ABSTRACT In this paper an experimental work is presented which main objective is the evaluation o... more ABSTRACT In this paper an experimental work is presented which main objective is the evaluation of the influence of different percentages of waste fibrous materials usage on the performance of fiber-reinforced mortars. Moreover, the influence of binder type is evaluated. Therefore mortars were produced with two different binders – cement and powder hydrated lime. Mortars performance evaluation was carried out through flow table and plunger penetration consistency, dynamic modulus of elasticity, flexural and compressive strength, capillary absorption, drying index and adherence tests. The benefits revealed in some characteristics of both mortars by the use of waste fibers are discussed.
This article presents the methodology used, in the Construction Laboratories, of Civil Engineerin... more This article presents the methodology used, in the Construction Laboratories, of Civil Engineering Department, of University of Beira Interior, for the determination of water absorption, oxygen and water permeability of concrete and aggregate. Aspects of samples preparation and of procedures of these tests are discussed, demonstrating that these two aspects can affect, significantly, the results obtained. It is also discussed here the significance of permeability determination when small differences in the variables of the tests occur, namely the applied pressure. Some examples of water absorption and of oxygen and water permeability obtained with different concrete types and different types of aggregates are presented. It is also presented a typical relationship between water absorption and oxygen permeability. Finally, it is concluded about the interest of the water absorption and permeability tests as parameters to evaluate concrete durability.
This article presents the methodology used, in the Construction Laboratories, of Civil Engineerin... more This article presents the methodology used, in the Construction Laboratories, of Civil Engineering Department, of University of Beira Interior, for the determination of water absorption, oxygen and water permeability of concrete and aggregate. Aspects of samples preparation and of procedures of these tests are discussed, demonstrating that these two aspects can affect, significantly, the results obtained. It is also discussed here the significance of permeability determination when small differences in the variables of the tests occur, namely the applied pressure. Some examples of water absorption and of oxygen and water permeability obtained with different concrete types and different types of aggregates are presented. It is also presented a typical relationship between water absorption and oxygen permeability. Finally, it is concluded about the interest of the water absorption and permeability tests as parameters to evaluate concrete durability.
The main objective of the experimetal work carried out was the evaluation of the influence of coa... more The main objective of the experimetal work carried out was the evaluation of the influence of coarse aggregates geological source, dimension and water content in the concrete permeability. Four different aggretates, obtained from different geological environments, were selected, like granite, basalt, calcareous and marble coarse aggregates. After their mechanical and physical characterization, three concrete mixtures were produced with constant volume proportions, workability, mixing and curing conditions using different sizes of each aggregate type. Concrete durability parameters, such as capillary water absorption and oxygen permeability, measured at 28 days, were found to be affected by coarse aggregate size and its water content rather than aggregate mineralogy, as presented and discussed.
This work presents the results of a comparative study of the capillary absorption, accomplished i... more This work presents the results of a comparative study of the capillary absorption, accomplished in mixtures of self-compacting concrete with different types of additions and a normal concrete compacted by vibration. The mixtures self-compacting presents slump-flow of 650 ± 50 mm and have the same cement content. In the self-compacting mixtures, were used, as additions, fly ash, silica fume, hydraulic lime and a mixture of fly ash and hydraulic lime. A modified carboxylates superplasticizer was used to obtain the wanted workability. The capillary absorption was carried out at 7, 14 and 28 days of age, through a methodology described in the work. The results permit to conclude that the used additions propitiate the self-compacting concrete. In terms of capillary absorption, occurs that the mixtures with fly ash have better performance.
Communications in Computer and Information Science, 2010
This paper presents the development and properties assessment of braided reinforced composite rod... more This paper presents the development and properties assessment of braided reinforced composite rods (BCR) able to both reinforce and monitor the stress state of concrete infrastructures. The research study aims at understanding the tensile behaviour and self-monitoring ability of composite rods reinforced by a textile structure – braided structure with core reinforcement – for civil engineering applications, namely for concrete
ABSTRACT In this paper an experimental work is presented which main objective is the evaluation o... more ABSTRACT In this paper an experimental work is presented which main objective is the evaluation of the influence of different percentages of waste fibrous materials usage on the performance of fiber-reinforced mortars. Moreover, the influence of binder type is evaluated. Therefore mortars were produced with two different binders – cement and powder hydrated lime. Mortars performance evaluation was carried out through flow table and plunger penetration consistency, dynamic modulus of elasticity, flexural and compressive strength, capillary absorption, drying index and adherence tests. The benefits revealed in some characteristics of both mortars by the use of waste fibers are discussed.
