Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated ... more Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.
This paper describes an experimental study on the flexural ductility of lightweight-aggregate con... more This paper describes an experimental study on the flexural ductility of lightweight-aggregate concrete beams including concretes with compressive strengths between 22.0 and 60.4 MPa and dry densities between 1651 and 1953 kg/m3. Nineteen simply supported beams were tested until failure. Two symmetrical concentrated loads were applied at approximately one third of the span. Ductility was studied by defining ductility indexes. The main variables are the concrete compressive strength and the longitudinal tensile reinforcement ratio. It is shown that the parameter with higher influence on ductility is the longitudinal tensile reinforcement ratio. The test results are also compared with the requirements from some codes of practice. It is shown that ACI Code requirements give more guaranties as far as ductility is concerned, when compared with European codes.
this article describes a study on the plastic behaviour of lightweight-aggregate concrete beams. ... more this article describes a study on the plastic behaviour of lightweight-aggregate concrete beams. the experimental results of nineteen simply supported beams previously tested by the authors were used in this study. the experimental plastic rotation capacity of the tested beams was characterized by a parameter called plastic trend parameter (ptp). the main variables studied were the concrete compressive strength and the longitudinal tensile reinforcement ratio. it was found that plastic rotation capacity slightly increases as the concrete compressive strength increases. An appropriate range for the longitudinal tensile reinforcement ratio to ensure plastic rotation capacity is proposed. the results of this study were also compared with the requirements from some codes of practice. From this analysis, it was shown that ACi Code requirements give more guaranties as far as plastic rotation capacity is concerned, when compared with european codes.
ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rh... more ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rheological behaviour. In fact, some powders materials and the new generation superplasticizer have been employed to attain the self-compactability in concrete mixtures. Normally, the SCC mixtures present a high amount of mortar in their composition. Thus, the SCC mortar phase has a very important influence on the SCC rheological behaviour that is also influenced by the materials used to compose the mortar phase. Some rheological properties as plastic viscosity and thixotropy are important to define the self compacting concrete workability. These properties are critical mainly when filling the formwork on site to achieve the compactness of the final product, since this type of concrete is applied without any vibration or other form of compaction. Thus, an approach of SCC rheological behaviour by previous mortar phase behaviour knowledge is especially relevant. This article describes an experimental study to evaluate the influence of different SCC mortar phase composition on the rheological behaviour. Powders materials of different nature, some them from wastes materials, are used to compose the mortar phase. The rheological parameters as relative yield stress and plastic viscosity was determined with a rheometer and others tests as slump flow (spread cone) and fluidity (v-funnel) were also used. The results provided a comparative and critical analysis of the relative influence of the mortars materials on the rheological parameters. It was found that the rheological behaviour of SCC mortar phase is represented by the Herschel-Buckley model.
ABSTRACT Palavras-chave: Reologia, Argamassas de revestimento, Agregados de cortiça, Tensão de ce... more ABSTRACT Palavras-chave: Reologia, Argamassas de revestimento, Agregados de cortiça, Tensão de cedência, Viscosidade plástica Resumo. Neste estudo, avaliaram-se argamassas com dois tipos de cortiça: cortiça natural (COR) e cortiça expandida (CEX). Para o efeito, produziram-se diferentes misturas que apresentaram em comum a mesma consistência de 170 ± 10 mm na mesa de espalhamento. Essas misturas incluíram: uma argamassa de referência na proporção em volume de 1:1:5 agregados finos naturais e britados [1,2] concluíram que a grande quantidade de finos, muitas vezes resultantes da britagem do agregado, têm principal influência na tensão de cedência da argamassa contribuindo para a viscosidade plástica devido ao aumento do atrito interpartículas. trabalhabilidade. Umas das características destas argamassas é o seu elevado valor de viscosidade plástica, que é vantajoso do ponto de vista do controlo da segregação [3]. A proporção W/C, o teor de vazios não compactados, o tamanho, forma e conteúdo de agregados possuem um papel predominante na fluidez da argamassa [1]. A fluidez da argamassa diminui com o aumento do teor de agregados e com a diminuição da razão W/C para um determinado tamanho do agregado.
ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rh... more ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rheological behaviour. In fact, some powders materials and the new generation superplasticizer have been employed to attain the self-compactability in concrete mixtures. Normally, the SCC mixtures present a high amount of mortar in their composition. Thus, the SCC mortar phase has a very important influence on the SCC rheological behaviour that is also influenced by the materials used to compose the mortar phase. Some rheological properties as plastic viscosity and thixotropy are important to define the self compacting concrete workability. These properties are critical mainly when filling the formwork on site to achieve the compactness of the final product, since this type of concrete is applied without any vibration or other form of compaction. Thus, an approach of SCC rheological behaviour by previous mortar phase behaviour knowledge is especially relevant. This article describes an experimental study to evaluate the influence of different SCC mortar phase composition on the rheological behaviour. Powders materials of different nature, some them from wastes materials, are used to compose the mortar phase. The rheological parameters as relative yield stress and plastic viscosity was determined with a rheometer and others tests as slump flow (spread cone) and fluidity (v-funnel) were also used. The results provided a comparative and critical analysis of the relative influence of the mortars materials on the rheological parameters. It was found that the rheological behaviour of SCC mortar phase is represented by the Herschel-Buckley model.
