About LTBP

This research was conducted 

as part of the Federal Highway 

Administration’s Long-Term 

Bridge Performance (LTBP) 

Program. The LTBP Program is 

a minimum 20-year research 

effort to collect scientific performance field data, from 

a representative sample of 

bridges nationwide, that will 

help the bridge community 

better understand bridge 

deterioration and performance. 

The products from this program will be a collection of 

data-driven tools including 

predictive and forecasting 

models that will enhance the 

abilities of bridge owners to 

optimize their management 

of bridges.

Literature Review of Chloride 

Threshold Values for Grouted 

Post-Tensioned Tendons

SUMMARY REPORT

This document describes the outcomes of a literature review 

conducted by the Federal Highway Administration (FHWA) to 

support an ongoing laboratory study on corrosion of grouted 

post-tensioned (PT) bridges that are affected by chloridecontaminated grouts. 

Introduction

The number of prestressed concrete bridge structures utilizing 

high-strength 7-wire strands has increased steadily in recent 

years. Since the highly stressed prestressing strand is less tolerant to corrosive environments than ordinary reinforcing steel, 

many bridge deterioration problems associated with corrosion 

of prestressing strands have been reported. This trend is a 

particularly serious matter for PT concrete structures such as 

precast segmental box girder bridges. The same problem exists 

for stay cables of cable-stayed bridges. Although PT concrete 

structures are supposed to have multiple corrosion protection 

systems, many reported PT tendon failures occurred within 

6–17 years in service. The Florida Department of Transportation 

(FDOT) has spent more than $55 million repairing 11 PT 

concrete bridges.(1) The biggest challenge for bridge owners 

and maintenance engineers is to ensure that these bridges 

are safe despite the lack of widely used, reliable inspection 

technologies to detect insidious strand corrosion hidden in 

the ducts or stay cables. A recent FHWA study determined 

that a magnetic-flux-based non-destructive evaluation (NDE) 

FHWA Publication No.: FHWA-HRT-12-067

FHWA Contacts: Paul Y. Virmani, HRDI-60, (202) 493-3052, paul.virmani@dot.gov; Hamid Ghasemi, 

HRDI-60, (202) 493-3042, hamid.ghasemi@dot.gov.

Research, Development, and Technology | Turner-Fairbank Highway Research Center | 6300 Georgetown Pike, McLean, VA 22101-2296

http://www.fhwa.dot.gov/research/
2

technology is potentially field-deployable to detect 

corrosion damage. However, it is still in the early 

stages of development and may take some years 

before becoming a common NDE method for 

routine bridge inspections. Until then, insufficient 

methods such as visual inspection, sounding, and 

destructive excavation are necessary to examine 

physical conditions of PT bridges. 

Due to the importance of high-quality grout in 

PT concrete structures and cable-stayed bridges, 

commercially available prepackaged grout bags 

were introduced to the construction market 

along with enhanced grout installation guidelines 

and training certification programs. However, 

the recent discovery of chloride-contaminated 

grout in a PT concrete bridge located in Corpus 

Christi,  TX, led to a full investigation of the risk 

caused by corrosion problems that may be the 

result of chloride-contaminated grout. The highest total chloride content found in an anchorage 

area of the bridge in Texas was 5.27 percent by 

weight of cement, and the chloride concentrations 

in the retained bags were as high as 0.5 percent 

by weight of cement.(2) These numbers exceed the 

past and current allowable limits for prestressed 

concrete and grout set by domestic and international regulatory committees. A prominent 

corrosion researcher, the late Dr. David Whiting, 

defined allowable chloride limit as the maximum 

amount of chloride in fresh concrete permitted by 

a code authority.(3) A chloride threshold is an actual 

chloride concentration causing corrosion initiation of a passivated (i.e., immune from corrosion) 

metal embedded in concrete and grout. In other 

words, an allowable chloride limit is “an artificial 

criterion set by man” as a guideline to ensure corrosion protection, whereas a chloride threshold 

value is the minimum concentration of chloride 

ions “set by nature” and is usually determined 

through actual experiments and experience in laboratory conditions.(3) The chloride threshold value 

is also called critical chloride content. In general, 

preset chloride limits are lower than experimentally 

determined chloride threshold values.

The corrosion process of metals, including the PT 

strands and cable wires in cementitious materials, 

consists of two steps: (1) corrosion initiation and 

(2)  corrosion propagation. Corrosion initiates 

when the protective oxide film is compromised at 

and above a chloride concentration value, namely 

the chloride threshold value, or by carbonation 

(lowering pH). For chloride-induced corrosion, it 

is desirable to have a reliable chloride threshold 

value to predict when corrosion can initiate on 

metals embedded in a particular cementitious 

material, including grout. Once the corrosion 

begins, the corrosion propagation stage follows 

a kinetic process in the given condition. The rate 

of corrosion is influenced by many factors, including electrical resistance, temperature, dissolved 

oxygen, humidity, and moisture content. 

Objectives

This summary report reviews historical chloride 

threshold values for metals in cementitious 

materials reported in the literature and summarizes the chloride threshold values relevant 

to the PT strands. Consequently, a range of 

reasonable chloride threshold values for PT 

strands based on the literature review is provided 

at the end of the document. 

Background

Existing Codes and Standards

Internationally, there are at least 10 design codes 

that specify maximum allowable chloride contents 

in concrete and grout. Among them, domestic 

sources are three American Concrete Institute 

(ACI) codes, an American Association of State 

Highway and Transportation Officials (AASHTO) 

code, and a Post-Tensioning Institute (PTI) code. 

(See references 4–8.) The other five codes identified are from Canada, Japan, Europe, Hong Kong, 

and New Zealand. (See references  9–13.) The 

allowable chloride limits specified in the codes 

are listed in table 1. Only four codes have maximum allowable chloride limits specifically for 

grout. The remaining codes are for prestressed 

and regular reinforced concrete structures. Since 

both grout and prestressed concrete are cementitious materials that are in contact with highly 

stressed high-strength 7-wire strands and develop 

a protective oxide film, it is reasonable to assume 

that the codes and standards for prestressed 

concrete are applicable to grouted tendons, at 

least to some degree. In table 1 and throughout 

this summary report, chloride concentration data 

that were reported in units other than percent 

by weight of cement are converted so that the 

chloride data can be easily compared and plotted. 

