The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

T J Fowler - One of the best experts on this subject based on the ideXlab platform.

  • Structural Assessment of Bridges with Premature Concrete Deterioration due to Expansive Reactions
    Aci Structural Journal, 2009
    Co-Authors: A Boenig, Richard E Klingner, L M Funez, L S Memberg, J M Roche, B Tinkey, T J Fowler
    Abstract:

    After noticing premature Concrete Deterioration in many in-service bridges in the state, the Texas Department of Transportation launched a comprehensive investigation on the structural performance of these bridges. The investigation, spanning 1998 through 2003, comprised five principal tasks: 1) field studies; 2) development of a simple damage index; 3) laboratory tests on damaged girders; 4) laboratory studies on cores from damaged girders; and 5) nondestructive evaluation of field and laboratory specimens. This paper reviews and summarizes the results from each of these tasks. Findings showed that premature Concrete damage reduced the static capacity and fatigue life of the affected bridges, but generally not to a significant extent. Potentially affected bridges should be monitored, and simple damage indexes should be used to predict their probable remaining service life. The findings from this study can be used to help reduce costs while preserving public safety.

  • Mitigation techniques for in-service structures with premature Concrete Deterioration: a literature review
    2004
    Co-Authors: Amy E. Eskridge, Michael E. Kreger, R E Klingner, T J Fowler
    Abstract:

    The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. The parts of Project 0-4069 reported here consist of: a literature search for mitigation or remediation techniques; fabrication of Concrete specimens intentionally susceptible to premature Deterioration; and the application and monitoring of the mitigation techniques using laboratory testing and acoustic emission (AE) procedures. Specimens were exposed to three series of environmental conditions: an indoor series; an outdoor series; and a wet/dry series. Expansion and internal relative humidity were measured to determine the efficacy of the mitigation techniques at reducing expansion from premature Concrete Deterioration. Based on the test results, recommendations are made for choosing mitigation treatments now, and for additional research.

  • Bridges with premature Concrete Deterioration: damage indices, strand-pullout tests, and field observations
    2002
    Co-Authors: L S Memberg, R E Klingner, T J Fowler
    Abstract:

    This report describes part of the work associated with TxDOT Study 1857 ("Structural Assessment of In-Service Bridges with Premature Concrete Deterioration"). The primary objective of this report is to determine the effects of premature Concrete Deterioration on the bond between prestressing strands and Concrete, using damage indices and strand-pullout tests. Sixty-four strand-pullout tests were performed on sixty strands from four laboratory specimens taken from full-size precast Concrete box girders. The field observation program, begun earlier in this study, of five large TxDOT structures in different parts of Texas was continued for two additional years. Recommendations are made for addressing Deterioration in the FM 1929 structure over the Lake Ivie Reservoir in Concho, Texas. Results from the laboratory tests and the field observation program are used to relate external damage to reductions in structural capacity of in-service structures with premature Concrete Deterioration.

  • Bridges with Premature Concrete Deterioration: Field Observations and Large-Scale Testing
    2001
    Co-Authors: A Boenig, Richard E Klingner, L M Funez, T J Fowler
    Abstract:

    The focus of this report is the use of observations from in-service structures and laboratory specimens with premature Concrete Deterioration, along with core tests and large-scale tests of laboratory specimens, to predict the capacity of a large element with premature Deterioration. The theoretical background of premature Concrete Deterioration, while not the focus of this report, is reviewed. Large-scale tests to failure were conducted on 3 flexure-dominated and 3 shear-dominated specimens. Results from those tests were compared with tested compressive strength and elastic modulus of cores removed from the specimens, and with visual damage indices. Results were also evaluated in the light of observed damage to in-service structures, obtained over two years of field observation of 5 large Texas Department of Transportation structures in different parts of Texas. These comparisons are used to propose approaches for evaluating the structural integrity of in-service structures with premature Concrete Deterioration.

  • Bridges with Premature Concrete Deterioration: Fatigue Testing of Full-Scale, Prestressed Concrete Box Girders Failing in Shear
    2001
    Co-Authors: J M Roche, R E Klingner, T J Fowler
    Abstract:

    Fatigue tests were conducted on two full-scale Concrete box girders with premature Concrete Deterioration due to a combination of delayed ettringite formation and alkali-silica reaction. The specimens were loaded so that their response would be dominated by shear. Test results were used to establish an experimental S-N curve. Based on the results of these tests, premature Concrete Deterioration, while reducing shear capacity, does not reduce fatigue life below that assumed by the AASHTO LRFD Design Specification. Similar elements with premature Concrete Deterioration should be monitored visually and by nondestructive evaluation (NDE) techniques. Visual observations should include crack widths and damage indices (extent of cracking over characteristic surface areas). NDE techniques should include acoustic emission.

R E Melchers - One of the best experts on this subject based on the ideXlab platform.