Construction using refurbished shipping containers is a recent building system, with already many... more Construction using refurbished shipping containers is a recent building system, with already many successful examples around the world. This system presents a huge potential in the field of sustainable construction provided by the recycling of used containers. This paper aims to contribute to a better knowledge of this construction system in what concerns to the structural project. The general constitution of two maritime shipping containers is presented as well as some aspects of their structural behavior. For this purpose, numerical analyses were performed using a finite elements analysis program. Normative aspects for the structural project are also presented. This paper also presents the analysis of a case study with the use of refurbished shipping containers to build a single-family house. The evaluation of the strength of the refurbished shipping containers to building actions is carried out. It is shown that such evaluation is not easy because some mechanical parameters of noncommercial steel section of the elements that compose the shipping containers are unknown. Nevertheless, this study shows the feasibility of this building system.
h i g h l i g h t s A methodology for SCC mix design was proposed to reconcile workability and st... more h i g h l i g h t s A methodology for SCC mix design was proposed to reconcile workability and strength. Interaction between the coarse aggregates and mortar phase particles was evaluated. Maximum volume of coarse aggregates strongly depends on the mortar phase properties. L-box test is more effective than Box test to evaluate the self-compactability level.
h i g h l i g h t s High thermal energy storage and low mass are compatible in PCM-filled LWA mor... more h i g h l i g h t s High thermal energy storage and low mass are compatible in PCM-filled LWA mortars. The thermal energy storage increase with PCM to a certain limit and then decrease. Two processes to dry the surface of LWA pre-soaked in PCM were design. The LWA surface dry with compressed air has advantages on mechanical properties.
This paper presents the results of an experimental investigation to verify the feasibility of usi... more This paper presents the results of an experimental investigation to verify the feasibility of using acrylic textile fibre to improve cement based mortars properties. The assessment of acrylic fibres influence on mortars properties was performed comparing the physical, mechanical and durability behaviour with mortars produced using glass and polypropylene fibres. The influence of the mixing procedures was also investigated. Effects of acrylic fibre aspect ratio (l/d) and volume fraction (V f) on mortar bulk density, compressive strength, flexural strength, water absorption and plastic shrinkage were investigated. For this purpose, acrylic fibres having six different l/d ratios 93, 148, 222, 278, 444 and 833 were used and the volume percentage of fibres were added to mortar mixes was of 0.2%, 0.5% and 1.0%. The mortar plastic shrinkage was also studied on slabs casted with 0.5%, 0.2%, 0.1% and 0.05% acrylic fibres volume. It was found that acrylic fibre reinforced mortars have physical, mechanical and durability related properties similar to the mortar reinforced with glass or polypropylene fibres. These results indicate that there is a potential technical feasibility of using this type of fibres in cementitious composites.
h i g h l i g h t s Permeability properties of SCC with 20%, 40% and 100% of coarse recycled aggr... more h i g h l i g h t s Permeability properties of SCC with 20%, 40% and 100% of coarse recycled aggregates were studied. According to the air permeability method applied, the SCC mixtures are considered airtight. The recycled coarse aggregate incorporation did not significantly affect the water permeability. Water capillarity coefficient is slightly decreased when 100% of coarse recycled aggregate is used. Water penetration depth is reduced with the increasing of the recycled aggregate in SCC.
This paper compares several different simplified methodologies for building energy performance as... more This paper compares several different simplified methodologies for building energy performance assessment during winter time selected based on its large application and/or its user friendly characteristics. Hourly values for energy demand are calculated by a detailed comparison tool based on hourly weather data. A simplified building procedure spreadsheet to evaluate energy demand is also presented. It gives reliable results, needs only a little input data to describe the building design and low time consumption. The spreadsheet is therefore useful for preliminary design tasks in the early design stages where rough estimates of the building design and preliminary energy use are needed for primary decision support. The method is based on a seasonal heating calculation of heat losses and usable heat gains for the building, where the heat-accumulating capacity of the building is considered. The seasonal mean values of the solar radiation and degree days are applied. This paper describe...
Razão água / (materiais cimentíceos) versus resistência à compressão para betões de diferentes el... more Razão água / (materiais cimentíceos) versus resistência à compressão para betões de diferentes elementos constituintes e diferentes dosagens ...
Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated ... more Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.