All domestic codes and the Canadian code limit 

either maximum allowable total (acid-soluble) 
3

chloride ions to 0.08 percent or maximum 

allowable water-soluble chloride ions to 

0.06 percent by weight of cement. Water-soluble 

chloride ions are currently available for corrosion, 

and acid-soluble chloride is the total amount of 

chloride ions potentially available for future corrosion. Most of the published data were reported 

in total chloride content. European Standard 

EN  447 does not provide details about type of 

chloride (water-soluble or acid-soluble) or type 

of concrete placement (class 0.10 or class  0.20), 

but it grants the highest allowable chloride 

content (0.20  percent) in prestressed concrete 

among all the codes.(11) The Hong Kong and New 

Zealand codes also have high limits of 0.14 and 

0.1 percent, respectively.(12,13)

Table 1. Summary of codes/standards defining maximum allowable chloride limits in grout and prestressed concrete.

Item 

No. Source Section Material Limit Chloride Type

1

AASHTO LRFD Bridge 

Construction Specifications, 3rd 

Edition

Section 10, 

Prestressing, 

table 10.9.3.2

Grout

0.08 percent 

by weight of 

cementitious 

material

Total (acid-soluble) 

per ASTM C1152(14)

2

Specifications for Grouting of 

Post-Tensioned Structures, PTI 

M55.01-03

Section 3.3.4, 

Chloride Ion Content Grout 0.08 percent by weight of cement

Total (acid-soluble) 

per ASTM C1152(14)

3 Guide to Durable Concrete, ACI 

201.2R-08

Chapter 7, Corrosion 

of Metals and Other 

Materials Embedded 

in Concrete, table in 

section 7.2.3.4

Prestressed 

Concrete

0.08 percent by 

weight of cement

Total (acid-soluble) 

per ASTM C1152(14)

0.06 percent by 

weight of cement

Water-soluble per 

ASTM C1218(15)

4 Protection of Metals in Concrete 

Against Corrosion, ACI 222R-01

Chapter 3, Protection 

Against Corrosion in 

New Construction, 

table 3.1

Prestressed 

Concrete

0.08 percent by 

weight of cement

Total (acid-soluble) 

per ASTM C1152(14)

0.06 percent by 

weight of cement

Water-soluble per 

ASTM C1218(15)

5

Building Code Requirements 

for Structural Concrete and 

Commentary, ACI 318M-11 

Chapter 4, Durability 

Requirements, 

table R4.3.1

Prestressed 

Concrete

0.06 percent by 

weight of cement

Water-soluble per 

ASTM C1218(15)

6

Grout for prestressing 

tendons—Basic requirements, 

European Standard EN 447

Chapter 6. 

Properties of Grout, 

section 6.1

Grout 0.10 percent by 

weight of cement

Sulfate ≤ 4.5 percent 

by weight of 

cement; Sulfide 

≤ 0.01 percent by 

weight of cement. 

7

Limits on Chloride Ion Content, 

Canadian Standards Association 

(CSA) A23.1-09

Section 4.1.1.2, 

Limits on chloride 

ion content

Prestressed 

Concrete

0.06 percent 

by weight of 

cementitious 

material

Water-soluble

8

Chloride Content of Fresh 

Concrete, New Zealand Ready 

Mixed Concrete Association, Inc.

Table 1, Maximum 

Values of Chloride 

Ion Content in 

Concrete as Placed

Prestressed 

Concrete

0.5 kg/m3

 chloride 

in concrete or 

0.14 percent by 

weight of cementa

Total (acid-soluble)

9

Guidelines for Design and 

Construction of Grouting for 

Prestressed Concrete Structures, 

Japan Prestressed Concrete 

Engineering Association

Volume 1, 

section 4.2, 

Verification for 

corrosive materials 

existing in grout

Grout

0.3 kg/m3

 chloride 

in grout or 

0.023 percent by 

weight of cementb

Total (acid-soluble)

10

Code of Practice for Precast 

Concrete Construction, Hong 

Kong Buildings Department

Chapter 2, Design, 

table 2.3

Prestressed 

Concrete

0.10 percent by 

weight of cement Total (acid-soluble)

1 kg/m3 = 1.69 lb/yd3

a

A converted value from 0.9 lb/yd3 (0.5 kg/m3) of chloride content in normal weight concrete assuming 4,100 lb/yd3 (2,400 kg/m3) 

containing 610 lb of cement/yd3 (360 kg of cement/m3). b

A converted value from 0.5 lb/yd3 (0.3 kg/m3) of chloride content in normal grout assuming 2,200 lb of cement/yd3 (1,300 kg 

of cement/m3).

Note: See references 4–13 for documents listed in the “Source” column.
4

In addition to these codes, some States have their 

own allowable chloride contents. For example, 

section 934 of FDOT’s standard specifications 

requires a maximum chloride content of 0.40 lb/yd3 

(0.24 kg/m3).(16) This is equivalent to approximately 

0.067 percent by weight of cement, assuming 

600  lb of cement/yd3

 of concrete (360  kg of 

cement/m3

 of concrete). 

Corrosion of Metals in Cementitious Materials

Corrosion of metals in cementitious materials 

(concrete, mortar, and grout) progresses in two 

phases. The first phase is time to corrosion initiation, and the second phase is time to corrosion 

propagation. Some researchers add an intermediate phase of time to cracking, the first indication 

of destructive corrosion damage. Corrosion 

protection of metals in a cementitious material 

is offered by formation of a protective oxide film 

(passivity) on the metal surface in highly alkaline 

(typically pH > 13.2) environments. The corrosion 

initiation mechanism is a reversal of the corrosion 

protection mechanism: corrosion starts if the oxide 

film is compromised when the concentration of 

chloride ions at any metal/cementitious material 

exceeds a certain level (chloride threshold value) 

or when the pH of the cementitious medium 

drops below ~10 (carbonation). Therefore, time 

to corrosion initiation can be greatly extended 

for metals having substantially high chloride 

threshold values. A good example is high-grade 

stainless steel rebar versus conventional mild 

carbon steel rebar in concrete. It is widely accepted 

that carbon steel rebar has a chloride threshold 

value of about 1.2  lb/yd3

 (0.71 kg/m3), which is 

equivalent to 0.03  percent by weight of concrete 

or 0.2 percent by weight of cement.1

 The reported 

chloride threshold values for different grades of 

stainless steel are at least 12 times higher than that 

of conventional rebar. In addition, the stainless 

steel bars exhibit a very low rate of corrosion once 

corrosion initiates. The rate of corrosion during 

corrosion propagation is also influenced by many 

factors, including level of chloride contamination, 

electrical resistance, moisture in concrete, and 

temperature. Once corrosion starts, reinforced 

concrete structures containing conventional rebar 

may take approximately 20 years to the first repair 

due to chloride-induced corrosion damage.(17) For 

1

One yd3 (1 m3) of normal weight concrete is assumed to be 

4,000 lb (2,400 kg) containing 600 lb (360 kg) of portland cement.

stainless steel rebar, the inherently high chloride 

threshold values and low rates of corrosion can 

result in service life of 100 years or more in a 

corrosive environment.

