Related to Concrete Construction for Heavy Civil Projects
Case Study: Chicago Bridge Abutment Concrete Blowout (2018)
Project Overview
- Name: Chicago River Bridge Reconstruction
- Location: Chicago, Illinois
- Year: 2018
- Project Size: $275 million
- Scope: Cast-in-place reinforced concrete abutment construction
- Lead Agencies/Contractors: Illinois DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Formwork Failure
- Construction Safety
Summary of the Issue, Problem, or Challenge
During concrete placement, excessive hydrostatic pressure caused formwork blowout on an abutment pour, leading to loss of concrete and partial collapse of formwork.
Root Cause Analysis
| Factor | Details |
| Underestimated Hydrostatic Pressure | High slump concrete and rapid pour rate increased pressure. |
| Inadequate Formwork Design | Formwork not designed for lateral pressures encountered. |
| Lack of Monitoring | Insufficient monitoring of formwork deflection during pour. |
Impacts Due to the Issue, Problem, or Challenge
- Concrete loss and structural delays
- Safety hazard to workers requiring evacuation
- Additional costs for formwork redesign and re-pour
Corrective Actions Taken
- Revised formwork to withstand calculated hydrostatic pressures
- Reduced concrete slump and staged concrete pours
- Increased on-site monitoring during placement
Lessons Learned
- Formwork design must consider concrete properties and pour rates
- Real-time observation and adjustment prevent failures
- Safety protocols for formwork failure must be enforced
Case Study: San Francisco Pier Cap Reinforcement Corrosion during Construction (2019)
Project Overview
- Name: Bay Area Bridge Retrofit
- Location: San Francisco, California
- Year: 2019
- Project Size: $400 million
- Scope: Retrofit and construction of reinforced concrete pier caps
- Lead Agencies/Contractors: California DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Materials Durability
- Construction Exposure
Summary of the Issue, Problem, or Challenge
Excessive reinforcement corrosion was observed on stored rebar and partially constructed pier caps exposed to high humidity and marine atmosphere.
Root Cause Analysis
| Factor | Details |
| Prolonged Exposure | Rebar and fresh concrete exposed to salt-laden air without protection. |
| Lack of Protective Measures | Absence of curing membranes and corrosion inhibitors. |
| Storage Practices | Rebar improperly stored directly on ground and exposed. |
Impacts Due to the Issue, Problem, or Challenge
- Reduced structural durability
- Additional work to replace corroded reinforcement
- Schedule delays due to extended material preparation
Corrective Actions Taken
- Implementation of protective coatings and membranes during construction
- Improved rebar storage and handling protocols
- Use of corrosion-resistant materials and admixtures
Lessons Learned
- Construction staging in coastal environments requires corrosion control
- Proper storage and handling of reinforcement are critical
- Early identification and mitigation reduce long-term risk
Case Study: Houston Bridge Girder Concrete Segregation (2020)
Project Overview
- Name: Houston Highway Bridge Replacement
- Location: Houston, Texas
- Year: 2020
- Project Size: $350 million
- Scope: Cast-in-place reinforced concrete girders construction
- Lead Agencies/Contractors: Texas DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Concrete Placement Quality
- Structural Integrity
Summary of the Issue, Problem, or Challenge
Segregation and voids were detected in cast-in-place girders due to improper concrete placement methods and excessive drop heights.
Root Cause Analysis
| Factor | Details |
| Improper Placement | Concrete dropped from excessive heights causing segregation. |
| Inadequate Vibration | Insufficient consolidation of concrete around reinforcement. |
| Poor Supervision | Lack of qualified personnel monitoring placement process. |
Impacts Due to the Issue, Problem, or Challenge
- Structural weaknesses requiring partial demolition and re-pour
- Cost overruns and schedule impacts
- Increased inspection and testing requirements
Corrective Actions Taken
- Training for crews on proper concrete placement techniques
- Use of tremie methods and pumps to reduce drop height
- Enhanced field supervision and testing protocols
Lessons Learned
- Proper concrete placement methods are essential for structural quality
- Skilled supervision ensures compliance with best practices
- Early detection via NDT avoids costly rework
Case Study: Seattle Bridge Deck Cracking from Early Load Application (2021)
Project Overview
- Name: Puget Sound Bridge Deck Replacement
- Location: Seattle, Washington
- Year: 2021
- Project Size: $210 million
- Scope: Reinforced concrete bridge deck construction with staged loading
- Lead Agencies/Contractors: Washington State DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Construction Sequencing
- Structural Damage
Summary of the Issue, Problem, or Challenge
Premature application of construction and equipment loads on a newly cast bridge deck caused early-age cracking and compromised slab integrity.
Root Cause Analysis
| Factor | Details |
| Inadequate Cure Time | Loads applied before concrete reached design strength. |
| Poor Scheduling Coordination | Lack of clear timelines and load restrictions on site. |
| Weak Communication | Insufficient communication between construction teams. |
Impacts Due to the Issue, Problem, or Challenge
- Cracking requiring repair with epoxy injections and overlays
- Delays due to remediation and additional inspections
- Potential future maintenance risks
Corrective Actions Taken
- Strict curing and load application protocols enforced
- Improved scheduling and communication among stakeholders
- Implementation of strength testing before load placement
Lessons Learned
- Load restrictions critical during early concrete curing
- Scheduling coordination avoids premature stresses
- Communication protocols must be robust
Case Study: Atlanta Bridge Abutment Formwork Failure (2017)
Project Overview
- Name: I-285 Bridge Replacement
- Location: Atlanta, Georgia
- Year: 2017
- Project Size: $320 million
- Scope: Cast-in-place reinforced concrete abutments
- Lead Agencies/Contractors: Georgia DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Formwork Failure
- Construction Safety
Summary of the Issue, Problem, or Challenge
During concrete placement for abutments, formwork failed due to inadequate bracing, resulting in partial collapse and loss of fresh concrete.
