2012 12 18 Pcine Repair Manual Revised

8/12/2019 2012 12 18 Pcine Repair Manual Revised

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Report No:

PCINER-01-BMRG

Title:

Bridge Member Repair Guidelines

Developing Organization:

Precast/Prestressed Concrete Institute Northeast RegionTechnical CommitteePhone 888-700-5670Email [email protected]

Report Date: Revision Dates:

October 2001 July 2002, Nov. 2002, Jan. 2003, Oct. 2012

Status of Report: Final

Abst ract:

This report is intended to serve as a guide to identify defects that may occur during thefabrication and handling of bridge elements. The report gives guidance on possiblecause and prevention. It will help determine the consequences of the defects and assistin making a judgment as to acceptance/repair or rejection.

This report can be utilized by State Inspectors, Designers, Plant Production Managers,Plant Quality Control Inspectors and Plant Engineers.

Number of Pages: 49

PCI cannot accept responsibility for any errors or oversights in the use of this material.The user must recognize that no guidelines or regulations can substitute for experienced

judgment. This guideline is intended for use by personnel competent to evaluate thesignificance and limitations of its contents and able to accept responsibility for the appli-cation of the material it contains.

Northeast Region

Bridge Member Repair Guidelines

Report Number PCINER-01-BMRG


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ii

Foreword

This manual has been prepared by the PCI Northeast Technical Committee. A sub-committee first developed the contents, and the main committee then reviewed it. PCINational is also developing a manual, and we have reviewed and incorporated com-ments and sections from their second draft. Regional adoption of the national documentwill be determined when it is published.

The manual will be used to improve a greater degree of uniformity between owners, en-gineers and industry, with respect to repairs of precast prestressed concrete bridgebeams and panels.

Subcommittee Members (2001)

Mike Culmo CME AssociatesPete Stamnas New Hampshire Department of TransportationNed Newton Massachusetts Highway DepartmentMike Kane J. F. White ContractingEd Barwicki Lin AssociatesBill Augustus Northeast Concrete ProductsRita Seraderian PCI Northeast

Main Committee Members (2001)

Jim Braun - Blakeslee Prestress, Inc.Vartan Sahakian - Commonwealth Engineers & ConsultantsGordon Barton - Connecticut Department of TransportationRobert Zaffetti - Connecticut Department of TransportationEric Thorkildsen - Collins EngineeringJoe Carrara - J.P. Carrara and SonsBob Bulger - Maine Department of TransportationEric Calderwood - Maine Department of Transportation

Alex Bardow - Massachusetts Highway DepartmentDavid Scott - New Hampshire Department of TransportationDuane Carpenter - New York State Department of TransportationTony DaCosta - Oldcastle PrecastChris Fowler - Rotondo PrecastMike Savella - Rhode Island Department of TransportationGeorge Colgrove III - Vermont Agency of TransportationCraig Keller - Vermont Agency of Transportation


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iii

TABLE OF CONTENTS

Section 1. INTRODUCTION 1

Section 2. TROUBLE SHOOTING GUIDE 2

Section 3. STANDARD REPAIR PROCEDURES 27

Section 4. REFERENCES 44


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Section 1. INTRODUCTION

Plant cast prestressed bridge products are produced in PCI certified plants. Such facili-ties meet the minimum standards for equipment, trained supervisory and quality controlstaff operating under published procedures. Products are manufactured in accordancewith the Manual for Quality Control for Plants and Production of Structural Precast Con-

crete Products Fourth Edition MNL 116-99.

As with any manufacturing process defects can occur in precast concrete bridge prod-ucts. Examples may include voids, crack in concrete, as well as missing, improperly lo-cated, or damaged reinforcement and hardware. These defects fall into one of three cat-egories:

Those that can be accepted without repair Those that can be repaired Those that must be rejected

This document has been prepared to be a resource to guide owners, designers and fab-

ricators in reaching informed and considered decisions on which option is appropriate. Itis not an original document, but brings together excerpts and expansions on severalprevious publications, and is compiled by a subcommittee composed of owners, designengineers and fabricators, reaching consensus, in the best interests of all parties. Its ul-timate value is dependent upon the sound engineering judgment of those who will use it.


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Section 2. TROUBLE SHOOTING GUIDE

Contents:

1. Transverse Cracks Originating at Tops of Beams 3

2. Vertical and Diagonal Cracks at Bottom of Beams 5

3. Vertical Through Cracks in Beams 7

4. Horizontal End Cracks in Webs and Flanges 9

5. Bottom Flange Cracks at Beam Ends 11

6. Corner Spalls or Corner Crack 13.

7. Partially Cracked Top Flanges 15

8. Random Honeycombing and Voids 17

9. Random Top Flange Cracks 19

10. Short Projected Strand or Rebar, Missing Projected Strand or Rebar 21

11. Cracks and Honeycombing in Precast, Partial Depth Deck Panels 23


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TS #1

TROUBLE SHOOTING FOR TRANSVERSE CRACKS ORIGINATING AT TOPS OF

BEAMS

Description These cracks are typically perpendicular to the longitudinal axis of the beam and extend

across the top of the member, usually visible on both vertical faces, but do not extend to the

bottom prestress strands.

CAUSES

A. Excessive top fiber tension

1. Inadequate top reinforcement2. Incorrect placement of top reinforce-

ment3. Low release strength4. Lack of strand debonding at beam ends

or insufficient number of draped strands

5. Improper location of lifting or dunnage

points6. Prestress uplift force at mid-spanhold-down points exceeds the weight

of the beam or exceeds the beams

top fiber tensile capacity

B. Shrinkage1. Shrinkage of beam concrete prior to or

during curing

2. Contraction of beam prior to prestressforce release

3. Contraction of exposed strand in un-used portion of the bed.

C. Form Expansion with Temperature RiseD. Excessive Side tension

Due To Lateral Displacement

During Movement

PREVENTION

A. Reduce Top Fiber Tension

1. Provide adequate tensile reinforcementto control cracks or add top prestress-ing. This option may include lightlytensioned strand (5000 psi+).

2. Improve inspection prior to concreteplacement

3. Increase release strength4. Reduce eccentricity at beam ends by

debonding or draping strand pattern,add strands at tops of beams or modifystrand pattern to reduce eccentricity

5. Adjust lifting or dunnage points6. Limit uplift force at hold-down points

to 75 per cent of member weight.

B. Improve Production Methods1.Minimize Shrinkage

a.Apply covers rapidly and/or mistspray with water.

b. Adjust concrete mix by reducingcement, adding pozzolans or changingaggregate gradation.

c. Provide uniform heat and humidity.

2. Detension as covers are removed andprevent rapid cool-down of the beam3. Prevent exposed strand from cooling

differentially with respect to the beam.

C. Lengthen Set Time-In Accordance withASTM C4031. Minimize temperature differential be-

tween beam, exposed strand, and bed

2. Detension as covers are removed anddo not allow section to cool rapidly

D. Provide Lateral Bracing withstrongbacks


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TS #1

TROUBLE SHOOTING FOR TRANSVERSE CRACKS ORIGINATING AT TOPS OF

BEAMS

Description These cracks are typically perpendicular to the longitudinal axis of the beam and extend

across the top of the member, usually visible on both vertical faces, but do not extend to

the bottom prestress strands.

ENGINEERING EFFECTS

1. Cracks that close upon detensioning of thebeam, or that will close when the beam isplaced upon its designated bearing areas, or

can be expected to close when the composite

slab is poured, need not be repaired forsimple beam applications.

For beams made continuous for composite

dead and live loads, calculations may be re-

quired to determine the need for repair. Ifstresses under service loads do not exceed

3.0 fc, it may be presumed that the beamwill behave as an un-cracked section, inwhich case no repairs are necessary. If the

stresses exceed 3.0 fc, the beam should berepaired by epoxy injection.

2. For cracks that do not close afterdetensioning, an assessment of the need to

repair based on continuity considerations aswell as environmental exposure will be re-

quired. In the latter regard, ACI Committee

224 report Control of Cracking in ConcreteStructures states that tolerable crack widths

are 0.006-in. for concrete exposed to sea-

water spray with wetting and drying, 0.007-

in. for concrete exposed to de-icing chemi-

cals, and 0.012-in. for concrete exposed tohumidity.

REPAIR CONSIDERATIONS

Before Detensioning. No repairs are recom-mended until after detensioning, as cracks may

close.

After Detensioning

1. Closed cracks The decision to repair or notrepair should be made in consideration of

the Engineering Effects.

2. If the decision is made that repairs arewarranted, the cracks should be epoxy in-

jected, accordance with Standard RepairProcedure #10.

