Programa de Pós-graduação em Geotecnia, Estruturas e Construção Civil
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Item Contribuição ao estudo da durabilidade e do transporte de fluidos em concretos contendo adições minerais(Universidade Federal de Goiás, 2016-09-21) Almeida, Marina Augusta Malagoni de; Carasek, Helena; http://lattes.cnpq.br/3023241186996790; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Amaral, Tatiana Gondim do; Lopes, Anne Neiry de MendonçaBrazil's current water crisis, generated by the low level of reservoirs, has threatened the national energy production. Faced with this problem, the wind towers present themselves as a viable solution. It is known that these towers are constructed in regions of high aggressiveness and therefore, it is necessary to develop high performance concretes that are able to withstand environmental action to which they are submitted, so that these structures reach the lifespan previously defined in project, ensuring the viability of the towers. In this sense, the present study evaluates the mass transport mechanisms (permeability and absorption) that takes place inside the concrete containing mineral pozzolanic admixtures of high performance, in order to evaluate the influence of the presence of these additions in these properties. Three different study mixes were prepared containing, respectively, 9% of silica fume in composition with 1% of nanossílica, 5% of a metakaolin with high fineness in composition with 5% of a metakaolin slightly less fine, both with high pozzolanic activity, a mix containing only 10% of the metakaolin with higher fineness, and a reference proportioning. The analysis presented in this work involve the scanning electron microscope (SEM) to characterize the internal structure of the material, the trace reconstruction test to analyze the aggregate/binder ratio in the regions of the cover and the interior of concrete, and the analyzes related to the mass transport: water absorption by immersion and capillarity and the air permeability obtained by the Figg’s method, in addition to the mechanical characterization. The concrete with addition of pozzolanic admixtures showed significant improvements in compressive strength, in the modulus of elasticity, in the air permeability and in the refinement of pores. Furthermore, the evaluation of the microstructure by scanning electron microscope showed that the use of mineral admixtures may cause an improvement in the adhesion and in the densification of the transition zone between aggregate and cement paste. The trace reconstitution test showed that the concrete cover has lower ratio aggregate/binder, which corroborates the results of the capillary absorption test in which it was found that the cover of concrete presents a mean capillarity absorption lower than the interior region. Thus, it was concluded that the incorporation of the different mineral admixtures studied in this work significantly alter the properties of concrete, with positive emphasis on the properties related to the durability, in which the benefits of using mineral admixtures is more pronounced and, in addition, it was also concluded that the concrete cover presents itself more favorable to the durability than the interior region.Item Avaliação das características de diferentes metacaulins e sua influência na estrutura interna do concreto e em propriedades ligadas à durabilidade(Universidade Federal de Goiás, 2016-02-25) Alves, Rodrigo Teodoro; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Carasek, Helena; Ribeiro, Daniel VérasCementitious materials have been used since antiquity. The development of silica fume as a pozzolana has afforded significant improvements to concrete technology. Now, new high performance mineral admixtures have come to light, such as highly-reactive metakaolin. This material has presented great results, trough more than a decade, in researches made by the group of study of concrete durability of UFG. The fact of metakaolin concretes shows great performance towards durability and mechanical strength is controversial, once the silica content is about 55%, which, theoretically, would result in a smaller volume of C-S-H, from the pozzolanic reaction. However, as it is a very fine material, its physical effect in concrete seems to be more prominent, besides, the alumina that there is in metakaolin also produces interesting hydrated compounds. This way, the goal of the present work is to evaluate the changes in the microstructure of concrete using three types of metakaolin, manufactured by the same company. The main differences between than is their fineness. The specific surface area, measured by BET method, varied from about 8 000 m²/kg to 31 000 m²/kg. Moreover, one of them – the coarser one – differs from the other because it has a high chemical and mineralogical purity. In order to have a better understanding of the properties of the three types of metakaolin, a wide characterization of the physical, chemical and mineralogical properties of this mineral admixtures were carried out. Concrete mixtures were than prepared for the purpose of knowing the influence of the characteristics of the metakaolins in the mechanical and durability related properties and microstructure of the concrete. Metakaolin concretes studied in this work showed significant improvement in mechanical strength, total porosity, pore refinement, electrical resistivity and non-steady state chloride migration. The evaluation of concrete microstructure shows that metakaolin promoted a densification of