PPG Engenharia Civil

Estudo de revestimento compósito de porcelanato e borracha reciclada para atenuação do ruído de impacto

Mon, 18 Aug 2025 00:00:00 GMT

Estudo de revestimento compósito de porcelanato e borracha reciclada para atenuação do ruído de impacto Klippel Filho, Sérgio When analyzing building acoustics, the propagation of impact sounds through the structure of the building can be considered one of the most relevant problems, being a recurring subject of complaints. In these cases, floating floor systems are efficient solutions to reduce the transmission of vibrations generated by impacts on floors, consisting of a rigid walking surface on a resilient material. Acting as a spring, the resilient layer must have damping properties and compression strength against permanent and accidental loads adequate to guarantee its performance over time. In this context, the objective of this study is to develop and evaluate lightweight floating floors formed by ceramic tiles and recycled rubber agglomerate mats to attenuate the transmission of impact sounds in vertically adjacent rooms, analyzing their current and future performance. The study was based on the development of a lightweight floating floor and the physical and acoustic characterization of its components, proposing a model to predict the reduction of impact sounds, calibrated from full-scale measurements in a laboratory environment (ISO 10140), based on the dynamic stiffness (ISO 9052-1) of the rubber agglomerate mats and the physical characteristics of the rigid walking layer. The determination of the future behavior of the lightweight floating floor was carried out based on the compression creep test (ISO 16534) and the evaluation was carried out from its virtual application in a hypothetical building, considering direct and indirect transmission (ISO 12354-2). The results indicated that the lightweight floating floor compositions have adequate performance, with ΔLw values in the order of 16 to 18 dB, demonstrating efficiency, considering that the compositions have a total thickness of 11.5 to 20.5 mm. In the time domain, when subjected to loads of up to 15 years, the damping capacity, in terms of weighted impact sound pressure levels reduction, of the compositions was reduced by up to 2 dB. However, the developed compositions have a considerable impact sounds reduction and adequate maintenance of performance in the time domain.

Avaliação de microplásticos em lixiviado de aterro sanitário

Mon, 22 Sep 2025 00:00:00 GMT

Avaliação de microplásticos em lixiviado de aterro sanitário Schmitt, Graziela Taís Microplastics (MPs) are plastic particles ranging in size from 0.001 to 5 mm, whose presence in the environment has raised increasing concern due to potential risks to biota and human health. Despite advances in research in aquatic environments, the occurrence and characterization of MPs in landfill leachates remain scarcely explored in Brazil. In this context, the aim of this study was to identify and characterize MPs present in raw leachate samples from a landfill located in the municipality of São Leopoldo – RS. Three sampling campaigns were conducted throughout 2024. The samples underwent sieving, oxidative treatment with Fenton’s reagent, vacuum filtration, and subsequently, suspected particles were confirmed as MPs by Raman spectroscopy. Only after this chemical confirmation were the particles physically characterized in terms of morphology, shape, color, and size. Concentrations ranged from 13 to 73 items/L. Polypropylene (PP) and polyethylene (PE) polymers predominated, together representing the majority (80%) of identified MPs. Fragment-type particles were predominant (98%), indicating a secondary origin, i.e., derived from the fragmentation of plastic waste disposed of in the landfill. Most particles were smaller than 75 µm, suggesting high mobility and potential for percolation in the environment. MP abundance correlated with leachate physicochemical variables, such as turbidity, organic load, and color, as well as environmental factors, including temperature and precipitation. The results indicate that landfills may act as significant sources of MPs. This study helps fill knowledge gaps on the topic in Brazil and may support environmental education initiatives and the development of strategies to mitigate plastic pollution.

Estudo da passivação dos aços CA-50 e ASTM 1035 9100 submetidos a soluções alcalinas simuladas de cimentos álcali-ativados sob carbonatação

Tue, 25 Mar 2025 00:00:00 GMT

Estudo da passivação dos aços CA-50 e ASTM 1035 9100 submetidos a soluções alcalinas simuladas de cimentos álcali-ativados sob carbonatação Krein, Laércio Antonio Concrete is widely used in construction due to its strength; however, its production consumes large amounts of energy and emits significant quantities of carbon dioxide. With population growth and the increasing demand for infrastructure, the environmental impacts of this process become even more critical. In this context, alkaliactivated materials have gained attention for their ability to reduce emissions and enable the reuse of industrial residues, although further research is still required regarding their protective performance for embedded steel reinforcement. Additionally, since concrete is a highly alkaline medium, the potential for carbon dioxide capture by concrete structures can be explored. However, alternatives to CA-50 steel, widely used in reinforced concrete structures in Brazil, must also be considered. In this context, corrosion-resistant ASTM A1035 9%Cr (MMFX) steel emerges as a promising option. Thus, the present study aimed to evaluate the protective capacity of simulated alkaliactivated and Portland cement solutions on CA-50 and MMFX steel, both in their original pH and during the pH reduction of the solutions. Steel samples were exposed to the testing environment in their as-produced state, without surface treatment to remove the oxide layer commonly present on rebars. Moreover, the passive film was formed in different simulated solutions based on alkali-activated cements (with pH values and ionic concentrations much higher than those of Portland cement, used as a reference). These same samples remained in contact with the solutions throughout the carbonation process (with pH ranging from 14.57 to 8), ensuring that the components formed at higher pH levels continued to interact with the medium on the sample surface at lower pH levels. After conducting tests such as corrosion potential, polarization resistance, Tafel, cyclic voltammetry, and electrochemical impedance spectroscopy, it was observed that simulated alkali-activated solutions with excessively high pH levels, while forming passive films on CA-50 steel, did not form protective films on MMFX steel. This behavior is likely due to the high solubility of chromium hydroxides in these environments. However, as pH decreased due to carbonation, alkali-activated solutions began to provide protection to the steels. Notably, even at pH levels below 11, MMFX steel reinforcements remained passivated, indicating the potential for stimulating carbonation in reinforced concrete structures to capture and store CO₂ within the cement matrix. Nonetheless, despite these promising Therefore, future research should also include testing on physical specimens to validate these results.

Ligantes álcali-ativados à base de metacaulim, cinza de casca de arroz e fíler calcário

Fri, 27 Sep 2024 00:00:00 GMT

Ligantes álcali-ativados à base de metacaulim, cinza de casca de arroz e fíler calcário Lima, Cristian Jonathan Franco de The increasing population demand, day after day, for greater infrastructure in cities, with more homes, buildings, highways and special works of art, makes concrete one of the most consumed materials in the world. As a result, the production of Portland cement generates high carbon dioxide emissions into the atmosphere. Faced with the need to reduce this environmental footprint, alkali-activated cements have been gaining ground in research and practical applications, as they are based on minimally processed natural materials or industrial solid waste, tending to provide important reductions in carbon emissions. The objective of this research is to analyze the mechanical properties and the appearance of efflorescence in alkali-activated cements produced from the concomitant use of metakaolin (MK), rice husk ash (CCA) and limestone filler (FC). The raw materials were properly processed and defined through chemical and physical tests and the mixtures were evaluated through tests to verify mechanical performance: resistance to axial revision; durability: flower formation; Thermogravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC) tests; Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Four mixtures were developed: 100% with metakaolin precursor, two binary mixtures, one with 20% replacement by limestone filler and the other 20% by rice husk ash, a ternary mixture with 10% replacement by limestone filler and 10% % by rice husk ash, using potassium hydroxide (KOH) solution as a chemical activator. The mixtures prepared did not develop resistance to high axial compression for use in structural concretes, with the best averages being the binary mixture of MK+CCA, followed by the ternary mixture with MK+CCA+FC. Regarding the formation of efflorescence, the best results were for the binary mixture of MK+FC and ternary mixture of MK+CCA+FC, which did not show degradation. The TG/DTG, DSC, FTIR and XRD tests and results confirmed the formation of the K-A-S-H amorphous gel, corroborating and assisting in the analysis and understanding of the other results and data obtained.

Habitação de interesse social: sistema de indicadores para orientar decisões referentes à implantação de novos empreendimentos em áreas urbanas

Sun, 04 Aug 2024 00:00:00 GMT

Habitação de interesse social: sistema de indicadores para orientar decisões referentes à implantação de novos empreendimentos em áreas urbanas Souza, Claiton de Oliveira The public policy for implementing social housing units is directly linked to the need to eliminate or reduce the housing deficit. The need for housing, especially social housing, amounts to billions of units, and in Brazil this number reaches 6 million units. The objective of the study is to develop a system of indicators to guide the implementation of new social housing projects in urban areas. The System seeks to assist public servants and those interested in implementing new housing projects by indicating possible implementation problems, which have been widely identified in many projects carried out, especially in the outskirts of large cities. To develop the System, indicators based on Laws, Ordinances and Standards were used, in addition to those created during the preparation of the study and validated by professionals and public servants involved in public housing policy. A housing project in Porto Velho/RO and one in the city of Rio Branco/AC Orgulho do Madeira in PVH/RO were used as parameters and assessments for the System. The system includes four categories of indicators that refer to up to five characteristics inherent to them. The categories are: Demand, with a total of 40 points; Location of the Condominium/Development, with a total of 20 points; Local Infrastructure, with a total of 20 points; and Development/Condominium, with a total of 50 points. The sum of the categories reaches the total weights measured by the system, for a total of 110 points. This dynamic of points is linked to tables that show the percentages obtained in each category, as well as being linked to the lighthouse with the colors: blue, (indicating the feasibility of implementing the project); green, where implementation is feasible but requires attention (in this case the proponent must check which category is attracting attention); yellow, implementation of the project is shown to be unfeasible, as it will generate many problems; and finally, red, which indicates the impossibility of implementation. The Indicator System was applied to three projects, one in Porto Velho/RO, one in Rio Branco/AC and a Model Project in Porto Velho/RO, and the results expressed the reality of the first with major problems, the viability of the second, as well as the viability of implementing the Model Project.

