The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

Marcos Garcia Alberti - One of the best experts on this subject based on the ideXlab platform.

J C Galvez - One of the best experts on this subject based on the ideXlab platform.

  • influence of Fiber distribution and orientation in the fracture behavior of Polyolefin Fiber reinforced concrete
    Materials, 2019
    Co-Authors: A Enfedaque, Marcos Garcia Alberti, J C Galvez
    Abstract:

    Polyolefin Fiber-reinforced concrete (PFRC) has become an attractive alternative to steel for the reinforcement of concrete elements, mainly due to its chemical stability and the residual strengths that can be reached with lower weights. The use of Polyolefin Fibers can meet the requirements of standards, although the main constitutive relations are based on experience with steel Fibers. Therefore, the structural contributions of the Fibers should be assessed by inverse analysis. In this study, the Fiber dosage was fixed at 6 kg/m3, and both self-compacting concrete and conventional concrete were used to compare the influence of the positioning of the Fibers. An idealized homogeneous distribution of the Fibers with such Fibers crossing from side to side of the specimen was added to self-compacting concrete. The experimental results of three-point bending tests on notched specimens were reproduced by using the cohesive crack approach. Hence, constitutive relations were found. The significance of this research relies on the verification of the formulations found to build constitutive relations. Moreover, with these results, it is possible to establish a higher threshold for the performance of PFRC and the difficulties of limiting the first unloading branch typical of fracture tests of PFRC.

  • structural cast in place application of Polyolefin Fiber reinforced concrete in a water pipeline supporting elements
    Journal of Pipeline Systems Engineering and Practice, 2017
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, Luis Pinillos
    Abstract:

    AbstractResearch has shown that Polyolefin-based macroFibers can meet the requirements of the standards to consider their postcracking contribution in the structural design of Fiber-reinforced conc...

  • improving the reinforcement of Polyolefin Fiber reinforced concrete for infrastructure applications
    Fibers, 2015
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez
    Abstract:

    The increase in the use of Polyolefin Fiber-reinforced concrete (PFRC) is in contrast to the limited amount of published research about its fracture behavior. This study assesses the main mechanical and fracture properties of PFRC by using conventional and self-compacting concrete with various dosages. The results highlight the significant performance of PFRC and revealed that improving its residual strength for small deformations would enhance its use for structural purposes. For that matter, a combination of Polyolefin and steel-hooked Fibers was used, improving the results and showing synergies between the two types of Fibers that could be exploited for infrastructure applications. The significance of this research is, in addition to the characterization of PFRC, the optimum selection and definition of the proportions and characteristics of the types of Fibers chosen for the combination. The results proved that, by combining hooked-steel Fibers and macro-Polyolefin Fibers, it is possible to preserve the high-performance fresh properties and obtain a reliable behavior with synergies in the fracture results. The latter provides an efficient use of the materials, as well as a better mechanical behavior in both service and failure states.

  • Polyolefin Fiber reinforced concrete enhanced with steel hooked Fibers in low proportions
    Materials & Design, 2014
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, M F Canovas, I R Osorio
    Abstract:

    Abstract Over the past few years, Polyolefin Fiber reinforced self-compacting concrete has shown high performance in both fresh and hardened state. Its fracture behavior for small deformations could be enhanced with a small amount of steel-hooked Fibers, obtaining a hybrid Fiber-reinforced concrete well suited for structural use. Four types of conventional Fiber-reinforced concrete with steel and Polyolefin Fibers were produced on the basis of the same self-compacting concrete also manufactured as reference. These concrete mixtures were manufactured separately with the same Fiber contents being subsequently used for two more hybrid mixtures. Fracture properties, in addition to fresh and mechanical properties, were assessed. The research showed both synergies (with the two types of Fibers working together in the fracture processes) and an improvement of the orientation and distribution of the Fibers on the fracture surface.

  • on the mechanical properties and fracture behavior of Polyolefin Fiber reinforced self compacting concrete
    Construction and Building Materials, 2014
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez
    Abstract:

    Abstract Fiber-reinforced self-compacting concrete uses the flowability of concrete in fresh state to improve Fiber orientation, in due course enhancing toughness and energy absorption capacity. In the past few years there has been a boost in the development of concretes with macro-synthetic Fibers added. In this paper the mechanical properties of a self-compacting concrete with low, medium and high-Fiber contents of macro Polyolefin Fibers are studied. Their fracture behavior is compared with a plain self-compacting concrete and also with a steel Fiber-reinforced self-compacting concrete. The results obtained showed that a Polyolefin Fiber-reinforced self-compacting concrete has fracture properties analogous to a steel Fiber-reinforced self-compacting concrete. Furthermore, it is possible to fit this behavior within the existing standards requirements. Dispersion obtained for fracture mean values among the different amounts was analyzed by using a fracture surface analysis and the amount and distribution of Fibers.