interfacial transition zone between the paste matrix and aggregate. Furthermore, there are indications suggesting that in metakaolin concrete can occur the formation of Friedel’s salt. Thus, it follows that the addition of the three different types of metakaolin had significantly changed the properties of concrete, with positive highlight for the properties associated to concrete durability, in which the benefits of the mineral admixtures were more pronounced.Item Avaliação das infraestruturas cicloviárias implantadas no corredor universitário em Goiânia(Universidade Federal de Goiás, 2015-08-13) Antunes, Luiza Lemos; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Carasek, Helena; Paiva, Mariana deThe bicycle is a vehicle used extensively in Brazil and comes as a transport option to mitigate the impacts caused by the indiscriminate use of individual motorized transport. However, despite the use of bicycles in Brazil has a century of history, the lack of an effective cycling policy translates the main factor limiting the insertion of the bicycle as a mode of transport. The cycle planning must act comprehensively where all variables such as geometry, materials and execution should be considered jointly. Thus, this study aimed to conduct an analysis of the performance and the cycle system service conditions implanted in Goiania in conjunction the preferred range stretch of public transport, named Corredor Universitário. The study has also brought a survey of pathological problems and occurrence of nonconformities, associated with the project design stages, material specifications and implementation. Supported by requirements established for cycle planning and by technical standards, design aspects and used technologies were evaluated, such as materials and implementation process, in order to diagnose the system's deficiencies. To assess cycle pavement, in the absence of a specific methodology, we used an adapted method for evaluation and conceptualization of road pavements, by means of the calculation of Pavement Condition Index (PCI). Several flaws were identified in the implanted cycle system. Among the main ones are: the inadequacy of the signage of cycle paths, drainage problems, lighting of bike lanes way compromised by the lack of maintenance, damaged street furniture, lack of bike parking and severe paving problems. Several factors such as the absence of a paving design and the lack of a technological control of concrete influenced the pavement performance of cycle paths, which, with only 3 years of service, have exhibited numerous pathologies. Thus, the analyzed sections were characterized Good the Bad as concepts presented by the adopted method. Therefore, problems diagnosed in the cycle system of Corredor Universitário are due to a variety of factors, ranging from the stage of design planning and conception, as well as the deficiency or absence of the executive design and the low quality control of all execution process.Item Avaliação técnica dos resíduos gerados em ETA como substituto parcial de agregados em componentes cimentícios - PAVERS(Universidade Federal de Goiás, 2017-08-25) Araújo, Flávio de Carvalho; Scalize, Paulo Sérgio; http://lattes.cnpq.br/0957896448117207; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Carasek , Helena; Albuquerque, AntônioThe present research proposes a technical evaluation for the use of the waste generated in the Water Treatment Plant, Eng. Rodolfo José Costa e Silva, located in the city of Goiânia, State of Goiás, Brazil, as a partial substitute for the fine aggregates of cementitious elements. The study conducted the analysis of the residues, from the material science point of view, through the physical and mineralogical characterization, as well as the investigation concerning the possibility of pozzolanic activity of the material. Therefore, the parameters found were compared based on specific literature and current normalizations, and the study evaluated the similarity between the residue characteristics and the traditional raw materials used in the production of cementitious materials, such as sand, clay, and limestone; in this context, an experiment was carried out with the application of WTP residues in a component used in construction: concrete floor (Paver). The results of the mechanical tests were statistically analyzed to see the influence of the residue, age and interaction between these variables in the results. It was found that the proportion of 5% of residue significantly improved the mechanical resistance of Pavers (33.5%) at 28 days in the control sample, but water absorption increased (68.8%). In this way, a sustainable alternative of insertion of the waste in the productive chain of the construction was sought, producing a cement element, and at the same time contributing to reduce the environmental impact caused by the release of the residues in the springs. Aiming at reducing the environmental liabilities of the water industry, as well as reducing the extraction of raw material for cement production.Item Influência da cura térmica a vapor sob pressão atmosférica em características e propriedades de blocos de concreto(Universidade Federal de Goiás, 2013-04-30) Brito, Mário Henrique Gomes; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Carasek, Helena; Camarini, GladisThe overall objective of this research, which was essentially experimental, is to study the influence of the isothermal period and the maximum temperature of the thermal cure cycle steam under atmospheric pressure in the development of