Análise de desempenho de três estações de tratamento de esgoto municipais com diferentes tecnologias, quanto aos parâmetros físico-químicos, microbiológicos e o Bisferol A

Fri, 02 Aug 2024 00:00:00 GMT

Análise de desempenho de três estações de tratamento de esgoto municipais com diferentes tecnologias, quanto aos parâmetros físico-químicos, microbiológicos e o Bisferol A Räder, Arlindo Soares Among many micropollutants, the plasticizing agent bisphenol A (BPA), widely used in the food and beverage industry, in the manufacture of polymeric materials and utensils, is considered a xenoestrogen and endocrine disruptor, which justifies continuous research in the area. The present work carried out a performance analysis of three municipal Wastewater Treatment Plant (WWTP), comprising the association of several technologies available on the market: Upflow Anaerobic Sludge Blanket, added to an aerobic biological filter with natural aeration, activated sludge and anoxic reactor, Morada dos Eucaliptos WWTP (ME WWTP); Moving Bed Biofilm Reactor, added to a physical-chemical treatment, high-rate decanter and ultraviolet disinfection, Vila Palmeira WWTP (VP WWTP); and activated sludge of the Sequential Batch Reactor type, Mundo Novo WWTP (MN WWTP). The results observed allowed us to conclude that the best overall efficiency for the treatment of the BOD, COD, Nam, TSS and SSed set was observed in the MN WWTP (95.3%, 89.8%, 94.9%, 92.8% and 88.4%). For the PT parameter, the best results were in the ME WWTP (61.5%) and VP WWTP (61.2%). All the WWTPs studied presented removal greater than 92% for the CT and E. coli set, with the best result observed in the VP WWTP (98.7% and 98.2%). Regarding the micropollutant BPA, a calibration curve was created in the raw sewage environmental matrix, where the linearity results indicated a working range of 10ng.L-1 to 900ng.L-1. The lowest known concentration point of the calibration curve, 10ng.L-1, was adopted as the Limit of Quantification (LQ). Thus, it was possible to analyze and quantify the presence of BPA in raw and treated sewage for the three WWTPs. Quantified BPA concentrations were observed within the linearity range of the curve. BPA presented complex and adverse behavior, being present in raw and treated sewage in the three WWTPs. This behavior corroborates previous research, which identified that BPA is present in all environmental matrices, characterizing it as a ubiquitous micropollutant. This alone justifies monitoring WWTPs for the possibility of micropollutants (in this case, BPA) occurring, considering the sewage treatment processes adopted, as well as the advancement of methodologies and analytical techniques for identification and quantification, to verify their presence and removal from environmental matrices for future and adequate legal regulation.

Desenvolvimento de reagente remediador a base de biocarvão e ferro zero valente

Mon, 27 Mar 2023 00:00:00 GMT

Desenvolvimento de reagente remediador a base de biocarvão e ferro zero valente Souza, Débora Machado de Brazil is a country with a strong influence of the agribusiness sector on the Gross Domestic Product - GDP, with crops distributed in the five regions of the country. It stands out among world agricultural production rankings, such as rice production, in which it ranks ninth, with 1.5% of total production. The country is still rich in biomass, generated in the production and processing processes of agribusiness. On the other hand, contamination of groundwater has been generated due to anthropic actions, in particular, by industrial activity. One of the problems is that the contaminating compounds are difficult to degrade, and another is that there is a shortage of specific remedial products in the country. It is in this context, in which the present work sought to develop a national remedial reagent to recover groundwater, contaminated by organochlorines, organic compounds that are difficult to degrade. The work also aimed to promote the valorization of biomass and residues from the agricultural and cutlery industry. The reagent developed has as its main composition carbon and metallic iron. The carbon source used is biochar, obtained from rice husks in natura by the thermochemical process of slow pyrolysis, and the source of metallic iron is waste from cutting cutlery blades. The experimental program was divided into stages: characterization of a commercial remedial reagent, production of the reducing reagent from industrial waste (agribusiness and metalworking) and its characterization. It was considered that potential effluents generated during the research were treatable and a brief study was carried out on the feasibility of producing a national innovative commercial product. The efficiency of the remedial reagent produced was evaluated through a bench treatability test, lasting 42 days. The results of the treatability test identified a degradation potential of the remedial reagent, developed on a laboratory scale, above 90%, of the organochlorines present in the studied water samples. The results obtained in the chemical and physical analyzes of the remedial reagent produced, presented some characteristics similar to the studied commercial reagent: iron content of 27.54% and the commercial reagent 28.56; adsorption content of 92% and the commercial reagent 90%; specific mass of 2.0023 g cm-3 and that of the commercial reagent 1.9444 g cm-3; zero charge point between pH 7 and 7.5 and commercial reagent pH 7. As for the inorganic elemental chemical composition of the remedial reagent produced, the combination of iron and silicon elements was identified, which suggests that both are acting together in aqueous environment, supporting a greater degradation or decontamination of contaminants. By evaluating the results obtained, it was possible to conclude that the remedial reagent produced has a high innovative potential for future production on an industrial scale.

Contribuição ao estudo do CLT – Cross-Laminated Timber – em elevadas temperaturas via simulação computacional

Thu, 30 Nov 2023 00:00:00 GMT

Contribuição ao estudo do CLT – Cross-Laminated Timber – em elevadas temperaturas via simulação computacional Ribeiro, Lívia Maria Palácio Cross-Laminated Timber (CLT) is a contemporary product in civil construction, and therefore has undergone great evolution in terms of its constructive applicability in Brazil and around the world. Despite being a product made from a combustible material, many studies regarding the use of CLT have emerged, and one of the main aspects is its performance in a fire situation, which can compromise a structure. Through computer simulations, using the Ansys software, thermomechanical analyzes were carried out on CLT panels, floor-to-floor type, joined by countersunk screws, varying the thickness in 3, 5 and 7 layers of lamellas, called panels P1, P2 and P3. To this end, the behavior of the panels in a fire situation was investigated, imposing temperature levels between 200ºC, 400ºC, 600ºC, 800ºC, 1000ºC and 1200ºC, with a maximum exposure time to fire of 60 minutes, with the objective of check the effect of heat transfer on the wood and connections as well as their mechanical behavior. As a result, as the temperature of the wooden panels increased, it was progressively linear in terms of heat transfer within the piece, reaching a maximum time of 60 minutes, with all models exceeding the carbonization point when reaching the level of T400ºC at 45min. However, for thermal analysis, the number of layers inhibited heat transfer in the screws, with only panel P1 obtaining a significant value of 162.27ºC maximum temperature in relation to panels P2 and P3, with 5 and 7 layers. As for the glued displacements, the wooden panels had small deflections, with panel P1 moving 6.3% more in relation to panel P2, and 8.2% more in relation to panel P3. And the displacement of the screws was also small, largely due to the applied support condition, reaching a maximum of d = 5.28x10-3 mm for panel P3. Thus, the investigations carried out indicated that as the thickness of the lamellas in the panels increases, the elements tend to acquire better thermomechanical results.

Sistema de requisitos de sustentabilidade ambiental para edifícios públicos – SRS-EdiP: proposta para integrar o uso de BIM com foco no atendimento aos ODS

Wed, 28 Jun 2023 00:00:00 GMT

Sistema de requisitos de sustentabilidade ambiental para edifícios públicos – SRS-EdiP: proposta para integrar o uso de BIM com foco no atendimento aos ODS Postay, Renata The civil construction sector is experiencing pressure to increase levels of sustainability throughout its life cycle and adopt digitization and innovative technologies in its processes. The set of 17 Sustainable Development Goals (SDGs) and respective targets is a reference for the international sustainability agenda. Building Information Modeling (BIM) represents an essential path to innovation and digitalization of construction. However, the implementation of both still challenges the sector. This work aims to propose a system of environmental sustainability requirements for public buildings, focusing on meeting the SDGs and BIM use. To this end, it uses existing regulations and programs, such as the BIM Execution Plan, proposed by the Brazilian Agency for Industrial Development (ADBI), Casa Azul Seal (proposed by Caixa Econômica Federal), and LEED (North American seal). The study was carried out according to the phases of (1) contextualization; (2) analysis of environmental sustainability requirements in the building's life cycle; (3) proposed system (4) analysis of the proposed system. The proposed system is called SRS-EdiP and is structured into 9 categories, aligned with the 9 SDGs related to construction and public buildings. In all, 62 guiding requirements are proposed for different professionals throughout the life cycle of the building, involving different BIM uses. The analysis of the SRS-EdiP indicates that 60% of the requirements are related to the Project phase, covering the nine Categories/SDGs, with the second stage with more SDGs involved being the Preliminary Study. Applying the SRS-EdiP involves fifteen categories of professionals, and ten potential BIM uses linked to the requirements. Including the SRS-EdiP in the BIM ADBI Plan increases the environmental sustainability bias of the Plan, initially little discussed, demonstrating that it can be a potential articulator between environmental sustainability, BIM, and public works based on a reorganization of existing documents.