ABSTRACT Enhancing the performance and lightness of different structures has already been achieve... more ABSTRACT Enhancing the performance and lightness of different structures has already been achieved by the employment of fibre reinforced composite materials. Nowadays, a new challenging perspective is being given to these materials by the inclusion of non-metallic conductive components. This emerging technology will lead to multifunctional composites with possible applications in structural health monitoring and traffic monitoring. The aim is to avoid corrosion problems from metallic components, as well as to eliminate the need of expensive equipments used for the health monitoring of large infrastructures. In the present research, the strain-sensing capability of a core-reinforced hybrid carbon fibre/glass fibre braided composite has been investigated in order to develop continuous monitoring system. The characterization of sensing behaviour was performed with the help of an instrumental set-up capable of measuring the change in electrical resistance with mechanical stresses applied to the samples. The effect of core composition (carbon fibre/glass fibre weight ratio) on the strain sensitivity of the braided composites has been studied in order to find out the optimum composition for best sensing capability. Among the three compositions studied (23/77, 47/53 and 100/0), composites with lowest amount of carbon fibre showed the best strain sensitivity with gauge factors up to 23.4 at very low flexural strain (0.55%). Attempts have also been made in this research to develop a piezoresistive matrix for the braided composites in order to further enhance their strain sensitivity. For this purpose, the strain sensing capability of an unsaturated polyester matrix dispersed with chopped carbon fibres (1mm and 3 mm lengths) at various weight % (0.5, 0.75 and 1.25%) was evaluated in order to find out their optimum length and concentration. It was observed that chopped fibres with different lengths showed similar strain sensitivity, which however, improves with the decrease in their concentrations.
ABSTRACT In this paper an experimental work is presented which main objective is the evaluation o... more ABSTRACT In this paper an experimental work is presented which main objective is the evaluation of the influence of different percentages of waste fibrous materials usage on the performance of fiber-reinforced mortars. Moreover, the influence of binder type is evaluated. Therefore mortars were produced with two different binders – cement and powder hydrated lime. Mortars performance evaluation was carried out through flow table and plunger penetration consistency, dynamic modulus of elasticity, flexural and compressive strength, capillary absorption, drying index and adherence tests. The benefits revealed in some characteristics of both mortars by the use of waste fibers are discussed.
This article presents the methodology used, in the Construction Laboratories, of Civil Engineerin... more This article presents the methodology used, in the Construction Laboratories, of Civil Engineering Department, of University of Beira Interior, for the determination of water absorption, oxygen and water permeability of concrete and aggregate. Aspects of samples preparation and of procedures of these tests are discussed, demonstrating that these two aspects can affect, significantly, the results obtained. It is also discussed here the significance of permeability determination when small differences in the variables of the tests occur, namely the applied pressure. Some examples of water absorption and of oxygen and water permeability obtained with different concrete types and different types of aggregates are presented. It is also presented a typical relationship between water absorption and oxygen permeability. Finally, it is concluded about the interest of the water absorption and permeability tests as parameters to evaluate concrete durability.
This article presents the methodology used, in the Construction Laboratories, of Civil Engineerin... more This article presents the methodology used, in the Construction Laboratories, of Civil Engineering Department, of University of Beira Interior, for the determination of water absorption, oxygen and water permeability of concrete and aggregate. Aspects of samples preparation and of procedures of these tests are discussed, demonstrating that these two aspects can affect, significantly, the results obtained. It is also discussed here the significance of permeability determination when small differences in the variables of the tests occur, namely the applied pressure. Some examples of water absorption and of oxygen and water permeability obtained with different concrete types and different types of aggregates are presented. It is also presented a typical relationship between water absorption and oxygen permeability. Finally, it is concluded about the interest of the water absorption and permeability tests as parameters to evaluate concrete durability.
