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Darwin David - One of the best experts on this subject based on the ideXlab platform.
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Implementation of Crack-Reducing Technologies for Concrete in Bridge Decks: Synthetic Fibers, Internal Curing, and Shrinkage-Reducing Admixtures
University of Kansas Center for Research, 2020Co-Authors: Feng Muzai, Darwin DavidAbstract:Technologies to reduce cracking in Bridge Decks, including shrinkage-reducing admixtures (SRAs), shrinkage-compensating admixtures (SCAs), fiber reinforcement, and internal curing (IC), are evaluated based on laboratory tests of concrete mixtures with and without slag cement and silica fume and the cracking performance of in-service Bridge Decks. Additionally, the influence of construction practices used by contractors is evaluated by field evaluation of Bridge Decks constructed with and without construction issues. The laboratory portion of this study involves eleven concrete mixtures evaluated based on free shrinkage, scaling resistance, and freeze-thaw durability. The mixtures were cast with or without slag cement and silica fume and contained various quantities of internal curing water; four additional mixtures containing a shrinkage-reducing admixture or one of two shrinkage- compensating admixtures (one of which also contains an SRA) were also evaluated. Results show that the mixtures with slag cement, silica fume, and internal curing exhibited less shrinkage after 20 and 365 days of drying and that shrinkage decreased as the quantity of internal curing water increased from 5.3% to 9.7% by weight of cementitious material. Mixtures with slag cement, silica fume, and 5.3% or 6.5% internal curing water performed well in the freeze-thaw durability test while the mixture with slag cement, silica fume and 9.7% internal curing failed the test. Mixtures with slag cement, silica fume, and internal curing had high mass losses in the scaling resistance test, which was likely due to the harsher test method used in this study or an inadequate air content in the concrete mixture. When a shrinkage-reducing admixture, either by itself or as a part a shrinkage-compensating admixture, is added to the mixture with slag cement, silica fume, and 6.5% internal curing, the freeze-thaw durability and scaling resistance of the mixture was drastically compromised; the mixture with slag cement, silica fume, 6.5% internal curing, and a CaO-based shrinkage-compensating admixture, on the other hand, performed satisfactorily in the freeze-thaw durability and scaling resistance tests. The second portion of this study evaluates the cracking performance of 74 Bridge deck placements: 10 cast with fiber-reinforced concrete (FRC), four Bridge deck placements containing SRAs, six containing IC, and 54 without crack-reducing technologies. The influence of crack- reducing technologies and poor construction practices are evaluated. Results indicate that using a low paste content in the concrete mixture is the most effective way to reduce Bridge deck cracking. Bridge Decks with paste contents exceeding 27.3% had higher crack densities than Decks with lower paste contents. When used in conjunction with a low paste content, SRAs and IC can further reduce cracking in Bridge Decks. On the other hand, if the contractors fail to follow proper procedures to consolidate, finish, or cure concrete, Bridge Decks will exhibit substantially greater cracking, even when low paste contents are used. The use of fiber-reinforced concrete can slightly alleviate, but not overcome, the negative effects of poor construction
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Low-Cracking High-Performance Concrete (LC-HPC) for Durable Bridge Decks
'American Concrete Institute', 2020Co-Authors: Darwin David, Lafikes James, Khajehdehi Rouzbeh, Feng Muzai, Ibrahim Eman, O’reilly MatthewAbstract:The goal of this study was to implement cost-effective techniques for improving Bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 Decks constructed with LC-HPC specifications and 13 matching control Bridge Decks based on crack surveys. The LC-HPC Bridge Decks exhibit less cracking than the matching control Decks in the vast majority of cases. Only two LC-HPC Bridge Decks have higher overall crack densities than their control Decks, which are the two best performing control Decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in Bridge Decks.ACI Committees 130, Sustainability of Concrete and 224, Crackin
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Durability, Construction, and Early Evaluation of Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks
