The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Masoud Motavalli - One of the best experts on this subject based on the ideXlab platform.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

Julien Michels - One of the best experts on this subject based on the ideXlab platform.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

Raafat Elhacha - One of the best experts on this subject based on the ideXlab platform.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

  • bond strength between cast in place ultra high performance concrete and glass fibre reinforced polymer plates using Epoxy bonded coarse silica sand
    Journal of Astm International, 2012
    Co-Authors: Donna Chen, Raafat Elhacha
    Abstract:

    A significant amount of attention has been directed toward the use of fibre reinforced polymer (FRP) materials in structural applications, particularly as main components in hybrid structural members. As a result, the need for an effective connection mechanism that can maintain full composite action at the interface between adjacent dissimilar materials is critical in order to achieve optimum performance of the hybrid structural members. The objective of this experimental program was to investigate the bond performance between glass fibre reinforced polymer (GFRP) plates and cast-in-place Ultra-High-Performance- Concrete (UHPC) using Epoxy bonded coarse silica sand aggregates at the bond interface. Both shear and tension tests were conducted using three different types of Epoxy Adhesives. The general effectiveness of the connection mechanism at the bond interface as well as the relative performance of each Epoxy Adhesive used were investigated. Analysis showed that, of the three Epoxy Adhesives tested, the specimens bonded at the interface between the UHPC and GFRP plates using the moisture tolerant Epoxy Adhesive intended for bonding of hardened concrete and steel performed the best.

Miguel Azenha - One of the best experts on this subject based on the ideXlab platform.

  • influence of temperature on the curing of an Epoxy Adhesive and its influence on bond behaviour of nsm cfrp systems
    Composites Part B-engineering, 2016
    Co-Authors: Andrea Benedetti, Jose Senacruz, Pedro Miguel Gomes Fernandes, Jose Luis Duarte Granja, Miguel Azenha
    Abstract:

    Abstract In NSM-CFRP installations, the mechanical behaviour of the strengthening system is strongly influenced by the Epoxy Adhesive, particularly at early ages. In the present work, the influence of temperature on the curing process of the Epoxy was investigated. Three distinct temperatures were studied: 20, 30 and 40 °C. The elastic modulus of the Adhesive was monitored through EMM-ARM (Elasticity Modulus Monitoring through Ambient Response Method). Direct pull-out tests with concrete specimens strengthened with NSM CFRP strips were carried out at the same three distinct temperatures to compare the evolution of bond performance with the E-modulus of Epoxy since early ages. The results showed that increasing the curing temperature significantly accelerated both the curing process of the Epoxy Adhesive and the evolution of bond performance. The EMM-ARM technique has revealed its ability in clearly identifying the hardening kinetics of Epoxy Adhesives, allowing also thermal activation analysis. Finally, existing models for predicting temperature-dependent mechanical properties were extended to also describe the bond behaviour of NSM-CFRP applications.

  • quality control and monitoring of nsm cfrp systems e modulus evolution of Epoxy Adhesive and its relation to the pull out force
    Composites Part B-engineering, 2015
    Co-Authors: Pedro Miguel Gomes Fernandes, Jose Senacruz, Jose Luis Duarte Granja, Andrea Benedetti, Miguel Azenha
    Abstract:

    Abstract Background In Fibre-Reinforced Polymer (FRP) applications, the mechanical behaviour of the strengthening system strongly depends on the Epoxy Adhesive, particularly at early ages. Methods The present paper describes the application of an innovative technique (termed EMM-ARM: Elasticity Modulus Monitoring through Ambient Response Method) for continuous monitoring of the stiffening process of an Epoxy Adhesive used in structural reinforcements applications. A simultaneous study of direct pull-out tests with concrete specimens strengthened with near-surface mounted (NSM) carbon FRP laminate strips was carried out to compare the evolution of bond performance with the E-modulus of Epoxy since early ages. Results The peak pull-out force and the Epoxy E-modulus obtained by EMM-ARM exhibit very similar evolution kinetics. Conclusions A relationship between the evolution of Epoxy E-modulus and the maximum pull-out force is assessed, highlighting the potential of applying EMM-ARM for quality control and decision-making assistance of NSM systems.

Christoph Czaderski - One of the best experts on this subject based on the ideXlab platform.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.

  • temporary bond strength of partly cured Epoxy Adhesive for anchoring prestressed cfrp strips on concrete
    Composite Structures, 2012
    Co-Authors: Julien Michels, Christoph Czaderski, Rolf Bronnimann, Masoud Motavalli, Raafat Elhacha
    Abstract:

    Abstract Externally bonded Carbon Fiber Reinforced Polymer (CFRP) strips have been used for strengthening reinforced concrete structures. This paper presents an experimental study on the debonding of externally bonded CFRP strips anchored to a concrete substrate by a commercial Epoxy Adhesive. The study represents the basis for the characterization of an innovative ‘gradient method’, giving the possibility to anchor prestressed CFRP strips to concrete without the use any mechanical anchorage systems such as plates and bolts. Bond between the two components is achieved by an Epoxy Adhesive able to carry loads after an accelerated curing process under elevated temperatures. The effect of heating configuration/duration, strip thickness and bond length on the temporary bond resistance have been investigated using prestressed and non-prestressed CFRP-strips. Besides the optimization of the heating elements necessary for the curing process, curing parameters for an optimal temporary bond strength could be determined. Twenty-five minutes of heating and curing at 90 °C was found to be an optimum heating configuration, resulting in better short-term mechanical performances than after conventional curing at room temperature for several days. The main reason is a temporarily softer Adhesive which allows the use of the full bond length by reducing shear force peaks.