Root Cause Analysis
| Factor | Details |
| Insufficient Bracing | Formwork bracing not designed for lateral concrete pressure. |
| Rapid Pour Rate | High pour rate increased lateral pressure beyond design limits. |
| Lack of Supervision | Insufficient onsite monitoring of formwork integrity. |
Impacts Due to the Issue, Problem, or Challenge
- Material loss and costly re-pour
- Safety hazards requiring site evacuation
- Schedule delays and additional costs
Corrective Actions Taken
- Redesigned formwork and bracing to handle hydrostatic loads
- Controlled pour rates with staged pours
- Increased field supervision and inspection
Lessons Learned
- Formwork design must anticipate actual pour conditions
- Continuous monitoring during placement is critical
- Safety plans should address formwork failure scenarios
Case Study: Denver Pier Concrete Strength Deficiency (2019)
Project Overview
- Name: Denver Urban Bridge Expansion
- Location: Denver, Colorado
- Year: 2019
- Project Size: $280 million
- Scope: Reinforced concrete piers construction
- Lead Agencies/Contractors: Colorado DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Material Quality
- Structural Integrity
Summary of the Issue, Problem, or Challenge
Testing revealed several pier concrete samples with compressive strengths below specified limits, leading to structural concerns and work stoppages.
Root Cause Analysis
| Factor | Details |
| Poor Concrete Mix Control | Variability in mix proportions and water-cement ratio. |
| Inadequate Curing | Inconsistent curing led to uneven strength development. |
| Testing Protocol Lapses | Delay in testing and reporting hampered early detection. |
Impacts Due to the Issue, Problem, or Challenge
- Partial demolition and re-casting of piers
- Project delays and increased costs
- Reduced confidence among stakeholders
Corrective Actions Taken
- Revised concrete mix design and quality control processes
- Implemented standardized curing protocols
- Accelerated testing frequency and reporting
Lessons Learned
- Strict mix design adherence is critical for structural concrete
- Proper curing ensures consistent strength development
- Timely testing allows prompt corrective action
Case Study: Miami Pier Cap Reinforcement Misplacement (2020)
Project Overview
- Name: Miami Coastal Bridge Construction
- Location: Miami, Florida
- Year: 2020
- Project Size: $350 million
- Scope: Reinforced concrete pier caps
- Lead Agencies/Contractors: Florida DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Construction Error
- Structural Safety
Summary of the Issue, Problem, or Challenge
During pier cap construction, inspection found reinforcement bars incorrectly placed outside specified tolerances, risking structural performance.
Root Cause Analysis
| Factor | Details |
| Inadequate Supervision | Lack of onsite quality control checks during rebar placement. |
| Confusing Drawings | Ambiguous reinforcement drawings led to misinterpretation. |
| Insufficient Training | Field crews lacked adequate training on reinforcement placement standards. |
Impacts Due to the Issue, Problem, or Challenge
- Rework to correct reinforcement placement
- Project schedule delays and additional labor costs
- Increased inspection and oversight requirements
Corrective Actions Taken
- Strengthened onsite QA/QC with qualified inspectors
- Clarified design documents and drawings
- Conducted training workshops for field crews
Lessons Learned
- Clear, unambiguous drawings critical for accurate construction
- Skilled supervision prevents costly mistakes
- Continuous training improves workforce competence
Case Study: New York Bridge Deck Cold Joint Cracking (2021)
Project Overview
- Name: Brooklyn Bridge Rehabilitation
- Location: New York, New York
- Year: 2021
- Project Size: $420 million
- Scope: Reinforced concrete bridge deck replacement
- Lead Agencies/Contractors: New York State DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Construction Sequencing
- Quality Control
Summary of the Issue, Problem, or Challenge
Cold joints developed cracks due to improper timing and preparation between successive concrete pours in the bridge deck.
Root Cause Analysis
| Factor | Details |
| Poor Scheduling | Delays between pours exceeded recommended time limits. |
| Inadequate Surface Prep | Insufficient cleaning and roughening of prior concrete surface. |
| Lack of Bonding Agents | No bonding agents applied at the cold joint interface. |
Impacts Due to the Issue, Problem, or Challenge
- Cracking requiring repair and surface treatments
- Potential durability concerns if untreated
- Additional costs and minor delays
Corrective Actions Taken
- Revised pour scheduling to maintain cold joint time limits
- Improved surface preparation protocols
- Specified use of bonding agents at cold joints
Lessons Learned
- Timely pours and surface prep critical for monolithic action
- Bonding agents improve cold joint performance
- Planning and communication reduce cold joint defects
Case Study: Houston Box Girder Bottom Deck Honeycombing (2018)
Project Overview
- Name: I-45 Gulf Freeway Expansion
- Location: Houston, Texas
- Year: 2018
- Project Size: $290 million
- Scope: Reinforced concrete bottom deck of precast box girders
- Lead Agencies/Contractors: Texas DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Defects / Honeycombing
- Quality Control
Summary of the Issue, Problem, or Challenge
Visual and ultrasonic inspections detected honeycombing and voids in the bottom deck concrete of several box girders, compromising durability and load transfer.