3. Experience has shown that cracks as narrowas 0.002-in. can be injected successfully,

however the surface of cracks narrower than

0.006-inches should be sealed. See RepairProcedure #14.


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TS #2

TROUBLE SHOOTING VERTICAL AND DIAGONAL CRACKS AT BOTTOM OF BEAMS

Description This crack starts at the bottom of the member and extends upward. In severe cases,

Crack will extend diagonally toward the mid-height (neutral axis) of the beam.

CAUSE

A. Bond of strands1. Strand contamination2. Incorrect placement of debonding

shields3. Insufficient vibration of concrete4. Excessive debonding termination at one lo-

cation

B. Shrinkage

C. Detensioning Procedure1. Low release strength

2. Improper detensioning se-quence/procedures

3. Failure to release hold-down mechanismprior to release of horizontal strands

D. Formwork1. Indentions or joint offsets in forms2. Concrete binding to forms3. Bottom plates at beam ends anchored or

hung up at bottom (soffit) of form

E. Incorrect Prestress Force1. Inadequate prestress strand in design

2. Under-estimate of prestress losses3. Under tensioning of strand4. Incorrect number of strand in bed

PREVENTION

A. Ensure against unintended slip1. Inspect strand for cleanliness and

absence of lubricants after stressing

strand2. Verify proper shielding installation3. Use internal and external vibration in

congested ends of beams

4. Stagger debonding terminations

B. Improve Production Methods1. Apply covers rapidly after concrete

pours

2. Detension as covers are removed3. Prevent exposed strand from cooling

differentially with respect to the

beam4. Adjust concrete mix by reducing ce-

ment, adding pozzolans or changing

aggregate gradation

5. Provide uniform heat and humidity

C. Use proper detensioning procedure1. Assure proper concrete strength prior

to release

2. Keep prestressed forces balanced

while detensioning, using an estab-lished procedure

3. Assure hold-downs are released priorto detensioning strand and are not

binding on the soffit

D. Inspect form condition prior to placingConcrete

1. Insure smooth form alignment2. Oil forms thoroughly3. Assure any bottom plates will not

bind on soffit

E. Apply Correct Prestress Force1. Check design calculations2. Recompute losses3. Compare measured elongation of

strand with computed elongation4. Check shop drawings5. Check camber of beam verses calcu-

lated camber


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TS #2

TROUBLE SHOOTING VERTICAL AND DIAGONAL CRACKS AT BOTTOM OF BEAMS

Description This crack starts at the bottom of the member and extends upward. In severe cases the crack

will extend diagonally toward the mid-height (neutral axis) of the beam

ENGINEERING EFFECTS

1. For vertical cracks that intercept bonded ordebonded strand within their respective

transfer lengths, it is recommended that the

engineer re-compute the moment and shearcapacity based on transfer initiating at the

point of the crack. If the re-computed capac-

ities are acceptable the beam can be re-

paired. These cracks should be injected.2. Vertical cracks that intercept bonded or

debonded strand beyond their respective

transfer lengths and close to a width lessthan 0.006-in. after detensioning, need no

re-evaluation. Cracks 0.006-in. or greater inwidth should be referred to the engineer for

evaluation, to affirm adequate design.

3. Vertical cracks at any location on the beamthat do not intercept strand need no evalua-

tion by the engineer.

4. Diagonal cracks of any size, at any location,require evaluation by the engineer, to deter-mine whether the shear design for the beam

is adequate or the accidental loading causing

the crack will not be duplicated in service.


1. It is recommended that cracks not be re-paired prior to detensioning as repairs will

mask the cause and seriousness of the crack

2. All cracks less than 0.006-in. in width, afterdetensioning and deemed acceptable, should

be sealed. See Repair Procedure #14. If

these cracks are within the transfer zone, an

epoxy injection repair should be considered

(see below).3. All cracks 0.006-in. or greater in width, after

detensioning and deemed acceptable, should

be repaired by epoxy injection in accordancewith Standard Repair Procedure #10.


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TS #3

TROUBLE SHOOTING VERTICAL THROUGH CRACKS IN BEAMS

Description These cracks can develop in beams during the curing process or cool-down period prior to

detensiong of strand. This problem is more common to long beams manufactured with higherstrength concrete.

CAUSE

A. Shrinkage

1.Shrinkage of the beam prior to detensioning

B. Temperature Effects

1.Contraction of exposed strand in unusedportion of bed

2.Contraction of beam due to cooling priorto transfer of prestress

3.Uneven distribution of heat

C. Production/Formwork

1.Indentations or joint offsets in forms2.Concrete binding to forms3.Bottom plate at end of member anchored or

restrained in form

PREVENTION

A. Modify mix design or curing methods to

minimize shrinkage

1.Reduce cement content; add pozzolans2.Change aggregate gradation3.Apply covers rapidly and/or mist spray

with water

B. Control Temperature During Production

1.Minimize temperature differential be-tween beam, exposed strand, and bed

2.Detension as covers are removed and do

not allow section to cool rapidly3.Provide uniform heat and humidity during

curing

C. Improve production methods

1.Keep forms in good repair; fabricateforms with even, smooth joints

2.Keep forms clean and properly oiled3.Release restraint of all plates before de-

tensioning

Reference:Zia, Paul, and Caner, Alp, Cracking in Long-SpanPrestressed Concrete AASHTO Girders DuringProduction, Center for Transportation Engineering

Studies, North Carolina State University, Raleigh,N.C.


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TS #3

TROUBLE SHOOTING VERTICAL THROUGH CRACKS IN BEAMS

Description These cracks can develop in beams during the curing process or cool-down period prior to

detensioning of strand. This problem is more common to long beams manufactured withhigher strength concrete.

ENGINEERING EFFECTS1. For cracks falling within the transfer length

of bonded or debonded strand, it is recom-

mended that the engineer re-compute the

moment and shear capacity based on transferinitiating at the point of the crack. If the re-

computed capacities are acceptable the beam

can be repaired. These cracks should be in-

jected.2. For cracks falling beyond the transfer length

of bonded or debonded strand that close to a

width of less than 0.006-in. or less, afterdetensioning, no re-evaluation is needed.

For cracks 0.006-in. or greater should bereferred to the engineer for evaluation.

3. Full depth cracks that close after detension-ing to a width of less than 0.006-in., or are0.006-in. or greater and repaired meet the

constituative rules of the modified compres-

sion field theory for shear capacity. The

subject theory, as a basic given, presumes afull depth crack along the inclined plane of

theta degrees. Under full design load if the

bottom flange at the pre-existing crack goesinto tension, the crack will open along its

vertical path until the neutral axis is reached,

at which point the crack will turn and extendalong the inclined plane, theta. As the com-

pression strut can transmit stress across the

vertical portion of the crack, the constitua-

tive rules are not compromised


1. It is recommended that cracks not be re-paired prior to detensioning as repairs will

mask the cause and seriousness of the crack.

2. All cracks less than 0.006-in. in width, afterdetensioning and deemed acceptable, should

be sealed. See Repair Procedure #14. If

these cracks are within the transfer zone, an

epoxy injection repair should be considered

(see below).3. All cracks 0.006-in. in width, after

detensioning and deemed acceptable, should

be repaired by epoxy injection in accordancewith Standard Repair Procedure #10


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TS #4

TROUBLE SHOOTING HORIZONTAL END CRACKS IN WEBS AND FLANGES

Description This crack usually begins at the end of the beam and extends across the end of the beam and

is visible on both sides.

CAUSE

A. Detensioning

1. Improper procedures for detensioningstrands

2. Improper detensioning sequence

B. Design

1. Low release strength specified2. Inadequate end vertical reinforcing3. Excessive prestress force or concentra-

tion of force

4. Excessive number of debonded strandsin the bottom plane and/or lack of con-

fining stirrups

5. Excessive vertical force from deflectedstrands

C. Production

1. Concrete binding in forms2. Bottom plates, sleeves or inserts at end

of beam3. Shrinkage and curing4. Improper removal of header or strand

caught in header5. Settlement of wet concrete below a

concentration of strand or mild rein-

forcing near the top at beam end

6. For box beams, delayed web pourscausing a cold joint

PREVENTION

A. Proper Release Procedure

1. Heat strand to allow slow elongation(annealing) and avoid sudden release

2. Keep prestress forces balanced using apre-stablished procedure1

B. Improve Design

1. Establish adequate release strength2. Use adequate anchorage zone end rein-

forcement to control width and length

of cracks3. Properly space and distribute strand at

beam ends

4. Debonding strands for a short distanceis effective in reducing stress concen-

trations. Debonding of an entire row of

strand or debonding the outer strand in

a layer are not recommended. Provideconfinement reinforcement near beam

ends

5. Fan out deflected strands or combinedebonding and deflecting strand

C. Improve Production Technique

1. Keep forms well oiled2. Assure forms will not interfere with

hardware if forms expand or during

detensioning3. Provide uniform heat and humidity

during curing

4. Separate header from forms before lift-ing

5. Improve vibration techniques6. Pour webs prior to set of bottom slab

of box beams

1. Balancing of prestress force is key to mini-

mizing the potential for horizontal cracks.See Release Methodology of Prestress

Strands, Kannel J., French C. and Stolurski,H., PCI Journal Vol. 42, No. 1, Jan-Feb.