University of Kansas Center for Research Inc., 2020Co-Authors: Lafikes James, Darwin David, O’reilly MatthewAbstract:Laboratory evaluations of concrete mixtures based on specifications for low-cracking high-performance concrete (LC-HPC) incorporating internal curing (IC) and supplementary cementitious materials (SCMs) are described. In addition, the development, construction, and evaluation of four IC-LC-HPC Bridge Decks with IC provided by pre-wetted fine lightweight aggregate (FLWA) in conjunction with a partial replacement of portland cement with slag cement are described along with the evaluation of two Control Decks without IC constructed in accordance with standard high-performance concrete (HPC) specifications in Minnesota. Bridge Decks containing IC provided by pre-wetted FLWA and SCMs are also evaluated, including two Bridge Decks in Utah with a partial replacement of portland cement with Class F fly ash and six Bridge Decks in Indiana, four with IC and a partial replacement of portland cement with silica fume and either slag cement or Class C fly ash constructed in accordance with Indiana HPC specifications (IN-IC-HPC), one with IC and portland cement as the only binder, and one Control without IC. The laboratory evaluations were performed on three groups of concrete mixtures, one for each for the first three years of IC-LC-HPC Bridge deck construction in Minnesota. Variations in IC-LC-HPC mixture proportions include the amount of IC water (contents ranging from 0 to 14.1% by total weight of binder), total absorbed water content (IC water from the FLWA plus water absorbed by the normalweight coarse and fine aggregates ranging from 2.9 to 17.7% by total weight of binder), water-to-cementitious material (w/cm) ratios ranging from 0.39 to 0.45, and binder compositions examining the effects of using only portland cement, a 35% Class F fly ash replacement of portland cement, 27 to 30% slag cement replacements of portland cement, and a 2% addition of silica fume of cement for the mixtures containing 27 to 28% slag cement, all by total weight of binder. Tests for scaling resistance, freeze-thaw durability, rapid chloride permeability (RCP), and surface resistivity measurements (SRMs) were completed. The scaling resistance of the IC-LC-HPC mixtures was affected most by the air content, with mixtures having an air content below 7% exhibiting more mass loss than similar mixtures with more than 7% air. Including IC and slag cement did not negatively affect scaling resistance. Freeze-thaw durability was affected most by the total absorbed water content, with increases in absorbed water leading to a decrease in freeze-thaw durability. RCP and SRM results were affected most by the binder composition (specifically, including a partial replacement of portland cement with slag cement). Experiences and lessons learned during the construction of the first four IC-LC-HPC Bridge Decks along with the failed placement of one deck indicate that the primary aspects of successfully implementing IC with LC-HPC include determining the moisture content of the FLWA shortly before batching and adjusting mixture proportions to maintain the target quantity of IC water (based on the FLWA absorption). Evaluation of the IC-LC-HPC Decks and IN-IC-HPC Decks demonstrate that low cracking can be achieved for concrete containing IC and SCMs as long as the paste content (volume of cementitious materials and water) is kept below 26%. An overlay with a paste content of 34.3% on one of the IC-LC-HPC Decks exhibited high cracking within the first two years after placement. The two IC Decks in Utah and one IC deck in Indiana with paste contents of 28% and 27.6%, respectively, also had high cracking. Durability issues in the form of scaling and aggregate popouts were observed during surveys of the IN-IC-HPC Decks; the Decks had higher IC water contents than planned (leading to a high total absorbed water content), lower air contents than the IC-LC-HPC Decks, and late-season placement dates that provided minimal time for the concrete to dry prior to being exposed to freezing conditions.ACI FoundationCONSTRUCTION OF LOW-CRACKING HIGH-PERFORMANCE Bridge Decks INCORPORATING NEW TECHNOLOGY TRANSPORTATION POOLED-FUND PROGRAM PROJECT NO. TPF-5(336
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Construction Of Low-Cracking High-Performance Bridge Decks Incorporating New Technology
University of Kansas Center for Research Inc., 2019Co-Authors: Lafikes James, Feng Muzai, Darwin David, O'reilly Matthew, Bahadori Alireza, Khajehdehi RouzbehAbstract:Construction and early-age crack evaluations of four Bridge Decks in Minnesota placed from 2016 to 2018 that incorporate specifications for Internally-Cured Low-Cracking High-Performance Concrete (IC-LC-HPC) are documented in this study. Two additional Decks that serve as Controls followed specifications for high-performance concrete and paired with IC-LC-HPC Decks are included. Pre-wetted fine lightweight aggregate was used to provide a targeted internal curing water content of 8% by total weight of binder. The IC-LC-HPC mixtures included 27 to 30% slag cement by total binder weight while