Root Cause Analysis
| Factor | Details |
| Inadequate Concrete Consolidation | Poor vibration during concrete placement led to entrapped air pockets. |
| Improper Formwork Sealing | Leakage at form joints caused loss of cement paste. |
| Insufficient Quality Checks | Lack of early detection during concrete pouring. |
Impacts Due to the Issue, Problem, or Challenge
- Partial removal and patch repair of affected areas
- Increased costs and schedule impacts
- Concerns over long-term structural performance
Corrective Actions Taken
- Improved vibration techniques and training for concrete crews
- Enhanced formwork sealing and monitoring during pours
- Increased QC inspections using NDT methods immediately after placement
Lessons Learned
- Proper consolidation critical to avoid honeycombing
- Formwork integrity directly affects concrete quality
- Early QC detection minimizes repair scope and costs
Case Study: Seattle Box Girder Top Deck Cracking Due to Early Loading (2019)
Project Overview
- Name: SR-520 Bridge Replacement
- Location: Seattle, Washington
- Year: 2019
- Project Size: $400 million
- Scope: Reinforced concrete top deck placement on box girders
- Lead Agencies/Contractors: Washington State DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Construction Sequencing
- Load Management
Summary of the Issue, Problem, or Challenge
Premature loading of the top deck before adequate curing caused hairline cracks and micro-fractures, necessitating remedial treatments.
Root Cause Analysis
| Factor | Details |
| Inadequate Curing Time | Construction schedules pressured early traffic or equipment loading. |
| Lack of Strength Testing | Concrete strength was not confirmed before allowing loads. |
| Insufficient Communication | Poor coordination between design and construction teams. |
Impacts Due to the Issue, Problem, or Challenge
- Surface cracking requiring sealing and monitoring
- Potential durability issues if unaddressed
- Delays to traffic opening and additional repair costs
Corrective Actions Taken
- Revised curing and strength testing protocols before loading
- Improved schedule coordination and communication
- Adoption of stricter load monitoring on new concrete decks
Lessons Learned
- Respect curing times for concrete structural elements
- Load testing or verification essential before service loads
- Coordination between teams prevents premature loading risks
Case Study: Chicago Bridge Box Girder Overhang Spalling (2020)
Project Overview
- Name: Lake Shore Drive Reconstruction
- Location: Chicago, Illinois
- Year: 2020
- Project Size: $330 million
- Scope: Reinforced concrete overhangs of box girders
- Lead Agencies/Contractors: Illinois DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Durability / Spalling
- Construction Quality
Summary of the Issue, Problem, or Challenge
After formwork removal, several box girder overhangs exhibited concrete spalling and exposed reinforcement due to poor concrete cover and surface defects.
Root Cause Analysis
| Factor | Details |
| Insufficient Concrete Cover | Placement tolerance issues led to inadequate cover over rebar. |
| Early Formwork Stripping | Removing formwork before sufficient concrete strength gained. |
| Cold Weather Conditions | Low temperatures caused delayed hydration and surface weakness. |
Impacts Due to the Issue, Problem, or Challenge
- Costly patch repairs and corrosion protection
- Risk of accelerated reinforcement corrosion
- Project delays due to remediation works
Corrective Actions Taken
- Enforced minimum concrete cover standards with detailed inspections
- Adjusted formwork removal timing based on strength tests
- Introduced cold weather concrete curing methods and protections
Lessons Learned
- Strict enforcement of concrete cover critical for durability
- Formwork removal timing impacts surface quality
- Environmental factors must guide curing and formwork stripping decisions
Case Study: San Francisco Box Girder Stem Wall Settlement (2021)
Project Overview
- Name: Bay Area Bridge Seismic Retrofit
- Location: San Francisco, California
- Year: 2021
- Project Size: $500 million
- Scope: Reinforced concrete stem walls supporting box girders
- Lead Agencies/Contractors: Caltrans /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Geotechnical Interaction
- Settlement Issues
Summary of the Issue, Problem, or Challenge
Post-pour monitoring revealed unexpected differential settlement of stem walls, causing misalignment and stresses on the box girder superstructure.
Root Cause Analysis
| Factor | Details |
| Unanticipated Soil Conditions | Subsurface variability with compressible soils not fully characterized. |
| Incomplete Pre-Construction Geotech Investigation | Insufficient borings and lab testing missed weak zones. |
| Load Transfer Miscalculations | Underestimated load effects on the stem wall foundations. |
Impacts Due to the Issue, Problem, or Challenge
- Design revisions and underpinning required
- Delays and increased costs for remediation
- Structural monitoring and long-term maintenance planned
Corrective Actions Taken
- Additional geotechnical investigations and soil improvement
- Modified foundation design with deeper piles and spread footings
- Implemented real-time settlement monitoring during construction
Lessons Learned
- Comprehensive geotech studies essential before stem wall construction
- Foundation design must incorporate soil variability
- Early monitoring detects settlement before severe damage occurs
Case Study: Denver Box Girder Top Deck Delamination (2019)
Project Overview
- Name: I-70 East Reconstruction
- Location: Denver, Colorado
- Year: 2019
- Project Size: $450 million
- Scope: Reinforced concrete top deck of box girders
- Lead Agencies/Contractors: Colorado DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Delamination
- Quality Control
Summary of the Issue, Problem, or Challenge
During curing, large delaminated areas appeared on the top deck surface, requiring removal and re-pouring of affected sections.