1997, pp. 42-55


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TS #4

TROUBLE SHOOTING HORIZONTAL END CRACKS IN WEBS AND FLANGES

Description This crack usually begins at the end of the beam and extends across the end of the beam and

is visible on both sides.

ENGINEERING EFFECTS

1. Cracks not intercepting strand are not ofstructural consequence, provided the area of

vertical shear reinforcement in the webs

meets horizontal shear requirements. Afterinstallation of the beams, the cracks would

not be expected to grow, given adequate re-

inforcement against horizontal shear, since

the dead load weight of the slab and otherdead loads will induce vertical compression

in the beams ends.

2. For cracks that intercept or are co-linearwith strands, the shear and moment capacity

will require recomputation due to a changein location of transfer length of affected

strands.

3. Cracks in beam ends under expansion joints,should be considered for epoxy injection to

avoid future deterioration from water and

salt intrusion. Cracks in box beams, in side-

by-side (butted) configurations should beepoxy injected in any case due to potential

leakage through grouted joints.

4. In deciding whether to inject cracks or leavethem unfilled, ACI Committee 224 report

Control of Cracking in Concrete Struc-

tures states that tolerable crack widths are0.006-in. for concrete exposed to seawaterspray with wetting and drying, 0.007-in. for

concrete subject to de-icing chemicals and

0.012-in. for concrete exposed to humidity.


1. No repairs to beams used in composite con-struction in accordance with the discussion

in ENGINEERING EFFECTS 1.

2. For cracks discussed in ENGINEERINGEFFECTS 2:

a. Cracks that have been verified by theowner to not have diminished the beam

capacity below acceptable levels shouldbe injected, in accordance with Stand-

ard Repair Procedure #10.

b. Beams verified by the engineer to havecapacity reduced to unacceptable levels

will be rejected.3. Durability concerns, discussed in ENGI-

NEERING EFFECTS 3 and 4 may favor

epoxy injection, in accordance with Stand-ard Repair Procedure #10. The surface of

cracks narrower than 0.006-inches should be

sealed. See Repair Procedure #14.


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TS #5

TROUBLE SHOOTING BOTTOM FLANGE CRACKS AT BEAM ENDS

Description The crack is located at the end of the beam and generally runs parallel to the longitudinal axis

CAUSE

A. Production

1. Binding in the forms during stripping2. Indentation in the forms3. Improper detensioning sequence

B Reinforcement

1. Incorrect placement or omission ofconfining reinforcement

2. Reinforcement improperly detailed orfabricated

3. Debonding problem

4. Contaminated strand

D. Detensioning1. Localized differential strainsand stresses between the web and flange

during detensioning

E. Handling

1. Non-uniform bearing on dunnage orimpact while being lowered on dunnage

PREVENTION

A. Improve Production

1. Keep forms well oiled and clean2. Keep forms in good repair3. Keep forces balanced during detension-

ing

B. Attention to Reinforcing Details

1. Verify correct placement of reinforce-ment

2. Scrutinize drawings and fabricated barsto be used

3. Allow for swelling (Hoyer Effect) ofdetensioned strand that have been

debonded by providing confinement re-

inforcing or relocating debondedstrands away from edges of the flange.

4. Inspect strand for contamination anddrawing oil residue

C. Detensioning1.Heat strand to allow slow elongation (An-

nealing) to minimize shock of detensioning

D. Handling

1.Assure uniform bearing and avoid impactswhen handling beams


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TS #5

TROUBLE SHOOTING BOTTOM FLANGE CRACKS AT BEAM ENDS

Description The crack is located at the end of the beam and generally parallel to the longitudinal axis.

ENGINEERING EFFECTS

1. Cracks co-linear with strands affect the un-bonded length and it will be necessary to

recompute the shear and moment capacity

based on the revised transfer and/or devel-

opment length location for the strands.Weak axis bending may need checking.

2. In any event, these cracks should be repairedto insure the integrity of the bearing area and

to prevent water and salt intrusion at expan-sion devices or through grouted shear keys

of side-by-side (butted) box beams.


1. All bottom flange cracks should be epoxyinjected in accordance with Standard Repair

Procedure #10.

2. In the case of strand involvement the engi-neer should be notified to assess conditions

prior to repairs.


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TS #6

TROUBLE SHOOTING CORNER SPALLS OR CORNER CRACKS

Description These spalls and cracks can be found at any right angle surfaces of flanges along the beam

CAUSE

A. Improper Handling

1. Impacting edges2. Uneven dunnage

B. Production

1. Binding in forms during stripping2. Indentation in forms3. Inserts hanging up in forms4. Sole plates not flush with soffit of forms5. Improper shielding of strands

6. Thermal expansion of forms prior toconcrete setting

7. Improper bulkhead removal8. Bleeding of concrete under header

C. Release Procedures

1. Improper detensioning sequence2. Binding in forms during detensioning3. Dragging of bottom flange end induced

by cambering and shortning at deten-sioning

4. Impact and bursting forces from deten-

sioned strand

D. Design

1. Inadequate edge reinforcement

PREVENTION

A. Care in Handling

1. Insure adequate room for transport ofbeams

2. Provide uniform dunnage

B. Improve Production Methods

1. Keep forms clean and well oiled2. Keep forms in good repair and insure

all seams mortar tight

3. Insure inserts are free during stripping4. Insure sole plates are flush with soffit

prior to concrete pours

5. Shielding in the bottom row of strandsshould be minimized and shielding of

strands adjacent to the edges of flanges

should be avoided

6. Assure concrete set prior to startingcuring

7. Keep bulkheads in good condition andwell oiled to avoid the need to pry themloose

8. Provide mortar-tight header

C. Proper Release Procedures

1. Keep prestress forces balanced duringdetensioning

2. Provide sufficient clearance betweenforms and beam during detensioning

3. Provide skid plates, radii, bevels orcompressible material for the bottomedge of flanges

4. Heat strand sufficiently to slowly elon-gate (annealing) to avoid impact and to

mitigate swelling of strand (Hoyer Ef-

fect) at release5. Ensure all strands are completely sev-ered prior to removal from forms

D. Design

1. Provide proper reinforcement as close toedges as clearance requirements allow


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TS #6

TROUBLE SHOOTING CORNER SPALLS OR CORNER CRACKS

Description These spalls and cracks can be found at any right angle surfaces of flanges along the beam

ENGINEERING EFFECTS

1. Corner spalls in top flanges used as the rid-ing surface of the completed bridge require

repair to insure sufficient live load capacity

and durability

2. Corner spalls in bearing areas of beamsshould be repaired to insure proper bearings

as well as to protect strands from water and

salt intrusion when beam ends are adjacent

to expansion joints.3. Corner spalls in the bottom flange that may

significantly reduce protection from salt and

water spray from traffic underneath or leak-ing grouted joints from above,such as side-

by-side boxes and deck bulb-ts, should berepaired

4. Top flange edges incorporated into slabpours need not be repaired


1. Where corner spalls are deemed in need ofrepair, the repairs should be made in accord-

ance with Standard Repair Procedures #3 or#4

2. Corner spalls on edges to be incorporatedinto composite slab or end diaphragms may

not need repair3. Minor spalls that do not compromise protec-

tion from water, salt spray or humidity, or

are not exposed to direct view need not berepaired


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15

TS #7

TROUBLE SHOOTING PARTIALLY CRACKED TOP FLANGES

Description Crack does not cross the width of the beam and may be found anywhere along the flange.

The crack width is usually visible and exhibits a clean break line.