the Control mixtures included 25 or 35% Class F fly ash by total weight of binder. For one IC-LC-HPC deck, mixture proportions were modified based on a higher FLWA absorption than originally used to design the mixture. One IC-LC-HPC placement failed due to errors in FLWA moisture corrections and concrete batching that led to rejections of batches, leaving an inadequate supply of material to complete the deck. Crack surveys were completed for the IC-LC-HPC and Control Decks placed in 2016 and 2017. Crack densities at these ages were low compared to most Low-Cracking High-Performance Concrete Decks in Kansas and Internally-Cured High-Performance Concrete Decks in Indiana, with the exception of one IC-LCHPC deck that exhibited extensive cracking within one year after placement, which had an overlay with a high cement paste content and no internal curing. This project serves as a foundation for implementing IC-LC-HPC in upcoming Bridge Decks in Kansas and Minnesota.Kansas Department of Transportation and Minnesota Department of Transportation “Construction of Low-Cracking High-Performance Bridge Decks Incorporating New Technology” Transportation Pooled Fund Study, Project No. TPF-5(336)
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Controlling Cracks in Bridge Decks
University of Kansas Center for Research Inc., 2019Co-Authors: Khajehdehi Rouzbeh, Darwin DavidAbstract:Laboratory studies incorporating crack-reducing technologies with those included in specifications for low-cracking high-performance concrete (LC-HPC) Bridge Decks and analyses of data from crack surveys and construction observations on more than 50 concrete Decks are described. The laboratory investigations include the combination of supplementary cementitious materials (SCMs), slag cement and silica fume, as partial replacements for portland cement, internal curing through use of pre-wetted lightweight aggregates (IC), and calcium oxide-based (CaO) or magnesium oxide-based (MgO) shrinkage compensating admixtures or expansive additives (SCA) with LC-HPC. A modified version of ASTM C157 in which length-change measurements begin 5½ ± ½ hr after casting concrete is developed and used to evaluate swelling and shrinkage including the combined effects of supplementary cementitious materials (SCMs), internal curing (IC), and MgO- and CaO-shrinkage compensating admixture (SCAs) on shrinkage of concrete specimens designed according to LC-HPC specifications. The results show that the modified version of ASTM C157 helps to capture the early-age behavior of concrete mixtures. IC is effective in reducing 0 to 20-day drying shrinkage in concrete, but the opposite is observed regarding 20 to 180-day drying shrinkage. SCMs induce increased first-day expansion and reduce shrinkage. A further increase in first-day expansion and a reduction in shrinkage is obtained when IC is used in conjunction with SCMs. The SCAs evaluated in this study reduce the tendency to develop shrinkage strain. The CaO-based SCA induces the more rapid expansion of greater magnitude, while the MgO-based SCA expands more gradually. When the CaO-based SCA is incorporated in a mixture containing SCMs or SCMs and IC, expansion is further increased, an observation that cannot be made for mixtures incorporating SCMs with the MgO-based SCA. Analyses of crack survey results and construction observations for more than 50 Bridge Decks are used to better understand the principal factors affecting cracking, evaluate the effects of construction practices on cracking, and assess the effectiveness of crack-reducing technologies, such as synthetic fibers and IC. The results indicate that Bridge deck cracking increases with age. Paste content (volume of cementitious materials plus water) is the most dominant factor affecting cracking, and parameters such as slump, compressive strength, and air content have much less effect. Decks cast with concrete with paste contents exceeding 27.2% exhibit substantially greater cracking than those with lower paste contents, regardless of other factors. The incorporation of a crack-reducing technology such as IC in the Decks cast with concrete having paste contents exceeding 27.2% cannot overcome the negative effect of the greater paste content on cracking. Individual contractors and poor construction practices, particularly poor consolidation and overfinishing the concrete, can significantly affect cracking even when the Decks are cast with a low-shrinkage concrete (paste content limited to 27.2%) even where a crack-reducing technology is used. Bridge Decks with precast partial-depth concrete deck panels with cast-in-place concrete toppings show excellent cracking performance if the topping has a low paste content and good construction procedures are used. Greater average crack widths correspond with greater crack densities
Khajehdehi Rouzbeh - One of the best experts on this subject based on the ideXlab platform.