compressive strength of concrete blocks over time. The influences of two other types of curing are also being investigated; curing by enveloping with plastic sheet and open air curing, considered the last case scenario for reference. This study specifically aimed to further our understanding on how to; a) evaluate and quantify the importance of adopting procedures for curing the average resistance (Fbm) and characteristic (fbk) strength to compression of concrete blocks, comparing the processes of thermal curing and curing by enveloping plastic sheet to open air curing; b) evaluate statistically the aging effect of blocks over its compressive strength; c) evaluate the interaction effects of the variables "type of cure" and "age analysis" of the results of compressive strength of concrete blocks; and d) identify the main changes in the microstructure of the blocks subjected to a thermal curing process, especially observing eventual delayed ettringite formation in the internal structure of the material. To examine the influence of maximum curing temperature, two levels were adopted; 65°C and 85°C. As for analyzing the influence of isothermal period, three levels were adopted; 3 hours, 4 hours and 5 hours. The age analysis was evaluated in five levels; 1, 3, 7, 28 and 91 days. The results showed that the worst condition for curing, or curing type, was the open air curing (curing time approximately equal to 24 hours), which led to a lower overall average result of compressive strength of concrete blocks, proving the importance of adopting procedures of curing to optimize the mechanical performance of concrete blocks. Furthermore, it was also determined that the best curing conditions were the curing with enveloping plastic sheet (curing time approximately equal to 24 hours) and the thermal curing with steam under atmospheric pressure isotherm of 65°C and isothermal period of 3 hours (curing time approximately equals 8.5 hours), which were considered statistically equal. It was also observed that there was no significant influence of the curing in maximum temperature in relation to the compressive strength of the blocks. In the other hand, the isothermal period was very significant; the best condition was 3 hours, while 4 hours and 5 hours were considered statistically equal. Regarding the delayed ettringite formation, it was only verified for thermal curing conditions of isothermal of 85°C and isothermal period of 4 hours and 5 hours.Item Estudo da carbonatação natural de concretos com diferentes adições minerais após 10 anos de exposição(Universidade Federal de Goiás, 2013-04-29) Ferreira, Murillo Batista; Carasek, Helena; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Hasparyk, Nicole Pagan; Isaia, Geraldo CechellaAmong lots of pathologies that attack the concrete structures stands out the corrosion of the reinforcements, that may be triggered by the phenomenon of carbonation of the concrete, which consists in a physico-chemical process between the carbon dioxide (CO2) from the atmosphere and the cement paste compounds, which has as main result the calcium carbonate precipitation (CaCO3) in a region of the concrete cover, with the formation of a layer that has less alkalinity than that not affected by this phenomenon. The carbonation moves from outside to inside the concrete through a carbonated front, that when it reaches the depth of the reinforcement causes destabilization of the protective passive layer, providing the onset of the corrosion. How many researches are conducted by accelerated carbonation tests, it is of paramount importance that the evaluation process by comparing it with data obtained from samples that have suffered natural carbonation. Facing this reality, this research is conducted based on samples that are exposed in the natural environment (external housed) for a period of ten years, with the general objective of evaluating the results (coefficients and carbonation depths) of natural carbonation process of concrete with different mineral additions, water/binder ratios and curing conditions (moist and dry) over this period. For this realization, samples of concrete produced in 2002, produced in Castro's dissertation (2003). The variables included in the experimental program are: concretes with five types of mineral additions (silica fume (10%), rice husk ash (10%), metakaolin (10%), fly ash (25%), blast furnace slag (65%), these amounts being in partial replacement of cement mass) and the reference concrete, without mineral addition; three water/binder relationships (0.40 , 0.55 and 0.70) and two curing conditions (moist and dry). Measurements were made of natural carbonation through of pH indicator based on phenolphthalein, elaborating a database along time, through measurements with periods of exposure of 0.25 years (91 days), 0.50 years (182 days), 0.82 years (301 days), 3 years, 7 years, 9 years and 10 years, allowing comparative performance evaluation of various concrete containing mineral additions, taking as a base carbonated depths and natural carbonation coefficients data. The results showed that there are significant differences of behavior between different concretes studied and that in the overall analysis of the carbonation natural coefficients, the reference concrete showed the best alone performance, showing that the alkaline reserve is still the predominant effect in terms of against carbonation, but the microstructure refinement provided by additions (physical effect) approaches such chemical aspect, as detected, for example, in concrete with