, ignitability tests were carried out, in accordance with the requirements of ISO 10534-2:1998, on materials with and without passive fire protection. Applying the proposal, was found that the samples of raw PET wool and the samples of PET wool with fabric with retardant suffered ignition, while the samples with intumescent paint did not have ignition. As for the sound absorption coefficient, the samples with and without the application of intumescent paint were compared and was found that the loss of sound absorption is bigger in the medium and high frequencies, representing, in the worst case, a difference of αs=0,11, in the densest wool. However, was identified that the density difference of the tested materials is more significant than the presence or absence of the passive fire protection coating.

Beneficiamento físico-químico do resíduo sólido dregs da indústria de celulose e papel para emprego em misturas asfálticas

Thu, 31 Mar 2022 00:00:00 GMT

Beneficiamento físico-químico do resíduo sólido dregs da indústria de celulose e papel para emprego em misturas asfálticas Souza, Vitória da Luz de The pulp and paper industry has great relevance in the global economy, being one of the top waste generating industry. As a large part of this waste is still disposed of in industrial landfills, studies that enable its recycling are increasingly necessary, promoting the mitigation of negative environmental impacts allied to the reduction of the consumption of non-renewable natural resources. The general objective of this research was to evaluate the effect of the treatment of dregs (waste generated in Kraft process) to enable its use as a filler in bituminous mixtures. For this, is was proposed washing and filtration of the waste, promoting the reduction of the content of soluble salts, responsible for the increase in the consumption of petroleum asphalt cement (PAC) and reduction of the mechanical resistance of bituminous mixtures. To verify the efficiency of the treatment, the physical, chemical and mineralogical characterization of the waste was carried out before and after the treatment, as well as the physical and mechanical characterization of the asphalt mixtures produced with and without the incorporation of the waste. There was a reduction in pH values and mainly in electrical conductivity over the 3 washes applied, being the EC reduced by 98% when compared to the untreated waste. In the Marshall test, the mixes containing dregs in their composition met all normative limits, and the mixture containing 4% of dregs showed lower fluence than the reference mix. The treatment of this material can enable its use in more sustainable pavements, paying attention to the specifications established by current standards.

Avaliação da influência do uso de agregados com diferentes coeficientes de dilatação térmica no comportamento de argamassas de revestimento submetidas a envelhecimento acelerado

Fri, 08 Apr 2022 00:00:00 GMT

Avaliação da influência do uso de agregados com diferentes coeficientes de dilatação térmica no comportamento de argamassas de revestimento submetidas a envelhecimento acelerado Zanolla, Ieda Maria Fagundes The present work aims to evaluate the behavior of rendering mortars with aggregates with different thermal expansion coefficients when subjected to thermal stresses generated by accelerated aging. Four cementitious rendering mortars have been developed, using natural fine aggregates (AN) and fine aggregates from crushed basaltic rock (ABB), crushed granitic rock (ABG) or crushed quartzite rock (ABQ). The thermal expansion coefficients of the aggregates and the characterization of mortars in the fresh state were determined. In the hardened state, the rendering mortars were subjected to accelerated aging and analyzed before and after the thermal stress. The evolution of the cracking in the microstructure of the rendering mortars was analyzed by scanning electron microscopy. The results have demonstrated that mortars composed by natural fine aggregate (AAN) have shown a significant degradation when compared to the rendering mortars composed by crushed basaltic rock (AABB), crushed granitic rock (AABG), and quartzite crushed rock (AABQ). The importance of textural parameters and of the thermal properties of the aggregates in the mortar composition has been proven in all rendering mortars made out from crushed rock aggregates, as well as the influence of the superplasticizer used in the increase of the mechanical strength during the accelerated aging.

Recuperação de fósforo de efluente líquido de parboilização de arroz e avaliação como potencial fertilizante de liberação lenta a partir de nanocompósito à base de nanomateriais lamelares e biopolímeros