CAUSE

A. Handling

1. Impacting edges

B. Production

1. Binding in forms during stripping2. Placement of concrete in excessively

hot forms

3. Thermal expansion of forms prior toconcrete setting or contraction duringcool-down

C. Release Procedures

1. Improper detensioning sequence2. Strands not free from bulkhead

D. Strand Placement

1. Concentration of prestressing forces atthe edges of top flanges

PREVENTION

A. Proper Handling

1. Insure adequate room fortransport of beams

B. Improve Production Methods

1. Keep forms clean and welloiled. Keep forms in good

repair, free of dents and

dimples2. Insure forms are cooled to an

appropriate temperature priorto placing concrete

3. Regulate heat during curingand cool-down uniformly

C. Proper Release Procedures

1. Keep prestress forces balancedduring detensioning

2. Insure any top strands arecompletely severed prior toremoval from forms

3. Provide sufficient clearance

between forms and beams dur-ing detensioning

D. Proper Design Detailing

1. Avoid placement of prestressnear edges of top flange, or if

this is unavoidable, add

transverse reinforcement toflanges


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16

TS #7

TROUBLE SHOOTING PARTIALLY CRACKED TOP FLANGE

Description Crack does not cross the width of the beam and may be found anywhere along the flange.

The crack width is usually visible and exhibits a clean break line.

ENGINEERING EFFECTS

1. For beams whose top flange is to be used asthe riding surface of the completed bridge,

cracks in the top flange can affect durability

and live load capacity, if not repaired2. For beams to receive a cast-in-place slab,

repairs may not be warranted

REPAIR CONSIDERATION

1. When the top flange is to be the riding sur-face, and concrete is displaced, fractured or

loose, use Standard Repair Procedure #6.

If the crack is clean and no concrete is dis-placed use Standard Repair Procedures #10.

2. When the top flange is to be encased in acast-in-place slab, and concrete in the flange

is displaced, the engineer should be notifiedto determine if the flange should be repaired

using Standard Repair Procedures #6 or if

the displaced concrete can be left and en-cased in the slab. If the crack is clean and no

concrete is displaced, no repairs are war-ranted.


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TS #8

TROUBLE SHOOTING RANDOM HONEYCOMBING AND VOIDS

Description Missing volume of cement paste from around aggregate or voids containing neither paste nor

aggregate, in flanges and webs.

CAUSE

A. Production

1. Inadequate vibration2. Improper placement of concrete3. Shifted/misplaced rebar cage

B. Concrete Mix Design

1. Mix too stiff2. Early set in plasticised concrete3. Delayed placement of concrete4. Flash set of concrete in forms

C. Design Details

1. Congested reinforcement

PREVENTION

A. Improved Production Procedures

1. Provide thorough internal and, wherewarranted, external vibration

2. Start placement away from bulkheadsand use vibration to cause the concrete

to flow toward bulkheads

3. Verify location of and anchor rein-forcement

B. Adjust Mix Design

1. Adjust mix by adding plasticisers orreducing aggregate size

2. Improve delivery time of the concrete3. Cool forms prior to concrete placement

C. Improve Details

1. Reduce reinforcement conjestion tothe extent possible

2. Provide clear spacing between rein-forcement larger than 1 times themaximum aggregate size


21/49

18

TS #8

TROUBLE SHOOTING RANDOM HONEYCOMBING AND VOIDS

Description Missing volume of cement paste from around aggregate, or voids, containing neither paste

nor aggregate, in flanges and webs.

ENGINEERING EFFECTS

1. Honeycombing and voids in bearing areasnot only affect the strength and durability of

the bearing but, the moment capacity if bond

on the strand is impacted. Under modifiedcompression field theory, loss of bond of

strand can also affect shear capacity. These

areas must be repaired. Honeycombing and

voids in other areas of the bottom flange canaffect moment capacity, but more likely, on-

ly durability.

2. Honeycombing and voids in webs affectshear capacity and must be repaired.

3. Honeycombing and voids in top flanges thatwill be the riding surface of the bridge affect

both moment capacity and durability, requir-

ing repair. Where the top flange is to be en-cased in a cast-in-place slab, the honey-

combing and voids may significantly affect

the non-composite strength but not durabil-

ity.


1. For conditions discussed in EngineeringEffects 1, repair using Standard Repair Pro-

cedures #1 or #2, as appropriate.

2. For conditions discussed in EngineeringEffects 2, repair using Standard Repair Pro-

cedures #5 or #9, as appropriate.

3. For conditions discussed in EngineeringEffects 3, if repairs are required, use Stand-ard Repair Procedures #6 or #9, as appropri-

ate.


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TS #9

TROUBLE SHOOTING RANDOM TOP FLANGE CRACKS

Description These cracks are generally oriented longitudinally and are shallow in depth, occurring in a

random pattern, often parallel with reinforcement.

CAUSE

A. SHRINKAGE

1. Excess bleed water at the top flangesurface

2. Rapid moisture loss prior to curing3. Excessive curing temperature4. Delayed start of curing

B. Settlement of concrete around top rein-forcement (subsidance)

C. Insufficient Vibration

PREVENTION

A. PREVENT SHRINKAGE

1. Reduce water in mix and or avoid over-working surface finish

2. Use retardant admixtures cover beamscompletely and as soon as possible (es-

pecially in windy, hot and dry condi-

tions). If necessary, mist-spray exposedtop flange surface, with water.

3. Reduce curing temperature4. Determine proper Pre-set time to suit

curing operations, using ASTM C403.

Limit start of curing to 2-3 hours

B. Allow time for initial settlement, then re-vibrate concrete.

C. See B.


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TS #9

TROUBLE SHOOTING RANDOM TOP FLANGE CRACKS

Description These cracks are generally oriented longitudinally and are shallow in depth, occurring in a

random pattern, often parallel with reinforcement.

ENGINEERING EFFECTS

1. Other than concern for durability for topflanges that will become the riding surface

of the completed bridge, there are no con-

cerns. These cracks will be covered by theslab in composite construction


1. Where the top flange will be the riding sur-face, seal with a low viscosity epoxy or

methylmethacrylate product.

2. Where composite construction is used, norepairs are needed.


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TS #10

TROUBLE SHOOTING SHORT PROJECTED STRAND OR REBAR, MISSING PROJECTED

STRAND OR REBAR

Description This type of defect is usually caused by improper production detailing. It is usually limited toprojecting strand or rebar for continuity connections or horizontal shear reinforcement

CAUSE

A. Formwork

1. Bulkhead shift

B. Reinforcement

1. Improper placement2. Improper cutting3. Improper bending4. Incorrect fabrication drawing or design

drawing

5. Shifting during casting6. Improper handling

PREVENTION

A. Formwork

1. Check bulkhead locations and integrity

B. Reinforcement

1. Re-check rebar/strand locations priorto concrete placement

2. Re-check strand/rebar lengths beforecutting

3. Follow CRSI requirements for mini-

mum bending radius4. Re-check fabrication and design draw-

ings

5. Place additional ties on reinforcement6. Review shop handling practices


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TS #10

TROUBLE SHOOTING SHORT PROJECTED STRAND OR REBAR, MISSING PROJECTED

STRAND OR REBAR

Description This type of defect is usually caused by improper production or detailing. It is usually limitedto projecting strand or rebar for continuity connections or horizontal shear reinforcement.

ENGINEERING EFFECTS

1. Missing stirrups can materially affect thehorizontal shear capacity as well as verticalshear capacity. Calculations may verify no

significant reduction in shear capacity. If so,

repair may not be necessary.

2. Missing projecting strand will reduce thepositive moment restraint capacity at the in-

terior supports of beams made continuous

for composite dead and live loads.3. Where projected strand are to be developed

within cast-in-place diaphragms, to insureadequate longitudinal tension tie capacity

for beam vertical shear design may be com-

promised. Refer to AASHTO LRFD Article5.8.3.5.


Note: Repairs shall not be made without the de-

signers approval; the following are general

guidelines:

Missing Projected Strand

1. This procedure should only be used for re-pairing up to 25% of the projecting strand.

2. Each missing strand shall be replaced bytwo #6 rebar grouted with chemical adhesive

adjacent to the missing element with 24 ofembedment

3. The grouted rebar shall be as close as practi-cal to the missing element.

4. See Standard Repair Procedure #12

Missing Projected Rebar

1. This procedure should only be used for re-pairing up to 25% of the projected reinforc-

ing at beam ends.2. Each missing rebar shall be replaced by an

equivalent sized Grade 60 rebar.

3. The embedment shall be sufficient to devel-op a full lap splice with the internal reinforc-

ing where tension transfer is required.

4. The minimum embedment for other situa-tions shall be based on the chemical adhe-sive manufacturers recommendations.

5. See Standard Repair Procedure #12

Short Projecting Rebar1. Use a mechanical coupler that is approved

by the Owner.

2. Install coupler a per manufacturers recom-mendations

3. See Standard Repair Procedure #11.

Short Projecting Strands

1. This procedure can be used for any numberof short projecting strands per beam thathave at least 5 of strand remaining that is

tightly wound in order to follow this repair

procedure; if this cant be met, treat as amissing strand. Saw-cut strand cleanly with

a cut off saw and install a self seating splicechuck with additional piece of strand.