Root Cause Analysis
| Factor | Details |
| Poor Concrete Placement | Cold joints and inadequate bonding between pours. |
| Inadequate Curing | Drying shrinkage accelerated by environmental conditions. |
| Insufficient Surface Prep | Lack of proper surface roughening prior to successive pours. |
Impacts Due to the Issue, Problem, or Challenge
- Rework of large concrete areas, adding cost and delay
- Risk of durability and waterproofing failures if left untreated
Corrective Actions Taken
- Improved placement sequencing with continuous pours
- Enhanced curing procedures and moisture retention techniques
- Use of bonding agents at cold joints to improve adhesion
Lessons Learned
- Proper pour sequencing and surface preparation critical for monolithic slabs
- Environmental conditions must guide curing strategy
- Early detection and repair prevent larger durability issues
Case Study: Atlanta Box Girder Overhang Reinforcement Corrosion (2020)
Project Overview
- Name: I-285 Perimeter Expansion
- Location: Atlanta, Georgia
- Year: 2020
- Project Size: $375 million
- Scope: Reinforced concrete overhang construction of box girders
- Lead Agencies/Contractors: Georgia DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Corrosion Protection
- Construction Practices
Summary of the Issue, Problem, or Challenge
Inspection revealed early-stage corrosion of reinforcement in overhangs caused by insufficient concrete cover and poor concrete quality.
Root Cause Analysis
| Factor | Details |
| Insufficient Concrete Cover | Cover did not meet specified minimum thickness. |
| High Permeability Concrete | Use of high water-cement ratio concrete facilitated chloride ingress. |
| Lack of Protective Measures | No corrosion inhibitors or coatings applied to rebar. |
Impacts Due to the Issue, Problem, or Challenge
- Early deterioration and need for patch repairs
- Increased maintenance costs and structural longevity concerns
Corrective Actions Taken
- Strict enforcement of concrete cover requirements
- Implementation of low permeability concrete mixes
- Use of corrosion-inhibiting admixtures and coatings on reinforcement
Lessons Learned
- Concrete cover and mix design critical for durability, especially in exposed elements
- Protective measures against corrosion must be standard practice in aggressive environments
Case Study: New York Box Girder Stem Wall Cracking (2021)
Project Overview
- Name: Tappan Zee Bridge Replacement
- Location: New York
- Year: 2021
- Project Size: $3.9 billion
- Scope: Reinforced concrete stem walls supporting box girders
- Lead Agencies/Contractors: NYSDOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Structural Cracking
- Construction Material
Summary of the Issue, Problem, or Challenge
Significant cracking observed in stem walls shortly after formwork removal, linked to early-age shrinkage and thermal stress.
Root Cause Analysis
| Factor | Details |
| High Heat of Hydration | Large concrete pours generated excessive heat causing cracks. |
| Poor Joint Detailing | Lack of control joints led to uncontrolled cracking. |
| Inadequate Moisture Curing | Drying caused shrinkage stresses before strength gain. |
Impacts Due to the Issue, Problem, or Challenge
- Structural integrity concerns requiring detailed assessment
- Repair work involving epoxy injection and crack stitching
- Schedule impacts due to remediation
Corrective Actions Taken
- Use of low-heat cement and temperature control plans for large pours
- Incorporation of control joints and crack control reinforcement
- Strict curing protocols maintaining moisture for adequate duration
Lessons Learned
- Thermal management essential for mass concrete elements
- Control joints and reinforcement prevent crack propagation
- Proper curing critical to shrinkage crack control
Case Study: Portland Box Girder Bottom Deck Formwork Collapse (2020)
Project Overview
- Name: I-5 Columbia River Crossing
- Location: Portland, Oregon
- Year: 2020
- Project Size: $500 million
- Scope: Reinforced concrete bottom deck formwork of box girders
- Lead Agencies/Contractors: Oregon DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Formwork Failure
- Safety
Summary of the Issue, Problem, or Challenge
During concrete placement, a section of the bottom deck formwork collapsed due to inadequate shoring and improper load distribution.
Root Cause Analysis
| Factor | Details |
| Insufficient Formwork Design | Formwork system underestimated concrete load during pour. |
| Poor Shoring Installation | Shoring improperly installed and not inspected before pour. |
| Lack of Supervision | Inadequate oversight during critical pour stage. |
Impacts Due to the Issue, Problem, or Challenge
- Injury risks to workers; fortunately, no casualties
- Concrete pour delays and repair of damaged forms
- Costly investigation and redesign of formwork system
Corrective Actions Taken
- Redesigned formwork with higher safety factors
- Strict inspection and sign-off before concrete placement
- Enhanced supervision during critical construction phases
Lessons Learned
- Formwork design must consider all load cases thoroughly
- Proper installation and inspection critical to safety
- Supervision during pours essential to prevent accidents
Case Study: Seattle Box Girder Overhang Shrinkage Cracking (2020)
Project Overview
- Name: SR 520 Bridge Replacement
- Location: Seattle, Washington
- Year: 2020
- Project Size: $4 billion
- Scope: Reinforced concrete overhangs on box girder spans
- Lead Agencies/Contractors: WSDOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Shrinkage Cracking
- Material Properties
Summary of the Issue, Problem, or Challenge
Extensive shrinkage cracks appeared in the overhang slabs within weeks of curing, raising concerns about long-term durability.