Chloride Concentration

Chloride concentration can be classified by acidsoluble chloride and water-soluble chloride. The 

acid-soluble chloride concentration represents 

the total content of chloride, including free 

chloride ions in the cement paste pore water, 

chemically bound chloride ions, and physically 

bound chloride ions in the hydrated cementitious 

material. For this reason, it is also called total 

chloride concentration and includes all chloride 

ions that are potentially available for future corrosion in the concrete and grout matrix. The watersoluble chloride concentration is the amount 

of chloride ions dissolved in concrete, grout, or 

cementitious materials available for corrosion at 

the moment of analysis. Sometimes, it is referred 

to as the amount of free chloride ions. The range 

of water-soluble chloride ions is approximately 

70–80 percent of the acid-soluble chloride ions, 

depending on type of cementitious material. The 

chloride concentrations are expressed in terms 

of either percent by weight of cement or percent 

by weight of powder sample. Glass and Buenfeld 

suggested that total chloride content with respect 

to weight of cement is best for expressing the 

chloride threshold value.(18)

A dimensionless ratio of [Cl-

]/[OH-] can also be 

used as a chloride threshold for free chloride ions 

in synthetic or real pore water. A wide range of 

values from 0.22 to 40 have been reported.(18)

Because this ratio is mostly employed for sophisticated laboratory experiments and it is laborious 

to measure true [Cl-

] and [OH-] in extracted pore 

water, it may be less useful for practical applications. Therefore, the [Cl-

]/[OH-] ratios reported in 

the literature are not analyzed in this document. 

Extensive literature research revealed that there 

are many published chloride threshold values for 

reinforcing steel and prestressing steel in concrete 

but limited data for those in mortar and grout. 

This summary report compiles relevant findings of literature reviews grouped by laboratory 

studies and field studies and reported chloride 

threshold values for various metals including 

conventional rebar and 7-wire strand in concrete, 
5

mortar, and grout in chronological order. The 

next section includes discussion of the chloride 

threshold values specifically for PT strands 

in grout. Table  2 summarizes the selected data 

sets of reported chloride threshold values, testing media, testing materials, and sources of data. 

Figure 1 and figure 2 plot these values grouped by 

concrete and mortar/grout, respectively. 

Literature Review Findings on 

Laboratory Studies 

An early laboratory study on the corrosion of 

prestressed wire in concrete was published in 

1960.(19) The objective of the study was to gain a 

better understanding of parameters that could 

influence the corrosion of prestressed wires in 

Table 2. Published total chloride threshold values relevant to this literature review.

No. Researchers (Year)

Published Total Chloride 

Threshold Values (Percent 

by Weight of Cement) Testing 

Medium Material

Reference 

Max Min No.

1 Elsener and Bohmi (1986) 0.5 0.25 Mortar Sandblasted bar 23, 27

2 Hansson and Sorensen (1990) 1.6 0.4 Mortar Unknown 18, 23

3 Alonso et al. (2000) 3.08 1.24 Mortar Rebar and smooth bar 27

4 Zimmermann et al. (2000) 1.25 0.25 Mortar Unknown 27

5 Trejo and Pilai (2003) 0.24 0.04 Mortar Cleaned/degreased bar 27

6 Trejo and Monteiro (2005) 0.15 0.05 Mortar Mill scaled bar 27

7 Sagues et al. (2005)

0.08 by a conversion 

factor of 1.493 from grout 

weight to cement weight

Grout 

recharged with 

fresh water

7-wire strand

25

8 Azuma et al. (2007) 1.2 0.035 Grout 26

9 Trejo et al. (2009) 0.018 0.006 Grout 28, 29

10 Stark (1984) 0.17a 0.11a Concrete 35

11 Pfeifer et al. (1987) 1.4 1.2 Concrete 20, 21

12 Stratful et al. (1975) 1.4 0.17 Concrete Unknown 18, 23

13 Clear (1976) 0.2 Concrete Rebar 20

14 Locke and Siman (1980) 0.8 0.4 Concrete Rebar and cleaned bar 27b

15 Vassie (1984) 1.5 0.2 Concrete Unknown 18, 23

16 Lukas (1985) 2.2 1.8 Concrete Unknown 18, 23

17 Hope and Ip (1987) 0.19 0.1 Concrete Polished bar 27

18 Pfeifer et al. (1987) 0.26 0.17 Concrete Rebar 20, 21

19 Treadaway et al. (1989) 1.9 0.32 Concrete Unknown 18, 23

20 Schiesl and Raupach (1990) 2 0.5 Concrete Unknown 18, 23

21 Thomas et al. (1990) 0.5 Concrete Unknown 18, 23

22 Lambert et al. (1991) 2.5 1.6 Concrete Unknown 18, 23

23 Tuuti (1993) 1.4 0.5 Concrete Unknown 23

24 Henriksen (1993) 0.7 0.3 Concrete Unknown 18, 23

25 Bamforth and ChapmanAndrews (1994) 0.4 Concrete Unknown 18, 23

26 Thomas (1996) 0.7 0.5 Concrete Unknown 18, 23

27 Morris et al. (2004) 1.3 0.4 Concrete Unknown 27

28 Nygard and Geiker (2005) 0.75 0.52 Concrete Smooth bar 27

29 Manera et al. (2008) 2 1.1 Concrete Rebar and smooth bar 27

a

 Water-soluble chloride.

b Mean value of 0.6 reported in references 18 and 23.
6

concrete. The study parameters included chloride 

concentration, cement type, void size, curing temperature, exposure condition, stress level, and 

wire type. Many of the findings are already known 

or irrelevant to current practice. The following 

summarizes several findings that may be related 

to PT grout:

• Corrosion took place in all wires embedded 

in mortar containing 4 percent by weight of 

calcium chloride, regardless of cement type.

• Corrosivity of sodium chloride and calcium 

chloride was equal.

• Fracture of the stressed wires occurred when 

the cross-sectional area of the wires reduced by 

approximately 40 percent via pitting corrosion.