metakaolin. In the correlation between the accelerated carbonation coefficients and the natural carbonation ones, was verified a relation of direct proportionality between the coefficients found for the two procedures, with the coefficient signifying accelerated approximately 7.4 times the natural ratio. The useful life predictions showed periods of time until the carbonation front reaches the cover thickness ranging from 4 years up to 241 years, for the different concretes and situations analyzed.Item Estudo do calor de hidratação do concreto massa e contribuição ao cálculo térmico e à previsão de fissuras de retração(Universidade Federal de Goiás, 2017-08-31) Gambale, Patrícia Guedes; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Carasek, Helena; Kuperman, SelmoThe advancement of concrete technologies and methods of structural calculation nowadays makes buildings increasingly challenging, especially from the point of view of foundations. Foundation blocks with great volumes need attention as to the fissures arising from the exothermic process of hydration of the concrete, this concern defines the mixture as mass concrete, a widespread term in the construction of dams and that has been gaining space in urban civil construction. This study proposes the monitoring of prototypes of concrete blocks developed in the laboratory and foundation block in the field, with the use of thermocouples comparing with numerical methods of finite elements aiming to improve the prediction of cracks and to develop techniques so that they are avoided. This study will analyze the influence of the type and consumption of cement in the emergence of tensions arising from the energy released during its hydration. As results, a relation of the type interference and cement consumption is presented through the monitoring and analysis of the foundation block prototypes developed in the research, the development of a simplified unidirectional model of temperature and voltage prediction due to the heat of hydration for to evaluate the maximum temperature reached and the potential of cracking in the concrete mass and the comparison between the temperature results obtained in the Ansys program, which uses three- dimensional modeling and, as a way of validating the predictive model of thermal behavior as a reliable tool of analysis, the study also presents a field monitoring of a foundation block of a construction located in Goiânia and later application of the forecast model and the Ansys program. It was found, therefore, that the cement type has a considerable influence on the compressive strength and the adiabatic elevation, the latter being less significant. As for the cement consumption analysis, there was a notable increase in temperature in the concrete with higher consumption, causing cracks in the analyzed structure. By means of the results presented by the Ansys program, the monitoring of the prototypes and block in the field and the proposed forecast model, the validation of this model was confirmed as a good predictive tool of thermal behavior, highlighting some limiting conditions that surround it.Item Análise da estrutura porosa de materiais cimentícios por meio da interação e associação de técnicas avançadas de caracterização(Universidade Federal de Goiás, 2019-12-20) Hilário, Hanaelly Garcia do Carmo; Carasek, Helena; http://lattes.cnpq.br/3023241186996790; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Oliveira, Andrielli Morais de; Vieira, Janine DomingosCementitious materials such as concretes, mortars and pastes are naturally porous and they have a complex internal pore structure. This porosity has determining effects on the mechanical properties and durability of structures. Therefore it’s required a better understanding of the porous structure. This understanding is based on the use of techniques for measuring the porosity of cementitious materials, further analysis and interpretation of results and techniques. Thus, the objective of the present work was to analyze whether there is correlation, parallelism and complementation between the following advanced characterization techniques: Mercury Intrusion Porosimetry (MIP), Nitrogen Adsorption (BET), Nuclear Magnetic Resonance (NMR) and X-ray Computed Microtomography (μCT) when used for porosity measurement in cementitious matrices. As well as assess the responsiveness and sensitivity of these techniques through their results and output variables in relation to the various situations proposed in the dosage. The methodological steps taken to reach the objective include: the complete characterization of the materials used, the dosage of five different concretes (REF 0.40, REF 0.55, 0.55/10MK, 0.55/9SA1NS and REF 0.70 ), tests with concretes, such as: slump test, incorporated air content, compressive strength and modulus of elasticity, tests on pastes, such as: DRX; and tests on mortars: MIP, BET, NMR and μCT, for porosity studies. The results show that, depending on the range and structure of the pores, the results of BET, MIP, NMR and μCT may be more or less representative. The NMR tests captured a higher total porosity for the studied mortars. The NMR results also have good correlations with all other techniques studied, either with the whole sample scope or considering only the reference mortars. The same statement can be made for the BET technique. NMR and μCT techniques together occupy the largest pore diameter range and they have a number of similarities, in this way it is concluded that the combination of the two is the most viable.Item