Produção industrial de blocos de concreto para alvenaria à base de rocha vulcânica ácida álcali-ativada

Thu, 03 Aug 2023 00:00:00 GMT

Produção industrial de blocos de concreto para alvenaria à base de rocha vulcânica ácida álcali-ativada Conceição, Luís Cláudio Staudt Society's growing awareness of environmental degradation and the consequences of increased greenhouse gas emissions, coupled with the rising demand for raw materials in the construction industry, has spurred the search for more sustainable building materials and practices. Focusing on alkali-activated materials as an alternative, this research addresses a gap in the literature by integrating technical, environmental, and economic aspects, particularly on an industrial scale. Therefore, this study aims to provide a significant contribution to the development of industrial-scale production of alkali-activated concrete blocks using a mining byproduct (acidic volcanic rocks). This entails a comprehensive assessment of technical aspects, such as dimensional stability, water absorption, compressive strength, and water resistance, as well as environmental considerations, including CO2 emissions and embodied energy, along with large-scale production costs. The results demonstrate that, although these blocks exhibit lower strength compared to Portland cement, they meet the regulatory requirements established by NBR 6136 for use in construction. Furthermore, they present a substantial potential for reducing CO2 emissions (32% to 52%) and energy consumption (11% to 19%). Cost analysis revealed only a 2% increase compared to Portland cement. In this context, it was possible to evaluate, for the first time, the technical, environmental, and cost viability of producing concrete blocks using alkali-activated cement derived from acidic volcanic rock as a binder on an industrial scale. The consolidation of these results highlights the potential of using acidic volcanic rocks as a viable alternative to Portland cement in concrete block production.

Desenvolvimento e aplicação de um modelo de sustentabilidade baseado no sistema de gestão ambiental implementado de uma instituição de ensino superior brasileira

Wed, 02 Aug 2023 00:00:00 GMT

Desenvolvimento e aplicação de um modelo de sustentabilidade baseado no sistema de gestão ambiental implementado de uma instituição de ensino superior brasileira Dai-Prá, Léa Beatriz Higher Education Institutions (HEIs) play a relevant role in the education of the academic community and of the society to which they are inserted. As the concepts of sustainability emerged, many Universities also started their journey in sustainable development, managing their institutions environmentally, socially, and economically. To monitor and measure the Environmental Management Systems (EMS) of institutions, there are several tools and metrics, among them, certifications, which undergo auditing processes; and there are models developed with the objective of measuring sustainability, considering the particularities of the university and its environmental management. In this context, the main objective of this work was to develop and apply a sustainability model, based on existing EMS data from a Brazilian HEI, ISO 14001 certified, the Universidade do Vale do Rio dos Sinos (UNISINOS). The two university campuses (Unisinos São Leopoldo and Unisinos Porto Alegre) were used as case studies for the adoption of the model. Methodologically, four steps were used to achieve the main objective of this thesis: 1) analysis of UNISINOS EMS indicators (environmental, social and economic) from start (São Leopoldo – 2004; Porto Alegre - 2019); 2) conducting an online questionnaire applied to the academic community; 3) development of the model with its parameters and scores (using data from 2017 to 2022); 4) comparison between campuses and critical analysis of Unisinos' sustainability (based on previous steps). The indicator analysis stage showed that UNISINOS EMS has been applying monthly monitoring and working on improvements to its system since it started, including environmental education for the academic community. In the online questionnaire, the feedback from the community pointed mainly to the good development of the University's environmental management, in addition to indicating the concern with environmental awareness and the existence of environmental indicators. In the development of the model, Unisinos São Leopoldo, which has had the EMS for the longest time, evolved around 33 points, from 2017 to 2022, on the sustainability scale created, going from 'Sustainable medium level' to 'Sustainable ' in the model evaluation. And Unisinos Porto Alegre, with the most recent EMS, still has many fluctuations between the years studied (2019-2022), about 39 points of difference in the sustainability scale from 2019 to 2022, with an evaluation of 'Sustainable medium level' in the last year evaluated, requiring more attention and monitoring time to be fully evaluated, but despite this, it has shown good results in environmental indicators, for example . The period of the COVID-19 pandemic brought many uncertainties to the world and, consequently, to sustainable development, which was largely harmed, since attention was focused mainly on the health of the population and survival, pausing the development of several sectors, such as economic and environmental. Unisinos also suffered from this event and there was a setback in the evolution of the sustainability of both campuses, in the indicator’s evolution, which are now working on their recovery. Finally, the conclusion of this work is that the University must keep its strategies aligned, be they environmental, economic, or social management. All spheres of sustainability must be in order, for the sustainable development of the institution to succeed.

Correlação de imagem digital e modelagem numérica aplicada à determinação de propriedades elásticas em revestimentos de argamassa sob tração

Fri, 18 Aug 2023 00:00:00 GMT

Correlação de imagem digital e modelagem numérica aplicada à determinação de propriedades elásticas em revestimentos de argamassa sob tração Lacerda, Benício de Morais Cementitious coating mortar, which works adhered to ceramic or concrete substrates, is a construction material in constant evolution. The elastic properties of the mortar are influenced by the properties of the substrate, the mortar and the interfacial connection between them, where adhesion occurs, and have a great influence on the durability of the system. This work aims to systematize a methodology for applying digital image correlation (DIC) and using numerical modeling to evaluate the elastic properties of coating mortars applied to ceramic substrates when subjected to tensile stress. A single batch of mortar was used, applied to two types of ceramic substrates. The samples were subjected to accelerated carbonation in a chamber with 3% CO2 concentration for a period of 147 days and subsequently subjected to the effect of degradation through accelerated aging resulting from 20 cycles of wetting and drying. The work consisted of two stages, one experimental and the other numerical. In the experimental stage, a test program was developed in order to quantify and evaluate the parameters of tensile adhesion strength, modulus of elasticity and Poisson's ratio in tests monitored by digital image correlation. The second stage consisted of modeling and numerical simulation of the experimental program using, as input data, the average results obtained from digital image correlation. The experimental results indicated that there are differences in elastic modulus throughout the thickness of the same coating, which decrease from the external face, towards the central region and the interface with the ceramic substrate. The tensile adhesion strength among the REF samples was higher compared to the aged and carbonated samples. Numerical simulation allowed the construction and analysis in finite elements of a model suitable for the proposed scale of the experimental study based on the DIC results. The boundary conditions applied in the numerical models under the tensile bond strength test directly influenced the interface connection, a region susceptible to rupture planes, as well as its global behavior.

Avaliação da eficiência do processo de biocarvãoe das potencialidades de recuperação de bio-óleo em uma carvoaria de Rondônia-Brasil

Mon, 31 Jul 2023 00:00:00 GMT

Avaliação da eficiência do processo de biocarvãoe das potencialidades de recuperação de bio-óleo em uma carvoaria de Rondônia-Brasil Ribeiro, Umberto Gonçalves In Brazil, most of the biochar produced is used in the steel industry, to reduce iron ore and produce pig iron. Other uses include domestic and commercial consumption in cooking food. Some regions maintain planted forests to provide raw materials for this purpose, but in small-scale production this does not occur. These productions generally use artisanal techniques. The objectives of this thesis included drawing up a diagnosis of this ancient form of human activity, to record the main parameters of production in a district of Rondônia-Brazil, where a resulting bio-oil was identified as a co-product – potential renewable energy source, but which is not recovered locally. A production in the district of Triunfo, RO-Brazil was selected to monitor the process. Monitoring involved data collection, with no intention of interfering in the existing process, to support a diagnosis and suggest proposals for improvements. The work was carried out on site (in the exact location where the materials are produced), during the diagnosis stage. Biomass and bio-oil samples were collected; the bio-oil was fractionated by vacuum distillation. Then, subjected to chemical and physical-chemical analyzes in the laboratory (pH, viscosity, density), during the characterization stage. The results showed low yields of both biochar (19.5% by mass) and total bio-oil (1.3 L/m3 of solid wood). The temperatures used were suitable for the production of biochar (average of 220 °C) and well distributed inside the oven (coefficient of variation ~11%). However, they are not suitable for producing bio-oil. The techniques for identifying both functional groups (FT-IR) and chemical composition (GC-MS/MS) showed mainly ketones, esters, acids, traces of nitrogen and phenols/aromatics. These products generate environmental impacts due to their toxicity, and therefore should not be disposed directly on the ground. Suitable applications may include the chemical industry, composite materials and the pharmaceutical industry. The diagnosis of the process indicates the need for investments in structuring and regularizing the activity, promoting the well-being of communities, on terms of environmental and economics.

Modelo de decisão para priorização de ações sanitárias, infraestrutura e saneamento à COVID-19

Fri, 31 Mar 2023 00:00:00 GMT

Modelo de decisão para priorização de ações sanitárias, infraestrutura e saneamento à COVID-19 Chagas, Vladimir José The COVID-19 pandemic has a virus of zoonotic origin, which has evolved and infected humans worldwide. Studies that aim to propose management tools to combat COVID-19 and, similarly, other diseases with the same origin that occurred in recent years. In the state of Rondônia, in the municipality of Ji-Paraná, based on this thesis, a decision model was proposed to prioritize health actions, infrastructure and sanitation to COVID-19. For this purpose, data from daily Epidemiological Bulletins (01/05/2020 to 09/14/2021) issued by the State Health Surveillance Agency, used as sources of official information for this research. Based on the SIRD deterministic model, which divides the population into susceptible (S), infected (I), recovered (R) and dead (D) categories, the main parameters that make up the matrix were defined. Data were organized in Excel spreadsheets, with the parameters (18) evaluated for each neighborhood. Cluster sampling with sections represented by neighborhoods. Thus, the Prioritization/Risk Matrix with the parameters (Deaths, Contaminated and Recovered) receive weights that represent degrees of severity. The score by neighborhood generated a ranking in spreadsheets and spatio-temporal-dynamic maps, with daily updates, integrated with information regarding municipal conditions in the areas of sanitation, infrastructure and environment, resulting in an Urban Development Index (IDU) associated with COVID cases -19. Thus, lacking areas and possible APP areas with disease contamination vectors were identified. The model will allow the public manager to prioritize the neighborhoods for the necessary actions related to the pandemic. In the case of Ji-Paraná, the study indicated the IDU among the neighborhoods, the best: Nova Brasília, Jardim dos Migrantes, Centro, and the worst: Jardim Florida, Vila de Rondônia, Nova Ji-Paraná.