Root Cause Analysis
| Factor | Details |
| High Water-Cement Ratio | Concrete mix had higher than recommended water content. |
| Inadequate Curing | Surface dried prematurely leading to plastic shrinkage. |
| Lack of Shrinkage-Reducing Admixtures | Mix design did not include shrinkage mitigation additives. |
Impacts Due to the Issue, Problem, or Challenge
- Increased permeability and risk of corrosion
- Repair and sealing required, causing additional cost and delay
Corrective Actions Taken
- Revised mix design with lower water-cement ratio
- Introduction of shrinkage-reducing admixtures
- Strict curing and moisture retention enforcement
Lessons Learned
- Mix design critically influences shrinkage behavior
- Curing protocols must prevent early moisture loss
- Additives can significantly reduce shrinkage cracking risk
Case Study: Miami Box Girder Bottom Deck Rebar Placement Errors (2021)
Project Overview
- Name: Miami I-395 Expressway
- Location: Miami, Florida
- Year: 2021
- Project Size: $300 million
- Scope: Reinforced concrete bottom deck of box girders
- Lead Agencies/Contractors: Florida DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Reinforcement Placement
- Quality Control
Summary of the Issue, Problem, or Challenge
During inspection, numerous rebar placement errors were found in the bottom deck, including incorrect spacing and insufficient concrete cover.
Root Cause Analysis
| Factor | Details |
| Inadequate Supervision | On-site inspection failed to catch placement deviations. |
| Confusing Design Documents | Ambiguities in reinforcement drawings caused errors. |
| Workforce Training Deficit | Laborers unfamiliar with complex rebar layouts. |
Impacts Due to the Issue, Problem, or Challenge
- Need for partial removal and rework of concrete decks
- Project delays and increased labor costs
Corrective Actions Taken
- Clearer, more detailed reinforcement drawings
- Enhanced on-site QA/QC with third-party inspectors
- Additional workforce training and mock-ups
Lessons Learned
- Clear design and documentation essential to correct placement
- Continuous supervision avoids costly rework
- Skilled labor and training critical for complex reinforcement tasks
Case Study: San Francisco Box Girder Top Deck Cold Joint Weakness (2019)
Project Overview
- Name: Bay Area Rapid Transit Extension
- Location: San Francisco, California
- Year: 2019
- Project Size: $2 billion
- Scope: Reinforced concrete top deck for box girders
- Lead Agencies/Contractors: BART /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Cold Joint Failure
- Structural Integrity
Summary of the Issue, Problem, or Challenge
Cold joints in the top deck showed weak bonding and microcracking, compromising the structural integrity of the deck.
Root Cause Analysis
| Factor | Details |
| Poor Surface Preparation | Existing concrete surface not adequately cleaned or roughened. |
| Delays Between Pours | Extended time lapses caused cold joints to form. |
| Lack of Bonding Agents | No epoxy or bonding agents used to improve interlayer adhesion. |
Impacts Due to the Issue, Problem, or Challenge
- Reduced load capacity of affected deck sections
- Costly remediation via surface treatment and additional concrete overlay
Corrective Actions Taken
- Mandatory surface preparation protocols for successive pours
- Use of bonding agents at construction joints
- Minimized time between concrete pours
Lessons Learned
- Cold joints require rigorous preparation and bonding measures
- Time control between pours crucial to structural continuity
- Advanced joint materials improve long-term durability
Case Study: Denver Box Girder Overhang Concrete Delamination (2020)
Project Overview
- Name: I-25 South Gap Project
- Location: Denver, Colorado
- Year: 2020
- Project Size: $350 million
- Scope: Construction of reinforced concrete overhangs on box girder bridges
- Lead Agencies/Contractors: Colorado DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Concrete Delamination
- Construction Defects
Summary of the Issue, Problem, or Challenge
Within months of casting, delamination and spalling were observed on several overhang sections, resulting in surface flaking and potential exposure of reinforcement.
Root Cause Analysis
| Factor | Details |
| Poor Concrete Mix Design | High air content and low cement paste strength. |
| Inadequate Consolidation | Insufficient vibration leading to trapped air pockets. |
| Early Exposure to Freezing | Cold weather conditions without proper curing protections. |
Impacts Due to the Issue, Problem, or Challenge
- Early deterioration risk requiring surface repairs
- Increased maintenance costs and project delays
Corrective Actions Taken
- Revision of mix design to optimize air content and strength
- Enhanced vibration and placement training for crews
- Implementation of cold weather curing protocols
Lessons Learned
- Mix design and environmental conditions must be balanced carefully
- Proper consolidation prevents air pockets that lead to delamination
- Weather protection during curing is critical in cold climates
Case Study: Atlanta Box Girder Stem Wall Reinforcement Corrosion (2021)
Project Overview
- Name: I-285 Perimeter Improvement
- Location: Atlanta, Georgia
- Year: 2021
- Project Size: $480 million
- Scope: Reinforced concrete stem walls for box girder bridge spans
- Lead Agencies/Contractors: Georgia DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Corrosion
- Materials Durability
Summary of the Issue, Problem, or Challenge
Early signs of corrosion were detected on reinforcement within stem walls during routine inspections less than a year after construction.