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Internal Curing and Supplementary Cementitious Materials in Bridge Decks
American Concrete Institute, 2020Co-Authors: Lafikes James, Khajehdehi Rouzbeh, Feng Muzai, O’reilly Matthew, Darwi DavidAbstract:Supplementary cementitious materials (SCMs) in conjunction with pre-wetted fine lightweight aggregate to provide internal curing are being increasingly used to produce high-performance, low-shrinking concrete to mitigate Bridge deck cracking, providing more sustainable projects with a longer service life. Additionally, the SCMs aid in concrete sustainability by reducing the amount of cement needed in these projects. This study examines the density of cracks in Bridge Decks in Indiana and Utah that incorporated internal curing with various combinations of portland cement and SCMs, specifically, slag cement, Class C and Class F fly ash, and silica fume, in concrete mixtures with water-cementitious material ratios ranging from 0.39 to 0.44. When compared with crack densities in low-cracking high-performance concrete (LC-HPC) and control Bridge Decks in Kansas, concrete mixtures with a paste content higher than 27% exhibited more cracking, regardless of the use of internal curing or SCMs. Bridge Decks with paste contents below 26% that incorporate internal curing and SCMs exhibited low cracking at early ages, although additional surveys will be needed before conclusions on long-term behavior can be made.ACI Committees 130, Sustainability of Concrete and 224, Crackin
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Low-Cracking High-Performance Concrete (LC-HPC) for Durable Bridge Decks
'American Concrete Institute', 2020Co-Authors: Darwin David, Lafikes James, Khajehdehi Rouzbeh, Feng Muzai, Ibrahim Eman, O’reilly MatthewAbstract:The goal of this study was to implement cost-effective techniques for improving Bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 Decks constructed with LC-HPC specifications and 13 matching control Bridge Decks based on crack surveys. The LC-HPC Bridge Decks exhibit less cracking than the matching control Decks in the vast majority of cases. Only two LC-HPC Bridge Decks have higher overall crack densities than their control Decks, which are the two best performing control Decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in Bridge Decks.ACI Committees 130, Sustainability of Concrete and 224, Crackin
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Construction Of Low-Cracking High-Performance Bridge Decks Incorporating New Technology
University of Kansas Center for Research Inc., 2019Co-Authors: Lafikes James, Feng Muzai, Darwin David, O'reilly Matthew, Bahadori Alireza, Khajehdehi RouzbehAbstract:Construction and early-age crack evaluations of four Bridge Decks in Minnesota placed from 2016 to 2018 that incorporate specifications for Internally-Cured Low-Cracking High-Performance Concrete (IC-LC-HPC) are documented in this study. Two additional Decks that serve as Controls followed specifications for high-performance concrete and paired with IC-LC-HPC Decks are included. Pre-wetted fine lightweight aggregate was used to provide a targeted internal curing water content of 8% by total weight of binder. The IC-LC-HPC mixtures included 27 to 30% slag cement by total binder weight while the Control mixtures included 25 or 35% Class F fly ash by total weight of binder. For one IC-LC-HPC deck, mixture proportions were modified based on a higher FLWA absorption than originally used to design the mixture. One IC-LC-HPC placement failed due to errors in FLWA moisture corrections and concrete batching that led to rejections of batches, leaving an inadequate supply of material to complete the deck. Crack surveys were completed for the IC-LC-HPC and Control Decks placed in 2016 and 2017. Crack densities at these ages were low compared to most Low-Cracking High-Performance Concrete Decks in Kansas and Internally-Cured High-Performance Concrete Decks in Indiana, with the exception of one IC-LCHPC deck that exhibited extensive cracking within one year after placement, which had an overlay with a high cement paste content and no internal curing. This project serves as a foundation for implementing IC-LC-HPC in upcoming Bridge Decks in Kansas and Minnesota.Kansas Department of Transportation and Minnesota Department of Transportation “Construction of Low-Cracking High-Performance Bridge Decks Incorporating New Technology” Transportation Pooled Fund Study, Project No. TPF-5(336)
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Controlling Cracks in Bridge Decks
University of Kansas Center for Research Inc., 2019Co-Authors: Khajehdehi Rouzbeh, Darwin DavidAbstract:Laboratory studies incorporating crack-reducing technologies with those included in specifications for low-cracking high-performance concrete (LC-HPC) Bridge Decks and analyses of data from crack surveys and construction observations on more than 50 concrete Decks are described. The laboratory investigations include the combination of supplementary cementitious materials (SCMs), slag cement and silica fume, as partial replacements for portland cement, internal curing through use of pre-wetted lightweight aggregates (IC), and calcium oxide-based (CaO) or magnesium oxide-based (MgO) shrinkage compensating admixtures or expansive additives (SCA) with LC-HPC. A modified version of ASTM C157 in which length-change measurements begin 5½ ± ½ hr after casting concrete is developed and used to evaluate swelling and shrinkage including the combined effects of supplementary cementitious materials (SCMs), internal curing (IC), and MgO- and CaO-shrinkage compensating admixture (SCAs) on shrinkage of concrete specimens designed according to LC-HPC specifications. The results show that the modified version of ASTM C157 helps to capture the early-age behavior of concrete mixtures. IC is effective in reducing 0 to 20-day drying shrinkage in concrete, but the opposite is observed regarding 20 to 180-day drying shrinkage. SCMs