Condition Evaluation ofBiidges on the V crmont State Highway System

INITIAL REPORT 1999-1 March 1999

Repotting on SPR Project# 6606

STATE OF VERMONT AGENCY OF TRANSPORTATION

MATERIALS AND RESEARCH SECTION

GLENN GERSHANECK, SECRETARY OF TRANSPORTATION JOHN PERKINS, PE, DIRECTOR OF TECHNICAL SERVICES

ROBERT F. CAULEY, PE, MATERIALS AND RESFARCH ENGINEER ALLAN E SCHNECK, PE, RESEARCH AND TESTING ENGINEER

Prepared By:

Craig Graham, Research and Development Supavisor Tracy M Phillips, Transportation Chemist

Reseruch and Development Urut

Reviewed By:

~~____;:;__a_ld~~ RF.Cauley,PE -/ Matelials and Reseruch Engineer

Date: /£, ~ flf

TECHNICAL REPORT STANDARD TITLE PAGE 1. Report NO. 2. Government Access1on No. 3. Rec1p1ent's Catalog No.

1999-1

4. TiUe and Subtitle 5. Report Date

Condition Evaluation of Bridges on the Vermont March 1999 State Highway System. 6. Perform1nglJrgan1zaT1on Code

VAOT 7. Author(s) 8. Performing Organization Report No.

C. Graham and T. Phillips 1999-1

9. Performing Organ1zabon Name and Address 10. Work Umt No.

Vermont Agency ofTransportation Materials and Research 133 State Street

11 . Contract or Grant No.

Montpelier, VT 05633 1z. ::;ponsoring Agency Name and Address 13. iype of Report and Period Covered

Federal Highway Administration Initial Report Vermont Division June 1998 - March 1999 Federal Building Montpelier VT 05602

14. Sponsoring Agency Code

15. :supplementary Notes

16. Abstract

The Vermont Agency ofTranspot1ation, Materials and Research Section's R&D Unit is conducting a State Planning and Research (SPR) funded study to determine the correlation between various testing and other procedures currently in use for analyzing the condition of concrete decks on Vermont bridge structures.

A total of thirty-five bridges have been selected for this study, and twelve of these have been tested to date. This investigation commenced in June 1998 and is expected to take two years to complete, with this interim report documenting the findings of this study to date. It is our intent to determine whether or not a correlation or a pattern exists between corrosion potential testing and analytical chloride analysis. This will provide us with a firm understanding of how chloride values in ppm relate to the half cell values of corrosion potential and delamination potential. This study has been conducted over three phases; Phase 1, consisting of selecting thirty-five bridges that are representative of the current bridges on the state highway system, Phase 2, which consisted of actually surveying and testing the selected bridges, and Phase 3, which dealt with the compilation and analyzation of the data acquired during the survey phase.

17. Key Words 18. DlstrTOution Statement

BRIDGEDECKS EVALUATION

19. Security Classif. (of thiS report) 20. Security Classif. (o ' this page) 21 . No.OfP"ages 21. Price

Unclassified Unclassified

Form DOT F 1700.7 (8-69)

Condition Evaluation ofBtidges on the Vetmont State Highway System

REFERENCES:

WP 1998-R-7 SPR Pmject # 6606

INfRODIJCfiON:

The Vamont Agency ofTranspmtation, Materials and Research Section's R&D Unit is conducting a State Planning and Research (SPR) funded study to detennine ti1e effects and degree of chlmide intrusion in Ve~:mont bridges. A total of thirty-five bridges have been selected for fuis study, and twelve ofd1ese have been tested as ofNovember 1998. This investigation commenced in June 1998 and is expected to be completed by September 2000, with this interim report doetnne11ting the findings of Ulis study thus far.