  • modelling Concrete Deterioration in sewers using theory and field observations
    Cement and Concrete Research, 2015
    Co-Authors: Tony Wells, R E Melchers
    Abstract:

    Abstract Samples of new and 70 year old pre-corroded OPC Concrete were exposed for up to 48 months in 6 sewers throughout Australia. Corrosion losses at each site followed the bi-linear trend originally proposed by Wells and Melchers [1]. During an initial phase (lasting 2 S concentrations was also developed. The equation predictions were in good agreement with rates determined from field observation and historical data.

Michael E. Kreger - One of the best experts on this subject based on the ideXlab platform.

  • Mitigation Techniques for Structures with Premature Concrete Deterioration due to ASR/DEF
    Aci Materials Journal, 2009
    Co-Authors: Amy E. Eskridge, Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    There was a comprehensive investigation in Texas from 1998 to 2003 on in-service bridge structural performance when premature Concrete Deterioration was present. Two expansive distress mechanisms are attributed to premature Concrete Deterioration: delayed ettringite formation (DEF) and alkali-silica reaction (ASR). Moisture is required by both mechanisms, although they are chemically different. There can be extension of deteriorated structure service life through suitable mitigation techniques. The comparative effectiveness of surface treatments is addressed by this study. Existing DEF and ASR ASTM tests were not found to be useful for this purpose. A new test method was found useful and involved controlled wetting and drying cycles. This method was used in comparing proposed surface mitigation treatment effectiveness. Using that comparison as a basis, it is recommended that a surface mitigation treatment consisting of silane followed by a breathable paint appearance coat be used for structural service life extension when premature Concrete Deterioration due to ASR/DEF is present.

  • Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration: Synthesis Report
    2005
    Co-Authors: Amy E. Eskridge, Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    This report is a synthesis of the technical results of Texas Department of Transportation Study 4069 ("Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration"). The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali-silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. Reports 4069-1 and 4069-2 consist, respectively, of a literature survey and an application of existing test methods to assess the comparative effectiveness of mitigation treatments for premature Concrete Deterioration. This report (Report 4069-3) describes the development and verification of a new test method, and the application of that test method to recommendations for specific treatments to mitigate premature Concrete Deterioration from ASR/DEF.

  • Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration: Development and Verification of New Test Method
    2005
    Co-Authors: Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    This report describes part of the work associated with Texas Department of Transportation Study 4069 (“Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration”). The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. The parts of Study 4069 reported here consist of: a review of existing test methods for possible application to evaluate mitigation treatments; development of a new test method, if necessary; verification of the test method; application of the selected test method to evaluate mitigation treatments; and recommendations of specific treatments to mitigate premature Concrete Deterioration from ASR/DEF.

  • Mitigation techniques for in-service structures with premature Concrete Deterioration: a literature review
    2004
    Co-Authors: Amy E. Eskridge, Michael E. Kreger, R E Klingner, T J Fowler
    Abstract:

    The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. The parts of Project 0-4069 reported here consist of: a literature search for mitigation or remediation techniques; fabrication of Concrete specimens intentionally susceptible to premature Deterioration; and the application and monitoring of the mitigation techniques using laboratory testing and acoustic emission (AE) procedures. Specimens were exposed to three series of environmental conditions: an indoor series; an outdoor series; and a wet/dry series. Expansion and internal relative humidity were measured to determine the efficacy of the mitigation techniques at reducing expansion from premature Concrete Deterioration. Based on the test results, recommendations are made for choosing mitigation treatments now, and for additional research.

Mohammed K Ibrahim - One of the best experts on this subject based on the ideXlab platform.

  • sulfate resistance of plain and blended cements exposed to varying concentrations of sodium sulfate
    Cement & Concrete Composites, 2003
    Co-Authors: Salah U Aldulaija, M M Alzahrani, Mohammed Maslehuddi, A M Sharif, Mohammad Shameem, Mohammed K Ibrahim
    Abstract:

    Concrete Deterioration due to sulfate attack is the second major durability problem, after reinforcement corrosion. This type of Deterioration is noted in the structures exposed to sulfate-bearing soils and groundwater. Though Concrete Deterioration due to sulfate attack is reported from many countries, the mechanisms of sulfate attack have not been thoroughly investigated, particularly the effect of sulfate concentration and the cation type associated with the sulfate ions on Concrete Deterioration. This study was conducted to evaluate the performance of plain and blended cements exposed to varying concentrations of sodium sulfate for up to 24 months. Four types of cements, namely Type I, Type V, Type I plus silica fume and Type I plus fly ash, were exposed to five sodium sulfate solutions with sulfate concentrations of 1%, 1.5%, 2%, 2.5% and 4%. These concentrations are representative of the sulfate concentration in highly saline soils. The sulfate resistance was evaluated by visual examination and measuring the and reduction in compressive strength. The maximum Deterioration, due to sulfate attack, was noted in Type I cement followed by silica fume and Type V cements. The performance of Type V, Type I plus silica fume and Type I plus fly ash was not significantly different from each other. The enhanced sulfate resistance noted in the Type I cement blended with either silica fume or fly ash indicates the usefulness of these cements in both sulfate and sulfate plus chloride environments.