This paper describes an experimental study on the flexural ductility of lightweight-aggregate con... more This paper describes an experimental study on the flexural ductility of lightweight-aggregate concrete beams including concretes with compressive strengths between 22.0 and 60.4 MPa and dry densities between 1651 and 1953 kg/m3. Nineteen simply supported beams were tested until failure. Two symmetrical concentrated loads were applied at approximately one third of the span. Ductility was studied by defining ductility indexes. The main variables are the concrete compressive strength and the longitudinal tensile reinforcement ratio. It is shown that the parameter with higher influence on ductility is the longitudinal tensile reinforcement ratio. The test results are also compared with the requirements from some codes of practice. It is shown that ACI Code requirements give more guaranties as far as ductility is concerned, when compared with European codes.
this article describes a study on the plastic behaviour of lightweight-aggregate concrete beams. ... more this article describes a study on the plastic behaviour of lightweight-aggregate concrete beams. the experimental results of nineteen simply supported beams previously tested by the authors were used in this study. the experimental plastic rotation capacity of the tested beams was characterized by a parameter called plastic trend parameter (ptp). the main variables studied were the concrete compressive strength and the longitudinal tensile reinforcement ratio. it was found that plastic rotation capacity slightly increases as the concrete compressive strength increases. An appropriate range for the longitudinal tensile reinforcement ratio to ensure plastic rotation capacity is proposed. the results of this study were also compared with the requirements from some codes of practice. From this analysis, it was shown that ACi Code requirements give more guaranties as far as plastic rotation capacity is concerned, when compared with european codes.
ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rh... more ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rheological behaviour. In fact, some powders materials and the new generation superplasticizer have been employed to attain the self-compactability in concrete mixtures. Normally, the SCC mixtures present a high amount of mortar in their composition. Thus, the SCC mortar phase has a very important influence on the SCC rheological behaviour that is also influenced by the materials used to compose the mortar phase. Some rheological properties as plastic viscosity and thixotropy are important to define the self compacting concrete workability. These properties are critical mainly when filling the formwork on site to achieve the compactness of the final product, since this type of concrete is applied without any vibration or other form of compaction. Thus, an approach of SCC rheological behaviour by previous mortar phase behaviour knowledge is especially relevant. This article describes an experimental study to evaluate the influence of different SCC mortar phase composition on the rheological behaviour. Powders materials of different nature, some them from wastes materials, are used to compose the mortar phase. The rheological parameters as relative yield stress and plastic viscosity was determined with a rheometer and others tests as slump flow (spread cone) and fluidity (v-funnel) were also used. The results provided a comparative and critical analysis of the relative influence of the mortars materials on the rheological parameters. It was found that the rheological behaviour of SCC mortar phase is represented by the Herschel-Buckley model.
ABSTRACT Palavras-chave: Reologia, Argamassas de revestimento, Agregados de cortiça, Tensão de ce... more ABSTRACT Palavras-chave: Reologia, Argamassas de revestimento, Agregados de cortiça, Tensão de cedência, Viscosidade plástica Resumo. Neste estudo, avaliaram-se argamassas com dois tipos de cortiça: cortiça natural (COR) e cortiça expandida (CEX). Para o efeito, produziram-se diferentes misturas que apresentaram em comum a mesma consistência de 170 ± 10 mm na mesa de espalhamento. Essas misturas incluíram: uma argamassa de referência na proporção em volume de 1:1:5 agregados finos naturais e britados [1,2] concluíram que a grande quantidade de finos, muitas vezes resultantes da britagem do agregado, têm principal influência na tensão de cedência da argamassa contribuindo para a viscosidade plástica devido ao aumento do atrito interpartículas. trabalhabilidade. Umas das características destas argamassas é o seu elevado valor de viscosidade plástica, que é vantajoso do ponto de vista do controlo da segregação [3]. A proporção W/C, o teor de vazios não compactados, o tamanho, forma e conteúdo de agregados possuem um papel predominante na fluidez da argamassa [1]. A fluidez da argamassa diminui com o aumento do teor de agregados e com a diminuição da razão W/C para um determinado tamanho do agregado.
ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rh... more ABSTRACT The workability of self-compacting concrete is strongly dependent of its mortar phase rheological behaviour. In fact, some powders materials and the new generation superplasticizer have been employed to attain the self-compactability in concrete mixtures. Normally, the SCC mixtures present a high amount of mortar in their composition. Thus, the SCC mortar phase has a very important influence on the SCC rheological behaviour that is also influenced by the materials used to compose the mortar phase. Some rheological properties as plastic viscosity and thixotropy are important to define the self compacting concrete workability. These properties are critical mainly when filling the formwork on site to achieve the compactness of the final product, since this type of concrete is applied without any vibration or other form of compaction. Thus, an approach of SCC rheological behaviour by previous mortar phase behaviour knowledge is especially relevant. This article describes an experimental study to evaluate the influence of different SCC mortar phase composition on the rheological behaviour. Powders materials of different nature, some them from wastes materials, are used to compose the mortar phase. The rheological parameters as relative yield stress and plastic viscosity was determined with a rheometer and others tests as slump flow (spread cone) and fluidity (v-funnel) were also used. The results provided a comparative and critical analysis of the relative influence of the mortars materials on the rheological parameters. It was found that the rheological behaviour of SCC mortar phase is represented by the Herschel-Buckley model.