BACKGROUND:

Steel reinforcing bars are embedded into concrete to provide reinforcement offue concrete. 1l1is steel can conooe when it is exposed to high concentrations of chlmides. The adjacent concrete will also be danwged and in some cases, will become delaminated armmd d1e rebar. In Ye1mon~ as in other norfueaste111 states, bridges are subjected to deicing salts during the winter months. On average, in Vennon~ 250 to 500 pounds of salt is used per lane mile, dllling a single snow event Over time fue chloride from these salts will seep into Ule concrete bridge structures. Much of ti1e chlmide will bind to fue cement paste and aggregates (bound chlorides), and tl1e remaining chloride (fire chloride) will continue to penetrate down into ti1e btidge swface.

When cement san1ples a-e extracted from btidge decks and analytical laboratory chlmide tests at-e performed on fuese samples, an litempt is made to detaminc fuc total chlmide (bound at1d fire chloride) content in fue cen1ent in parts per million (ppm). However, in actuality, depending on how deep into fue bridge deck drilling and 5an1ple collection occurs, primarily bound chloride may be the product being analyzed, since ti1e fire dllotides have sccpcd fin1her into the btidge deck. Therefore, several san1ples are collected and tested over fue span(s) of a bridge at 1 and 11

/2 ioches deep. Samples at-e collected fi:om bofu tile wheel paths and tl1e cwb locations on fue deck, which allows evaluation of fue oveJ:-all chloride intrusion of the structut-e. It has been established by convrntion fuat fue chlotide corrosion fureshold is 250-330 ppm Chloride results above this range are capable of inducing conusion of tile reinforcing steel.

1he conusion potential (or half-cell) sUtvey is a test metl1od fuat is designed to assess fue condition offue rebat· in concttte bridge structures. It eat1 detect boti1 tl1e potential of conusion (readin~-0.35V), and potential for delanlination (reading')? -0.40V). This test is less invasive than testing for total dllorides in blidge structUt-es. It requires dlilling into a bridge deck to locate a piece ofd1e steel rebar wifuin the structure, to which a pmbe is al1ached to act as a ground connection Then readings arc taken using Ule copper sulfirte half-cell electtooe, which is placed over ti1e tcinforcing steel in a pattern fuat will pmvide a representation of tl1e entire btidge condition.

1

An increasing number of bridges on both state and town highways have been t:reaterl with membrane watetproofing systems. Typically these membranes are applied on rehabilitated decks, which may or may not still have a significant amount of chloride present in the deck below the repair area. The membrane is designed to an'est the intrusion of any further chlorides into the concrete deck. The presence of these membrane systems has made corrosion potential testing increasingly difficult Any holes drilled into these decks will damage the membrane, and ~'Rfdeckrmue stB:eptible to the ingress ofcblorides:-lherefore,-investigatielffif-th~f-an alternative half cell method that is less invasive is being initiated.

OBJECI1VE; .

A majority ofbridges on the state highway system are inspected every two years by the Structures Section of the Agency. However, a bridge inspection does not include an analysis of corrosion It is primarily a visual inspection of the bridge's condition The analytical chloride determinations and the half-cell StUVeys finnish data that represents the bridge's internal condition in terms of corrosion The intent is to detetmine whether or not a correlation or a pattem exists between fuese two test methods currently available. This will provide a fum understanding ofhow chloride values in ppm relate to the half cell values of conosion potential and delamination potentiaL Results of these methods on thirty-five randomly selected bridges throughout V ennont will be compared. This study is being conducted over three phases, as described below.

CONDUcr OF TilE EVALUADON:

Phase 1 consisted of selecting thirty-five bridges that are representative of the current bridges on the state highway system. The initial bridges selcxted are listed in Table 1. However, depending on various situations that may arise, fuese bridges are subject to change. At fuis time, most of the bridges sel<Xted are on state highways with a small number located on interstate and town highways. Once these were selected, copies of the most cwrent bridge inspection evaluations available fiom the Structures Section, were obtained to provide additional data for the evaluations.