2. See Standard Repair Procedure #11.


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TS #11

TROUBLE SHOOTING CRACKS AND HONEYCOMBING IN PRECAST, PARTIAL DEPTH DECK

PANELS

Description Longitudinal, transverse and diagonal cracks, and honeycombing in panels.

CAUSES

A. Longitudinal cracks running co-linear tostrands

1. Improper detensioning procedures2. Excessive prestressing force3. Inadequate end reinforcement trans-

verse to strand pattern

4. Casting concrete in hot forms5. Low release strength of concrete

B. Longitudinal cracks not co-linear to strand,transverse cracks or diagonal cracks in

panels

1. Improper handling (impact)2. Improper storage3. Shrinkage4. Improper detensioning procedures5. Strand pattern eccentric to panel mid-

depth

C. Random Honeycombing

1. Improper vibration

PREVENTION

A. Longitudinal cracks running co-linear tostrand

1. Keep prestressing forces balanced dur-ing detensioning. Heat strand to insure

slow elongation of strand (annealing)

during detensioning.

2. Keep the average prestress force overthe end face of panels to 750 psi.

3. Provide transverse mild reinforcingsteel above and below the strand at

panel ends.

4. Cool forms, headers, strand and mildreinforcing, that comes in contact with

wet concrete, at or below 90F.

5. Increase release strength.

B. Longitudinal cracks not co-linear to strand,transverse cracks or diagonal cracks in pan-

els.

1. Provide adequate draft for moving pan-els. Avoid impacts

2. Keep dunnage level and, uniformlyspaced. Provide uniform bearing of

panels transverse to strands.3. Avoid rapid cooling, after curing has

stopped and until detensioning is com-

plete.

4. Keep prestressing forces balanced dur-ing detensioning.

5. Keep strand placement at mid-depth.

C. Random Honeycombing

1. Properly vibrate


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TS #11TROUBLE SHOOTING CRACKS AND HONEYCOMBING IN PRECAST, PARTIAL DEPTH DECKPANELS

Description Longitudinal, transverse and diagonal cracks and honeycombing in panelsENGINEERING EFFECTS

1. Cracks co-linear with strand, either extend-ing from the top or bottom face to strands,

or through cracks are an indicator of

debonding. Experience has shown that evencracks that are partial length of strand will

continue to grow full length of strand over

time, even after epoxy injection. The ownershould be consulted when more than 6 per

cent of strand have such cracks. Two con-

secutive strand having cracks should because for rejection.

2. Longitudinal cracks, parallel but not co-linear to strand are of no structural conse-

quence.3. Transverse and diagonal cracks that cross

more than 6 per cent of strand require an as-

sessment by the owner. Because of the rela-

tively short length of panels, compared tothe transfer and development length of the

strands it is likely that any crack intercept-

ing strands will cause debonding.4. Honeycombing not more than one-inch

deep, in the top or bottom face of panels

and not of extensive plan area are of no

structural consequence if repaired. Honey-

combing deeper than one-inch may com-

promise strand bond.


1. Cracks co-linear with strand and extending

from one face to the strand, or throughcracks co-linear with strand over more than

12 percent of strand should be rejected.

2. Longitudinal cracks parallel to but not co-linear with strand that exceed 0.007 inches

in width should be considered for epoxy in-

jection in accordance with Standard Repair

Procedure #10.3. Transverse or diagonal cracks extending

over more than 12 per cent of strand should

be rejected.4. Honeycombing not exceeding one-inch in

depth at either face, of an acceptable plan

area, should be repaired in accordance with

Standard Repair Procedures #1, #2 or #5.


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TS #12

TROUBLE SHOOTING PARTIALLY CRACKED TOP FLANGES NEXT BEAMS

Description Crack running parallel to beam centerline along inside face of stem.

This crack is expected in obtuse corners of skewed beams adjacent to the interior face ofthe stem, but can occur in any beam.

CAUSE PREVENTION

A. Detensioning

1. Release stresses brought on by skew ef-fects. Uneven lift-off of beam stems

brought on by skew.

2. Release stresses due to uneven detension-ing sequence between beam stems.

3. Binding in forms during stripping

A. Adjust Reinforcement and detensioning se-quence

1. Place additional transverse steel reinforcementin flange to intercept and minimize crack

width. The bars should be located as close to

the bottom of the top flange as allowed bystate specifications for deck reinforcement (1

is recommended).

Consider adding FRP reinforcement along in-

side radius with minimal (1/2) cover to inter-cept crack near surface of concrete.

Note: The reinforcement described above wasadded to the typical details on October 25,

2012.

2. Release one strand at a time alternating fromstem to stem.

3. Keep forms clean and well oiled. Keep formsin good repair, free of dents and dimples.

B. Shrinkage

1. Shrinkage of top flange concrete restrictedby the fixed 2 stem form.

B. Modify Fabrication Methods

1. Avoid rapid cooling, after curing has stoppedand until beam is removed from form.

2. Place additional transverse reinforcement inflange to intercept and minimize crack width.


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TS #12

TROUBLE SHOOTING PARTIALLY CRACKED TOP FLANGES NEXT BEAMS

Description Crack running parallel to beam centerline along inside face of stem.

This crack is expected in obtuse corners of skewed beams adjacent to the interior face ofthe stem, but can occur in any beam.

ENGINEERING EFFECT REPAIR CONSIDERATIONS1. For beams that will be topped with a composite

concrete slab (NEXT F), there are no concerns.

These cracks will be covered by the slab in

composite construction.2. For beams whose top flange is to be used as the

riding surface of the completed bridge (NEXT

D), cracks in the top flange can affect durabil-

ity, if not repaired

1. Where a composite concrete deck is embeddedin concrete in the finished structure (integral

abutment), no structural repairs are needed.

2. NEXT F: If the crack is exposed on the under-side of the finished structure and the bridge is

in a corrosive environment:

Cracks less than 0.006 inch wide should beignored (See Note).

Cracks greater than or equal to 0.006 inchwide and less than 0.016 inch wide should

be sealed with epoxy paste. See RepairProcedure #14.

Cracks greater than or equal to 0.016 wideshould be sealed using epoxy injection by

the pressure injection method. See RepairProcedure #10.

3. NEXT D: Where the top flange will be the rid-ing surface and the crack width is greater than

0.006 inches, the crack at the top surface of thedeck can be sealed with a low viscosity epoxy

or methylmethacrylate product. See Standard

Repair Procedure 14.

Note: The AASHTO LRFD Bridge Design Specifi-

cations limits crack widths in Class 2 exposure con-ditions (bridge decks) to 0.0085 inches (Article

5.7.3.4). Therefore these recommendations are con-

servative.


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Section 3. STANDARD REPAIR PROCEDURES

1. Confined Spells Inside Bearing Areas 26

2. Confined Spells Outside Bearing Areas 27

3. Non-Confined Bearing Area Spells 28

4. Voids in the Bottom Flange That Expose Prestressing Strand 29

5. Honeycombed or Voided Web Areas 30

6. Damaged Flanges Requiring Removal and Replacement of Concrete 31

7. Taking Cores and Patching Cored Holes in Girders 32

8. Misshapen Bearing Recesses 33

9. Honeycombed Areas Left in Place 34

10. Epoxy Injection of Cracks 35

11. Short Projecting Mild Reinforcing Bars or Projecting Prestressing Strands 37

12. Replacement of Missing Projected Mild Steel or Prestressing Strand 38

13. Missing or Incorrectly Located Diaphragm Inserts 39

14. Sealing Cracks 40


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STANDARD REPAIR PROCEDURE #1

FORCONFINED SPALLS INSIDE BEARING AREAS

CASE 1: NO STRANDS EXPOSED

A. Remove all loose concrete, taking care to not damagereinforcing or strand.

B. Square all sides of the depression. Takecare to not damage any mild reinforcement.

C. Clean the excavated area and reinforcing with a stiff wire brush,blowing away dust, with high pressure air.

D. Repair Option 1 Fill the voided area using approved polymermodified cementitious, shrinkage-compensated patching material,

with a compressive strength equal or greater than the specified

design strength of the beam. Prepackaged patching material is

preferred to control quality. Cure properly.

C. Repair Option 2 Coat surface to be adhered to with an approved bonding agent, follow-ing the manufactures instructions. Fill the voided area with a high strength, cement based,

shrinkage-compensated mortar, following the manufactures instruction. Cure properly.