• Although the stressed wires and unstressed 

wires experienced comparable corrosion 

damage in a wet exposure condition, it was 

inconclusive that stress would not affect the 

penetration rate of pitting corrosion.

• Under normal conditions, conventional concrete 

provided excellent protection against corrosion 

of prestressing wire. However, serious corrosion 

was possible under certain conditions for a long 

period of time, even when initial concentration of 

chloride ions was less than 1 percent in concrete. 

FHWA sponsored 2 laboratory studies to investigate 11 corrosion protective systems for new 

prestressed concrete structures.(20,21) The 3-year 

study employed a total of 124 small reinforced 

concrete slabs and 19 full-size concrete specimens 

simulating columns, beams, prestressed piles, and 

deck panels. They were tested under two different 

cyclic wet and dry saltwater exposure schemes. 

The study determined that acid-soluble chloride 

threshold values for conventional rebar ranged 

between 0.17 and 0.26  percent by weight of 

cement depending on the water-to-cement ratio. 

The average value was 0.21 percent by weight 

of cement. For unstressed normal prestressing strands, the average acid-soluble chloride 

threshold values were 1.2 and 1.4  percent by 

weight of cement for as-received and ultrasonically cleaned conditions, respectively. This means 

that unstressed prestressing strands can withstand 

1.40

0.20

0.80

1.50

0.11

2.20

0.19

0.26

1.40

1.90

2.00

0.50

2.50

1.40

0.70

0.40

0.70

1.30

0.75

2.00

0.17

0.40

0.20 0.17

1.80

0.10

0.17

1.20

0.50

1.60

0.32

0.50

0.40

0.52

1.10

0.0

0.5

1.0

1.5

2.0

2.5

Total chloride content by percent of weight of ce

ment (binder)

Researchers (year)

7-wire

strand

7-wire

strand

7-wire

strand

Figure 1. Reported chloride threshold values for a variety of metals in concrete.
7

approximately six times as many chloride ions as 

conventional rebar. According to the experimental 

data collected from the concrete slabs containing 

prestressing strands with a 0.5  water-to-cement 

ratio and 1-inch cover, the average time to 

corrosion was about three times longer compared 

to regular rebar counterparts. Based on their 

findings, the authors proposed a new water-soluble 

chloride limit of 0.10 percent by weight of cement, 

instead of 0.06 percent, in prestressed concrete.(21)

However, none of the ACI codes adopted the 

investigators’ recommended limit.

The first comprehensive literature review of 

chloride threshold values was done during efforts 

to investigate the most accurate way of representing chloride threshold values.(18) Among 20 chloride 

threshold values reported by Glass and Buenfeld, a 

total of 12 values relevant to this literature review 

are included in table 2 and plotted in figure  1 

and figure  2. None of the values was related to 

prestressed strands in grout. Their analysis of literature did not find evidence to support that the 

soluble hydroxyl ions [OH-

] associated with free 

0.50

1.60

3.08

1.25

0.24

0.15 0.08

1.20

0.018

0.25

0.40

1.24

0.25

0.04 0.05 0.04 0.006 0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Elsener and

Bohni (1986)

Hansson and

Sorensen (1990)

Alonso et al.

(2000)

Zimmermann et 

al. (2000)

Trejo and Pilai 

(2003)

Trejo and

Monteiro

(2005)

Sagues et al.

(2005)

Azuma et al.

(2007)

Trejo et al.

(2009)

Total chloride content by percent of weight of ce

ment (binder)

Researchers (year)

7-wire

strand

7-wire

strand

7-wire

strand

Figure 2. Reported chloride threshold values for variety of metals in mortar and grout.

chloride ions [Cl-] in the pore water is an accurate 

measure of the corrosion inhibition properties of 

cement. Instead, they reasoned that bound chloride 

indicates a better corrosion risk than a [Cl-

]/[OH-] 

ratio. They concluded that total chloride content 

relative to weight of cement is best for expressing a chloride threshold value. This measure may 

be viewed as the total potentially harmful chloride 

content rather than the total corrosion-inhibiting 

hydroxyl content.

Another literature review on chloride threshold 

contents for reinforced concrete was done by 

Taylor et al. in 1999.(22) The authors expressed their 

concern that, despite a large uncertainty involving 

chloride threshold values, a single threshold 

value was often accepted and then applied to a 

variety of situations. They also found researchers 

who believed that there is not a single threshold 

value but rather a range based on conditions and 

materials used. The authors recommended that 

chloride threshold content of concrete should 

be determined over a range of water-to-cement 

ratios and that these chloride contents should 
8

be distinguished by total (acid-soluble), watersoluble, and free chlorides.

Metallurgical effects on chloride threshold 

values for steel in concrete were investigated in 

conjunction with a limited literature review by 

Li and Sagues.(23) This study focused mainly on 

electrochemical behaviors of reinforcing steel in 

simulated pore water having different [Cl-

]/[OH-] 

ratios. Due to its theoretical nature, only two conclusions from this study are relevant to prestressing strands in grout, as follows: 

• The chloride threshold value increased 

significantly with higher pH, suggesting that 

the inhibiting effect of [OH-

] ions was stronger 

at higher concentrations. This means that the 

[Cl-

]/[OH-] ratio is not a constant.

• The large variability in the reported chloride 

threshold values for metals in concrete may be 

attributed to variability of concrete pore water 

pH and of chloride binding capacity.

After severe corrosion failures were observed in two 

major PT bridges in Florida, a laboratory study was 

conducted to examine corrosion susceptibility in the 

PT tendon anchorage area in the presence of grout 

voids, bleeding water, and recharging water.(24,25)

The study appears to be the first major laboratory 

study concerning corrosion of PT tendons. Design 

of the study was based on several common observations related to corrosion problems found in the 

PT bridges, as follows:

• Corrosion was found mainly at or near the 

anchorages.

• The anchorage assemblies consisted of 

dissimilar metals (ductile cast iron anchors and 

forged steel wedge plates).

• Corrosion was always associated with grout 

voids, the presence of grout bleeding water, 

and soft and chalky grout in the affected areas.

• Corrosion was always, except for one instance, 

associated with grout containing only trace 

levels of chloride ions.

