Pub Date : 2023-07-31DOI: 10.1590/1517-7076-rmat-2023-0073
Melissa Lago de Jesus Silveira Silva, M. Lobo, Rita Dione Araújo Cunha, S. César
RESUMO A Madeira Lamelada Colada (MLC) é uma alternativa viável para o aproveitamento racional da madeira, possibilitando o uso de madeiras jovens. Ainda, ao engenheirar a madeira, pode-se viabilizar o uso de troncos de menor qualidade e menor diâmetro. Entretanto, o desempenho do produto depende da espécie utilizada, das espessuras e posições das lamelas, do tipo de adesivo, do desempenho da colagem. Este trabalho teve como objetivo estudar a viabilidade do uso de uma madeira de rápido crescimento para a produção de MLC. A espécie de madeira selecionada foi Eucalyptus urophylla, clonal COP 1404, que se caracteriza por ter rápido crescimento e por ter uma lacuna em estudos que visam sua aplicação na construção civil. Empregou-se o adesivo poliuretano bicomponente à base de óleo mamona. O programa experimental teve como foco a caracterização da madeira in natura e o desempenho mecânico da MLC comparada à madeira maciça, empregando métodos estatísticos para a análise de resistência dos protótipos. Os resultados indicaram que o adesivo foi eficiente na colagem da madeira, de modo que o cisalhamento ocorreu na madeira, além da verificação à flexão ter mostrado comportamento de um corpo único, não tendo pontos de descontinuidade por conta da linha de cola.
{"title":"Viabilidade do uso de madeira clonal de Eucalyptus urophylla de rápido crescimento para produção de madeira lamelada colada (MLC) com adesivo poliuretano à base de mamona","authors":"Melissa Lago de Jesus Silveira Silva, M. Lobo, Rita Dione Araújo Cunha, S. César","doi":"10.1590/1517-7076-rmat-2023-0073","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0073","url":null,"abstract":"RESUMO A Madeira Lamelada Colada (MLC) é uma alternativa viável para o aproveitamento racional da madeira, possibilitando o uso de madeiras jovens. Ainda, ao engenheirar a madeira, pode-se viabilizar o uso de troncos de menor qualidade e menor diâmetro. Entretanto, o desempenho do produto depende da espécie utilizada, das espessuras e posições das lamelas, do tipo de adesivo, do desempenho da colagem. Este trabalho teve como objetivo estudar a viabilidade do uso de uma madeira de rápido crescimento para a produção de MLC. A espécie de madeira selecionada foi Eucalyptus urophylla, clonal COP 1404, que se caracteriza por ter rápido crescimento e por ter uma lacuna em estudos que visam sua aplicação na construção civil. Empregou-se o adesivo poliuretano bicomponente à base de óleo mamona. O programa experimental teve como foco a caracterização da madeira in natura e o desempenho mecânico da MLC comparada à madeira maciça, empregando métodos estatísticos para a análise de resistência dos protótipos. Os resultados indicaram que o adesivo foi eficiente na colagem da madeira, de modo que o cisalhamento ocorreu na madeira, além da verificação à flexão ter mostrado comportamento de um corpo único, não tendo pontos de descontinuidade por conta da linha de cola.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84648614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-28DOI: 10.1590/1517-7076-rmat-2023-0078
L. Fortunato, G. A. Parsekian, A. Neves Junior
Carbonation chambers, in general, are used in civil engineering laboratories both for verification tests of the useful life of reinforced concrete, and for CO 2 curing tests of unreinforced cementitious materials. These chambers can be purchased from specialized manufacturers at a high cost, or they can be built by the researchers themselves. It so happens that in the literature there is no manual for making and operating an accelerated carbonation chamber. It is observed that its development and manufacture depend a lot on the needs and financial conditions of the research, with no standard or Technical Norm to be followed. This article presents a compilation of concepts related to the accelerated carbonation reaction and brings a bibliographical review about the different carbonation chambers made by researchers, in which it was possible to verify a great variation regarding the material to be used in the structure of the chamber, location of CO 2 and air inlet and outlet valves, temperature and humidity control, among others; and in addition, it presents a descriptive memorial for the construction of an automated and accessible carbonation chamber to be used in laboratories.