Desenvolvimento de misturas asfálticas contendo material fresado e ligante asfáltico modificado com grafite

Fri, 24 Mar 2023 00:00:00 GMT

Desenvolvimento de misturas asfálticas contendo material fresado e ligante asfáltico modificado com grafite Pereira, Alex Gomes In Brazil, the study and development of modified asphalt mixtures are justified due to the scarcity of raw materials and the high number of pathological symptoms identified on the highways. Within this context, the development of new asphalt mixtures is a subject that arouses great interest, but requires further research. The general objective of this research was to verify the technical viability of using milled material and graphite-modified asphalt binder as a component of asphalt mixtures. It presents and discusses results regarding the mechanical behavior of asphalt mixtures produced simultaneously with recycled material and modified binder using commercial graphite and comminuted in a high-energy mill. In order to achieve the specific objectives of this research, in addition to the characterization of the tested materials (waste and graphite), ten asphalt concrete compositions were produced, namely: CA-REF110, CA-REF120, CA-GRAF210, CA-GRAF220, CA-GRAF310 , CA-GRAF320, CAGRAFC410, CA-GRAFC420, CA-GRAFC510 and CA-GRAFC520 that were subjected to static indirect tensile strength and modulus tests. The mechanical resistance tests showed a superior behavior in the compositions produced simultaneously with recycled material and binder modified with comminuted graphite in the order of 31.86% and 19.81%, followed by the behavior of the mixtures produced with recycled material and binder modified with commercial graphite in the order of 66.56% and 84.69% compared to conventional mixtures. In the evaluation of the resilience modulus, the mixtures CA-GRAF210, CA-GRAF220, CA-GRAF310 and CA-GRAF320 presented superior resilience modulus in 9.55%, 12.76%, 17.36% and 17.18%, respectively, compared to conventional concrete. While the mixtures CA-GRAFC410, CAGRAFC420, CA-GRAFC510 and CA-GRAFC520 showed an increase of modulus of resilience in the order of 20.77%, 18.39%, 25.39% and 26.74% compared to the reference compositions, thus constituting a strong instrument to provide improvements to the road sector in the country. Therefore, the results of the mechanical tests showed a positive performance of the modified asphalt mixtures. This conclusion contributes to confirm that the use of RAP in asphalt compositions can be an alternative to conventional aggregates for the production of asphalt mixtures.

Influência da mineralogia de fíleres carbonáticos na hidratação de cimentos ternários com argila calcinada oriundos da região amazônica

Thu, 22 Dec 2022 00:00:00 GMT

Influência da mineralogia de fíleres carbonáticos na hidratação de cimentos ternários com argila calcinada oriundos da região amazônica Piovesan, Jayne Carlos One of the great contemporary challenges to mitigate CO2 emissions in the earth's atmosphere is the production of cements with reduced emissions of this gas that causes the greenhouse effect. Therefore, seeking to reduce the use of clinker in cement, new alternatives are tested, among these, the study of ternary compositions, such as LC3. The use of calcitic limestone is discussed a lot, but very little is said about the use of dolomitic limestone filler, due to the hypothesis that the magnesium present causes a negative impact. Thus, we sought to investigate the hydration of ternary compositions composed with carbonate fillers of different mineralogies and calcined clay from the Amazon region. The composition used is in accordance with the literature, being 50% clinker, 5% gypsum, 30% calcined clay and 15% limestone. Pastes with three types of carbonates were prepared for proper comparisons. In view of the climate in the states of the Legal Amazon, and its effect on the temperature of cement hydration, the produced pastes were cured at temperatures of 21 °C and 60 °C, and tested for 7, 28 and 91 days of age. The results showed that excess magnesium tends to react in the composition with the alumina of the cement, forming products such as brucite, at both temperatures, but with more evident formations at the temperature of 60 °C, according to DRX. When magnesium and alumina are mixed in excess, portlandite tends to be completely consumed, which may lead to problems in compressive strength. The paste containing magnesium carbonate and cement proved to be the ideal scenario regarding the amount of magnesium and alumina for hydrotalcite formation at both curing temperatures, being more intense at 60 °C. The dolomitic limestone used in LC3 showed results similar to the reference limestone, usually used as calcitic limestone, with compressive strength results above 30 MPa, without formation of brucite, hydrotalcite or thaumasite, with curves of calorimetry, thermogravimetry and product phases hydrates similar to each other. In view of the study carried out, it is possible to state that dolomitic limestone has the potential to be used as a dolomitic filler in LC3, under the boundary conditions of this study.

Desempenho térmico e eficiência energética como estratégias de preservação do patrimônio arquitetônico

Tue, 13 Dec 2022 00:00:00 GMT

Desempenho térmico e eficiência energética como estratégias de preservação do patrimônio arquitetônico Giralt, Rômulo Plentz The first references to environmental issues in buildings of cultural interest appear after the oil crisis, in the 70s of the last century, showing that the concern with interventions in this type of buildings, aiming at user comfort and energy efficiency, is not such a recent issue. The reduction in energy availability and the new demands for energy efficiency brought the need to evaluate the ability of these buildings to conserve energy, also considering the improvement of their thermal performance. On the other hand, there is concern that in architectural heritage, many measures may result in inappropriate changes to important architectural aspects or cause serious damage to the materiality of the building. In this way, requalification strategies are discussed that achieve thermal performance and energy savings with minimal alteration of the buildings, through the use of materials that do not cause damage and that represent a reliable economic investment. The problem is not limited to introducing new materials, equipment and systems in buildings of cultural interest, but respecting the significance, integrity, authenticity and also the reversibility of the intervention, fundamental principles of the theory of restoration of architectural heritage, prescribed in charters and international conventions, in order to safeguard the elements that give it value. In this context, the main goal of the research is to propose strategies for the requalification of residential architectural heritage in Rio Grande do Sul with a view to thermal performance and energy efficiency. The work method categorizes the architectural heritage in the context of the occupation of the territory of Rio Grande do Sul, defining the case studies. Different rehabilitation strategies are proposed for the interventions: floor and subfloor insulation, roof insulation, wall insulation and strategies related to openings. All were submitted to a quantitative evaluation, through computer simulations, and a qualitative evaluation, through the application of questionnaires to researchers in the area of historical heritage. The results, for each case study, showed which strategies had better thermal performance, energy efficiency and greater heritage compatibility. Next, a mechanism for weighting the evaluations was presented, which pointed out the most appropriate strategies, providing the creation of a simulation model, for each case study, combining these strategies, whose results showed significant reductions in energy consumption. The most appropriate requalification strategies can be incorporated into norms and manuals for intervention in buildings of cultural interest.; Die ersten Hinweise auf Umweltaspekte in Gebäuden von kulturellem Interesse erscheinen nach der Ölkrise in den 70er Jahren des letzten Jahrhunderts und zeigen, daß die Sorge um Eingriffe in diese Art von Gebäuden, die auf Benutzerkomfort und Energieeffizienz abzielen, nicht so neu ist. Die Verringerung der Energieverfügbarkeit und die neuen Anforderungen an die Energieeffizienz machten es erforderlich, die Fähigkeit dieser Gebäude zur Energieeinsparung zu bewerten, auch unter Berücksichtigung der Verbesserung ihrer thermischen Leistung. Auf der anderen Seite besteht die Sorge, daß im architektonischen Erbe viele Maßnahmen zu unangemessenen Veränderungen wichtiger architektonischer Aspekte führen oder die Materialität des Gebäudes ernsthaft beschädigen könnten. Auf diese Weise werden Requalifizierungsstrategien diskutiert, die mit minimaler Veränderung der Gebäude thermische Leistungen und Energieeinsparungen erzielen, durch den Einsatz von Materialien, die keine Schäden verursachen und eine zuverlässige wirtschaftliche Investition darstellen. Das Problem beschränkt sich nicht auf die Einführung neuer Materialien, Anlagen und Systeme in Gebäuden von kulturellem Interesse, sondern respektiert die Bedeutung, Integrität, Authentizität und auch die Reversibilität des Eingriffs, grundlegende Prinzipien der Theorie der Restaurierung des architektonischen Erbes, vorgeschrieben in Chartas und internationale Konventionen, um die wertvollen Elemente zu schützen. In diesem Zusammenhang besteht das Hauptziel der Forschung darin, Maßnahmen für die Requalifizierung des architektonischen Erbes von Wohngebäuden in Rio Grande do Sul im Hinblick auf thermische Leistung und Energieeffizienz vorzuschlagen. Die Arbeitsmethode kategorisiert das architektonische Erbe im Zusammenhang mit der Besetzung des Territoriums von Rio Grande do Sul und definiert die Fallstudien. Für die Intervention werden verschiedene Sanierungsmaßnahmen vorgeschlagen: Boden- und Unterbodendämmung, Dachdämmung, Wanddämmung und Strategien in Bezug auf Öffnungen. Alle wurden einer quantitativen Bewertung durch Computersimulationen und einer qualitativen Bewertung durch die Anwendung von Fragebögen an Forscher im Bereich des historischen Erbes unterzogen. Die Ergebnisse für jede Fallstudie zeigten, welche Maßnahmen eine bessere thermische Leistung, Energieeffizienz und größere Kompatibilität mit dem Erbe aufwiesen. Als nächstes wurde ein Mechanismus zur Gewichtung der Bewertungen vorgestellt, der die am besten geeigneten Maßnahmen aufzeigte und die Erstellung eines Simulationsmodells für jede Fallstudie vorsah, das dieses Maßnahmen kombinierte, deren Ergebnisse signifikante Verringerung des Energieverbrauchs zeigten. Die am besten geeigneten Requalifizierungsmaßnahmen können in Normen und Handbücher für Eingriffe in Gebäude von kulturellem Interesse aufgenommen werden.