D. Use care to insure that the repaired area does not project below the bottom of the flangenear the bearing area.

NOTE: With the prior approval of the owner/engineer, spalls that involve no more

than 20% of the bearing area may be patched, in the presence of the owners

inspector without submitting the repair for formal approval. Repairs of spalls in

excess of 20% of the bearing area will require submission of a repair plan to the

owner/engineer for approval.

CASE 2: STRANDS EXPOSEDThe full extent of strand exposure shall be determined and a repair plan submitted

for approval by the owner/engineer, regardless of the size of the spall, as the design

capacity may be affected. Generally, if the design capacity is judged to have not been

diminished, or diminished an acceptable amount, the repair procedures for Case 1

will remain applicable.


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FORCONFINED SPALLLS OUTSIDE BEARING AREAS

CASE 1: No strands exposed; spall

located between the end

of the beam and the

point.

A. With the prior approval of the owner/engineer, individual spalls or collective multiplespalls not exceeding 10% of the bottom flange plan area, within the defined limits, may be

repaired in the presence of the inspector utilizing either repair option specified in Standard

Repair Procedure #1.

B. If an individual spall or collective multiple spalls exceed 10% of the bottom flange plan

area, a repair plan must be submitted to the owner/engineer for approval.

CASE 2: No Strands Exposed:Spall located between

the point and

point of the beam.

A. With the prior approval of the owner/engineer, individual spalls or collective multiplespalls not exceeding 10% of the bottom flange plan area, within the defined limits, may be

repaired in the presence of the inspector. The repair options described in Standard RepairProcedure #1 may be used, however an approved shrinkage compensating patch material,

with a compressive strength meeting the design strength of the beam, must be used.

CASE 3: Strands Exposed

Spalls located anywhere on the bottom of the beam flange that exposes strands requires submis-

sion of a repair plan for approval by the owner/engineer. The full extent of strand exposure

should be identified. Generally, if the design capacity is judged to have not been diminished or

diminished an acceptable amount, the repair procedures for Cases 1 & 2, as applicable, may be

used.

Note: In cases where the patch is located over vehicular traffic or pedestrian walkways, thepatching material must be mechanically anchored either by encapsulating existing reinforcement,

be anchored by supplemental reinforcement, or by other anchoring devices.


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FOR

NON-CONFINED BEARING AREA SPALLS

A. Remove all loose concrete.

B. Square interface with existing concrete to be in contactwith the patch, to the extent practical. Take care to not

damage any mild reinforcement or prestressing strands.

C. Clean the excavated area, blowing away dust.

D. Repair Option 1 Fill the spall area with approved polymer

modified cementitious, shrinkage-compensated patching

material, with a compresseive strength equal or greater

than the specified design strength of the beam. Pre-

packaged patching material is preferred to control quality.

D. Repair Option 2 Coat surface to be adhered to with anapproved bonding agent, following the manufactures

instructions. Fill the spall area with a high strength, cementbased, shrinkage-compensated mortar, following the manu-

factures instructions.

E. In cases where the patch is located over vehicular traffic or pedestrian walkways, thepatching material must be mechanically anchored either by encapsulating existing reinforce-

ment, be anchored by supplemental reinforcement, or by other anchoring devices.

NOTE: With the prior approval of the owner/engineer, spalls in the end regions of the beam,

within the bounds stated herein, may be patched, in the presence of the owners inspector without

submitting the repair for formal approval. Repairs of spalls larger than shown herein will require

submission of a repair plan to the owner/engineer for approval.


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FORSPALLS AND VOIDS IN THE BOTTOM FLANGE THAT

EXPOSE PRESTRESSING STRAND

NOTE: This repair applies only to those voids which do not

exceed 4 inches in depth, 4 feet in length and expose no more

than 2 strands, and when no more than one spall or void appears

in a given section of the girder. A section is defined as the

length of the girder. No two such spalls or voids shall have their

closest dimensions nearer than two beam depth apart. With the

prior approval of the owner/engineer, this repair may be made,

in the presence of the owners inspector without submitting the

repair for formal approval.

Repairs at beam ends should be made after detensioning because

any repairs made prior to detensioning will most likelyfail due to high transfer stresses.

Repairs away from beam ends should be made prior to detensioning

so that precompression stresses are induced in the patch material

A. Remove all loose concrete.

B. Square interfaces with existing concrete to be in contact with the patch.


D. Repair Option 1 Fill the voided area with approved polymer modified cementitious,

shrinkage-compensated patching material, with a compressive strength equal or greater

than the specified design strength of the beam. Prepackaged patching material is pre-

ferred to control quality.

E. Repair Option 2 Coat surface to be adhered to with an approved bonding agent, fol-

lowing the manufactures instructions. Fill the voided area with a high strength, cement

based, shrinkage-compensated mortar, following the manufactures instructions.

F. Detensioning should not occur until the patch reaches the specified compressive releasestrength.

G. For larger spalls of a similar nature and/or involving more strands, the same repair tech-niques may be employed but must be submitted to the owner/engineer for evaluation and

approval.

H.In cases where the patch is located over vehicular traffic or pedestrian walkways, the

patching material must be mechanically anchored either by encapsulating existing rein-

forcement, be anchored by supplemental reinforcement, or by other anchoring devices.


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FORHONEYCOMBED OR VOIDED WEB AREAS

CASE 1: No strand exposed, but reinforcing exposed

A. Remove all loose concrete with a maximum 15 poundpneumatic chipping hammer.

B. Square all sides of the depression except thetop of the void. Bevel the surface as shown

in the detail on this sheet.


D. Repair Option 1 Fill the voided area with

approved modified cementitious shrinkage

compensated patching material, with a compressive

strength equal or greater that the specified

design strength of the beam. Prepackaged patching

material is preferred to control quality.

E. Repair Option 2 Coat surface to be adhered to

with an approved bonding agent, following the

manufactures instructions. Fill the voided area with

a high strength, cement based, shrinkage-compensated

mortar, following the manufacturers instructions.

NOTE: With the prior approval of the owner/engineer, individual areas

with a width, measured vertically not greater than 20% of the web

depth and a length, measured horizontally not greater than

the web depth may be repaired, in the presence of the owners

inspector, without formal submission of a repair plan for approval.

CASE 2: Strands exposed, or areas larger than defined for above case requires submission of a

repair plan for approval and the extent of strand exposure identified for structural

evaluation, with approval, the repairs above may still be applicable.

SPECIAL DETAIL FOR VERTICAL PATCHING

NOTE: See Section 4 for further discussion


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FORDAMAGED FLANGES REQUIRING REMOVAL

AND REPLACEMENT OF CONCRETE

Preferably, these repairs should be made priorto detensioning. (However, this type damage can

occur in handling after detensioning.)

CASE 1: The beam will subsequently be topped

with a composite structural slab

A. Remove all loose concrete

B. Preserve and thoroughly clean all mild reinforcement.

If reinforcement is epoxy coated, touch-up all damaged

areas

C. Clean the remaining concrete contact

surfaces.

D. Repair Option 1 Re-pour the missingsection with approved polymer modified,

cementitious, shrinkage compensated patching

material, with a compressive and tensile

strength equal or greater than the design

strength of the beam. Prepackaged material

is preferred for quality control.

E. Repair Option 2 Coat the surfaces tobe adhered to with an approved bonding

agent, following the manufacturers instructions.

Repour with concrete meeting or exceeding the

strength of the design specified. Moist cure

in accordance with contract specifications.

CASE 2: The beam flange is the final riding

surface or will be overlain by a

non-structural riding surface.

Under these conditions the owner/agent

should be consulted as to areas that may

be repaired using Standard Repair Procedures.

NOTE: With prior approval of the owner/engineer,

areas defined may be repaired in the presence

of the owners inspector without formal

submission of a repair plan. Larger area

repairs require a formal submission of a

repair plan to the owner/engineer for approval.


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FORTAKING CORES AND PATCHING CORED

HOLES IN GIRDERS

This procedure applies to the sampling by coring and the patching of holes. Cores may

be required for situations where the concrete strength of the girder is in question.

A. Obtain cores of the diameter specified by the owner/engineer. The engineer shall deter-mine the location of the core in the member. Preference should be for areas that will be

covered with concrete in the completed structure (i.e. within cast diaphragms, top of top

flanges, etc.)

B. Locate and mark all reinforcement and prestressing strand in the vicinity of the core.

C. Coat the cored holes with an approved bonding agent.

D. Patch using an approved high strength non-shrink or polymer modified,cementitious shrinkage compensated prepackage patching

material in accordance with the manufactures recommendations.

E. All work must be witnessed by the owners inspector.


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FOR

MIS-SHAPEN BEARING RECESSES

This repair applies to those bearing recesses that are concave, convex, sloping in the wrong direc-

tion or dimensionally out of tolerance.