{"title":"Developing an easy-to-build laboratory chamber for CO2 experiments","authors":"L. Fortunato, G. A. Parsekian, A. Neves Junior","doi":"10.1590/1517-7076-rmat-2023-0078","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0078","url":null,"abstract":"Carbonation chambers, in general, are used in civil engineering laboratories both for verification tests of the useful life of reinforced concrete, and for CO 2 curing tests of unreinforced cementitious materials. These chambers can be purchased from specialized manufacturers at a high cost, or they can be built by the researchers themselves. It so happens that in the literature there is no manual for making and operating an accelerated carbonation chamber. It is observed that its development and manufacture depend a lot on the needs and financial conditions of the research, with no standard or Technical Norm to be followed. This article presents a compilation of concepts related to the accelerated carbonation reaction and brings a bibliographical review about the different carbonation chambers made by researchers, in which it was possible to verify a great variation regarding the material to be used in the structure of the chamber, location of CO 2 and air inlet and outlet valves, temperature and humidity control, among others; and in addition, it presents a descriptive memorial for the construction of an automated and accessible carbonation chamber to be used in laboratories.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74224186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-24DOI: 10.1590/1517-7076-rmat-2023-0102
A. Jabar, P. T
In recent decades, concrete technology has reached the broad-based areas of operations through the implementation of Self Compacting Concrete to increase the concrete performance. Due to high silica content, the pozzo-lonic characteristic of RHA makes it as a supplementary material for cement. In this paper, Cement was partially replaced with Rice Hush Ash of 5%, 10% 15%, 20%, 30% and 40% influencing the properties of SCC. The aim of this report is to explore the effect of cement replacement by RHA on the fresh and mechanical properties of SCC. In addition, the bucking behaviour of the axial loaded reinforced concrete column was predicted using Artificial Neural Network. Experimental data are collected and 100 experimental data is used for training the ANN model and 20 sets of data is utilized for testing. From the results it is observed that SCC blended with RHA shows the positive relationship between 30% replacement of RHA with an increase in the strength of compression and tensile strength of around 6. The buckling behaviour of the 70% Cement + 30% RHA SCC reinforced column was predicted by ANN-PSO is a precision and efficient model.
{"title":"ANN- PSO modelling for predicting buckling of self-compacting concrete column containing RHA properties","authors":"A. Jabar, P. T","doi":"10.1590/1517-7076-rmat-2023-0102","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0102","url":null,"abstract":"In recent decades, concrete technology has reached the broad-based areas of operations through the implementation of Self Compacting Concrete to increase the concrete performance. Due to high silica content, the pozzo-lonic characteristic of RHA makes it as a supplementary material for cement. In this paper, Cement was partially replaced with Rice Hush Ash of 5%, 10% 15%, 20%, 30% and 40% influencing the properties of SCC. The aim of this report is to explore the effect of cement replacement by RHA on the fresh and mechanical properties of SCC. In addition, the bucking behaviour of the axial loaded reinforced concrete column was predicted using Artificial Neural Network. Experimental data are collected and 100 experimental data is used for training the ANN model and 20 sets of data is utilized for testing. From the results it is observed that SCC blended with RHA shows the positive relationship between 30% replacement of RHA with an increase in the strength of compression and tensile strength of around 6. The buckling behaviour of the 70% Cement + 30% RHA SCC reinforced column was predicted by ANN-PSO is a precision and efficient model.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88394860","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-21DOI: 10.1590/1517-7076-rmat-2023-0111
Y. Gonzalez, Jorge Mario Mendoza, Jair Restrepo Durán, Luis Carlos Tapia Vertel, J. D. Rhenals-Julio
Fused deposition modeling (FDM) has gained popularity recently due to its versatility and low cost. Considering that the quality of printed parts depends on many variables, a 3^3 factorial design of experiments was conducted, where three influential parameters in the process were studied: layer height (0.15, 0.2, and 0.25 mm), infill per - centage (30%, 60%, and 90%), and shell count (2, 3, and 4), using polylactic acid as the material. Their effects on tensile strength, flexural strength, printing time, and interactions were measured. The maximum tensile and flexural stress obtained were 33.5 MPa and 87.3 MPa, respectively, at a 90% infill percentage. It was found that layer height does not significantly affect mechanical strength, while infill percentage has the most significant influence, followed by the number of shells. The latter two factors show a meaningful interaction. Furthermore, all the studied parameters have a significant impact on printing time.