induce increased first-day expansion and reduce shrinkage. A further increase in first-day expansion and a reduction in shrinkage is obtained when IC is used in conjunction with SCMs. The SCAs evaluated in this study reduce the tendency to develop shrinkage strain. The CaO-based SCA induces the more rapid expansion of greater magnitude, while the MgO-based SCA expands more gradually. When the CaO-based SCA is incorporated in a mixture containing SCMs or SCMs and IC, expansion is further increased, an observation that cannot be made for mixtures incorporating SCMs with the MgO-based SCA. Analyses of crack survey results and construction observations for more than 50 Bridge Decks are used to better understand the principal factors affecting cracking, evaluate the effects of construction practices on cracking, and assess the effectiveness of crack-reducing technologies, such as synthetic fibers and IC. The results indicate that Bridge deck cracking increases with age. Paste content (volume of cementitious materials plus water) is the most dominant factor affecting cracking, and parameters such as slump, compressive strength, and air content have much less effect. Decks cast with concrete with paste contents exceeding 27.2% exhibit substantially greater cracking than those with lower paste contents, regardless of other factors. The incorporation of a crack-reducing technology such as IC in the Decks cast with concrete having paste contents exceeding 27.2% cannot overcome the negative effect of the greater paste content on cracking. Individual contractors and poor construction practices, particularly poor consolidation and overfinishing the concrete, can significantly affect cracking even when the Decks are cast with a low-shrinkage concrete (paste content limited to 27.2%) even where a crack-reducing technology is used. Bridge Decks with precast partial-depth concrete deck panels with cast-in-place concrete toppings show excellent cracking performance if the topping has a low paste content and good construction procedures are used. Greater average crack widths correspond with greater crack densities
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Controlling Cracks in Bridge Decks
University of Kansas, 2018Co-Authors: Khajehdehi RouzbehAbstract:Laboratory studies incorporating crack-reducing technologies with those included in specifications for low-cracking high-performance concrete (LC-HPC) Bridge Decks and analyses of data from crack surveys and construction observations on more than 50 concrete Decks are described. The laboratory investigations include the combination of supplementary cementitious materials (SCMs), slag cement and silica fume, as partial replacements for portland cement, internal curing through use of pre-wetted lightweight aggregates (IC), and calcium oxide-based (CaO) or magnesium oxide-based (MgO) shrinkage compensating admixtures or expansive additives (SCA) with LC-HPC. A modified version of ASTM C157 in which length-change measurements begin 5½ ± ½ hr after casting concrete is developed and used to evaluate swelling and shrinkage including the combined effects of supplementary cementitious materials (SCMs), internal curing (IC), and MgO- and CaO-shrinkage compensating admixture (SCAs) on shrinkage of concrete specimens designed according to LC-HPC specifications. The results show that the modified version of ASTM C157 helps to capture the early-age behavior of concrete mixtures. IC is effective in reducing 0 to 20-day drying shrinkage in concrete, but the opposite is observed regarding 20 to 180-day drying shrinkage. SCMs induce increased first-day expansion and reduce shrinkage. A further increase in first-day expansion and a reduction in shrinkage is obtained when IC is used in conjunction with SCMs. The SCAs evaluated in this study reduce the tendency to develop shrinkage strain. The CaO-based SCA induces the more rapid expansion of greater magnitude, while the MgO-based SCA expands more gradually. When the CaO-based SCA is incorporated in a mixture containing SCMs or SCMs and IC, expansion is further increased, an observation that cannot be made for mixtures incorporating SCMs with the MgO-based SCA. Analyses of crack survey results and construction observations for more than 50 Bridge Decks are used to better understand the principal factors affecting cracking, evaluate the effects of construction practices on cracking, and assess the effectiveness of crack-reducing technologies, such as synthetic fibers and IC. The results indicate that Bridge deck cracking increases with age. Paste content (volume of cementitious materials plus water) is the most dominant factor affecting cracking, and parameters such as slump, compressive strength, and air content have much less effect. Decks cast with concrete with paste contents exceeding 27.2% exhibit substantially greater cracking than those with lower paste contents, regardless of other factors. The incorporation of a crack-reducing technology such as IC in the Decks cast with concrete having paste contents exceeding 27.2% cannot overcome the negative effect of the greater paste content on cracking. Individual contractors and poor construction practices, particularly poor consolidation and overfinishing the concrete, can significantly affect cracking even when the Decks are cast with a low-shrinkage concrete (paste content limited to 27.2%) even where a crack-reducing technology is used. Bridge Decks with precast partial-depth concrete deck panels with cast-in-place concrete toppings show excellent cracking performance if the topping has a low paste content and good construction procedures are used. Greater average crack widths correspond with greater crack densities. Keywords: Bridge deck cracking, concrete, construction practices, crack control, crack-reducing technologies, crack width, internal curing, paste content, shrinkage compensating admixtures, synthetic fiber
O’reilly Matthew - One of the best experts on this subject based on the ideXlab platform.