For this study, seven mock-up anchorage assembly 

specimens were fabricated using commercially 

available ductile cast iron anchorage assemblies, 

unstressed high-strength 7-wire strands, two types 

of grout, and simulated grout voids. The specimens 

were subjected to simulated water recharging 

events with fresh water and 0.01N  sodium 

chloride solution. The results showed that either 

grout bleeding water or recharging water can be 

a major source of PT tendon corrosion by forming a galvanic corrosion cell. This was because 

the PT strands become anodic to the anchorage 

assembly in the presence of water. Depassivation 

of the strands can take place even if modest 

grout carbonation (pH = 8.7 ±0.5) occurs. It was 

observed that fresh water could initiate corrosion 

if the native chloride ions in the grout exceeded 

500 ppm (0.08 percent by weight of cement2

). From 

this, the investigators recommended lowering the 

allowable chloride limit. Furthermore, significant 

corrosion of strands was observed in the voids, 

especially in conditions of high relative humidity. 

The investigators were able to confirm that tendon 

failure by strand corrosion can be realized in as 

little as 7 years. This is consistent with the actual 

failure observed in the field. 

Another corrosion study with chloridecontaminated grout was performed in Japan.(26)

The objective of the study was to investigate 

whether the current allowable Japanese chloride 

content of 0.5 lb/yd3

 (0.3 kg/m3) in grout was

adequate for corrosion protection of stressed 

strands. The researchers employed five grout 

mixes that had a common water-to-cement 

ratio of 0.45 with different chloride contents 

of 0.035  (Japanese allowable chloride limit3

), 

0.08 (U.S. and European chloride limits), 0.30, 1.20, 

and 3.60 percent by weight of cement. Multiple 

unstressed strands and stressed strands at two 

levels (70 and 80  percent of the ultimate tensile 

strength) were covered with the grout materials. 

Their corrosion state was monitored by visual 

appearance, corrosion potential, and anodic polarization curves for up to 684 days. The study found 

that the prestressing level did not affect corrosion behaviors of the strands and that only strand 

specimens covered with 3.60 percent chloride 

content grout showed active corrosion by corrosion potential and anodic polarization data. At the 

end of the study, autopsy confirmed that corrosion 

was only on the strands covered with 3.60 percent 

chloride content grout. Therefore, the researchers 

concluded that grout mixes containing a chloride 

2

Portland cement weight is assumed to be 67 percent of 

the grout sample weight.

3

857 kg of portland cement in 1 m3 of grout (1,450 lb of 

portland cement in 1 yd3

 of grout).
9

concentration of 1.2 percent or less by weight of 

cement would not induce corrosion on the strands, 

regardless of the stress level.

The most thorough literature review was made by 

Angst et al. in 2009, with comprehensive analysis 

of the reported research data related to chloride 

threshold values.(27) The review emphasized 

concrete, and the majority of the information cannot be related to grout, except for the research 

included in table 2. The following are findings 

related to this literature review:

• A large scatter was observed in the reported 

total chloride threshold values, ranging from 

0.04 to 8.34 percent by weight of cement. The 

scatter is caused by different experimental procedures and numerous parameters affecting 

chloride-induced corrosion. The highest chloride 

threshold value, 8.34 percent by weight of 

cement, is not comparable to the other reported 

values and appears to be an outlier.

• It has been suggested that the condition of the 

steel-concrete interface is the most influencing 

factor along with the pH of the concrete pore 

water and the steel potential. Ordinary rebar 

with rib deformation had a higher corrosion 

susceptibility compared to smooth bars. 

• Moisture content is an influencing factor 

because it regulates the availability of water 

and oxygen at the steel/concrete interface. For 

either water-saturated concrete or dry concrete, 

higher chloride concentrations are needed to 

initiate corrosion. Other parameters include the 

following:

• Binder type.

• Surface condition of the steel.

• Oxygen availability at the steel surface.

• Water-to-cementitious binder ratio.

• Electrical resistivity of the concrete.

• Degree of hydration.

• Chemical composition of the steel.

• Temperature.

• Source of chloride (admixed versus penetration from external environment).

• Type of cation accompanying the chloride 

ion (mainly Na+

, Ca+2).

• Presence of corrosion-inhibiting substances.

• It is difficult to adopt a unique chloride threshold 

value in the real world, where there are a wide 

range of structures having different service 

conditions.

• The chloride threshold values determined in 

mortar and concrete tend to be higher than those 

measured in aqueous solutions. There is no significant difference between concrete and mortar.

• The most accurate way of determining the total 

chloride content in concrete powder is X-ray 

fluorescence spectrometry.

• The most accurate way of determining depassivation (precise chloride threshold value) is to 

measure corrosion potential, rate of corrosion 

by linear polarization resistance, and electrochemical impedance spectroscopy.

Extensive laboratory research on strand corrosion 

was carried out in 2009 to investigate the effect 

of voids in grouted PT tendons.(28,29) The objectives were to provide guidelines on corrosivity of 

PT stands under different environmental conditions, develop a reliability model for PT bridges 

suffering from strand corrosion, provide repair 

recommendations, and recommend inspection 

and repair methods of PT systems. Overall, the 

focus was more on structural aspects of the PT 

strand corrosion than on corrosion itself. Key 

experimental parameters included the following: 

• Grout type: Class A (portland cement and water, 

water-to-cement ratio of 0.44) and Class  C 

(prebagged commercial grout, water-to-cement 

ratio of 0.27).

• Moisture content: High (2 weeks ponding with 

chloride test solutions and 2 weeks drying) and 

low (lab air without wet and dry cycles).

• Chloride concentration: 0.0001, 0.006, 0.018, 

0.18, and 1.8 percent by weight of aqueous 

chloride solutions.

• Void type: No voids, parallel voids, orthogonal 

voids, inclined voids, and bleed water voids.

• Stress level: No stress and 150 ksi (1,000 MPa) 

(56  percent of guaranteed ultimate tensile 

strength).

A total of 26 batches were made to cast corrosion 

specimens that were cured in the lab environment 

for 28 days prior to corrosion testing. All of the 

specimens exhibited localized corrosion at or near 
10

the grout-air interface. The specimens exposed 

to test solutions containing 0.018 to 1.8  percent 

chloride ions during the wetting cycles experienced pitting corrosion, whereas those exposed 

to 0.006 percent chloride ions exhibited no pitting 

corrosion except for severe localized corrosion at 

the grout-air void interface. From this finding, the 

researchers suggested that the chloride threshold 

value for the PT strands is likely between 0.006 

and 0.018 percent chloride ions. The study found 

that condensation could lead to higher corrosion 

rates, but high humidity alone did not result in 

the same level of deterioration. When the strands 

were directly exposed to moisture with and without chloride ions, reduction of significant strand 

capacity occurred (assumed to be caused by pitting 

corrosion) and grout voids played a significant role. 