Root Cause Analysis
| Factor | Details |
| Insufficient Concrete Cover | Actual cover thickness less than specified minimum. |
| Poor Concrete Quality | Low slump and inadequate consolidation increased permeability. |
| Inadequate Curing | Rapid drying led to microcracks allowing moisture ingress. |
Impacts Due to the Issue, Problem, or Challenge
- Risk of premature structural deterioration
- Need for corrosion mitigation and monitoring systems
Corrective Actions Taken
- Strict enforcement of cover requirements on-site
- Improved quality control of concrete mix and placement
- Use of corrosion inhibitors in concrete mix for future pours
Lessons Learned
- Concrete cover is a critical parameter for reinforcement durability
- Proper curing significantly affects concrete permeability and corrosion risk
- Proactive corrosion mitigation extends structure service life
Case Study: Minneapolis Box Girder Top Deck Formwork Failure (2018)
Project Overview
- Name: I-35W Mississippi River Bridge Replacement
- Location: Minneapolis, Minnesota
- Year: 2018
- Project Size: $500 million
- Scope: Top deck reinforced concrete construction on box girders
- Lead Agencies/Contractors: MnDOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Formwork Failure
- Construction Safety
Summary of the Issue, Problem, or Challenge
During concrete placement, partial formwork collapse occurred causing concrete spillage and partial deck damage.
Root Cause Analysis
| Factor | Details |
| Under-Designed Formwork | Formwork did not meet load requirements for fresh concrete. |
| Insufficient Bracing | Temporary bracing was inadequate and poorly installed. |
| Lack of Inspection | No third-party inspection before pour to verify formwork integrity. |
Impacts Due to the Issue, Problem, or Challenge
- Concrete waste and material cost increase
- Schedule delays due to remediation and rework
- Safety hazards for workers
Corrective Actions Taken
- Engineering review and redesign of formwork systems
- Mandatory third-party inspections prior to concrete placement
- Enhanced worker safety training and protocols
Lessons Learned
- Formwork design must accommodate all loads during pours
- Inspections prevent failures and improve safety
- Proper bracing and support are critical
Case Study: Dallas Prestressed Girder Camber Loss and Cracking (2020)
Project Overview
- Name: Dallas Highway Expansion Project
- Location: Dallas, Texas
- Year: 2020
- Project Size: $310 million
- Scope: Prestressed precast concrete bridge girders spanning over 150 feet each
- Lead Agencies/Contractors: TxDOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Structural Performance
- Material Quality
Summary of the Issue, Problem, or Challenge
Significant camber loss and flexural cracks were observed in multiple girders shortly after erection but prior to deck placement, affecting bridge geometry and load distribution.
Root Cause Analysis
| Factor | Details |
| Prestressing Strand Corrosion | Improper storage exposed strands to moisture, reducing prestress force. |
| Inadequate Concrete Strength | Concrete strength lower than design assumptions weakened girder capacity. |
| Fabrication Deficiencies | Strand tensioning and anchorage procedures not strictly followed. |
| Insufficient Post-Tension Testing | Lack of early-stage testing allowed problem to go unnoticed. |
Impacts Due to the Issue, Problem, or Challenge
- Need for girder reinforcement or partial replacement
- Realignment of bridge geometry delaying follow-on work
- Increased inspection and testing costs
Corrective Actions Taken
- Enhanced strand storage and handling protocols to prevent corrosion
- Strict adherence and verification of prestressing procedures at fabrication plants
- Implementation of mandatory post-tension force testing on all girders before shipment
- Use of corrosion-resistant strand materials for future projects
Lessons Learned
- Prestressing strand condition critical to girder performance
- Early detection via testing can prevent costly structural issues on site
- Controlled fabrication environment and procedures reduce defects
Case Study: Seattle Precast Girder Joint Misalignment and Seat Failures (2019)
Project Overview
- Name: Seattle Waterfront Bridge
- Location: Seattle, Washington
- Year: 2019
- Project Size: $275 million
- Scope: Prestressed precast girders with bolted splice joints over large bridge spans
- Lead Agencies/Contractors: WSDOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Construction Tolerance
- Structural Connection
Summary of the Issue, Problem, or Challenge
During girder erection, several joints exhibited misalignment beyond allowable tolerances causing stress concentrations and failure of bearing seats requiring realignment and repairs.
Root Cause Analysis
| Factor | Details |
| Inaccurate Surveying | Poor field measurement and control led to improper placement. |
| Tolerances Not Verified | Contractor did not perform intermediate checks during erection. |
| Bearing Seat Design | Inadequate design margin for small misalignments. |
| Poor Communication | Lack of coordination between fabrication, design, and erection teams. |
Impacts Due to the Issue, Problem, or Challenge
- Rework of girder supports and bearing seats increasing project cost and time
- Risk of long-term structural distress if issues had gone uncorrected
- Reduced confidence among stakeholders
Corrective Actions Taken
- Enhanced surveying and alignment verification protocols during erection
- Increased bearing seat design tolerances and adjustable components
- Improved communication protocols among all project teams
- Use of laser scanning and digital modeling for fit-up verification
Lessons Learned
- Precise surveying and verification critical for prestressed girder erection
- Design should anticipate small construction tolerances with adjustable features
- Collaboration between all teams during erection prevents misalignment
Case Study: Denver Prestressed Girder Shear Crack Development (2017)
Project Overview
- Name: Denver Interstate Bridge Replacement
- Location: Denver, Colorado
- Year: 2017
- Project Size: $290 million
- Scope: Replacement of aging bridge with prestressed precast girders spanning over a river
- Lead Agencies/Contractors: Colorado DOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Structural Cracking
- Construction Quality
Summary of the Issue, Problem, or Challenge
During the staged construction process, several prestressed girders developed diagonal shear cracks near the supports before concrete deck placement. The cracks raised concerns about girder load capacity and durability.