{"title":"Effect of printing parameters on mechanical properties and processing time of additively manufactured parts","authors":"Y. Gonzalez, Jorge Mario Mendoza, Jair Restrepo Durán, Luis Carlos Tapia Vertel, J. D. Rhenals-Julio","doi":"10.1590/1517-7076-rmat-2023-0111","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0111","url":null,"abstract":"Fused deposition modeling (FDM) has gained popularity recently due to its versatility and low cost. Considering that the quality of printed parts depends on many variables, a 3^3 factorial design of experiments was conducted, where three influential parameters in the process were studied: layer height (0.15, 0.2, and 0.25 mm), infill per - centage (30%, 60%, and 90%), and shell count (2, 3, and 4), using polylactic acid as the material. Their effects on tensile strength, flexural strength, printing time, and interactions were measured. The maximum tensile and flexural stress obtained were 33.5 MPa and 87.3 MPa, respectively, at a 90% infill percentage. It was found that layer height does not significantly affect mechanical strength, while infill percentage has the most significant influence, followed by the number of shells. The latter two factors show a meaningful interaction. Furthermore, all the studied parameters have a significant impact on printing time.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82174917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-17DOI: 10.1590/1517-7076-rmat-2023-0071
Isis Siqueira Fernandes, Laís da Costa Saboia, Vinicius Soares Gonçalves, Jorge Luiz Siqueira da Costa Neto, A. Moreira, Natália Dias Souza, Alexandre Miguel do Nascimento, D. Chaves, L. Rosado, L. Silva, G. Bauerfeldt, A. Middea, R. N. Oliveira
Acute wound dressings can be based on PVA hydrogels, which present many characteristics of an ideal dressing, e.g., fluid uptake, a moisturized environment, etc. The lack of antimicrobial properties leads to the addition of natural active agents. The present work aims to manufacture and compare PVA gels loaded with Barbatimão bark extract, Leucaena bark extract, Aloe vera, and Lavender essential oil. They were characterized by FTIR, swelling tests, SEM, actives release. There were interactions between PVA and the active agents. The addition of Leucaena and Barbatimão increased the PVA ability to swell, but the opposite was found for Aloe vera and Lavender essential oil. PVA-Lavender essential oil samples presented interconnected pores, while samples with essential oil or extracts presented high crystallinity. Lavender essential oil and Aloe vera presented the highest release. The Barbatimão and Leucaena samples’ release may be related to the samples’ swelling, but the initial release of Aloe vera and Lavender samples was diffusion controlled by swelling. Their long-term release was dose-dependent for Aloe vera, while it was a non-Fickian diffusion for Lavender essential oil related to the hydrogel’s relaxation step. There is a synergistic effect when Aloe vera and Lavender essential oil are loaded in PVA hydrogels.