Wed, 30 Mar 2022 00:00:00 GMT

Recuperação de fósforo de efluente líquido de parboilização de arroz e avaliação como potencial fertilizante de liberação lenta a partir de nanocompósito à base de nanomateriais lamelares e biopolímeros Röhnelt, Maurício Gammertt The rampant rate of population growth in recent decades has demanded an exacerbated use of fertilizers in the agricultural sector to meet global food demand, leading to the depletion of natural resources and negative environmental impacts such as eutrophication. In this context, the objective of this research was to synthesize a nanocomposite of alginate hydrogel (ALG) and polyvinyl alcohol (PVA) incorporated with layered double hydroxides (LDH) based on steel slag, evaluating its efficiency in the recovery of phosphorus from washing effluent of parboiled rice, and potential use as a slow-release fertilizer. LDH synthesis was performed by the coprecipitation method in variable pH up to a value of 12, resulting in two groups of samples of LDH12-25 (pH=12, T= 25°C) and LDH-12-65 (pH= 12, T=65°C). The LDH was characterized by the FRX, EDX, SEM, DRX, and BET techniques. A higher concentration of calcium and iron cations was found in these, with the majority crystalline phase being iron and calcium hydroxysilicate-like compound (Ca3Fe2Si1,15O4,6(OH)7.4) (35.2%). Subsequently, the nanocomposites were formed with 8% (m/v) of LDH in ALG-PVA (concentration of 1% [m/v] and 0.5% [m/v]) and submitted to an adsorption batch test. (24h, 25ºC, and 125 rpm, adsorbent dosage from 3 gL-1 to 11 gL-1 ). It was found that the LDH-12-25 sample presented both textural (surface area of 87.084±4.919 m²/g) and morphological characteristics (regular crystals with dimensions of 168 ± 45 nm) more favourable, the better performance in phosphorus recovery (91.33±0.70%) of diluted effluent (factor 1:10, C0= 10 mg.L-1 ) when incorporated in ALG-PVA. The isotherm profile was considered favourable, with the Langmuir and Freundlich models being consistent with the results (R²> 0.9). The maximum adsorption capacity calculated assumed an average value of 1.583 mg. g1, following worldwide research cited in this work. Finally, when the sample ALG-PVALDH-12-25 was submitted to a kinetic test of phosphorus release, a release of 95.36% was verified over 14 days of testing, suggesting a linear release curve. Therefore, it was evidenced a promising technology of phosphorus recovery with controlled release, becoming an alternative to supply the global demand for fertilizers as well as decreasing natural resources depletion such as phosphate rocks.

Avaliação de métodos de moagem de imãs provenientes de HDs de computadores e notebooks em fim de vida útil

Fri, 14 Jan 2022 00:00:00 GMT

Avaliação de métodos de moagem de imãs provenientes de HDs de computadores e notebooks em fim de vida útil Wong, Wei Wei Hard Disks (HDs) magnets have neodymium (Nd) in their composition, a chemical element belonging to the lanthanide group and known as the Rare Earth element. The need for this element in the development of cutting-edge technology and the global dependence on Chinese supply, brings a great alert regarding the need to seek alternative sources to meet the demand for this material. With the growing increase in waste from electrical and electronic equipment (WEEE), urban mining can be applied to obtain raw material from WEEE, in order to minimize environmental impacts and recover the materials and metals present in these wastes. Recycling is one of the alternatives to meet this demand for products that use rare earths and, at the same time, reduce pollution. In this way, this study carried out the steps that precede the recycling of magnets: disassembly and mass balance of the HDs as well as their components, the segregation of components, demagnetization and evaluation of magnetism. Afterwards, the magnets were milled. Some assumptions were defined to determine the most appropriate grinding methodology, such as lower energy consumption and higher yield in the grinding process. Demagnetization was achieved in 45 minutes by heating to 350°C in a muffle furnace. In the methods determined in the present study, the most efficient grinding is performed in the eccentric mill, compared to the ball mill. The result indicates that the time of 45 minutes showed the best yield, with 20.95% efficiency in grinding, reaching a granulometry of of <0.25mm. Therefore, it was determined that grinding in the eccentric mill is the most efficient in terms of time and energy consumption, according to the method used in this work.