Permeabilidade ao gás em concreto com adições minerais e sua contribuição no campo dos indicadores de durabilidade(Universidade Federal de Goiás, 2018-11-29) Macedo, Raquel Hellu; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Cascudo, Helena Carasek; Silva Júnior, Paulo FrancineteThere is a continuing concern in scientific-technical environment regarding concrete durability considering that Brazilian standards are based on a prescriptive approach, resulting only in specifications concerning water/ binder ratio and cover thickness values. In this context, this study is focused on the durability indicator of concrete gas permeability, making use of the most used method in the world, CEMBUREAU, in order to contribute to the measurement of the permeability coefficient (to the gas) applied to local and regional concretes. Three different study proportions were elaborated, each one containing respectively, 9% of active silica in composition with 1% of nanosilica, 5% of a high fineness metakaolin in composition with 5% of a metakaolin a little less fine, both with high pozzolanicity and a proportion containing exclusively 10% of metakaolin of higher fineness, along with a reference proportion, all of them with two water/binder ratio, two spots for analysis (covering and interior) and two situations of relative humidity (75% and oven dried). The specimens were tested with CEMBUREAU permeameter, the object of this study, using the AFREM-AFPC method to measure the gas permeability coefficient. Next, an analysis of variance (ANOVA) was performed to verify if the chosen variables were influential in the gas permeability values. All the chosen variables, namely: mineral addition, water/binder ratio, extraction spot, inlet pressure, and relative humidity were influential in the concrete gas permeability. The results from the permeability coefficients were compared with those from literature and submitted to criteria. Straight after, correlations among durability properties were tested with a previous study (MALAGONI, 2016) which used the same concrete proportioning of this research. It is concluded that the additions used modified significantly the gas permeability coefficient, the water/binder is also influential in this values, what is repeated to the sample extraction spot and relative humidity. For correlations with durability properties, good values were tested and found to compressive strength, elasticity modulus, capillary absorption and air permeability (Figg). Therefore, the AFREM-AFPC test methodology was investigated to national validation and is ready for study and conception of a national standard related to the gas permeability indicator.Item Transporte de cloretos em concretos com adições minerais e o desempenho em relação à corrosão das armaduras(Universidade Federal de Goiás, 2016-12-16) Martins, Alex Mizael; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Carasek, Helena; Oliveira, Andrielli Morais deThe introduction of wind energy into the brazilian energy matrix is of paramount importance for national energy policy. In this context, the viability of wind towers is a fundamental issue. In Brazil, these towers are built mainly in reinforced concrete, in regions of high aggressiveness (coastal regions, because of their greater wind potential) and, therefore, it is necessary to develop high performance concretes that are able to withstand environmental actions to which they are subjected, mainly the action of the chlorides, so that these structures reach the previously defined project life, thus guaranteeing the viability of the towers. In this sense, the present work evaluates the mechanical properties, the mechanisms of transport of chlorides and the performance in relation to the corrosion of the reinforcement, in concretes that contain high performance pozolanic mineral additions, in order to evaluate the influence of the presence of these additions in these properties. Three different study mixes were developed containing respectively, 9% of silica fume in composition with 1% of nanosilica, 5% of a high fineness metakaolin in composition with 5% of a slightly less fine metakaolin, both with high pozzolanic activity and a mix containing only 10% of the finest metakaolin, in addition to a reference mix. Analyzes related to the chloride transport are presented: penetrability and diffusion; analyzes related to the corrosion of reinforcement: induction of corrosion by aggressive solution wetting cycles and air drying, surface electrical resistivity of concrete and corrosion potential, besides the mechanical characterization. The concretes with incorporation of pozzolanic addition showed, in general, improvements in the mechanical properties. In the chloride transport properties and corrosion performance of the reinforcements, the improvements from the mineral additions were significant. Thus, it was concluded that the incorporation of the different mineral additions studied in the present work significantly altered the properties of the concrete, with a positive highlight for the properties associated with durability, in which the benefits of using mineral addition are more pronounced.Item Influência do metacaulim na durabilidade de concretos usuais de mercado sujeitos à carbonatação acelerada(Universidade Federal de Goiás, 2013-09-30) Perim, José Roberto; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Carasek, Helena; Kazmierczak, Cláudio de SouzaThe concrete, to be one of the most consumed material in the world, has been the object of several studies and researches in