TABLE 1

Addison

Alburg

Bradford

Berkshire

Btighton

Bristol

Bristol

Calais

Castleton

Charleston

Cornwall

Flrnore Vf= Vmnont TH=Town Highw.l)'

VT17,#4 Essex

VT78,#1 Fairfax

VT25, #9 Fayston

VT105,#27 London deny

VT111,#12 Lyndon

vr 116,#10 Mendon

vr 116#11 Morristown

VT14,#74 Montgomery

VT4A, #4 N .springfield

vr 105, #80 Pawlet

vr 125,#9 Poultney

vr 12,#91 Poultney

VT128,#3 Randolph VT12,#42

VT128,#8 Royalton 1H 13,#21

vr 17,#35 Rutland US7,#103

VT100,#91 Rupert VT30,#66

I-91, #92S Ryegate US302, #40

US4, #24 Stowe vr 108, #3

Vf 100,#213 Shaftsbuty VT67, #4

Vfll8,#21 Townshend Vf30,#15

TI-!6,#57 1\mbridge vr 110,#4

VD0,#70 Waterford I-93,#58

TI-!6, #7 Woodford Vf9,#12

VT140,#3

2

Phase 2 consisted of SUiveying and testing the selected bridges using the following Materials and Research test procedures:

Method ofT est for Deteunining Conosion Activity in .Remtorced Concrete. MRD41-88 :MRD47 Vennont Method for Detennination ofTotal Cl:lla.ide Ion Content in Cerrentitious Material

MRD 41-88 is a test method that evaluates the conductivity over a bridge deck and allows for the detennination of the extent of rebar corrosion MRD 47 consists of testing for chlorides in cement powder, which was sampled at curb and wheel path locations on the bridge.

Phase 3 consists of compiling and analyzing the data acquired

Table 2 shows the results of these tests for the twelve bridges smveyed in 1998. Those bridges on which steel could not be located or cement powder sampled will be retested or resampled in 1999.

TABLE2

Bridge Year Type of Average Anrage AverngeCUW Avm~geM Avet-agcO ld4itttlJlcalion Comtruaro Structure Corrosion CorTOSion CorTOSion Cof'T'O.'iion parts per

Adivily o/~.3SV Activity 0/~AOV Activity% Activity% mil6on(ppm) ~.35V/~AOV ~.35VI~AOV Gnu

Bristol 1927 Concn:tcT- 83"/c, 77% 83% w;., 82"/o 77% 1075 vrtt6,#IO Beam

Bristol 1926 CCJ1crele 72% 66% 98% 93% 75% 69% 006 Vf 116#11 T-Beam

Unlonde!Ty 1934 CalCide Unable to locale Ulablc to locate NIA NIA N/A NIA 1294 Vf100,#91 T-Beam steel steel

Montgormy 1953 Sire! Beam 74% 65% 68% 44% 94% 83% NoSarple VTI18,#21 AcquirtXI

N.Spmgfield 1927 S!Ccl Beam 665% 55.5% 73% 48% 64% 59% 184 1116,#57

P:lwlet 1934-1949 S!ccl Beam 1!Y'/o 3% 12% ()'>A, 11% 7% 203 VTJO,f(]()

Poullney 1925-1968 Sleel Pony 8% 1% 18% 15% 5% 4% 769 1116,#7 Tlt5S

Poultney 1934 ConcrcteT- 33% 15.5% 38% 4% 32% 20'/c, 597 vr 140,#3 Beam

Rupert 1939 Ca1<.wteT- 5% 4% 5% 4"/o 4% 2% 106 VTJO,ti(X) Beam

Ryegate 1965 StreiBeam J% 1% (Yllc, 0% 7% 2% NoSanlJics US302,#40 AcquirtXI

TOI\1\Shend 1952 Coocretc 51% 42"/c, 22% II% 77% 6?0/c, 388 VTJO,#J5 Strel Beam

Walelfad 1982 Steel Beam 2% 1% !Y'Io !Y'Io 5% 2"/o 81 I-9J,#5S or Girder

Average a pariS pel'

million (ppm) Whoo! Path

2<.Xl9

899

2297

3239

185

96

Jm

994

169

No S:ln1>lcs Acquired

2399

42

Chlaide Threshold Value (250-330 ppm) As ofJanuary II, 1999

3

Three charts have been designed which represent the wheel pith and cwb compuisons for each bridge. Chart# l portrays the percentage of each deck that is undergoing active corrosion, represented by values of0.35V and greater. Chart #2 shows the percentage of each deck that most likely is exhlbiting delamination in the top few inches of concrete, which is represented by values greater than 0.40\\ Chart #3 portrays total chloride content oftbe CUib and wheel pith in ppm