Uso de lama de carbonato de cálcio gerada no processo kraft como material de enchimento em concreto asfáltico usinado à quente

Fri, 25 Feb 2022 00:00:00 GMT

Uso de lama de carbonato de cálcio gerada no processo kraft como material de enchimento em concreto asfáltico usinado à quente Próspero, Kidner Angelino The use of solid waste in hot-machined asphalt concrete has the potential to provide an economic gain not only for the sector in which they are generated, but also in sectors such as civil construction, especially when these industrial wastes have basically constituted of inorganic material. The general objective of this work was to evaluate the technical feasibility of using calcium carbonate slurry, generated in the KRAFT process, as a filling material, in the production of hot-machined bituminous asphalt mixture. In the methodology used, based on the respective regulations in force, the reference trace of the asphalt mixture was determined based on the Marshall dosage, measuring the optimal content of petroleum asphalt cement (PAC) and also the percentage of residue (sludge of calcium carbonate) that would best fit the trace. Mixtures with 2%, 3% and 4% calcium carbonate slurry were tested. For the stability and creep parameters, the results did not show a statistically significant difference, despite increasing up to a certain amount of LCC inserted in the mixture. As for the percentage of voids and bitumen-voids ratio, the values showed a statistically proven improvement, even verified by the analysis of the images using a magnifying glass, where in the mixture with 4% there were signs of exudation from the CAP, thus indicating the possibility of decreasing the percentage of voids. CAP in its composition, thus demonstrating its potential for use as a filler in hot-machined asphalt mixtures.

Estudo de caso aplicado a logística reversa de pneus inservíveis no município de Porto Velho/RO

Wed, 22 Dec 2021 00:00:00 GMT

Estudo de caso aplicado a logística reversa de pneus inservíveis no município de Porto Velho/RO Moreira, Marcos Vinicius Carneiro This study aims to evaluate the application of the reverse logistics of waste tires in the city of Porto Velho-RO, based on the diagnosis of the process and guided by the principles and guidelines of Law No. 12,305 - National Solid Waste Policy (PNRS) for a Solid Waste Management Plan (PGRS) and as recommended by CONAMA (National Solid Waste Council) Resolutions No. 258/1999 and No. 416/2009. The proposed methodology involves field research in the municipality and refers to a quali-quantitative approach, which is configured in a case study, and in which the current situation of actions taken to manage waste tires was evaluated. The research had as steps the identification of the agents involved, diagnosis of waste tire management in the municipality, the survey of environmental aspects and impacts based on the sources of generation, final disposal and quantification of waste, the identification of failures and opportunities for improvement based on the requirements for compliance with CONAMA Resolutions No. 258/1999 and 416/2009 and on the requirements for compliance with legislation. The study also aimed at proposing guidelines for the management of these wastes in the municipality with a view to their use as raw material. The results obtained from the survey show that most companies evaluated receive tires that are not in use. It is observed that most companies do not receive support from suppliers, which implies the lack of information about the reverse logistics of waste tires. As guidelines, and based on the diagnosis carried out through exploratory research via a questionnaire in interviews, it is proposed that companies provide training courses on the PNRS and awareness of the importance of proper management of waste tires; it is proposed that the autarchies carry out the increase in the number of ecopoints scattered in strategic locations in the municipality and also draw up monitoring and inspection plans for both the collection and the final destination of these wastes.

Avaliação da resistência à corrosão de barras de aço galvanizados em grampos para obras de contenção

Sun, 21 Nov 2021 00:00:00 GMT

Avaliação da resistência à corrosão de barras de aço galvanizados em grampos para obras de contenção Souza, Stefania Darold The soil nail in recent years has been increasingly used in slope stabilization and excavation works. Until the beginning of 2020 there was no Brazilian standard for the design and execution of stapled soil structures. There were also no technical recommendations in relation to the injection material (cement paste) or the bar to be used and its respective durability, it was common agreement to use manuals or international standards. The durability of a structure is determined by several factors and when this structure involves metallic components, one of the main ones is corrosion. For this reason, the steel bars currently used in the market have a galvanizing layer, and, in addition to the galvanic protection, the second protection layer is made by cement paste, which needs to be fluid for better injection execution, which ends up by raising the water/cement ratio (w/c) of the mixture. Thus, in this work, ways to mitigate the intrinsic characteristics of the pastes that could somehow accelerate the corrosion process were studied. Fresh, hardened and electrochemical tests were carried out on two pastes with similar fluidity, but with different w/c ratios (0.50 and 0.35) with different types of cure and exposed or not to an aggressive environment with the presence of chlorides. Thus, it was possible to see that the pastes with w/c 0.35 presented more satisfactory results for porosity, less absorption and cracking and greater strength than the pastes with w/c 0.50. When the pulps were compared in relation to chloride penetration, an average penetration rate was seven times higher for the pulp with a relation w/c 0.50, compared to the pulp with a relation w/c 0.35 and additive.