Construction using refurbished shipping containers is a recent building system, with already many... more Construction using refurbished shipping containers is a recent building system, with already many successful examples around the world. This system presents a huge potential in the field of sustainable construction provided by the recycling of used containers. This paper aims to contribute to a better knowledge of this construction system in what concerns to the structural project. The general constitution of two maritime shipping containers is presented as well as some aspects of their structural behavior. For this purpose, numerical analyses were performed using a finite elements analysis program. Normative aspects for the structural project are also presented. This paper also presents the analysis of a case study with the use of refurbished shipping containers to build a single-family house. The evaluation of the strength of the refurbished shipping containers to building actions is carried out. It is shown that such evaluation is not easy because some mechanical parameters of noncommercial steel section of the elements that compose the shipping containers are unknown. Nevertheless, this study shows the feasibility of this building system.
h i g h l i g h t s A methodology for SCC mix design was proposed to reconcile workability and st... more h i g h l i g h t s A methodology for SCC mix design was proposed to reconcile workability and strength. Interaction between the coarse aggregates and mortar phase particles was evaluated. Maximum volume of coarse aggregates strongly depends on the mortar phase properties. L-box test is more effective than Box test to evaluate the self-compactability level.
h i g h l i g h t s High thermal energy storage and low mass are compatible in PCM-filled LWA mor... more h i g h l i g h t s High thermal energy storage and low mass are compatible in PCM-filled LWA mortars. The thermal energy storage increase with PCM to a certain limit and then decrease. Two processes to dry the surface of LWA pre-soaked in PCM were design. The LWA surface dry with compressed air has advantages on mechanical properties.
This paper presents the results of an experimental investigation to verify the feasibility of usi... more This paper presents the results of an experimental investigation to verify the feasibility of using acrylic textile fibre to improve cement based mortars properties. The assessment of acrylic fibres influence on mortars properties was performed comparing the physical, mechanical and durability behaviour with mortars produced using glass and polypropylene fibres. The influence of the mixing procedures was also investigated. Effects of acrylic fibre aspect ratio (l/d) and volume fraction (V f) on mortar bulk density, compressive strength, flexural strength, water absorption and plastic shrinkage were investigated. For this purpose, acrylic fibres having six different l/d ratios 93, 148, 222, 278, 444 and 833 were used and the volume percentage of fibres were added to mortar mixes was of 0.2%, 0.5% and 1.0%. The mortar plastic shrinkage was also studied on slabs casted with 0.5%, 0.2%, 0.1% and 0.05% acrylic fibres volume. It was found that acrylic fibre reinforced mortars have physical, mechanical and durability related properties similar to the mortar reinforced with glass or polypropylene fibres. These results indicate that there is a potential technical feasibility of using this type of fibres in cementitious composites.
h i g h l i g h t s Permeability properties of SCC with 20%, 40% and 100% of coarse recycled aggr... more h i g h l i g h t s Permeability properties of SCC with 20%, 40% and 100% of coarse recycled aggregates were studied. According to the air permeability method applied, the SCC mixtures are considered airtight. The recycled coarse aggregate incorporation did not significantly affect the water permeability. Water capillarity coefficient is slightly decreased when 100% of coarse recycled aggregate is used. Water penetration depth is reduced with the increasing of the recycled aggregate in SCC.
This paper compares several different simplified methodologies for building energy performance as... more This paper compares several different simplified methodologies for building energy performance assessment during winter time selected based on its large application and/or its user friendly characteristics. Hourly values for energy demand are calculated by a detailed comparison tool based on hourly weather data. A simplified building procedure spreadsheet to evaluate energy demand is also presented. It gives reliable results, needs only a little input data to describe the building design and low time consumption. The spreadsheet is therefore useful for preliminary design tasks in the early design stages where rough estimates of the building design and preliminary energy use are needed for primary decision support. The method is based on a seasonal heating calculation of heat losses and usable heat gains for the building, where the heat-accumulating capacity of the building is considered. The seasonal mean values of the solar radiation and degree days are applied. This paper describe...
Razão água / (materiais cimentíceos) versus resistência à compressão para betões de diferentes el... more Razão água / (materiais cimentíceos) versus resistência à compressão para betões de diferentes elementos constituintes e diferentes dosagens ...
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