Avaliação das propriedades físicas e mecânicas de UHPC dosados pelo método UNISINOS

Mon, 12 Dec 2022 00:00:00 GMT

Avaliação das propriedades físicas e mecânicas de UHPC dosados pelo método UNISINOS Lopes, Raduan Krause Ultra-High Performance Concrete (UHPC) is the most significant evolution in recent years of cementitious composites, and, due to its mechanical properties combined with high durability compared to conventional concrete (CC), it becomes a structural material with great potential use. Despite this promising potential, its mixing process is sometimes complex to use more widely. In the quest to make the use of UHPC more comprehensive, the UNISINOS dosing method was developed, which made the process of mixing this composite simpler and more rational. However, some parameters that influenced the search for the best mechanical properties of UHPC's still needed to be defined. Thus, the objective of this research was to evaluate the variation of the particle distribution modulus - q - with values of 0.20 and 0.25 and the percentage of cement consumption (15%, 20% and 25%) in obtaining the lowest indices marshaling deviation (IDE) of the method. The compressive and flexural strength properties were evaluated regarding the variation of the two parameters, as well as the workability of the mixtures through the spreading test. The compressive strength results showed that the variation of the modulus q did not show changes in this property, on the other hand, the cement percentage of 20% that generated the lowest IDE's (190 and 180) obtained the highest compressive strength, 151.16 MPa and 147.03 MPa, respectively at 91 days of normal curing. For the results obtained in flexion, the modulus q was also not predominant for significant variations in the values obtained, and as for the percentage of cement linked to the FDI, an inverse correction to the compressive strength is evident, with the highest compression results, showed the lowest values in flexion. Based on the results obtained, mainly the compressive strengths at 28 and 91 days, it is possible to state that the UNISINOS method of measurement is promising in the search for minimum normative mechanical properties for UHPC.

Análise quantitativa da influência da rugosidade e da área de interface entre substratos cerâmicos e revestimento cimentício na resistência de aderência à tração

Wed, 31 Aug 2022 00:00:00 GMT

Análise quantitativa da influência da rugosidade e da área de interface entre substratos cerâmicos e revestimento cimentício na resistência de aderência à tração Oliveira, Valéria Costa de The sealing system adopted in Brazil, traditionally, consists of ceramic blocks and mortar renderings. The property that relates the junction between the substrate and the mortar is adhesion. Ceramic blocks are characterized according to their porosity, surface roughness and capillary suction, depending on the composition of the raw material, the process and the sintering temperature used in their production. Mortars are multiphase materials, composed of particles with different granulometric distributions, homogenized in the fresh state and which in the hardened state will result in volumetric changes, including the cement hydration products. In this sense, the main objective is the quantitative analysis of the influence of roughness and interface area between ceramic substrates and cementitious coating on the tensile bond strength. Thus, it was proposed to work with a single cement paste, apply it on five ceramic blocks with different roughness and thus quantify the adhesion of the paste in different topographies of substrates and correlate the interface area between the substrates and the Portland cement paste. . The ceramic blocks were characterized for roughness using 3D methods by laser profilometry and photogrammetry. In this research, roughness parameters that showed a significant interference in the adhesion between the ceramic block and the cement matrix were quantified. The heterogeneity of the ceramic substrate implies that when the tensile strength between a cementitious matrix and the substrate is determined in a smaller area, less variability and greater strength is obtained than when it is determined in a larger area. Roughness has a great influence on the tensile bond strength, which is also influenced by other factors that overlap. A multiple linear regression, determined from different ceramic substrates, when used for the individual analysis of each substrate, cannot estimate adhesion results with a significant coefficient of determination. However, it is possible to relate a roughness matrix, correlating the average height of the valleys (Rvm) and the average roughness (Ra), with the respective average areas of the valleys (Amv) of the substrate and with the average tensile bond strengths.

Índice para a avaliação da gestão de resíduos sólidos urbanos no município de Porto Velho-RO: um olhar orientado à sustentabilidade

Thu, 15 Sep 2022 00:00:00 GMT

Índice para a avaliação da gestão de resíduos sólidos urbanos no município de Porto Velho-RO: um olhar orientado à sustentabilidade Urgal, Maria Aparecida Lopes

Análise comparativa da utilização de ácido orgânico versus ácido inorgânico na recuperação de neodímio presente em hard disk drives (HDs): uma abordagem técnica, ambiental e econômica

Thu, 28 Apr 2022 00:00:00 GMT

Análise comparativa da utilização de ácido orgânico versus ácido inorgânico na recuperação de neodímio presente em hard disk drives (HDs): uma abordagem técnica, ambiental e econômica Stalter, Carline Fabiane The improvement of electrical and electronic equipment (EE) and its growing demand has brought an alert regarding the increase in the consumption of raw materials and the generation of solid waste. Rare earth elements (REEs) are essential and irreplaceable in the production of this equipment. Therefore, solid waste of this nature is considered potential sources of recovery of secondary raw materials, thus enabling the reintroduction of these elements in the production chain. One of the most used REEs is neodymium (Nd), which is prominent in the production of neodymium-iron-boron (NdFeB) magnets used in computer Hard Disk Drives (HDs). Thus, the objective of the work presented here was to compare the use of hydrochloric acid (HCl) with acetic acid (CH3COOH) in the recovery of Nd from magnets from post-consumer HDs, from a technical, environmental and economic point of view. The study was divided into 5 stages: characterization and sample preparation, leaching, environmental assessment, economic assessment and compilation of results. The efficiency of the processes was evaluated through the leaching of magnets previously demagnetized, ground, sieved (<0.25mm) and roasted. This process was carried out with the leaching agents HCl 0.5M and CH3COOH 1.0M at room temperature and 95°C. After 5 hours of leaching, vacuum filtration was performed to remove the solid phase, followed by pH adjustment of the filtrate with 37% HCl and subsequent selective precipitation of Nd through the addition of oxalic acid (H2C2O4), forming Nd oxalate. The Nd oxide was obtained by roasting the oxalate at 850°C. The hot CH3COOH process showed the highest yield, followed by the hot HCl process. The processes carried out without heating showed the lowest yields. The environmental assessment was carried out through a simplified LCA study that highlighted electric energy as responsible for more than 90% of the potential environmental impacts in the evaluated impact categories: scarcity of fossil resources, GWP (global warming potential) and terrestrial ecotoxicity. Excluding energy consumption and making a new assessment, the greatest potential environmental impacts were identified in the leaching agents (HCl 0.5M and CH3COOH 1.0), HCl 37% and H2C2O4. The global analysis indicated that the greatest potential environmental impacts are associated with the hot CH3COOH process. The economic evaluation indicated that electric energy was responsible for more than 90% of the costs of the processes, and the hot HCl process was the one that best fit the condition of economic viability. Considering a global view of the results, it can be said that the process in which 0.5M HCl was used is the best option for Nd recovery under the conditions presented in this study. The great influence and contribution of energy consumption in the evaluated processes can also be highlighted.

Estudo de cenários econômico e tecnológico para alternativas de drenagem e tratamento de lixiviados de um aterro sanitário

Tue, 29 Mar 2022 00:00:00 GMT

Estudo de cenários econômico e tecnológico para alternativas de drenagem e tratamento de lixiviados de um aterro sanitário Marques, Vinícius Martins Monitoring the leachate generated in landfills is necessary, taking into consideration this liquid effluent should not be sent to water bodies in its raw form, which would cause surface and groundwater contamination, fauna and flora degradation, together with making the water unsuitable for human use. Therefore, the aim of this study was to evaluate the leachate generated in the landfill of the city of São Leopoldo and the disposal of the solid waste in six operational phases, which the effluent originated from. Also, through laboratory tests, 20 physic-chemical parameters were assessed, which enabled monitoring the area surrounding the landfill and performing the multivariate statistical analysis with the leachate samples. Finally, it was aimed to identify the financial viability through the establishment of four scenarios regarding the leachate storage and treatment, varying the leachate origin and the treatment site, assessing the costs and revenues in each scenario, enabling the financial assessment of the proposed changes. In Scenario 1, the current situation was identified, while in Scenario 2, the implementation of the Leachate Treatment Plant (LTP) was suggested. In Scenario 3, in addition to the implementation of the LTP, the separation of the leachate generated in each phase was adopted and in Scenario 4, the hypothesis was created that leachate generated in older phases would be forwarded directly to Phase 4, with the treatment carried out only by Nanofiltration and Reverse Osmosis. The monitoring of solid waste identified that more than 90% of it comes from municipal waste collection and, from the total amount of waste received at the landfill, 45% were made of putrescible solid waste, 24% of biological contaminants and 31% of recyclable material, making evident the possibility of implementation of a waste sorting facility at the landfill. Regarding the leachate analysis, 20 parameters were evaluated and, through Principal Component Analysis, it was possible to identify that the first three components (PC1, PC2 and PC3) had results referring to 69% and 82% of variance from the original data, showing the statistical difference between the phases, being the most representative ones Bicarbonate Alkalinity, True Color, Organic Nitrogen, Precipitation, Color, Ammoniacal Nitrogen, Total Organic Carbon, and BOD. Regarding the financial analysis of the proposed scenarios, all scenarios created were profitable, including scenario 4, which it is the most profitable among all scenarios, where the leachate generated in each stage is stored separately and its treatment is made in the landfill, assessing revenues and costs, it was identified that, with a 10% investment return rate, there would be a 90% profitability rate and a 7.3 months investment return time. Therefore, in addition to the positive environmental factors of the treatment plant on site, the financial viability of the scenario with the proposed changes suggests to be favorable.