A. Chip out surface to achieve correct profile or to intentionallyroughen to accept patching material.

B. Clean bearing recess of all unsound material.

C. Apply a solution of water and latex as a bonding agent, in the

area to be filled or apply an approved bonding agent.

D. Mix a mortar consisting of 5 parts No. 70 silica sand and

4 parts cement with latex and water to a dry consistency.

(For more information on dry consistency, see Section 4)

Use of a high strength, non-shrink grout is also acceptable.

E. Apply this mortar mix to produce the specified recess

dimensions.

F. Re-check the bearing surface, to assure that all dimensional

tolerances are satisfied as set forth in owners Standard

Specifications.


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FOR

HONEYCOMBED AREAS LEFT-IN-PLACE

NOTE: Repair procedures #1 through #5 cover spalls and voids.

They are equally applicable where it is deemed appropriate to

remove honeycombed constituents and fill the voids with

cementitious materials used for patching. In many cases it is

desirable to elect to repair honeycombed areas by filling the

voids with pressure injected epoxy resin binders.

A. Chip out to 1 inch of the exposed face ofhoneycombed area.

B. Apply a seal coat of polymer modified cementitiousshrinkage-compensated patching material, having a

compressive strength equal to or greater than the

design strength of the beam.

C. Insert injection tubes through the freshlyapplied seal coat such that the tubes

penetrate beyond the coating into the

honeycombed area (as an alternate to

B and C, insert tubes through hole

drilled into hardened seal coat and then

seal the annular space between holes

and tubes.)

D. Inject low viscosity epoxy into the honeycombedarea, using successive port-to-port injection

methods, starting at the lowest tube location,

taking care not to entrap air pockets

E. Each tube is pinched off when injection of itspart is complete.

NOTE: Use of Portland cement grout is equally acceptable

to epoxy for filling the voids.

NOTE: With prior approval of the owner/engineer, honeycombed

voids within the limitations described in standard repair

procedures #1 through #5 may be injected with approvedepoxy material, in the presence of the owners inspector.

For areas greater than the limitations in procedures #1

through #5, formal submission of repair procedures are

required. The same will apply to epoxy injection under

this procedure.


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FOREPOXY INJECTION OF CRACKS

NOTE: Cracks can occur during any stageof the beam fabrication/storage/

transportation process. If practical

cracks should be injected prior to

detensioning, but for obvious reasons

this is not always achievable. The

primary reason for injecting known

cracks prior to detensioning is that

during the detensioning process, it is

desirable that the stresses in the

beam be distributed to a monolithic,

symmetric section. However, while

cracks can cause stress redistribution,

cracks as narrow as 0.006 inches

can be restored such that the near

monolithic state can be achieved,

using proper injection techniques.

This procedure applies to cracks that occur in the precast

member with a crack width greater than 0.006 inches.

All workmen engaged in the injection process shall have

satisfactorily completed a program of instruction in utilizing

the specific epoxy injection process to be used.

The specific epoxy resin adhesive used must be approved

by the owner/engineer. Surface seal material, used to confine

the injected adhesive, must have adequate strength to hold

any injection fittings firmly in place and to resist injection

pressures and prevent leakage.

Epoxy components shall be mixed in accordance with the

maufacturers recommendations and expended or discarded

in accordance with the manufacturers designated pot life.

Injection equipment used must be capable of delivering the

pressure appropriate for the injection requirements.

CASE 1: Cracks accessible and visible from both sides

A. Prepare areas adjacent to the crack, cleaning away dirt, dust, grease, oil and other foreignmatter detrimental to the bonding of the injection surface seal system. Corrosives should not

be used for cleaning.

B. For cracks of sufficient width to permit entry of loose particles, blow out debris using highpressure air equipment capable of filtering out any oils from the compressor.


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STANDARD REPAIR PROCEDURE # 10

FOR

EPOXY INJECTION OF CRACKS (CONTINUED)

C. Apply an appropriate surface seal, to both sides of the crack, allowing sufficient curing time.

D. Install injection ports at intervals not less than eight inches. (Note: The maximum port spac-ing is a function of crack width and pump pressure and relies on judgement and injection

equipment used).

E. For essentially horizontal cracks, begin at either end of the crack. For cracks exhibiting anyverticality in orientation, start at the lowest port. Begin and continue injecting epoxy until the

adhesive reaches the next port.

F. Clamp or otherwise seal off the port and begin injecting through the next port. Do not skipsuccessive ports, in order to avoid entrapment of air which will prevent complete filling ofthe

crack.

G. Perform the injection procedure continuously until the crack is filled. If port-to-port travel ofthe adhesive is not indicated, immediately cease injection and notify the engineer. Determine

the cause of problem before continuing on a course of action.

H. When injection is complete, allow the adhesive to cure the length of time and manner speci-fied by the manufacturer.

I. Remove the surface seal by grinding so that the face of the crack is flush with the adjacentconcrete surfaces, with no depressions at the entry ports.

J. If the faces of the beam are not to be subsequently texture coated, apply a color-matchingsand and cement mix.

CASE 2: Blind Cracks, Not Visible or Accessible From Both Sides

Use the same procedures described in Case 1 with the exception that port spacing shall not

exceed the thickness of the member for through cracks. (Examples are cracks through the

web or flanges of box beams.)

NOTE: Sample cores of completed injections may be needed to verify the effectiveness of the

procedures used in both Case 1 and 2.

All work should be accomplished in the presence of the owners inspector.


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FORSHORT PROJECTING MILD REINFORCING BARS

OR PROJECTING PRESTRESSING STRANDS

CASE 1: Broken or Short Mild Steel Reinforcement used as Stirrups or End Projections

A. Mechanical Coupler

An approved coupler may be used, provided enough bar projection remains to install the

coupler. The coupler shall be installed according to the manufacturers recommenda-

tions.

B. Welding

As an alternative to a coupler, welding may be considered. For normally non-weldable

grades of reinforcing, such as ASTM A615, welding of the steel should be approached

with caution since no specific provisions have been included in the particular ASTM

specification to enhance weldability. When nominally non-weldable steel is to be weld-

ed, a welding procedure suitable for the chemical composition and intended use of the

bar must be prepared. The use of the latest edition of ANSI/AWS D 1.4 is recommend-

ed. For weldable grades of mild reinforcement, use of ANSI/AWS D 1.4 negates the

need for a separate weld procedure.

Butt weld the additional segment to achieve the plans projection. All welding must be in

conformance with AWS welding procedures for reinforcing steel. Bar preheat should be

determined from the carbon content and carbon equivalent (Determined from mill certi-

fications). Welding ground must be placed directly on the reinforcing bar being welded

and immediately adjacent to the weld. Grounding through the girder is strictly prohibit-

ed.

All work is to be witnessed by the owners inspector.

CASE 2: Broken or Short Prestressing Strand End Projections

A. Select a proprietary strand coupling device capable of reaching or exceeding the yieldstrength of the prestressing strand.

B. Cut off strand to a length appropriate for splicing and join the additional length strandrequired.

NOTE: As an alternate to the repairs outlined in Case 1 and 2, it may be acceptable to drill and

grout replacement bar or strand. See Standard Repair Procedure #12.


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STANDARD REPAIR PROCEDURE #12FOR

REPLACEMENT OF MISSING PROJECTED

MILD STEEL OR PRESTRESSING STRAND

NOTE: Unless otherwise required by the owner/engineer to satisfy design requirements, the

following procedure is deemed acceptable.

A. Drill the hole diameter to the oversize dimension suggested by the chemical adhesive manu-facturers recommendation, accounting for the upset lugs. Refer to the Troubleshooting Guide

#10 for the required depth of the hole. The hole shall be a minimum of 3 from any beam

edge, measured from to the centerline of the bar.

B. After drilling the hole, blow out any residue using filtered compressed air.

C. Pack the hole with chemical adhesive of the proper viscosity as recommended by the manu-facturer of the adhesive, which depends on the orientation of the hole.

D. Rotate and push the bar or strand into the hole until seated at the bottom. Do not drive the barwith percussion tools.

E. The chemical adhesive shall be on the owner/engineer approved products list, for the applica-tion intended, or otherwise submitted for approval prior to use.

F. All work should be witnessed by the owners inspector.


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FORMISSING, OR INCORRECTLY LOCATED

DIAPHRAGM INSERTS

A. Drill hole - inch greater than the nominal diameter of the bar. The depth of hole should be1 - inch less than stem width.

B. Fill hole with non-sag chemical adhesive following manufacturers instructions.

C. Insert rebar and maintain in position until the chemical adhesive cures per manufacturersinstructions.

NOTE: The path of the deflected strand should be determined and marked along the web prior to

drilling.