C H M Jenkins - One of the best experts on this subject based on the ideXlab platform.

  • Polyolefin Fiber reinforced concrete composites part i damping and frequency characteristics
    Cement and Concrete Research, 2000
    Co-Authors: C H M Jenkins, R L Pendleton
    Abstract:

    Abstract The investigation of the dynamic properties of Polyolefin Fiber-reinforced concrete composites (FRC) was conducted with a free–free beam vibration method. The damping ratio increase and response frequency decreased with an increase in the Maximum Response Amplitude. Crimped Fiber and fine smooth surface Fiber- (fine Fiber) reinforced concrete exhibited better damping than other FRC and plain concrete. This damping was sensitive to the Small Amplitude Response Frequency. The damping ratio, 1% minimum, in crimped FRC was double that in plain concrete at frequencies around 600 Hz and specimen age of 8 weeks. The damping ratios, 0.4% minimum, in crimped Fiber and fine-FRC were higher than those in other FRCs and plain concrete only when the Maximum Response Amplitude reached a certain value (0.001 cm) at a frequency range of 1050–1250 Hz and specimen age of 24 weeks. An increase in damping with an increase in the Maximum Response Amplitude was accompanied by a large decrease in response frequency in crimped Fiber and fine FRC. The damping ratio decreased and the response frequency increased with vibration cycle; again, strong tendencies existed in crimped Fiber and fine FRC.

  • Polyolefin Fiber reinforced concrete composites part ii damping and interface debonding
    Cement and Concrete Research, 2000
    Co-Authors: C H M Jenkins, R L Pendleton
    Abstract:

    Two damping mechanisms are suggested to explain the high damping found from preliminary dynamic testing of Polyolefin Fiber-reinforced concrete composites (FRC). A significant interfacial relative displacement, which may cause debonding and corresponding interfacial friction, is suggested as the fundamental energy dissipation mode during vibration. Such a displacement may easily take place over a great fraction of an interface between low-aspect ratio Fiber and cementitious matrix, resulting in high damping in crimped FRC. Debonding at the intersections of microcracks in matrix and Fiber due to the crack opening under tensile strain also consumes vibration energy, producing extra damping in fine FRC. In order to gain high damping without seriously degrading other mechanical properties of FRC, a combination of reinforcing Fibers with different geometric features is suggested.

  • interface morphologies in Polyolefin Fiber reinforced concrete composites
    Composites Part A-applied Science and Manufacturing, 1998
    Co-Authors: R L Pendleton, C H M Jenkins
    Abstract:

    Morphologies of Fiber-matrix interface in Polyolefin Fiber reinforced concrete composite (FRC) and Fiber surface were observed by using a scanning electronic microscope (SEM). Interfacial roughness, alternate bulges and grooves with breadth varying from less than 1 μm up to 20 μm, oriented along interface longitudinal direction. Fibrils and Fiber chips, with either end or both ends, were anchored in matrix. No patch of Fiber material stuck on the interface, after Fiber was peeled away from interface, was found. Fiber surface was roughened along Fiber axial direction during mixing in cementitious mix and abraded again during pullout. It is concluded that the interfacial roughness was formed due to Fiber surface roughness, and the bond between Polyolefin Fiber and concrete matrix is mainly mechanical.

A Enfedaque - One of the best experts on this subject based on the ideXlab platform.