Identificação microbiológica em lixiviados de aterro sanitário de diferentes fases de aterramento

Mon, 21 Mar 2022 00:00:00 GMT

Identificação microbiológica em lixiviados de aterro sanitário de diferentes fases de aterramento Ghesla, Pâmela Lisie The municipal solid waste production is part of daily activities, being necessary to have the proper management of these materials. Landfill is one of the main methods of waste treatment and disposal, it is used in several countries, as Brazil. Over time, the organic matter landfilled is degraded, in different processes, by aerobic microorganisms, generating gases and leachate. The characterization of this microbiota allows the biodigestion understanding, also can improve the operational issue of landfills, such as cell optimization, leachate treatment and biogas use. This work intended to contribute with information about the sanitary landfill of São Leopoldo (RS), where leachate from five different phases, with different ages (0 year, 1 year, 4 years, 5 years, 7 years), were sampled in distinct months. According to physical and chemical analyses, landfill phases could be classified as mixed, with acid and methanogenic stages of degradation. The microbial communities diversty was assessed by enrichment and next generation sequencing analysis, using PCR barcoding from 16S rRNA gene, of samples from two landfill phases. Recent phase reactors, enriched with substrate for hydrolytic microorganisms, showed the phylum Bacteroides with higher abundance. The oldest phase reactors, enriched with three different substrates, showed higher abundance for the phylum Proteobacteria and the only one that had Archaea Domain was the reactor enriched with methanol. The sequence analysis of samples without enrichment, directly from leachates of the five phases, presented the phylum Proteobacteria with higher abundance (around 50%), followed by Firmicutes. In contrast, in the most recent phases Firmicutes (around 40%) was the most abundant phlyum, followed by Thermotogae. The phyla Gemmatimondetes and Chloroflexi were observed only in some phases. The Archaea domain was only 0.68% of total sequenced, all belonging to the phylum Euryarchaeota, mainly Methanobacteriales, Methanomicrobiales and Methanosarcinales orders.

Sistema de Avaliação de Reabilitação e Comparativo de Custos (SARC): edifícios verticais de concreto armado para uso habitacional em centros urbanos do Brasil

Tue, 08 Mar 2022 00:00:00 GMT

Sistema de Avaliação de Reabilitação e Comparativo de Custos (SARC): edifícios verticais de concreto armado para uso habitacional em centros urbanos do Brasil Silva, Luiz Gustavo Zuliani da Given many abandoned, unfinished and uninhabited buildings in urban centers, the rehabilitation of buildings is an area that can be further explored by civil construction in Brazil. This study seeks to address solutions implemented in other countries, focusing on methods used to assess the state of these buildings with a view to rehabilitation. It aims to develop a rehabilitation evaluation system and comparative unit costs of vertical buildings with reinforced concrete structures compared to the cost of new construction. The research comprehends four cycles. In Cycle 1, subsystems and functional elements were determined, criteria were defined to assess the level of rehabilitation and cost weighting. In Cycle 2, cost estimates for rehabilitation and new works were chosen based on the compilation of data on the costs of rehabilitated works and new works in the Brazilian context. Cycle 3 presents the structuring of the system and, finally, Cycle 4 demonstrates the application of the pilot test. The validation of the system took place with the application of a pilot project in five selected buildings in the cities of Rio Grande do Sul and São Paulo. The system is structured in 4 modules and includes the evaluation of 21 functional elements by visual inspection and calculates a rehabilitation index that defines the level of rehabilitation of the building. The results are presented in cost estimates, comparing the cost of rehabilitation with the cost of new construction within a range (optimistic, realistic and pessimistic). The application of the system in the pilot project showed that the results are consistent, close to the results obtained in the rehabilitation of the five buildings studied.

Influência dos óxidos de ferro na reação pozolânica da metacaulinita

Mon, 20 Dec 2021 00:00:00 GMT

Influência dos óxidos de ferro na reação pozolânica da metacaulinita Nunes, David Brandão Pozzolans are materials that react with calcium hydroxide in the presence of water, forming secondary hydrated products and promoting gains in strength and durability in cementitious products. These materials must be composed mainly of silicon, aluminum and iron oxides, which, in amorphous phases, will provide the pozzolanic reaction. The objective of this work was to study the reactivity of iron oxide and its influence on the pozzolanic reaction of metakaolinite. Kaolin, with high purity, was calcined to obtain metakaolin with 97,17% dehydroxylation. The study was conducted in white cement paste, as it is Fe-free, with 25% replacement of the cement mass by compositions of the materials tested. The iron oxide contents used in relation to the total mass were 1,5%, 3%, 4,5%, 6%, 9% and 25%. To compare pastes with metakaolin and without iron oxide, but which had the same cement consumption, samples were produced with compositions of metakaolin and quartz powder (considered inert in this research) to evaluate hydration at 3, 7, 28 and 63 days. The samples produced with 25% metakaolin had a mechanical performance index at 63 days of 141,17% compared to the standard sample with 100% cement, while the samples with 25% iron oxide and 25% quartz powder obtained indexes of 82,11 and 83,86% respectively; while the samples with compositions of metakaolin with quartz powder or iron oxide showed an increase in the indexes as the metakaolin content increased, with no significant difference being observed when comparing pastes with the same iron oxide content and quartz powder. There was a reduction in the content of portlandite and growth in the formation of other hydrated products with the increase in the content of metakaolin in the compositions, verified by the areas of DTG curves and by the increase in the combined water; a method for calculating effective combined water (without portlandite) is also proposed. It is noteworthy that in XRD diffractograms it was not possible to identify the formation of hydrated products containing iron, implying that the oxide remained inert during the cement hydration process and during the pozzolanic reaction of metakaolinite. In view of the study carried out, it is understood that the only iron oxide present in calcined clays is hematite, observed in XRD analysis, which does not have pozzolanic activity and does not participate in the hydration of cement, and cannot be classified as pozzolanic oxide.

Análise do efeito da continuidade de lajes mistas com chapa de aço colaborante em situação de incêndio

Mon, 28 Jun 2021 00:00:00 GMT

Análise do efeito da continuidade de lajes mistas com chapa de aço colaborante em situação de incêndio Bolina, Fabrício Longhi Composite steel and concrete structures are an interesting solution in tall buildings, just where structural fire safety design procedures are rigorous. In the case of composite steel deck and concrete slabs, the exposure of the steel decking to the environment and its sensitivity to high temperatures presupposes rapid collapse in fire conditions, which has been resolved with the addition of reinforcements. This research evaluated the influence of the use of reinforcements on the fire performance of the composite slabs. It has been estimated that the replacement of positive (AP) by negative (AN) rebars will optimize the steel consumption of these slabs, since the steel decking already works as AP and the AN is more thermally protected. The AN also mitigate the sagging bending moments and the mechanical responsibility of the steel decking in fire, and also increasing the structural redundancy. To solve the problem, a numerical and experimental analysis of composite steel decking and concrete slabs structurally continuous in fire conditions was solved. The influence of the use of positive (AP) and / or negative (AN) rebars on the fire performance was compared. The slab without reinforcement was also analyzed. Numerically, two analysis criteria were adopted: (C1) constant temperature distribution with increased load on the slab over time, and (C2) variable temperature distribution with constant load on the slab over time. The C1 allows to determine the load capacity of the slab for a given temperature and / or time of ISO 834, while C2 its fire resistance rate (FRR). The stresses and deflections in the slabs were discussed for both C1 and C2 criteria. The numerical simulation was done in Abaqus software. The experimental research was used in the parametric calibration of the numerical models. 17 full-scale prototypes of composite slabs were built: 9 with dimensions of 886x4600 mm and 8 of 3000x4600 mm, evaluated at normal (five point bending test) and high temperatures (with horizontal furnace according the ISO 834 curve) with 540 days of age. These prototypes were tested with rigid intermediate support, forming 2 spans of 2300 mm. These tests allowed the calibration of the numerical model with 31 reading points. As a result, the C1 criterion showed thermomechanical responses, while C2 thermophysical-mechanical. It was clearly noted that the design procedure of EN 1994-1.2 and NBR 14323 is based on C1. However, C1 does not allow to identify the increase in the stress state in the slab due to thermal effects, such as tensile membrane action, which is only possible in C2. The C2 also makes it possible to identify the concrete cracks and the detachment of the steel decking in fire. C2 showed more realistic results, but it is more 7 complex and time-consuming than C1, as it involves thermo-physical-mechanical parameters and several tests to define the ultimate loading of the slab at each time of ISO 834. From the C1 and C2 perspective, the replacement of AP by AN was not interesting. The slabs with only AP showed the best results. Removing the AP compromised the ultimate moments of resistance for sagging bending, that becoming the weak point of the slab in fire. In this case, the use of AN was unnecessary, becoming underutilized. This is due to the loss of composite behavior in fire conditions, caused by the detachment of the decking before the initial 30 min. C2 also showed that the slabs with AP preserved the tensile membrane action for longer. The structural continuity was even affected by the concrete cracks produced by the thermal bowing since the first 10 min. Some adjustments are needed in the simplified method of EN 1994-1.2 and NBR 14323, which is based on C1. This motivated the proposal of new formulations, in an attempt to simplify the C2 phenomenons in the fire-resistant moment equations of the standard. A new method has also been proposed for the definition of temperatures in concrete, positive and negative rebars and steel decking. A new table for the definition of the thermal insulation was presented.