Richard E Klingner - One of the best experts on this subject based on the ideXlab platform.

  • Mitigation Techniques for Structures with Premature Concrete Deterioration due to ASR/DEF
    Aci Materials Journal, 2009
    Co-Authors: Amy E. Eskridge, Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    There was a comprehensive investigation in Texas from 1998 to 2003 on in-service bridge structural performance when premature Concrete Deterioration was present. Two expansive distress mechanisms are attributed to premature Concrete Deterioration: delayed ettringite formation (DEF) and alkali-silica reaction (ASR). Moisture is required by both mechanisms, although they are chemically different. There can be extension of deteriorated structure service life through suitable mitigation techniques. The comparative effectiveness of surface treatments is addressed by this study. Existing DEF and ASR ASTM tests were not found to be useful for this purpose. A new test method was found useful and involved controlled wetting and drying cycles. This method was used in comparing proposed surface mitigation treatment effectiveness. Using that comparison as a basis, it is recommended that a surface mitigation treatment consisting of silane followed by a breathable paint appearance coat be used for structural service life extension when premature Concrete Deterioration due to ASR/DEF is present.

  • Structural Assessment of Bridges with Premature Concrete Deterioration due to Expansive Reactions
    Aci Structural Journal, 2009
    Co-Authors: A Boenig, Richard E Klingner, L M Funez, L S Memberg, J M Roche, B Tinkey, T J Fowler
    Abstract:

    After noticing premature Concrete Deterioration in many in-service bridges in the state, the Texas Department of Transportation launched a comprehensive investigation on the structural performance of these bridges. The investigation, spanning 1998 through 2003, comprised five principal tasks: 1) field studies; 2) development of a simple damage index; 3) laboratory tests on damaged girders; 4) laboratory studies on cores from damaged girders; and 5) nondestructive evaluation of field and laboratory specimens. This paper reviews and summarizes the results from each of these tasks. Findings showed that premature Concrete damage reduced the static capacity and fatigue life of the affected bridges, but generally not to a significant extent. Potentially affected bridges should be monitored, and simple damage indexes should be used to predict their probable remaining service life. The findings from this study can be used to help reduce costs while preserving public safety.

  • Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration: Synthesis Report
    2005
    Co-Authors: Amy E. Eskridge, Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    This report is a synthesis of the technical results of Texas Department of Transportation Study 4069 ("Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration"). The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali-silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. Reports 4069-1 and 4069-2 consist, respectively, of a literature survey and an application of existing test methods to assess the comparative effectiveness of mitigation treatments for premature Concrete Deterioration. This report (Report 4069-3) describes the development and verification of a new test method, and the application of that test method to recommendations for specific treatments to mitigate premature Concrete Deterioration from ASR/DEF.

  • Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration: Development and Verification of New Test Method
    2005
    Co-Authors: Jeremy T Klahorst, Richard E Klingner, Michael E. Kreger
    Abstract:

    This report describes part of the work associated with Texas Department of Transportation Study 4069 (“Mitigation Techniques for In-Service Structures with Premature Concrete Deterioration”). The Texas Department of Transportation is interested in developing techniques for mitigating or remediating premature Concrete Deterioration due to alkali silica reaction (ASR), delayed ettringite formation (DEF), or both, in order to extend the life of potentially affected structures. The parts of Study 4069 reported here consist of: a review of existing test methods for possible application to evaluate mitigation treatments; development of a new test method, if necessary; verification of the test method; application of the selected test method to evaluate mitigation treatments; and recommendations of specific treatments to mitigate premature Concrete Deterioration from ASR/DEF.

  • Bridges with Premature Concrete Deterioration: Field Observations and Large-Scale Testing
    2001
    Co-Authors: A Boenig, Richard E Klingner, L M Funez, T J Fowler
    Abstract:

    The focus of this report is the use of observations from in-service structures and laboratory specimens with premature Concrete Deterioration, along with core tests and large-scale tests of laboratory specimens, to predict the capacity of a large element with premature Deterioration. The theoretical background of premature Concrete Deterioration, while not the focus of this report, is reviewed. Large-scale tests to failure were conducted on 3 flexure-dominated and 3 shear-dominated specimens. Results from those tests were compared with tested compressive strength and elastic modulus of cores removed from the specimens, and with visual damage indices. Results were also evaluated in the light of observed damage to in-service structures, obtained over two years of field observation of 5 large Texas Department of Transportation structures in different parts of Texas. These comparisons are used to propose approaches for evaluating the structural integrity of in-service structures with premature Concrete Deterioration.