> "' "' 0

.!'.. . ... u .. 0

0 ~

> 0 ... 0 ..!!. . >< u .. 0

0 ~

5 .. "E .5I .c: 0

120

tOO

eo

00

•o

20

0

100

80

eo

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20

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0 2 ... ....

0

Corrosion Potential >or= to 0 .35V Comparison Between Curb end Wheel Path

Brt•ol 1 N.Springllold Poultney 1 Rupert Waterford Brlllot 2 Powlot Poultnor 2 T ownlhend

Tow na

Corros ion Potential> or= to 0 .40V Comparison Batw aen Curb and Wheel Path

SriMol 1 N .Sprinafield Poultney 1 Rupert W•terford' Brlotol 2 Pawlet Poultnor 2 Townlhond

Tow na

hloride Content in parts per m illionll Comparison Between Curb and Wheel Patn ~

Brfltot 1 N .Spfingfield PouUner 1 Rupe•t Waterfotd BriRol 2 Pawlet Poultney2 Townthend

Tow na

4

c::::J Wheel Path

- Curb

c:::J Wheel Path

.:! Curb

Nine of the twelve bridges swveyed were tested for both chloride content and overall conusion potential in 1998. Although only a small portion of data has been collected, we have been able to establish that there seems to be rome type of

-corretatiorrbetweerrctrloride-Uatt fir pp111 anchxmosiomlCtivity:-Bridgeswith-chlorides-below-the-threshol~f33e-ppm-are­exhibiting low corrosion activity percentages of 12% or less. The North Springfield bridge is an outlier to this observation, in that, despite chloride results below the threshold values, high corrosion potential values are present Additionally, bridges with chloride results between 330 and 1000 ppm generally have a corresponding percentage of corrosion activity of38% or less. Once again there is an outlier to this observation as well. Bridge #11 in Bristol has chloride results in this range, but is exhibiting high con'Osion potentials of 69-98%. In gerreral, results above 1000 ppm have con'Osion potentials above 67%, with the exception ofPoultney #7, which is exhibiting low corrosion activity values. These observations will nero to be re­evaluated ~ additional bridges are Slllveyed and results are collected

FOLWWUP:

As stated above, the remaining three bridges from 1998 need to have all the tests completed on them prior to September 1999. Approximately twelve more bridges will be selected for testing in 1999. Additional tests, such as ground penetrating radar, may also be incorporated into this project A final rep01t will be published at the conclusion of this study.

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MAS SACHUSETTS

VERMONf AGENCY OF

TRANSPORTATION

1. Bristol, VT 116, #I 0 2. Bristol, VT 116, #11 3. Lodonderry, VT 100, #91 4. Montgomery, VT 118, #21 5. North Springfield, TH 6, #57 6. Pawlet, VT 30, #70 7. Poultney, 1H 6, #7 8. Poultney, VT 140, #3 9. Rupert, VT 30, #66 10. Ryegate, US 302, #40 11 . Townshend, VT 30, #15 12. Waterford, 1-93, #55

AGENCY OF TRANSPORTATION

i '? _ 1? -..us 5 t 5 tO 15 *.OMel~RS

Example of a corrosion potential swvey in progres:;

Bristol VT 116, BR#ll

Montgomery VT 118, BR#21

Not1h Springfield Main Street, BR #57

North Sptingfield Main Stree~ BR #57 Curb Distress

Poultney 1H6,BRff7