Proposta de modelo de gestão da fase de manutenção de edifícios, utilizando o conceito BIM, com foco na manutenção preventiva

Fri, 10 Sep 2021 00:00:00 GMT

Proposta de modelo de gestão da fase de manutenção de edifícios, utilizando o conceito BIM, com foco na manutenção preventiva Rosa, Fabiana Pires Considered an emerging issue in civil construction, facility management (FM) requires various agents and disciplines to carry out interventions that guarantee buildings' expected durability and performance. However, the lack of formalization of FM, dispersed, disconnected, and incomplete information results in little efficiency and preventive strategy. This study aims to propose a management model for the maintenance phase of buildings, using the BIM (Building information modeling) concept, focusing on preventive maintenance. The study was carried out from a case study, through three stages: FM diagnosis of an educational building (EB) and also of a residential building (RB); FM-BIM integration, and model proposal. The results showed that the EB management, as it has an infrastructure department, FM is carried out formally and with a preventive character. Still, the person responsible for management points out that there is a lack of information. In the RB, FM is performed with a corrective character and with little formalization. In both, the design of the buildings is not used. Through Dynamo software, FM activities were integrated into EB BIM design (Revit model), according to the criteria of frequency and status. The model proposes FM through sub-processes, planning and action and control. Through the FM-BIM integrated model, the building design starts to communicate the maintenance activities according to the adopted criteria visually. According to the perception of those responsible for maintaining the buildings studied, the use of the model greatly facilitates access to information over time. However, it requires that designs are carried out with maintenance information and someone who knows the software used, indicating a greater involvement of the construction company in the condominium segment.

Desenvolvimento de método para a análise quantitativa da rugosidade de substratos cerâmicos argilosos

Thu, 26 Aug 2021 00:00:00 GMT

Desenvolvimento de método para a análise quantitativa da rugosidade de substratos cerâmicos argilosos Arnold, Daiana Cristina Metz The diversification of materials used as substrates in Civil Construction hinders the standardization of building systems, increasing the probability of pathological manifestations. An example of this is the detachment of coatings. The variability of the surface texture, as well as the rheology of the mortar used are factors that directly influence the lack of adhesion of the coating systems. In this context, the construction industry usually analyzes its materials regarding the macrostructure, not knowing the microstructure of the surface. In this context, the present research developed a quantitative method to analyze the microstructural roughness of ceramic blocks. And as results, it points out that the constituent material and burning temperature influence the roughness and contact area of ceramic substrates. The 3D data acquisition method is more efficient than the 2D method in roughness characterization of ceramic blocks. The developed method allows precise location and detail levels for evaluation of surface roughness coefficients and facilitates the comparative analysis among different ceramic block surfaces with qualitative and quantitative data. The average roughness, as a single factor of analysis, can not be used to determine the adherence between the ceramic block substrate and the mortar, since the contact area and the rheology of the mortar will also influence this parameter. The application of the method indicated that the same material adopted as substrate can present significant variation of roughness and contact area, which will directly interfere in the adherence between the ceramic block and the cementitious matrix. After the multiscale analysis with the methods for measurement analysis of ceramic blocks it is concluded that the roughness must be analyzed with equipment that allows the measurements between 0,025µm and 0,50µm. The method for roughness determination of ceramic blocks proposed in this study, with data acquisition by 3D profilometer, is appropriate for the evaluation of the roughness of a ceramic substrate, being possible the mapping of the surface, the reproduction of the data and the classification of the roughness of the ceramic substrate.

Verificação do potencial de ativação alcalina de rochas vulcânicas ácidas: um estudo de desempenho mecânico e caracterização do ligante

Mon, 30 Aug 2021 00:00:00 GMT

Verificação do potencial de ativação alcalina de rochas vulcânicas ácidas: um estudo de desempenho mecânico e caracterização do ligante Koppe, Angélica Alkali-activated ligands are produced from the reaction between aluminosilicate precursors and an alkaline activating solution. Despite the current development of these used as supplemental cementitious materials precursors of the Portland cement industry, alternative natural sources can be explored. One of these sources is constituted by the acid volcanic resources of the Paraná Magmatic Province (PMP), which present a favorable chemical and mineralogical composition for the production of binders. However, due to the scarcity of studies alluding to their use, the gap addressed with the aim of investigating the relationship between the development of alkali-activated ligands and the chemical-mineralogical characterization of acidic volcanic rocks with a vitreous character, found south of the PMP, is outlined . Three rocks were used and quantitatively characterized for chemical and mineralogical composition, geological formation and physical form after comminution. In order to assess its potential, different activation conditions were used: with and without addition of extra soluble silicates, with and without addition of CaO and two hydrothermal curing temperatures. Activation susceptibility was evaluated by mechanical development, geopolymerization consolidation, X-ray diffraction and efflorescence appearance analysis. The results showed that the activation potential of rocks is influenced by the chemical composition of the amorphous fraction of the precursors. It was noticed that the matrices are improved with the insertion of the CaO source due to the mechanical behavior and consolidation of geopolymerization, however, with regard to efflorescence, larger outcrops were identified with the addition of CaO. As for the temperature, it was noticed that this does not influence the consolidation of geopolymerization, but induces better mechanical performance. The source of soluble silicates leads to better mechanical strength, but does not contribute to the consolidation of activation, indicating the formation of unstable products that do not represent geopolymers. Finally, it can be seen that it is possible to produce stable matrices from the studied rocks, indicating better results with the superposition of the effects of the temperature of 80 °C in the cure and addition of CaO.

Requisitos de desempenho de edificações habitacionais e o custo de construção: estudo de casos – projetos de referência SINDUSCON R1-B e SINAPI R1_2B_43C_2017

Mon, 23 Aug 2021 00:00:00 GMT

Requisitos de desempenho de edificações habitacionais e o custo de construção: estudo de casos – projetos de referência SINDUSCON R1-B e SINAPI R1_2B_43C_2017 Patzlaff, Jeferson Ost Important changes have marked the building sector over the last decades, including the topic performance, contemplated in the design and execution decisions of residential units. In this context, the objective was to evaluate the relationship between specifications that conform to the performance levels predicted by Performance Standard (ND) – (M), (I), and (S) – and the respective construction cost and the analysis of the behavior of construction cost references between 2007 and 2021. For evaluation purposes, data related to the variation of CUB, SINAPI, INCC, and other economic indices were analyzed. Also, the specifications of R1-B (SINDUSCON) and R1_2B_43C_2017 (SINAPI) projects were analyzed as to their potential of meeting the ND requirements and the increase in costs in order to achieve levels (I) and (S), when applicable. This analysis showed that concerning CUB-RS, the average accumulated percentage of residential types represents 101.86%, while for SINAPI-RS it represents 85.74% and, for INCC-M, 93.25%. Compared to the IPCA, in the same period, the accumulated percentages represent ratios equal to 1.33, 1.12, and 1.21, respectively. R1-B and R1_2B_43C-2017 projects did not have their specifications updated after the ND came into effect. The R1-B project presents divergences between the components of its basic production parcel (which enables the formation of cost) and the characterization of building blocks. In the context of the two projects, it can be concluded that the requirements contemplated in the DN are met, or have the potential to be met, for the most part. In addition, it's possible to achieve level (I) or (S) based on changes in the technical configurations of the walls, frames, roof, and internal floor, especially to meet the topics of Thermal Performance, Acoustic Performance, Durability, and Maintainability. Regarding the estimated cost increase to meet the performance at level (S), the simulations indicate that, for the R1- B project, the corresponding value is R$ 15,241.60 and, for the R1_2B_43C_2017 project, this value is R$ 14,911.51. When considering this amount against the C1 cost scenario (R$ 215,000.00), the increase corresponds to 7.09% and 6.94%, respectively. When considering them against scenario 2 (R$ 240,286.97 for R1-B and R$ 226,504.09 for R1_2B_43C_2017), the increase corresponds to 5.48% and 5.76%, respectively.

Estudo de matriz cimentícia reforçada com fibra têxtil para uso em painéis

Wed, 24 Feb 2021 00:00:00 GMT

Estudo de matriz cimentícia reforçada com fibra têxtil para uso em painéis Ortolan, Vinicius de Kayser Textile reinforced concrete (TRC) is a cementitious matrix with the addition of long oriented fibers produced with multifilament. This composite is able of producing slender elements with reduced thickness, and important mechanical properties of high durability. The present work aims to evaluate in an experimental way the characteristics of two alkali resistant (AR) glass textiles with different mesh openings, as well as the influence on the mechanical properties when used as reinforcement with different amounts of layers in a cementitious matrix, in order to obtain efficiency parameters to be considered in two analytical structural design models. The experimental program was developed in stages, and in the initial, the textiles were characterized in terms of geometry with the aid of a digital microscope and tensile strength, in the isolated yarn and the fabric, for both orientations, weft and warp. The compressive strength and young’s modulus of the cement matrix were determined at the ages of 7, 28 and 91 days. In the next stage, were molded TRC specimens to characterize the tensile and flexural strength. Were produced containing one and two layers for the AR122 textile and specimens of one to four layers with the AR192 textile, with the textiles positioned in the two orientations. The results obtained were satisfactory from two layers, as they characterized the desired properties of textile reinforced concrete. Step three, based on the previous results, were molded panels with dimensions of 500 x 1000 mm, containing two and three layers of the AR192 textile, with thickness of 20 and 30 mm, in order to determine the flexural strength, only the textile AR 192 was used, because it demonstrated superior mechanical resistance in relation to the AR122 textile. Finally, in the last step, based on the results of the previous steps, it was possible to obtain the efficiency coefficients k1 and FPI, as subsidies for analytical design procedures. The theoretical results demonstrated satisfactory behavior and consistent with the experimental results, making it possible to insert the coefficients for design panel elements.