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Internal Curing and Supplementary Cementitious Materials in Bridge Decks
American Concrete Institute, 2020Co-Authors: Lafikes James, Khajehdehi Rouzbeh, Feng Muzai, O’reilly Matthew, Darwi DavidAbstract:Supplementary cementitious materials (SCMs) in conjunction with pre-wetted fine lightweight aggregate to provide internal curing are being increasingly used to produce high-performance, low-shrinking concrete to mitigate Bridge deck cracking, providing more sustainable projects with a longer service life. Additionally, the SCMs aid in concrete sustainability by reducing the amount of cement needed in these projects. This study examines the density of cracks in Bridge Decks in Indiana and Utah that incorporated internal curing with various combinations of portland cement and SCMs, specifically, slag cement, Class C and Class F fly ash, and silica fume, in concrete mixtures with water-cementitious material ratios ranging from 0.39 to 0.44. When compared with crack densities in low-cracking high-performance concrete (LC-HPC) and control Bridge Decks in Kansas, concrete mixtures with a paste content higher than 27% exhibited more cracking, regardless of the use of internal curing or SCMs. Bridge Decks with paste contents below 26% that incorporate internal curing and SCMs exhibited low cracking at early ages, although additional surveys will be needed before conclusions on long-term behavior can be made.ACI Committees 130, Sustainability of Concrete and 224, Crackin
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Low-Cracking High-Performance Concrete (LC-HPC) for Durable Bridge Decks
'American Concrete Institute', 2020Co-Authors: Darwin David, Lafikes James, Khajehdehi Rouzbeh, Feng Muzai, Ibrahim Eman, O’reilly MatthewAbstract:The goal of this study was to implement cost-effective techniques for improving Bridge deck service life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the creation of Low-Cracking High-Performance Concrete (LC-HPC) specifications that minimize cracking through the use of low slump, low paste content, moderate compressive strength, concrete temperature control, good consolidation, minimum finishing, and extended curing. This paper documents the performance of 17 Decks constructed with LC-HPC specifications and 13 matching control Bridge Decks based on crack surveys. The LC-HPC Bridge Decks exhibit less cracking than the matching control Decks in the vast majority of cases. Only two LC-HPC Bridge Decks have higher overall crack densities than their control Decks, which are the two best performing control Decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. The results of this study demonstrate the positive effects of reduced cement paste contents, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, the use of good consolidation, minimizing finishing operations, and application of curing shortly after finishing and for an extended time on minimizing cracking in Bridge Decks.ACI Committees 130, Sustainability of Concrete and 224, Crackin
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Durability, Construction, and Early Evaluation of Low-Cracking High-Performance Concrete (LC-HPC) Bridge Decks
University of Kansas Center for Research Inc., 2020Co-Authors: Lafikes James, Darwin David, O’reilly MatthewAbstract:Laboratory evaluations of concrete mixtures based on specifications for low-cracking high-performance concrete (LC-HPC) incorporating internal curing (IC) and supplementary cementitious materials (SCMs) are described. In addition, the development, construction, and evaluation of four IC-LC-HPC Bridge Decks with IC provided by pre-wetted fine lightweight aggregate (FLWA) in conjunction with a partial replacement of portland cement with slag cement are described along with the evaluation of two Control Decks without IC constructed in accordance with standard high-performance concrete (HPC) specifications in Minnesota. Bridge Decks containing IC provided by pre-wetted FLWA and SCMs are also evaluated, including two Bridge Decks in Utah with a partial replacement of portland cement with Class F fly ash and six Bridge Decks in Indiana, four with IC and a partial replacement of portland cement with silica fume and either slag cement or Class C fly ash constructed in accordance with Indiana HPC specifications (IN-IC-HPC), one with IC and portland cement as the only binder, and one Control without IC. The laboratory evaluations were performed on three groups of concrete mixtures, one for each for the first three years of IC-LC-HPC Bridge deck construction in Minnesota. Variations in IC-LC-HPC mixture proportions include the amount