Root Cause Analysis
| Factor | Details |
| Early Loading | Girder loads exceeded design assumptions due to temporary supports. |
| Inadequate Shear Reinforcement | Design shear capacity underestimated for construction loading. |
| Concrete Curing Issues | Insufficient curing led to reduced concrete strength in critical regions. |
| Quality Control Gaps | Inspections missed early signs of cracking during storage. |
Impacts Due to the Issue, Problem, or Challenge
- Delayed construction to allow repair or reinforcement
- Additional costs for strengthening and monitoring
- Increased safety inspections and engineering reviews
Corrective Actions Taken
- Revised construction load plans to prevent overstressing girders before deck placement
- Added external shear reinforcement where cracks appeared
- Improved curing procedures and monitoring on site
- Strengthened QC processes during storage and handling
Lessons Learned
- Temporary construction loads must be rigorously evaluated in design
- Early detection of cracking allows timely intervention
- Curing quality has direct impact on structural performance
Case Study: Houston Prestressed Girder Anchorage Failures (2022)
Project Overview
- Name: Houston Beltway Widening
- Location: Houston, Texas
- Year: 2022
- Project Size: $350 million
- Scope: Widening highway with new prestressed concrete girders with post-tensioned anchorage systems
- Lead Agencies/Contractors: TxDOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Anchorage System Failure
- Materials & Installation
Summary of the Issue, Problem, or Challenge
During tensioning of prestressing strands, multiple anchorage points failed causing strand slippage and loss of prestress force. This compromised girder integrity and required replacement of affected girders.
Root Cause Analysis
| Factor | Details |
| Defective Anchorage Hardware | Poor quality anchor wedges and anchorage assemblies supplied. |
| Installation Errors | Improper seating and tensioning procedures by crew. |
| Lack of Inspection | No third-party verification during critical post-tensioning. |
| Inadequate Training | Workers unfamiliar with specialized anchorage systems. |
Impacts Due to the Issue, Problem, or Challenge
- Extensive girder rework and partial replacement
- Project delays and increased cost for replacement and testing
- Safety risks during tensioning operations
Corrective Actions Taken
- Implemented strict supplier pre-qualification for anchorage hardware
- Mandated on-site third-party inspection and testing for tensioning operations
- Provided specialized training and certification for post-tensioning crews
- Revised installation procedures with detailed quality checkpoints
Lessons Learned
- Quality and inspection of anchorage systems are critical to prestressed girder performance
- Training and oversight prevent installation failures
- Supplier control impacts project success
Case Study: Chicago Prestressed Girder Dimensional Tolerance Failures (2016)
Project Overview
- Name: Chicago Urban Overpass
- Location: Chicago, Illinois
- Year: 2016
- Project Size: $200 million
- Scope: Prestressed girders for a complex urban overpass with tight construction tolerances
- Lead Agencies/Contractors: IDOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Dimensional Control
- Fabrication Quality
Summary of the Issue, Problem, or Challenge
Numerous girders arrived at site with length and camber variations outside specification, causing fit-up problems and delays in erection sequence.
Root Cause Analysis
| Factor | Details |
| Fabrication Equipment Calibration | Outdated or improperly calibrated prestressing equipment caused inconsistencies. |
| Insufficient QA Procedures | Lack of in-plant dimensional checks during fabrication. |
| Communication Breakdown | Poor coordination between design tolerances and fabricator capabilities. |
| Tolerance Spec Misinterpretation | Ambiguities in drawings caused fabrication deviations. |
Impacts Due to the Issue, Problem, or Challenge
- Delays due to re-fabrication or on-site adjustments
- Increased costs for shipping and labor associated with rework
- Coordination challenges in congested urban site
Corrective Actions Taken
- Upgraded fabrication plant equipment and calibration schedules
- Introduced stricter in-process QC including dimensional verification
- Improved design-fabrication communication and clarified tolerances
- Adopted digital fabrication modeling and feedback loops
Lessons Learned
- Dimensional control is essential for large prestressed components
- Early communication and collaboration avoid costly rework
- Continuous quality verification during fabrication ensures compliance
Case Study: Atlanta Prestressed Girder Camber Mismatch (2019)
Project Overview
- Name: I-285 Eastside Connector
- Location: Atlanta, Georgia
- Year: 2019
- Project Size: $275 million
- Scope: Construction of a highway connector with prestressed precast girders over multiple ramps
- Lead Agencies/Contractors: Georgia DOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Dimensional Tolerance
- Structural Performance
Summary of the Issue, Problem, or Challenge
Several girders exhibited camber variations beyond allowable limits causing uneven deck slab placement and additional shimming work during erection.