{"title":"Delivery kinetics of natural active agents by PVA hydrogels intended for wound care","authors":"Isis Siqueira Fernandes, Laís da Costa Saboia, Vinicius Soares Gonçalves, Jorge Luiz Siqueira da Costa Neto, A. Moreira, Natália Dias Souza, Alexandre Miguel do Nascimento, D. Chaves, L. Rosado, L. Silva, G. Bauerfeldt, A. Middea, R. N. Oliveira","doi":"10.1590/1517-7076-rmat-2023-0071","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0071","url":null,"abstract":"Acute wound dressings can be based on PVA hydrogels, which present many characteristics of an ideal dressing, e.g., fluid uptake, a moisturized environment, etc. The lack of antimicrobial properties leads to the addition of natural active agents. The present work aims to manufacture and compare PVA gels loaded with Barbatimão bark extract, Leucaena bark extract, Aloe vera, and Lavender essential oil. They were characterized by FTIR, swelling tests, SEM, actives release. There were interactions between PVA and the active agents. The addition of Leucaena and Barbatimão increased the PVA ability to swell, but the opposite was found for Aloe vera and Lavender essential oil. PVA-Lavender essential oil samples presented interconnected pores, while samples with essential oil or extracts presented high crystallinity. Lavender essential oil and Aloe vera presented the highest release. The Barbatimão and Leucaena samples’ release may be related to the samples’ swelling, but the initial release of Aloe vera and Lavender samples was diffusion controlled by swelling. Their long-term release was dose-dependent for Aloe vera, while it was a non-Fickian diffusion for Lavender essential oil related to the hydrogel’s relaxation step. There is a synergistic effect when Aloe vera and Lavender essential oil are loaded in PVA hydrogels.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91204901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-10DOI: 10.1590/1517-7076-rmat-2023-0128
Archana Murugan, Ramasamy Vasudevan
In recent decades, greenhouse gas emission and global warming are the major threat to climatic change variability. The quality of concrete can be enhanced by the addition of a supplementary cementitious material to portland cement. In this study, fly ash is utilized as a supplemental cementitious material (SCM). The purpose of this research is to test and study the mechanical and thermal properties of blended concrete containing ordinary portland cement, fly ash and zinc sulphate as well as to investigate the microstructure in order to study the influence of zinc sulphate on the hydration process of concrete. This research mainly focused on the changes occurring in the strength, retarding mechanism, setting time, mineralogy, and microstructure caused by the addition of zinc sulphate in concrete. Ordinary portland cement, fly ash, pulverized fly ash and zinc sulphate are used in the blended concrete. The varied proportions of fly ash and zinc sulphate in the mix are 15%, 30%, 45%, and 60% respectively. The strength characteristics can be increased by fly ash pulverization. Hence the research focuses in exploring the addition of fly ash, pulverized fly ash and zinc sulphate anhydride to the concrete mix.
{"title":"Influence of zinc sulphate in microstructure and strength properties of blended cementitious concrete system","authors":"Archana Murugan, Ramasamy Vasudevan","doi":"10.1590/1517-7076-rmat-2023-0128","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0128","url":null,"abstract":"In recent decades, greenhouse gas emission and global warming are the major threat to climatic change variability. The quality of concrete can be enhanced by the addition of a supplementary cementitious material to portland cement. In this study, fly ash is utilized as a supplemental cementitious material (SCM). The purpose of this research is to test and study the mechanical and thermal properties of blended concrete containing ordinary portland cement, fly ash and zinc sulphate as well as to investigate the microstructure in order to study the influence of zinc sulphate on the hydration process of concrete. This research mainly focused on the changes occurring in the strength, retarding mechanism, setting time, mineralogy, and microstructure caused by the addition of zinc sulphate in concrete. Ordinary portland cement, fly ash, pulverized fly ash and zinc sulphate are used in the blended concrete. The varied proportions of fly ash and zinc sulphate in the mix are 15%, 30%, 45%, and 60% respectively. The strength characteristics can be increased by fly ash pulverization. Hence the research focuses in exploring the addition of fly ash, pulverized fly ash and zinc sulphate anhydride to the concrete mix.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"93 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73928933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-10DOI: 10.1590/1517-7076-rmat-2023-0110
Gopalakrishnan Palanisamy, Vidhya Kumarasamy
In this research, an investigational study on the use of CFRP laminates with 4 types of configurations (Series-A: laminated with confinement wrap, Series-B: single flat & L wrap, Series-C: confinement wrap, and Series-D: double flat & confinement wrap) to repair partially damaged reinforced cement composite column-beam joints is presented. The project’s primary goal was to examine how retrofitting configurations affected the behaviour of repaired RC column-beam junctions when subjected to cyclic loads (FL + RL). To examine the effectiveness of repairs for enhancing the stiffness, strength capacity, and behaviour of damaged RC joints (Partially – 25%, 50%, and 75%), seventeen samples were fabricated and investigated. Cyclic loading was used to test the control specimen all the way to failure. Sixteen samples were subjected to a load level that was around 75% of the projected pre-failure load (26 kN) under seismic condition. The maximum load, ductility index, and load versus displacement were all used to analyse the data. Also, CFRP debonding and the failure modes due to fracture pattern were observed. The findings highlighted the significance of repairing and improving joint performance. All repaired joints have increased strength that is virtually as strong as the beam-column joint’s actual shear strength. As a result, compared to the reference specimen, the Series-D joints had a substantially greater strength capacity (30.77%).