of IC water (contents ranging from 0 to 14.1% by total weight of binder), total absorbed water content (IC water from the FLWA plus water absorbed by the normalweight coarse and fine aggregates ranging from 2.9 to 17.7% by total weight of binder), water-to-cementitious material (w/cm) ratios ranging from 0.39 to 0.45, and binder compositions examining the effects of using only portland cement, a 35% Class F fly ash replacement of portland cement, 27 to 30% slag cement replacements of portland cement, and a 2% addition of silica fume of cement for the mixtures containing 27 to 28% slag cement, all by total weight of binder. Tests for scaling resistance, freeze-thaw durability, rapid chloride permeability (RCP), and surface resistivity measurements (SRMs) were completed. The scaling resistance of the IC-LC-HPC mixtures was affected most by the air content, with mixtures having an air content below 7% exhibiting more mass loss than similar mixtures with more than 7% air. Including IC and slag cement did not negatively affect scaling resistance. Freeze-thaw durability was affected most by the total absorbed water content, with increases in absorbed water leading to a decrease in freeze-thaw durability. RCP and SRM results were affected most by the binder composition (specifically, including a partial replacement of portland cement with slag cement). Experiences and lessons learned during the construction of the first four IC-LC-HPC Bridge Decks along with the failed placement of one deck indicate that the primary aspects of successfully implementing IC with LC-HPC include determining the moisture content of the FLWA shortly before batching and adjusting mixture proportions to maintain the target quantity of IC water (based on the FLWA absorption). Evaluation of the IC-LC-HPC Decks and IN-IC-HPC Decks demonstrate that low cracking can be achieved for concrete containing IC and SCMs as long as the paste content (volume of cementitious materials and water) is kept below 26%. An overlay with a paste content of 34.3% on one of the IC-LC-HPC Decks exhibited high cracking within the first two years after placement. The two IC Decks in Utah and one IC deck in Indiana with paste contents of 28% and 27.6%, respectively, also had high cracking. Durability issues in the form of scaling and aggregate popouts were observed during surveys of the IN-IC-HPC Decks; the Decks had higher IC water contents than planned (leading to a high total absorbed water content), lower air contents than the IC-LC-HPC Decks, and late-season placement dates that provided minimal time for the concrete to dry prior to being exposed to freezing conditions.ACI FoundationCONSTRUCTION OF LOW-CRACKING HIGH-PERFORMANCE Bridge Decks INCORPORATING NEW TECHNOLOGY TRANSPORTATION POOLED-FUND PROGRAM PROJECT NO. TPF-5(336
Jerome F Hajjar - One of the best experts on this subject based on the ideXlab platform.
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transverse cracking in concrete Bridge Decks
Transportation Research Record, 1999Co-Authors: Catherine E French, Laurice J Eppers, Quoc T Le, Jerome F HajjarAbstract:The dominant parameters that lead to premature transverse cracking in Bridge Decks are determined, and recommendations to reduce cracking tendency in Bridge Decks are developed. The project is divided into two parts: a field study and a parametric study. The objective of the field study is to determine the correlation between the observed cracking and available design-, material-, and construction-related data. Seventy-two Bridges in the Minneapolis/St. Paul metropolitan area are included in the field study. According to the results of the study and correlation with other research, restrained concrete deck shrinkage is the leading cause of cracking. The dominant factors affecting transverse cracking are the longitudinal end restraint, girder stiffness, cross-frame location, splice location, deck thickness, cutoff length of the deck supplemental reinforcing bar, size of the top transverse bar, concrete shrinkage, deck concrete modulus of elasticity, cement content, aggregate type and quantity, air content,...
Kien Dinh - One of the best experts on this subject based on the ideXlab platform.
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deterioration and predictive condition modeling of concrete Bridge Decks based on data from periodic nde surveys
Journal of Infrastructure Systems, 2019Co-Authors: Jinyoung Kim, Nenad Gucunski, Kien DinhAbstract:AbstractA novel approach and program are developed for deterioration and predictive modeling of concrete Bridge Decks based on nondestructive evaluation (NDE) data. Through an iterative process—com...