The main objective of the experimetal work carried out was the evaluation of the influence of coa... more The main objective of the experimetal work carried out was the evaluation of the influence of coarse aggregates geological source, dimension and water content in the concrete permeability. Four different aggretates, obtained from different geological environments, were selected, like granite, basalt, calcareous and marble coarse aggregates. After their mechanical and physical characterization, three concrete mixtures were produced with constant volume proportions, workability, mixing and curing conditions using different sizes of each aggregate type. Concrete durability parameters, such as capillary water absorption and oxygen permeability, measured at 28 days, were found to be affected by coarse aggregate size and its water content rather than aggregate mineralogy, as presented and discussed.
This work presents the results of a comparative study of the capillary absorption, accomplished i... more This work presents the results of a comparative study of the capillary absorption, accomplished in mixtures of self-compacting concrete with different types of additions and a normal concrete compacted by vibration. The mixtures self-compacting presents slump-flow of 650 ± 50 mm and have the same cement content. In the self-compacting mixtures, were used, as additions, fly ash, silica fume, hydraulic lime and a mixture of fly ash and hydraulic lime. A modified carboxylates superplasticizer was used to obtain the wanted workability. The capillary absorption was carried out at 7, 14 and 28 days of age, through a methodology described in the work. The results permit to conclude that the used additions propitiate the self-compacting concrete. In terms of capillary absorption, occurs that the mixtures with fly ash have better performance.
Communications in Computer and Information Science, 2010
This paper presents the development and properties assessment of braided reinforced composite rod... more This paper presents the development and properties assessment of braided reinforced composite rods (BCR) able to both reinforce and monitor the stress state of concrete infrastructures. The research study aims at understanding the tensile behaviour and self-monitoring ability of composite rods reinforced by a textile structure – braided structure with core reinforcement – for civil engineering applications, namely for concrete
ABSTRACT In this paper an experimental work is presented which main objective is the evaluation o... more ABSTRACT In this paper an experimental work is presented which main objective is the evaluation of the influence of different percentages of waste fibrous materials usage on the performance of fiber-reinforced mortars. Moreover, the influence of binder type is evaluated. Therefore mortars were produced with two different binders – cement and powder hydrated lime. Mortars performance evaluation was carried out through flow table and plunger penetration consistency, dynamic modulus of elasticity, flexural and compressive strength, capillary absorption, drying index and adherence tests. The benefits revealed in some characteristics of both mortars by the use of waste fibers are discussed.
ABSTRACT Enhancing the performance and lightness of different structures has already been achieve... more ABSTRACT Enhancing the performance and lightness of different structures has already been achieved by the employment of fibre reinforced composite materials. Nowadays, a new challenging perspective is being given to these materials by the inclusion of non-metallic conductive components. This emerging technology will lead to multifunctional composites with possible applications in structural health monitoring and traffic monitoring. The aim is to avoid corrosion problems from metallic components, as well as to eliminate the need of expensive equipments used for the health monitoring of large infrastructures. In the present research, the strain-sensing capability of a core-reinforced hybrid carbon fibre/glass fibre braided composite has been investigated in order to develop continuous monitoring system. The characterization of sensing behaviour was performed with the help of an instrumental set-up capable of measuring the change in electrical resistance with mechanical stresses applied to the samples. The effect of core composition (carbon fibre/glass fibre weight ratio) on the strain sensitivity of the braided composites has been studied in order to find out the optimum composition for best sensing capability. Among the three compositions studied (23/77, 47/53 and 100/0), composites with lowest amount of carbon fibre showed the best strain sensitivity with gauge factors up to 23.4 at very low flexural strain (0.55%). Attempts have also been made in this research to develop a piezoresistive matrix for the braided composites in order to further enhance their strain sensitivity. For this purpose, the strain sensing capability of an unsaturated polyester matrix dispersed with chopped carbon fibres (1mm and 3 mm lengths) at various weight % (0.5, 0.75 and 1.25%) was evaluated in order to find out their optimum length and concentration. It was observed that chopped fibres with different lengths showed similar strain sensitivity, which however, improves with the decrease in their concentrations.
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