{"title":"Rehabilitation of damaged RC exterior beam-column joint using various configurations of CFRP laminates subjected to cyclic excitations","authors":"Gopalakrishnan Palanisamy, Vidhya Kumarasamy","doi":"10.1590/1517-7076-rmat-2023-0110","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0110","url":null,"abstract":"In this research, an investigational study on the use of CFRP laminates with 4 types of configurations (Series-A: laminated with confinement wrap, Series-B: single flat & L wrap, Series-C: confinement wrap, and Series-D: double flat & confinement wrap) to repair partially damaged reinforced cement composite column-beam joints is presented. The project’s primary goal was to examine how retrofitting configurations affected the behaviour of repaired RC column-beam junctions when subjected to cyclic loads (FL + RL). To examine the effectiveness of repairs for enhancing the stiffness, strength capacity, and behaviour of damaged RC joints (Partially – 25%, 50%, and 75%), seventeen samples were fabricated and investigated. Cyclic loading was used to test the control specimen all the way to failure. Sixteen samples were subjected to a load level that was around 75% of the projected pre-failure load (26 kN) under seismic condition. The maximum load, ductility index, and load versus displacement were all used to analyse the data. Also, CFRP debonding and the failure modes due to fracture pattern were observed. The findings highlighted the significance of repairing and improving joint performance. All repaired joints have increased strength that is virtually as strong as the beam-column joint’s actual shear strength. As a result, compared to the reference specimen, the Series-D joints had a substantially greater strength capacity (30.77%).","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78085269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1590/1517-7076-rmat-2023-0059
Davi Cavalcante de Oliveira, J. Vaz, Marcelo de Oliveira e Silva, Edson Bruno Soares de Abreu, M. Galhardo, Leonam Ferreira de Araújo
Abstract In the Amazon, local electrical energy production is very important due to the large number of isolated communities, usually far from the conventional grid. In this context, steam turbines are relevant technologies to be used in the region, since waste biomass is widely available in several communities, besides, where sustainable agricultural activities take place, such as the use of açaí seeds, sugarcane bagasse, among others. Currently, there are not many relevant studies in the literature for small steam turbines operating at low pressure, conditioned to the reality of the Amazon region. Hence, the main goal of this work is to develop an experimental study of a small steam turbine operating at low pressure, in order to apply it to small energy demand, typically found in the Amazon. We developed measurements on the behavior of mechanical and electrical powers in relation to the shaft rotational speed of the small steam turbine, taking into account pressures of 0.1, 0.2 and 0.3 MPa. We concluded that the preliminary experimental survey, made in this work, demonstrates a good mechanical behavior of the small turbine and could be an alternative for electricity generation system to supply small demands in isolated communities in the Amazon, taking advantage of biomass from sustainable agricultural activities.