If the strands were embedded completely in grout, 

both unstressed and stressed strands experienced 

similar capacity reductions. If they were exposed 

in the voids, the stressed strands experienced 

much higher capacity losses (more corrosion 

damage) than the unstressed counterparts. The 

largest mean capacity reduction was observed 

when the stressed strands intersected the voids 

perpendicularly in grout that was exposed to 0.006 

and 1.8  percent chloride ions. The researchers 

concluded that it is important to protect the ducts 

and strands from water and chlorides and also 

to eliminate grout voids to prevent or minimize 

the strand capacity reduction. According to their 

reliability model, a PT bridge can fail as early as 

21 years after construction if the strands are subjected to high-chloride environments. 

Literature Review Findings on 

Field Studies

There have not been many field studies of PT 

bridges involving grout chloride analysis. For this 

report, four studies were reviewed. Table  3 lists 

the reported chloride data in the grout samples, 

and figure 3 shows the variability of the data.

A large-scale field study was conducted in the early 

1990s as part of the prestressed concrete technology review and condition surveys.(30) Twelve 

bridges exposed to a marine environment and 

deicing salts were surveyed in detail. They were 

located in Florida, Illinois, Connecticut, Rhode 

Island, Oregon, North Dakota, and Michigan. The 

field surveys utilized visual examinations, various 

NDE tests, and powder sampling for chloride 

analysis. Among the 12 bridges, 4 were PT 

bridges located in North Dakota, Connecticut, and 

Rhode Island. All of them exhibited few signs of 

corrosion, except for anchorage areas with varying 

degrees of corrosion. The Wolcott Avenue Bridge 

in Connecticut is a PT bridge providing useful 

information. Grout samples taken from the bridge 

were analyzed for total chloride content. As listed 

in table 3, the samples contained very high to very 

low chloride concentrations between 1.065 and 

0.001 percent by weight of sample. After observing 

no signs of corrosion on the ducts, the investigators suspected that the chloride was added as 

an admixture to the fresh grout mix. A valuable 

finding was the discovery of virtually corrosionfree strands for 25 years of service despite being 

exposed to grout with as high as 1.065 percent 

chloride by weight of grout sample (equivalent to 

1.590 percent by weight of cement4

). The strands 

in the high chloride-contaminated areas “exhibited 

slight amounts of corrosion, but no significant loss 

of cross section.”(30) The grout in question appeared 

to fill the ducts completely with little or no sign 

of voids. Therefore, the total chloride content of 

1.590 percent by weight of cement is considered 

the maximum chloride threshold value in this case. 

A series of field inspections and testing programs 

were carried out for the Sunshine Skyway 

Bridge in Florida after water was found inside 

28 of the high-level approach columns during a 

routine biennial inspection in 1996.(31) A total of 

146 grout samples were extracted from various 

locations in the columns and analyzed for acidsoluble chloride contents. A large variation of 

chloride concentrations was observed in the 

entire chloride database. The highest and lowest 

contents were 3.8 and 0.0026 percent by weight 

of grout sample, respectively. A tendon exposed 

to grout containing 2.26 percent total chloride by 

weight of cement was visually confirmed to suffer 

from severe corrosion. In general, the severity 

of the strand corrosion was related to the level 

of chloride concentration. The selective chloride 

data set having a description of observed strand 

corrosion is reproduced in table 3, grouped by 

degree of corrosion of the exposed strands. Some 

corrosion-free strands were observed during the 

investigations. The highest chloride concentration 

4

Portland cement weight is assumed to be 67 percent of 

the grout sample weight.
11

without corrosion was 0.099 percent (985 ppm) by 

weight of sample collected from a primary grout 

of column 133 northbound. If cement weight is 

assumed to be 67 percent of the sample, it is 

equivalent to 0.147 percent by weight of cement. 

This can be considered the maximum chloride 

threshold value determined in this study. 

On August 28, 2000, during a routine inspection 

of the Mid-Bay Bridge in Florida, significant distress was discovered in a PT tendon in span 28, 

including duct cracking and fracture of several 

strands.(32) Consequently, an onsite corrosion 

investigation was conducted in January 2001.(33)

The investigation found that active corrosion was 

attributed to the following factors:

• Accumulation of excessive bleeding water 

during grouting.

• A negative effect of the Intraplast® N expansive 

admixture on corrosivity of the bleeding water.

• Hygroscopic bleeding water residuals.

• Presence of cavities and grout voids.

• Carbonated local areas due to a high water-tocement ratio grout.

Table 3. Chloride data in the field PT grout samples.

Bridge ID Tendon ID

Total Chloride 

(ppm)

Total Chloride 

(percent by 

weight of 

grout sample)

Total Chloride 

(percent by 

weight of 

cement) 

Degree of 

Corrosion 

Sunshine 

Skyway Bridge

131 NB-SW tendon 311 0.031 0.046

None

132 NB-NE tendon 459 0.046 0.069

132 NB-NW tendon 220 0.022 0.033

133 NB-SE tendon 57 0.006 0.009

133 NB-SW tendon 985 0.099 0.147

133 SB-NE tendon 269 0.027 0.040

Wolcott Avenue 

Bridge

Span 2-5 10,650 1.065 1.590

Span 2-5 6,900 0.690 1.030

Span 2-5 8,430 0.843 1.258

Span 6-6 10 0.001 0.001

Span 6-6 20 0.002 0.003

Sunshine 

Skyway Bridge

133 NB-NE tendon 6,273 0.627 0.936

Minor

133 NB-NW tendon 1,531 0.153 0.229

131 SB-NW tendon 8,435 0.844 1.259

131 SB-SE tendon 320 0.032 0.048

131 SB-SW tendon 830 0.083 0.124

133 SB-NW tendon 74 0.007 0.011

133 SB-SE tendon 1,646 0.165 0.246

133 SB-SW tendon 2,821 0.282 0.421

131 SB-NE tendon 15,164 1.516 2.263

Severe

Mid-Bay Bridge Span 40-A tendon 2 (top) 1,000 0.010 0.012

Span 40-A tendon 2 (bottom) 700 0.007 0.009

Varina-Enon 

Bridge

Tendon 10-E, sample 2 < 20 < 0.002 < 0.003

Tendon 10-E, sample 3 < 20 < 0.002 < 0.003

Tendon 10-E, sample 4 < 20 < 0.002 < 0.003

Tendon 10-E, sample 5 < 20 < 0.002 < 0.003

Tendon 10-E, sample 6 < 20 < 0.002 < 0.003

Tendon 10-E, sample 7 < 20 < 0.002 < 0.003

NB = Northbound; SB = Southbound; NE = Northeast; NW = Northwest; SE = Southeast; SW = Southwest.
12

• Exposure to high relative humidity and condensation of moisture at temperatures below 

the dew point.