SECTION


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FORSEALING CRACKS

CRACKS ON HORIZONTAL SURFACESNOTE: This repair procedure addresses sealing cracks on horizontal surfaces with a low modu-

lus, high molecular weight methacrylate penetrating sealer and crack filler. The methacrylateresin is impervious to water, strong and quick setting (3-12 hours). It bonds to concrete and can

be applied in temperatures from 20 F to 100 F.

A. The specific methacrylate sealer material shall be approved by the owner/engineer.

B. Substrate shall be clean, sound and free of surface moisture. Remove dust, laitance, and oils,curing compounds and all other foreign material by mechanical means.

C. Cracks extending through the entire member thickness shall be sealed from the underside toprevent leakage.

D. The methacrylate sealer shall be applied to the surface according to manufacturers recom-mendations and allowed to pond over the crack. In some cases it may be necessary to build a

temporary dam on either side of the crack to facilitate ponding.

E. The treated surface can become smooth after curing. A dry sand can be broadcast on the par-tially cured surface if a smooth surface is undesirable.

CRACKS ON VERTICAL SURFACES

NOTE: This repair procedure addresses sealing cracks on vertical surfaces with various materi-

als.

I. EPOXY PASTE:

An epoxy paste applied by hand and worked into cracks can provide an effective moisture seal.This type of repair is typically used to seal individual cracks. The material used shall be ap-

proved by the owner/engineer and applied according to manufacturers recommendations.

A. Surface preparation1. Surface to be clean and sound2. Surface may be damp or dry3. Substrate must be 40 degrees F and rising with preferred temperatures ranging from 40

degrees F to no higher than 80 degrees F

B. Application of the epoxy paste1. Prepare the epoxy past according to the manufacturers recommendations

2. Using a thin, flexible, and square ended, plastic or nylon spatula, force the epoxy gelwith uniform pressure by squeegee action into the cracks

3. Finger application to the cracks is permissible, but uniformity in filling of the cracks isbest accomplished with the action of a spatula

4. Allow to set until tack free. Note Well: this is a temperature dependent process and at 40F and rising the set time will be longer than at 75 degrees F

5. Lightly hand sand the area to match texture and appearance of adjacent areas not re-paired


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FORSEALING CRACKS (CONTINUED)

II. SILANE AND SILOXANE SYSTEMS:

A silane or siloxane based water repellents can be applied to the surface surrounding a crack.

Experience has shown that the sealers will wick into and seal cracks 0.013 in width. Multiple

applications may be required. This type of repair is typically used on large network or series of

fine cracks. The material used shall be approved by the owner/engineer and applied according to

manufacturers recommendations.

A. Application of breathable water repellent: silane or siloxane sytems

1. Power mix materials per manufactures recommendation for the time specified, and periodi-cally thereafter to ensure uniform product

2. Apply with paint brush, roller or sprayer from the bottom up on vertical surfaces3. Apply to saturation per manufacturers recommendations

METHACRYLATE:

A low modulus, high molecular weight methacrylate sealer can be introduced into cracks at anyorientation using a vacuum-impregnation process. This type of repair can be used on a series of

fine cracks and on individual cracks. The cracks are prepared in a similar fashion to those under-

going an epoxy injection repair. The vacuum-impregnation process is patented by BALVAC,

Inc.


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Section 4 SUGGESTED REFERENCES

AASHTO"Standard Specifications for Highway Bridges" 17thed., American Association of StateHighway and Transportation Officials, Washington, D.C., 2002

Load and Resistance Factor Design Specifications For Highway Bridges", 2nded. Amer-ican Association of State Highway and Transportation Officials, Washington, D.C. 1998

AASHTO T197, "Standard Methods of Test for Time of Setting of Concrete Mixtures byPenetration Resistance, American Association of State Highway and Transportation Of-ficials, Washington, D.C.

AASHTO T24, Standard Methods of Obtaining and Testing Drilled Cores and SawedBeams of Concrete, American Association of State Highway and Transportation Offi-cials, Washington, D.C.

AASHTO Highway Subcommittee on Construction, "Implementation Manual for Quality

Assurance, (AASHTO IMQA), American Association of State Highway and Transporta-tion Officials, Washington, D.C., 1996

AASHTO Highway Subcommittee on Construction, "Quality Assurance Guide Specifica-tions, (AASHTO QA), American Association of State Highway and Transportation Offi-cials, Washington, D.C., 1996

ACIACI Committee 211, "Standard Practice for Selecting Proportions for Normal, Heavy-weight and Mass Concrete", (ACI 211.1-91) American Concrete Institute, FarmingtonHills, MI, 1991

ACI Committee 212, Chemical Admixtures for Concrete", (ACI 212.3R- 9 1), AmericanConcrete Institute, Farmington Hills, MI, 1991

ACI Committee 221, "Guide to Use of Normal Weight Aggregates in Concrete", (ACI-221R-89), American Concrete Institute, Farmington Hills, MI, 1989

ACI Committee 224, Control of Cracking in Concrete Structures, (ACI 224R-90), Amer-ican Concrete Institute, Farmington Hills, MI, 1990

ACI Committee 503, Use of Epoxy Compounds with Concrete", (ACI 503R-93, reap-proved 1998), American Concrete Institute, Farmington Hills, MI, 1998

ACI Committee 503, "Guide for the Selection of Polymer Admixtures with Concrete,(ACI 503.5R-92, reapproved 1997), American Concrete Institute, Farmington Hills, Ml,1997

ACI Committee 503, Guide for the Application of Epoxy and Latex Adhesives for Bond-ing Freshly Mixed and Hardened Concrete, (ACI 503.6R-97), American Concrete Insti-tute, Farmington Hills, MI, 1997


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ACI Committee 546, "Concrete Repair Guide", (ACI 546R-96), American Concrete Insti-tute, Farmington Hills, MI, 1996

ACI Committee 546, "Guide for Repair of Concrete Bridge Superstructures", (ACI546.lR-80, reapproved 1997), American Concrete Institute, Farmington Hills, MI, 1997

ACI Committee 548, Guide for the Use of Polymers in Concrete", (ACI- 548.lR-97),American Concrete Institute, Farmington Hills, MI 1997

Hanson, J.A., Optimum Steam-curing Procedures in Precasting Plants", Journal of theAmerican Concrete Institute, V. 60, No. 1, Jan 1963

ASTMASTM C403/C403M-99, Test Methods for Time of Setting of Concrete Mixtures by Pen-etration Resistance" American Society for Testing and Materials, West Conshohocken,PA, 1999

ASTM A615/A615M-96, " Standard Specification for Deformed and Plain Billet Bars for

Concrete Reinforcement" American Society for Testing and Materials, West Con-shohocken, PA 1996

PCIPCI Bridge Design Manual", Chapter 3, Precast/Prestressed Concrete Institute, Chica-go, IL, 1997

PCI Bridge Producers Committee, Recommended Practice for Precast/PrestressedConcrete Composite Bridge Deck Panels", PCI JOURNAL, V.33, Mar-Apr 1988, p.p. 67-109

PCI Committee on Quality Control Performance Criteria, Fabrication and Shipment

Cracks in Precast or Prestressed Beams and Columns, PCI JOURNAL, V.30, No. 3,May-Jun 1985, p.p. 24-49

Imper, R.R., Laszlo, G., Handling and Shipping of Long Span Bridge Beams", PCIJOURNAL, V. 32, No. 6, Nov-Dec 1987, p.p. 86-101

"Manual for Quality Control for Plants and Production of Precast and Prestressed Con-crete Products", MNL-116-85, Precast/Prestressed Concrete Institute, Chicago, IL, 1985

Other

Zia, P., Caner, A., Cracking in Large-Sized Long-span Prestressed Concrete AASHTO

Girders" Final Report, Research Project 23241-93-3, Center for Transportation Engi-neering Studies, Department of Civil Engineering, North Carolina State University, Ra-leigh, NC, October 1993, 98 pp. (FHWA/NC/94-003)

ANSI/AASHTO/AWS D 1.5-95 "Bridge Welding Code, American Welding Society, Mi-ami, FL, 1995

"1999 Concrete Repair Manual", International Concrete Repair Institute (ICRI)/ACI


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"Causes, Evaluation and Repair of Cracks in Concrete Structures" , International Con-crete Repair Institute

"Epoxy Injection in Construction", International Concrete Repair Institute

"Factors Related to the Performance of Concrete Repair Materials", International Con-

crete Repair Institute

"Concrete Repair and Maintenance Illustrated" Peter Emmons 1994

Documents

2012 12 18 Pcine Repair Manual Revised