  • influence of Fiber distribution and orientation in the fracture behavior of Polyolefin Fiber reinforced concrete
    Materials, 2019
    Co-Authors: A Enfedaque, Marcos Garcia Alberti, J C Galvez
    Abstract:

    Polyolefin Fiber-reinforced concrete (PFRC) has become an attractive alternative to steel for the reinforcement of concrete elements, mainly due to its chemical stability and the residual strengths that can be reached with lower weights. The use of Polyolefin Fibers can meet the requirements of standards, although the main constitutive relations are based on experience with steel Fibers. Therefore, the structural contributions of the Fibers should be assessed by inverse analysis. In this study, the Fiber dosage was fixed at 6 kg/m3, and both self-compacting concrete and conventional concrete were used to compare the influence of the positioning of the Fibers. An idealized homogeneous distribution of the Fibers with such Fibers crossing from side to side of the specimen was added to self-compacting concrete. The experimental results of three-point bending tests on notched specimens were reproduced by using the cohesive crack approach. Hence, constitutive relations were found. The significance of this research relies on the verification of the formulations found to build constitutive relations. Moreover, with these results, it is possible to establish a higher threshold for the performance of PFRC and the difficulties of limiting the first unloading branch typical of fracture tests of PFRC.

  • structural cast in place application of Polyolefin Fiber reinforced concrete in a water pipeline supporting elements
    Journal of Pipeline Systems Engineering and Practice, 2017
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, Luis Pinillos
    Abstract:

    AbstractResearch has shown that Polyolefin-based macroFibers can meet the requirements of the standards to consider their postcracking contribution in the structural design of Fiber-reinforced conc...

  • improving the reinforcement of Polyolefin Fiber reinforced concrete for infrastructure applications
    Fibers, 2015
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez
    Abstract:

    The increase in the use of Polyolefin Fiber-reinforced concrete (PFRC) is in contrast to the limited amount of published research about its fracture behavior. This study assesses the main mechanical and fracture properties of PFRC by using conventional and self-compacting concrete with various dosages. The results highlight the significant performance of PFRC and revealed that improving its residual strength for small deformations would enhance its use for structural purposes. For that matter, a combination of Polyolefin and steel-hooked Fibers was used, improving the results and showing synergies between the two types of Fibers that could be exploited for infrastructure applications. The significance of this research is, in addition to the characterization of PFRC, the optimum selection and definition of the proportions and characteristics of the types of Fibers chosen for the combination. The results proved that, by combining hooked-steel Fibers and macro-Polyolefin Fibers, it is possible to preserve the high-performance fresh properties and obtain a reliable behavior with synergies in the fracture results. The latter provides an efficient use of the materials, as well as a better mechanical behavior in both service and failure states.

  • Polyolefin Fiber reinforced concrete enhanced with steel hooked Fibers in low proportions
    Materials & Design, 2014
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, M F Canovas, I R Osorio
    Abstract:

    Abstract Over the past few years, Polyolefin Fiber reinforced self-compacting concrete has shown high performance in both fresh and hardened state. Its fracture behavior for small deformations could be enhanced with a small amount of steel-hooked Fibers, obtaining a hybrid Fiber-reinforced concrete well suited for structural use. Four types of conventional Fiber-reinforced concrete with steel and Polyolefin Fibers were produced on the basis of the same self-compacting concrete also manufactured as reference. These concrete mixtures were manufactured separately with the same Fiber contents being subsequently used for two more hybrid mixtures. Fracture properties, in addition to fresh and mechanical properties, were assessed. The research showed both synergies (with the two types of Fibers working together in the fracture processes) and an improvement of the orientation and distribution of the Fibers on the fracture surface.

  • on the mechanical properties and fracture behavior of Polyolefin Fiber reinforced self compacting concrete
    Construction and Building Materials, 2014
    Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez
    Abstract:

    Abstract Fiber-reinforced self-compacting concrete uses the flowability of concrete in fresh state to improve Fiber orientation, in due course enhancing toughness and energy absorption capacity. In the past few years there has been a boost in the development of concretes with macro-synthetic Fibers added. In this paper the mechanical properties of a self-compacting concrete with low, medium and high-Fiber contents of macro Polyolefin Fibers are studied. Their fracture behavior is compared with a plain self-compacting concrete and also with a steel Fiber-reinforced self-compacting concrete. The results obtained showed that a Polyolefin Fiber-reinforced self-compacting concrete has fracture properties analogous to a steel Fiber-reinforced self-compacting concrete. Furthermore, it is possible to fit this behavior within the existing standards requirements. Dispersion obtained for fracture mean values among the different amounts was analyzed by using a fracture surface analysis and the amount and distribution of Fibers.

R L Pendleton - One of the best experts on this subject based on the ideXlab platform.