Desenvolvimento de Engineered Cementitious Composites (ECC) autocicatrizantes com diferentes fibras poliméricas e agentes de cicatrização

Wed, 25 Nov 2020 00:00:00 GMT

Desenvolvimento de Engineered Cementitious Composites (ECC) autocicatrizantes com diferentes fibras poliméricas e agentes de cicatrização Ehrenbring, Hinoel Zamis This thesis aimed to develop self-healing ECCs with PVA, polypropylene and recycled polyester fibers. As healing agents, silica fume, crystallizing additive and bacterial solution were used. For autonomous agents, three contents (T1, T2 and T3, ascending order) were stipulated for each one. The experimental program was divided into 4 stages, starting with the determination of the equivalent fiber content between the composites. Then, the classification step of the mixtures was carried out to meet the requirements of the ECC class with structural application.

Hidratação do cimento portland na presença de elevados teores de fíler dolomito com diferentes finuras

Sat, 31 Oct 2020 00:00:00 GMT

Hidratação do cimento portland na presença de elevados teores de fíler dolomito com diferentes finuras Jordani, Bárbara Due to the growing demand for cements and the need to reduce CO2 emissions during their production, new cements containing high levels of filler and additional cementitious materials have been investigated. The limestone filler in partial replacement to cement is one of these alternatives, observing the adoption of increasing levels in cement from different countries, including Brazil, with the recent approval of the NBR 16697 standard. However, the use of dolomitic limestone as a filler is still it is not widespread and the formation of hydration products from the reaction of dolomite limestone fines - as present in southern Brazil, with high MgO content - in Portland cement pastes is still little known. Although the performance of limestone filler has been investigated in the past, in terms of durability, the formation of thaumasite is still poorly studied in Brazil, as most international publications report that thaumasite develops at low temperatures, in the range of 5º and 15ºC. Thus, this research sought to investigate the cement hydration products in the presence of dolomite, looking for the formation of thaumasite. A dolomite filler with 20% MgO was adopted, used in contents of 0%, 15%, and 35% to replace cement, with D50 of 10 µm, 6 µm and 4 µm. The pastes were cured at temperatures of 5ºC and 20ºC. The research results indicate that, in relation to rheological behavior, all cement pastes with dolomite incorporation showed better homogeneity compared to pastes without the presence of dolomite, and that the 35% filler content had the highest viscosity rate. The analysis by isothermal calorimetry showed that the presence of dolomite showed a nucleation and dilution effect, reducing the hydration heat of the pastes. In the results of resistance to compression, it was identified that the pastes submitted to a temperature of 5ºC showed the best mechanical performance. As for the different levels of dolomite, they did not present significant differences, and the 4µm fineness showed the best packaging in microscale, also showing higher strength values. The XRD detected the presence of thaumasite only at a temperature of 20ºC, indicating the possibility of formation of this mineral at higher temperatures.

Estimativa da condensação em edificações unifamiliares em território brasileiro: simulação higrotérmica computacional

Fri, 18 Sep 2020 00:00:00 GMT

Estimativa da condensação em edificações unifamiliares em território brasileiro: simulação higrotérmica computacional Pires, Josiane Reschke Superficial condensation is a fundamental parameter for building performance analysis and influences the habitability and durability requirements for buildings. This study evaluates the surface condensation, absorption, and hygrothermal performance for Brazilian climatic conditions, in residential buildings. A proposal was adopted in the standards EN ISO 13788:2012, EN 15026:2007 and ASHRAE 160:2009, proposing an adaptation for the Brazilian characteristics, using hygrothermal simulation and verifying the results of some typical construction characteristics. Through simulation with the WUFI® Plus software, four walls systems and four ceiling systems were analyzed, for eight Brazilian bioclimatic zones, using representative cities: Curitiba/PR (ZB1), São Lourenço/MG (ZB2), São Paulo/SP (ZB3), Brasília/DF (ZB4), Vitória da Conquista/BA (ZB5), Campo Grande/MS (ZB6), Cuiabá/MT (ZB7) e Manaus/AM (ZB8). The results indicate that natural ventilation and external climate increases internal moisture in all bioclimatic zones, except for ZB8. Regarding the types of housing units analyzed, those with the lowest volume were those with the highest surface condensation and internal moisture. The physical-chemical properties of the construction systems had a great influence on surface condensation and not only the thermal resistance, with a small impact on the user’s thermal comfort. The impact on hygrometer performance had a great influence of the thermal properties and climates and a minor influence of the moisture. This study contributes to the discussion about surface condensation and the impact of moisture on buildings, with different volumes, construction systems and Brazilian climates.

Análise da eficácia dos mecanismos de autocicatrização do concreto

Wed, 26 Aug 2020 00:00:00 GMT

Análise da eficácia dos mecanismos de autocicatrização do concreto Pacheco, Fernanda This research aimed to analyse four mechanisms of self-healing, by cement consumption, by pozzolans, by chemical and bacterial solutions. These compositions were submitted to water submersion cure and umid cure, also considering three conditions of exposition: reference, carbonation chamber and salt spray chamber. These traces were characterized by mechanical strength and fisical characteristics. Healing efficiency was assessed using a high-precision microscope. In addition, scanning electron microscopy (SEM) added to EDS and X-ray diffraction tests were performed. Pilot experiment were carried out, allowing to trace the growth curve of the bacterium B subtilis, and to compare perlite and clay as options for aggregates encapsulation. It was noticed that in the samples where cement consumption was evaluated, the exposure to carbonation may have affected the formation of healing productsProducts C-S-H, C-A-S-H and CaCO3 were formed. In samples with pozzolanic materials, it was noted that among the average values, the largest was 0.53 mm for continuous healing and 0.45 mm for punctual healing. Again, carbonation affected product formation. The same elements mentioned were identified in the DRX, in addition to products that make up the pozzolans used, such as SiO2, for example.In the samples containing chemical solutions, it is worth to notice that product occurs on the crack opening and also at sample surface. Among the products identified, there were C-S-H, CaCO3, SiO2 and CaO. Evaluating the samples containing bacterial solutions, in terms of the healing of fissures, a maximum 1.67 mm and maximum average of 1.48 mm countinuos healing was reached, demonstrating the potential of the technique. When analyzing the possibilities of submerged and moist healing, there was a balance between the number of occurrences. Assessing the impact of aggressive environments, it is worth noting that the presence of CO2 and Cl- did not affect the formation of healing. In terms of the identification of the products formed, it was noted the presence of calcite and C-S-H.

Avaliação do comportamento ao fogo de placas de vedação de concreto com inserção de resíduos de pneus inservíveis

Mon, 25 May 2020 00:00:00 GMT

Avaliação do comportamento ao fogo de placas de vedação de concreto com inserção de resíduos de pneus inservíveis Simonetti, Camila The inappropriate disposal of waste tires represents a major concern regarding the mitigation of sanitary and environmental impacts from this action. This issue has motivated several studies on possible methods for reusing these elements. Civil construction can be a potential consumer of this type of waste due to the following reasons: its capacity for consuming large amounts of materials, its search for alternatives to overcome the shortage of raw materials, its interest in reducing the environmental footprint from construction projects, and its capacity to encapsulate contaminants in the cement matrix. The possibility of incorporating waste tires residue into concrete has already been consolidated in several previous studies, but there is a gap in the knowledge about how the concrete made with recycled tire materials behaves when exposed to high temperatures. This study aims to investigate the performance of precast concrete panels made with waste tires residues when exposed to fire when using the recycled steel fiber and the recycled rubber aggregate separately. The experimental design consisted in essays for the characterization of the physical and mechanical properties of the concrete produced with the recycled materials, as well as fire reactions and fire resistance tests. Besides the reference concrete without any residues, mixtures were prepared containing rubber particles used as partial replacement of fine aggregate at a proportion of 5% and 10% in volume, and other mixtures containing recycled steel fibers included at 0.5% and 1.5% of total volume. In terms of fire reaction, the results indicated that both groups of concretes with residues, unlike the conventional concrete, were classified as combustible due to the presence of sustained flaming during non-combustibility tests. There was neither flame propagation nor the register of smoke optical density. In the fire resistance tests, the recycled steel fiber reinforced concretes and those containing 5% recycled rubber aggregate presented similar behavior when compared to the conventional concrete on thermal insulation, sealing, and stability. The concrete made with 10% recycled rubber aggregate registered the occurrence of explosive spalling and worse thermal insulation and sealing.

Proposição de um método de dosagem para concretos de ultra alto desempenho (UHPC)

Sun, 20 Oct 2019 00:00:00 GMT

Proposição de um método de dosagem para concretos de ultra alto desempenho (UHPC) Christ, Roberto Ultra High Performance Concrete (UHPC) is a promising material and, due to its excellent mechanical properties and durability, it becomes an attractive solution. Several studies showing the mechanical potential, durability and various applications in different structures vouch the use of UHPC. However, there is a gap in trace determination using a simple, easily accessible dosing method that enables the determination of an optimal ratio of all constituents of the mixture. The work developed with respect to UHPC mixtures, does not present a way to draw a trace with different materials with the ideal amount of fibers to be used, without losing the workability with high mechanical strengths. The objective of the research was to develop a dosing method that can, through informative parameters of the materials, obtain the best compressive and tensile strength of the compound, aiming to find the proportions of the materials in the mixture, as well as the amount of fibers to be inserted without losing workability. For such, it was worked with materials of different particle size distributions, evaluating the largest packing of the particles. Four compositions with different materials were evaluated: cement, active silica, fly ash, two types of fine aggregate, quartz powder and calcium carbonate. The proposed method for matrix compactness verification was based on the Andreasen and Andersen packing method. The results found in this research showed that the proposed dosing method provided greater potential for the mechanical strength of the mixture. A linear relationship between a higher matrix compactness and the compressive strength obtained in the mixture was noticed. In the composition with higher compactness, the compressive strength increased by 20% when compared to the mixture with lower compactness.