{"title":"™Small steam turbine operating at low pressure for generating electricity in the Amazon","authors":"Davi Cavalcante de Oliveira, J. Vaz, Marcelo de Oliveira e Silva, Edson Bruno Soares de Abreu, M. Galhardo, Leonam Ferreira de Araújo","doi":"10.1590/1517-7076-rmat-2023-0059","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0059","url":null,"abstract":"Abstract In the Amazon, local electrical energy production is very important due to the large number of isolated communities, usually far from the conventional grid. In this context, steam turbines are relevant technologies to be used in the region, since waste biomass is widely available in several communities, besides, where sustainable agricultural activities take place, such as the use of açaí seeds, sugarcane bagasse, among others. Currently, there are not many relevant studies in the literature for small steam turbines operating at low pressure, conditioned to the reality of the Amazon region. Hence, the main goal of this work is to develop an experimental study of a small steam turbine operating at low pressure, in order to apply it to small energy demand, typically found in the Amazon. We developed measurements on the behavior of mechanical and electrical powers in relation to the shaft rotational speed of the small steam turbine, taking into account pressures of 0.1, 0.2 and 0.3 MPa. We concluded that the preliminary experimental survey, made in this work, demonstrates a good mechanical behavior of the small turbine and could be an alternative for electricity generation system to supply small demands in isolated communities in the Amazon, taking advantage of biomass from sustainable agricultural activities.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"4 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89951943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-30DOI: 10.1590/1517-7076-rmat-2023-0109
A. Figueiredo, I. Pietra, Luís Antônio Guimarães Bitencourt Júnior
The use of construction and demolition (C&D) waste as aggregate in concrete results in a reduction in strength due to its porosity. To compensate, mix designs often require higher cement contents, which increase the material's environmental impact. This study presents an experimental and numerical analysis of the effect of steel fibres on the mechanical properties of the concrete produced with recycled C&D aggregates with varying densities. The variation in fibre content did not present any influence on the compressive strength of concrete, which is significantly affected by the lower density of the recycled C&D aggregate. The fibres collaborate to mitigate the loss of flexural strength of the steel fibre reinforcement in recycled coarse aggregate concrete (SFRRCAC) provoked by lower density of recycled aggregates when the water-to-cement ratio is lower. When the water-to-cement ratio is above 0.65, there is a great reduction of the matrix strengths due to the paste porosity and the influence of aggregate density and fibre content was insignificant.
{"title":"Influence of low content of steel fibre on concretes produced with recycled coarse aggregates with varying densities","authors":"A. Figueiredo, I. Pietra, Luís Antônio Guimarães Bitencourt Júnior","doi":"10.1590/1517-7076-rmat-2023-0109","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0109","url":null,"abstract":"The use of construction and demolition (C&D) waste as aggregate in concrete results in a reduction in strength due to its porosity. To compensate, mix designs often require higher cement contents, which increase the material's environmental impact. This study presents an experimental and numerical analysis of the effect of steel fibres on the mechanical properties of the concrete produced with recycled C&D aggregates with varying densities. The variation in fibre content did not present any influence on the compressive strength of concrete, which is significantly affected by the lower density of the recycled C&D aggregate. The fibres collaborate to mitigate the loss of flexural strength of the steel fibre reinforcement in recycled coarse aggregate concrete (SFRRCAC) provoked by lower density of recycled aggregates when the water-to-cement ratio is lower. When the water-to-cement ratio is above 0.65, there is a great reduction of the matrix strengths due to the paste porosity and the influence of aggregate density and fibre content was insignificant.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74709963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-23DOI: 10.1590/1517-7076-rmat-2023-0037
J. B. D. Silva, Rafaela Miranda da Silva, Andresa de Freitas Silva, Emanuel Laurertan Tavares França, E. P. Hernández, Patrícia Maria Albuquerque de Farias
RESUMO A construção civil exerce função importante no consumo de energia em todo o mundo e influência, de forma significativa, o consumo total de recursos naturais e as emissões de CO2. A utilização de materiais renováveis está intrinsecamente relacionada à pesquisa e à inovação. A reutilização, a reciclagem, bem como o desenvolvimento de novos materiais e a descoberta de novas aplicações para materiais renováveis já conhecidos, podem contribuir de maneira expressiva para o desenvolvimento sustentável. A quitosana (CS) é um biopolímero com uma estrutura química e características únicas aliadas à sua farta disponibilidade como derivado da quitina, fazem com que suas possibilidades de aplicação nos mais diferentes campos tecnológicos, tenha se expandido consideravelmente. No presente trabalho, a utilização da quitosana para produção de concretos por meio de teores ótimos é investigada. Os valores de quitosana incorporados na dosagem foram 0,1%; 0,3% e 0,4%, com relação à massa de cimento. Os diferentes concretos obtidos foram submetidos a ensaios de propriedades mecânicas e microestrutural. Os resultados mostraram que a microestrutura foi favorecida com a utilização da quitosana. Bem como, apresentaram resultados favoráveis à incorporação dos teores utilizados de quitosana (se desatacando as amostras com 0,1% de substituição), sendo positivos quanto às propriedades mecânicas para a maioria das técnicas utilizadas, o que indica fortemente que a quitosana pode ser considerada como material promissor a ser incorporado na produção de concreto.
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