  • Polyolefin Fiber reinforced concrete composites part i damping and frequency characteristics
    Cement and Concrete Research, 2000
    Co-Authors: C H M Jenkins, R L Pendleton
    Abstract:

    Abstract The investigation of the dynamic properties of Polyolefin Fiber-reinforced concrete composites (FRC) was conducted with a free–free beam vibration method. The damping ratio increase and response frequency decreased with an increase in the Maximum Response Amplitude. Crimped Fiber and fine smooth surface Fiber- (fine Fiber) reinforced concrete exhibited better damping than other FRC and plain concrete. This damping was sensitive to the Small Amplitude Response Frequency. The damping ratio, 1% minimum, in crimped FRC was double that in plain concrete at frequencies around 600 Hz and specimen age of 8 weeks. The damping ratios, 0.4% minimum, in crimped Fiber and fine-FRC were higher than those in other FRCs and plain concrete only when the Maximum Response Amplitude reached a certain value (0.001 cm) at a frequency range of 1050–1250 Hz and specimen age of 24 weeks. An increase in damping with an increase in the Maximum Response Amplitude was accompanied by a large decrease in response frequency in crimped Fiber and fine FRC. The damping ratio decreased and the response frequency increased with vibration cycle; again, strong tendencies existed in crimped Fiber and fine FRC.

  • Polyolefin Fiber reinforced concrete composites part ii damping and interface debonding
    Cement and Concrete Research, 2000
    Co-Authors: C H M Jenkins, R L Pendleton
    Abstract:

    Two damping mechanisms are suggested to explain the high damping found from preliminary dynamic testing of Polyolefin Fiber-reinforced concrete composites (FRC). A significant interfacial relative displacement, which may cause debonding and corresponding interfacial friction, is suggested as the fundamental energy dissipation mode during vibration. Such a displacement may easily take place over a great fraction of an interface between low-aspect ratio Fiber and cementitious matrix, resulting in high damping in crimped FRC. Debonding at the intersections of microcracks in matrix and Fiber due to the crack opening under tensile strain also consumes vibration energy, producing extra damping in fine FRC. In order to gain high damping without seriously degrading other mechanical properties of FRC, a combination of reinforcing Fibers with different geometric features is suggested.

  • Polyolefin Fiber-reinforced concrete composites ☆: Part I. Damping and frequency characteristics
    Cement and Concrete Research, 2000
    Co-Authors: C.h. Jenkins, R L Pendleton
    Abstract:

    Abstract The investigation of the dynamic properties of Polyolefin Fiber-reinforced concrete composites (FRC) was conducted with a free–free beam vibration method. The damping ratio increase and response frequency decreased with an increase in the Maximum Response Amplitude. Crimped Fiber and fine smooth surface Fiber- (fine Fiber) reinforced concrete exhibited better damping than other FRC and plain concrete. This damping was sensitive to the Small Amplitude Response Frequency. The damping ratio, 1% minimum, in crimped FRC was double that in plain concrete at frequencies around 600 Hz and specimen age of 8 weeks. The damping ratios, 0.4% minimum, in crimped Fiber and fine-FRC were higher than those in other FRCs and plain concrete only when the Maximum Response Amplitude reached a certain value (0.001 cm) at a frequency range of 1050–1250 Hz and specimen age of 24 weeks. An increase in damping with an increase in the Maximum Response Amplitude was accompanied by a large decrease in response frequency in crimped Fiber and fine FRC. The damping ratio decreased and the response frequency increased with vibration cycle; again, strong tendencies existed in crimped Fiber and fine FRC.

  • interface morphologies in Polyolefin Fiber reinforced concrete composites
    Composites Part A-applied Science and Manufacturing, 1998
    Co-Authors: R L Pendleton, C H M Jenkins
    Abstract:

    Morphologies of Fiber-matrix interface in Polyolefin Fiber reinforced concrete composite (FRC) and Fiber surface were observed by using a scanning electronic microscope (SEM). Interfacial roughness, alternate bulges and grooves with breadth varying from less than 1 μm up to 20 μm, oriented along interface longitudinal direction. Fibrils and Fiber chips, with either end or both ends, were anchored in matrix. No patch of Fiber material stuck on the interface, after Fiber was peeled away from interface, was found. Fiber surface was roughened along Fiber axial direction during mixing in cementitious mix and abraded again during pullout. It is concluded that the interfacial roughness was formed due to Fiber surface roughness, and the bond between Polyolefin Fiber and concrete matrix is mainly mechanical.