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an algorithm for automatic localization and detection of rebars from gpr data of concrete Bridge Decks
Automation in Construction, 2018Co-Authors: Kien Dinh, Nenad Gucunski, Trung H DuongAbstract:Abstract Picking rebars manually in the data from ground penetrating radar (GPR) surveys of concrete Bridge Decks is time consuming and labor intensive. This paper presents an automated rebar localization and detection algorithm for performing this task. The proposed methodology is based on the integration of conventional image processing techniques and deep convolutional neural networks (CNN). In the first step, the image processing methods, such as the migration, normalized cross correlation and thresholding, are used to localize pixels containing potential rebar peaks. In the second step, windowed images surrounding the potential pixels are first extracted from the raw GPR scans involved in the first step. Those are then classified by a trained CNN. In the process, likely true rebar peaks are recognized and retained, whereas likely false positive detections are discarded. The implementation of the proposed system in the analysis of GPR data for twenty-six Bridge Decks has shown excellent performance. In all cases, the accuracy of the proposed system has been greater than 95.75%. The overall accuracy for the entire deck library was found to be 99.60% ± 0.85%.
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capture and quantification of deterioration progression in concrete Bridge Decks through periodical nde surveys
Journal of Infrastructure Systems, 2017Co-Authors: Nenad Gucunski, Brian M Pailes, Jinyoung Kim, Hoda Azari, Kien DinhAbstract:AbstractMonitoring the condition of concrete Bridge Decks is essential because Bridge Decks are deteriorating faster than other Bridge components. This study concentrated on Bridge deck condition assessment using complementary nondestructive evaluation (NDE) techniques. The assessment had three main components: evaluation of the corrosive environment and corrosion processes, concrete degradation evaluation, and assessment with respect to deck delamination. Five NDE techniques were used: impact echo (IE) to detect and characterize delamination, ground-penetrating radar (GPR) to describe the corrosive environment, measurement of the concrete cover and description of its overall condition, half-cell potential (HCP) to assess corrosion activity, ultrasonic surface waves (USW) to describe concrete quality, and electrical resistivity (ER) to estimate corrosion rate. The ability of NDE methods to objectively characterize deterioration progression is illustrated by the results from four NDE surveys of a Bridge in...
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understanding depth amplitude effects in assessment of gpr data from concrete Bridge Decks
Ndt & E International, 2016Co-Authors: Kien Dinh, Nenad Gucunski, Jinyoung Kim, Trung H DuongAbstract:Abstract The variation of concrete cover thickness on Bridge Decks has been observed to significantly affect the rebar reflection amplitude of the ground penetrating radar signal. Several depth correction approaches have been previously proposed in which it is assumed that, for any Bridge, at least a portion of the deck area is sound concrete. The 90th percentile linear regression is a commonly used procedure to extract the depth-amplitude relationship of the assumed sound concrete. It is recommended herein that normalizing the depth-dependent amplitudes be divided into two components. The first component takes into account the geometric loss due to inverse-square effect and the dielectric loss caused by the dissipation of electromagnetic energy in sound concrete. The second component is the conductive loss as a result of increased free charges associated with concrete deterioration. Whereas the conventional depth correction techniques do not clearly differentiate the two components and tend to incorporate both in the regression line, they are separately addressed in this research. Specifically, while the first component was accounted for based on a library of GPR signals collected from sound areas of twenty four bare concrete Bridge Decks, the conductive loss caused by an increased conductivity is linearly normalized by the two-way travel time. The implementation of the proposed method in two case studies showed that, while the method significantly improves the accuracy of GPR data analysis, the conventional methods may lead to a loss of information regarding the background attenuation that would indicate the overall deterioration of Bridge Decks.
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clustering based threshold model for condition assessment of concrete Bridge Decks with ground penetrating radar
Transportation Research Record, 2015Co-Authors: Kien Dinh, Tarek Zayed, Sami Moufti, Ahmad Shami, Ahmad Jabri, Mona Abouhamad, Thikra DawoodAbstract:Ground-penetrating radar (GPR) has been extensively studied for condition assessment of concrete Bridge Decks in North America. Although several methods for analyzing GPR data have been proposed, the commonly accepted method evaluates the condition of concrete Bridge Decks on the basis of the difference between reflection amplitudes of the top rebar layer. It is assumed in the method that strong reflection indicates sound concrete, whereas the area with high-amplitude attenuation is associated with concrete corrosion. The final result is a contour map of reflection amplitude in decibel scale with the thresholds selected arbitrarily to define the severity of concrete deterioration. Because subjective determination of threshold values may lead to inconsistency in the result obtained, this paper proposes a robust method for resolving that issue. Specifically, after depth correction was performed for top rebar amplitudes, on the basis of K-means clustering technique these amplitude data were grouped into a nu...