The investigators expected that once the bleeding 

water was reabsorbed into the grout and drying 

occurred, the rate of corrosion would decrease 

substantially. Whenever temperature drops below 

the dew point and during periods of high humidity, corrosion of the strands will re-initiate within 

grout voids or where grout has carbonated. The 

researchers collected 12 grout samples and conducted an analysis of total chloride. The chloride 

contents ranged from 0.137 to 0.259 lb/yd3

 (0.0811 

to 0.153 kg/m3

) (0.007 to 0.012 percent by weight 

of cement5

). Considering the ACI 222R limit of 

total chloride of 0.08 percent by weight of cement 

was equivalent to 1.7 lb/yd3

 (1.0 kg/m3) of chloride 

in this study, all of the grout samples were well 

below the ACI allowable chloride limit.(6) However, 

four severely corroded wires were found where 

5

The report used 2,115 lb of cement/yd3 of grout (1,251 kg of 

cement/m3

 of grout) that had a unit weight of 2,550 lb (1,160 kg).

chloride concentrations in the grout were 0.180 

and 0.259 lb/yd3

 (0.107 and 0.153 kg/m3) (0.009 

to 0.012 percent by weight of cement). From this, 

they concluded that the chloride threshold value 

becomes progressively lower with decreasing pH 

(carbonation). Once the grout pH drops to where 

passivity cannot be maintained, active corrosion 

can occur in the presence of oxygen and moisture 

regardless of chloride concentration.

Another full investigation of a PT bridge was initiated 

in 2007 when routine inspection of the Varina-Enon 

Bridge in Virginia found that one PT tendon was 

severed by corrosion of strands and another one 

was damaged.(34) The objectives of the investigation were to determine the causes of the tendon 

corrosion, evaluate the condition of the remaining 

478 tendons, and develop a repair plan. The investigators claimed that the cause of the severed tendon 

(tendon 10-E) in span 12 southbound was caused 

by gypsum-based repair grout material containing 

excessive sulfate ions. The damage to the other 

tendon (tendon 1302-W) in span 19 southbound 

was a direct result of external corrosion initiated by 

0.147

1.259

2.263

0.009 0.011 0.0

0.5

1.0

1.5

2.0

2.5

None Minor Severe

Estimated total chloride content by percent of weight of ce

ment

Degree of strand corrosion

0.001

1.590

: Sunshine Skyway Bridge

: Wolcott Avenue Bridge

0.012

0.009

: Mid-Bay Bridge

: Varina-Enon Bridge

< 0.003

Figure 3. Comparison of total chloride concentration versus degree of strand corrosion in four bridges.
13

ponding water near a clogged drain hole in the box 

girder floor in the span. As shown in table 3, all six 

of the sample grout powders taken from the failed 

tendon had less than 0.003 percent total chloride by 

weight of cement. Although it is still uncertain that 

sulfate ions are responsible for the corrosion failure 

of the tendon strands, it is apparent that rapid corrosion can occur with virtually no chloride ions under 

certain conditions.

Findings of Chloride Threshold 

Values for Grouted PT Tendons

For grouted (bonded) PT tendons and cables, 

the grout is the last layer of corrosion protection for the highly stressed 7-wire strands and 

cable wires by providing a high pH environment 

to form a protective oxide film on the steel surface and by being a physical barrier to water and 

oxygen. According to the literature review, when 

PT tendons corrode, the common observations 

made are as follows:

• Accumulation of bleeding water was corrosive.

• Bleeding water residuals were hygroscopic.

• Cavities and grout voids were corrosion 

initiation spots.

• Carbonated local areas usually existed.

• High relative humidity and condensation of 

moisture facilitated active corrosion.

• Corrosion was found mainly at or near the 

anchorages.

• Corrosion was always associated with grout 

voids.

• Corrosion occurred with and without chloride 

ions. However, once corrosion initiated, 

severity of strand corrosion was closely linked 

to chloride concentration in the presence of 

moisture, water, and high humidity.

Therefore, any combination of the following 

seven deficiencies can trigger corrosion with 

the presence of moisture and oxygen: (1) voids, 

(2) bleeding water, (3) contamination with chloride 

ions, (4) low pH (carbonation), (5) sedimentation 

and soft grout (variable water-to-cement ratio), 

(6) duct cracks, and (7) water leak through anchorage zones. While some tendon corrosion cases 

were observed in the carbonated grouts exposed 

to water and oxygen, particularly in the voids, 

various amounts of chloride ions were found in 

other incidents. The effect of stress level on corrosion was inconclusive due to conflicting results.

If there are no appreciable tendon deficiencies, 

time to corrosion initiation of PT strands may 

depend on the chloride threshold values, which 

can be influenced by the following parameters: 

• Surface condition of the steel.

• pH at the strand-grout interface. (The chloride 

threshold value becomes progressively lower 

with decreasing pH.)

• Moisture content in the grout.

• Oxygen availability at the steel surface.

• Temperature.

• Electrical resistivity of the grout.

• Degree of hydration.

• Strand-grout interface characteristics (hard 

grout versus soft/pasty grout).

To obtain chloride threshold values in the real 

world, as Angst et al. stated, individual researchers 

employed different experimental procedures, 

numerous parameters, and a wide range of 

structures with different service conditions.(26) As 

a result, there is a large variation in published 

chloride threshold values. This problem can be 

represented by each of the data plots in figure 1 

through figure 3. The same plots also show that 

there are neither trends nor consistencies in the 

reported chloride threshold values. In figure 3, 

the total chloride contents corresponding to “no 

corrosion” are considered the observed chloride 

threshold values for two PT bridges. Recognizing 

the challenge in determining a chloride threshold 

value or a set of values based on the limited data 

reported in the literature, the following discussion 

is intended to draw conclusions with definite 

chloride threshold values for practical purposes. 

In high-quality dense grout with high pH and in 

the absence of voids and water, the maximum 

total chloride threshold value was 1.2 percent 

by weight of cement in a laboratory environment and 1.590 percent by weight of cement 

in the Wolcott Avenue Bridge.(26,30) The former 

employed grouted strands without ducts and 

exposed the grout to the ambient air. Therefore, 

there were no opportunities for the strands to 
14

be exposed to high levels of moisture content. 