order to improve and enhance its features with respect to technical, economical and environmental aspects, aiming a higher durability. Solutions have been searched and actions have been implemented in order to produce such concrete and to achieve these goals. One of which is the incorporation of mineral additions to replace part of the Portland cement used in the production of this material. Several additions have been studied over time, among them are the fly ash, the slag blast furnace, the silica fume, the ash from rice husk, the bagasse ash from sugar cane and the metakaolin. The latter is a high reactivity pozzolan and it is being studied to be an alternative material of great potential and abundance, it is found in several parts of the world and it has a great number of advantages, such as ease of exploration, the use of a relatively simple process in its industrialization, the low cost of production and trade, besides a lower environmental impact when compared to the clinker. Several researches have already proved its potential as pozzolanic material, however, a few studies have been conducted in order to verify the durability of concretecurrent market with the addition of metakaolin. The carbonation, which is, simplifying, a chemical reaction between the carbon dioxide from the air and the calcium hydroxide present in cement paste, and occurs in the surface layers in contact with the environment to which the concrete is exposed, is one of the most important phenomenon to the beginning of the process of corrosion that causes major problems related to the lack of durability of structures, can lead to the collapse of structures. In this research, two groups of concrete were studied. In the first group were addressed levels of 10%, 12,5%, 15%, 17,5% and 20% of metakaolin in replacement of the cement and with the same relation a/ag (0,60). And in the second group were used the substitution levels of 10%, 15% and 20%, keeping the same range of resistance with variation of the ratio a/ag. The behavior of these concrete was analyzed in relation of its resistance to compressive strength at ages 3, 7, 28, 56 and 91 days, to water absorption by immersion at 91 days, and to microstructural and mineralogical changes. It as also evaluated the advancing front of carbonationmeasurements of the depth of the carbonation and mass gain during 16 weeks after preconditioning, where these concrete were subjected to accelerated carbonation process in a CO2 incubator, whose parameters used were as follows: temperature of 20°C, 75% relative humidity and CO2 concentration from 6%. The results showed that as the level of metakaolin increases, there are strength gains by compression, reaching levels between 8% and 16% higher than the reference concrete. Regarding the carbonation process, the behavior of the concrete of the first group was very similar to the reference concrete, and that levels 10% and 15% of substitution had the best performances. The concrete of the second group performed well below the other group, showing the great influence of ratio a/g related to carbonation.Item Microconcreto de alto desempenho com fibras de polipropileno(Universidade Federal de Goiás, 2018-08-31) Silva, Reginaldo Virgilio da; Bacarji, Edgar; http://lattes.cnpq.br/2385473000869120; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Oswaldo; Bacarji, Edgar; Carasek, Helena; Mendes, Marcus Vinícius Araújo da SilvaThe microconcrete can be defined as a specific type of concrete in which the presence of small aggregates is predominant and can be used in light prefabrication, that is, in thin section structural elements. Thus, this work aims to evaluate the behavior, in the fresh and hardened states, of the high performance microconcrete with the use of polypropylene fibers. To do so, two fiber dimensions were used: a short 12 mm long, usually used to reduce cracking by plastic retraction, and another fiber of 54 mm, which has a structural function, contributing to improve the tensile strength of material. The fiber contents, in relation to the microconcrete volume, were 0.1%, 0.2%, 0.3% and 0.4% for the microfiber, 0.3%, 0.4% and 0, 5% for the macrofiber and for the hybrids, these being composed of 30% microfiber and 70% macrofiber. Part of the cement was replaced by active silica (SA) and fly ash (CV), in proportions of 7.5% for each one. The tests in the fresh state showed that the fibers reduced the workability, being this more accentuated in the microconcretes with addition of microfibres. Fibers contributed to increase fracture energy; this fact has shown that the application of the fibers in cementitious elements is promising in order to inhibit the brittle rupture and to provide ductile behavior to the element. The contents of 0.3% and 0.4% of microfibers presented a marked increase in porosity and, consequently, an increase in carbonation depth. The tests demonstrated that one must advance in researches with the use of hybrid mixtures and composites with contents of up to 0,12% of microfibres. The addition of the PP fibers provided positive mechanical results for additions of up to 0.1% of microfibers and for additions of up to 0.12% of microfibers in the hybrid composites. In terms of durability presented similar results, except for the additions from 0.2% of microfibers that reasonably elevated the carbonation depth. The high performance of the microconcrete was demonstrated by the results of axial compressive strength around 50 MPa, and by the increase of the tenacity provided by the addition of the PP fibers.