Root Cause Analysis
| Factor | Details |
| Material Variation | Variability in concrete modulus of elasticity affected camber. |
| Fabrication Control | Inconsistent prestressing force application during fabrication. |
| Lack of Mock-Up Testing | No prior validation of girder camber before full production. |
| Insufficient Communication | Fabricator not fully aligned with design assumptions on camber. |
Impacts Due to the Issue, Problem, or Challenge
- Increased erection time due to fit-up corrections
- Added cost for temporary supports and adjustments
- Minor delays to the overall schedule
Corrective Actions Taken
- Revised fabrication procedures to control prestress force within tighter tolerances
- Introduced mock-up girders for camber validation prior to mass production
- Improved specification clarity and communication between design and fabrication teams
Lessons Learned
- Camber control critical for seamless deck installation
- Early prototype testing prevents systemic errors
- Close collaboration between designers and fabricators is essential
Case Study: Seattle Prestressed Girder Transport Damage (2020)
Project Overview
- Name: Seattle I-5 Bridge Expansion
- Location: Seattle, Washington
- Year: 2020
- Project Size: $310 million
- Scope: Bridge widening using prestressed precast girders transported from off-site fabrication
- Lead Agencies/Contractors: Washington State DOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Transportation Damage
- Construction Handling
Summary of the Issue, Problem, or Challenge
Several girders sustained hairline cracks and spalling during off-site transport, attributed to improper handling and inadequate bracing on flatbed trucks.
Root Cause Analysis
| Factor | Details |
| Inadequate Transport Bracing | Lack of proper supports allowed girder movement and impacts. |
| Handling Procedures | Insufficient training of transport crew on fragile precast units. |
| Quality Inspection Lapses | Damage not identified or documented immediately upon delivery. |
| Weather Conditions | Transport occurred during rough road/weather conditions exacerbating damage. |
Impacts Due to the Issue, Problem, or Challenge
- Costly repair or replacement of damaged girders
- Delays in erection schedule due to waiting for new girders
- Added QA inspections and monitoring
Corrective Actions Taken
- Revised transport bracing standards for prestressed girders
- Implemented mandatory handling and transport training programs
- Established immediate on-site inspection and damage reporting protocols
- Adjusted transport scheduling to avoid adverse weather conditions
Lessons Learned
- Proper transport and handling critical for prestressed element integrity
- Early damage detection minimizes rework and delay
- Coordination across fabrication, transport, and field teams reduces risks
Case Study: Phoenix Prestressed Girder Strand Corrosion (2018)
Project Overview
- Name: Phoenix Loop 202 Expansion
- Location: Phoenix, Arizona
- Year: 2018
- Project Size: $280 million
- Scope: Loop highway expansion with prestressed precast girders
- Lead Agencies/Contractors: Arizona DOT /
Category of the Issue, Problem, or Challenge
- Prestressed Concrete
- Durability Issues
- Materials Quality
Summary of the Issue, Problem, or Challenge
Post-delivery inspections revealed early-stage corrosion on exposed prestressing strands at girder ends due to incomplete epoxy coating and exposure during storage.
Root Cause Analysis
| Factor | Details |
| Coating Deficiencies | Epoxy coating was thin or uneven at anchorage zones. |
| Storage Environment | Girders stored outdoors without adequate protection. |
| Inspection Oversight | Quality checks missed incomplete coating areas. |
| Material Specification Gaps | Ambiguity in coating requirements for field storage conditions. |
Impacts Due to the Issue, Problem, or Challenge
- Remediation and coating repairs required on site
- Delays due to extended inspection and repair
- Potential long-term durability concerns if untreated
Corrective Actions Taken
- Strengthened coating application procedures and standards
- Enforced covered and controlled storage environments
- Enhanced inspection protocols focused on coating integrity
- Revised specifications to clarify coating and storage requirements
Lessons Learned
- Prestressing strand protection vital for durability
- Storage conditions affect long-term performance
- Clear specs and thorough QC prevent costly corrosion repairs
Case Study: Portland Box Girder Bottom Deck Insufficient Concrete Strength (2020)
Project Overview
- Name: Portland Bridge Rehabilitation
- Location: Portland, Oregon
- Year: 2020
- Project Size: $270 million
- Scope: Bottom deck reinforced concrete repair and new pours for box girder bridge
- Lead Agencies/Contractors: Oregon DOT /
Category of the Issue, Problem, or Challenge
- Reinforced Concrete
- Strength Deficiency
- Quality Control
Summary of the Issue, Problem, or Challenge
Concrete compressive strength tests on bottom deck pours repeatedly fell below specified values, delaying formwork removal and stressing schedule.
Root Cause Analysis
| Factor | Details |
| Inconsistent Mix Proportions | Variability in batch plant production and batching errors. |
| Poor On-Site Sampling | Inadequate sampling techniques led to inaccurate early testing. |
| Lack of Proper Curing | Insufficient moisture curing resulted in strength loss. |
Impacts Due to the Issue, Problem, or Challenge
- Project delays and increased labor costs
- Re-pouring of some deck sections required
Corrective Actions Taken
- Stricter batch plant quality controls and monitoring
- Enhanced field sampling and testing procedures
- Improved curing methods with continuous moisture application
Lessons Learned
- Batch plant quality control is essential for consistent concrete strength
- Sampling procedures impact test reliability
- Proper curing is non-negotiable for achieving design strength