The test result suggests that the stressed strand 

can tolerate elevated total chloride content up to 

1.2  percent by weight of cement without developing corrosion if the grout is completely dry. 

A similar chloride threshold value was found in 

the Wolcott Avenue Bridge, where the ducts were 

filled completely with high-quality grout with 

little or no sign of voids and water. In the wet, 

low-oxygen environment found in the Sunshine 

Skyway Bridge columns, the total chloride 

threshold value was 0.147 percent by weight of 

cement.(31) In unfavorable environments with 

defective grout, low pH, and water recharging 

events, the total chloride threshold values were 

0.08 percent by weight of cement in a laboratory 

study and 0.009  percent by weight of cement 

in the Sunshine Skyway Bridge.(23,24,31) Another 

laboratory study suggested that the chloride 

threshold value is likely between 0.006 and 

0.018 percent of total chloride ions.(28,29)

It is reasonable to assume that the total chloride 

threshold value for PT strands is 1.5 percent by 

weight of cement in the best field conditions 

provided by defect-free ducts and anchorage zones 

completely filled with high-quality grout containing 

no voids and moisture. In other field conditions, 

the value falls to between approximately 0.01 and 

0.150 percent by weight of cement depending on 

the quality of installed grout and field exposure 

conditions. No matter what chloride threshold 

value is chosen, it is critical to remember that a 

chloride threshold value may suggest theoretically 

when corrosion of the PT strand can start. Actual 

chloride concentration is the main controlling 

factor of the active corrosion process in response 

to a given exposure condition. Therefore, corrosion risk will increase as chloride concentration 

increases under the same set of conditions.

Conclusions

Based on the findings of a literature review with 

emphasis on maximum allowable chloride limits 

and chloride threshold values pertaining to PT 

grout and prestressed concrete, the following 

conclusions are made:

• Currently, there are five domestic and five 

international codes that specify maximum 

allowable chloride contents in grout and 

prestressed concrete. AASHTO, PTI, European 

Standard EN 447, and the Japan Prestressed 

Concrete Engineering Association specify 

chloride limits in grout, and the others specify 

chloride limits for prestressed concrete. 

• All domestic codes allow either 0.08 percent total 

(acid-soluble) chloride or 0.06 percent watersoluble chloride by weight of cement. In the 

foreign codes, the allowable total chloride content 

limit varies between 0.023 percent (Japan) and 

0.2 percent (Europe) by weight of cement.

• For PT strands embedded in dry, high-quality 

grout with high pH and no voids at the strandgrout interface, the total chloride threshold value 

can be as high as 1.5 percent by weight of cement 

(or 1.0 percent by weight of grout sample). 

• In other circumstances, the total chloride 

threshold value varies significantly between 

0.01 and 0.150 percent by weight of cement 

(or 0.006 and 0.1 percent by weight of grout 

sample), depending on field exposure conditions and quality of installed grout, particularly 

characteristics at the strand-grout interface. 

• Although the AASHTO and PTI codes allow a 

maximum of 0.08 percent total chloride content 

by weight of cement in fresh grout, a lower 

total chloride threshold value may be required 

and appears more appropriate based on 

literature findings presented in this report. 

References

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2—Bridge Deterioration Caused by Corrosion.” 

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2. Kelly, P.L. (2011). “Sika Grout Update.” 

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3. Whiting, D.A. (1997). Origins of Chloride 

Limits for Reinforced Concrete, PCA R&D 

Serial No. 2153, Portland Cement Association, 

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4. American Concrete Institute (2011). Building 

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5. American Concrete Institute (2008). Guide to 

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201, ACI 201.2R-08, Farmington Hills, MI.
15

6. American Concrete Institute (2010). Protection 

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(Reapproved 2010), Farmington Hills, MI.

7. American Association of State Highway and 

Transportation Officials (2010). LRFD Bridge 

Construction Specifications, 3rd Edition, 

Washington, DC.

8. Post-Tensioning Institute (2011). Specifications 

for Grouting of Post-Tensioned Structures, PTI 

M55.01-03, Farmington Hills, MI.

9. Canadian Standards Association (2009). 

Limits on Chloride Ion Content, CSA A23.1-09, 

Section 4.1.1.2, Toronto, Ontario. 

10. Japan Prestressed Concrete Engineering 

Association (2007). Guidelines for Design 

and Construction of Grouting for Prestressed 

Concrete Structures, Vol. 1, Section 4.2 commentary, Tokyo, Japan.

11. European Committee for Standardization 

(2007). Grout for prestressing tendons—Basic 

requirements, European Standard EN 447, 

English version, Brussels, Belgium. 

12. Hong Kong Buildings Department (2003). 

Code of Practice for Precast Concrete, Hong 

Kong.

13. New Zealand Ready Mixed Concrete 

Association Inc. (2005). Chloride Content of 

Fresh Concrete, New Zealand.

14. ASTM C1152/C1152M (2004). Standard Test 

Method for Acid-Soluble Chloride in Mortar 

and Concrete, ASTM International, West 

Conshohocken, PA. 

15. ASTM C1218/C1218M-99 (2008). Standard Test 

Method for Water-Soluble Chloride in Mortar 

and Concrete, ASTM International, West 

Conshohocken, PA.

16. Florida Department of Transportation (2010). 

Standard Specifications for Road and Bridge 

Construction, Tallahassee, FL.

17. Darwin, D., Browning, J., O’Reilly, M., 

Locke, C.E., and Virmani, Y.P. (2011). Multiple 

Corrosion Protection Systems for Reinforced 

Concrete Bridge Components, Report 

No. FHWA-HRT-11-060, Federal Highway 

Administration, McLean, VA.

18. Glass, G.K. and Buenfeld, N.R. (1997). “The 

Presentation of the Chloride Threshold Level 

for Corrosion of Steel in Concrete.” Corrosion 

Science, Vol. 39, No. 5, pp. 1001–1013.

19. Monfore, G.E. and Verbeck, G.J. (1960). 

“Corrosion of Prestressed Wire in Concrete.” 

Bulletin 120, Portland Cement Association, 

Skokie, IL.

20. Pfeifer, D.W., Landgren, J.R., and Zoob, A.

(1987). Protective Systems for New 

Prestressed and Substructure Concrete, 

Report No. FHWA-RD-86-193, Federal Highway 

Administration, McLean, VA.

21. Pfeifer, D.W., Perenchio, W.F., and Hime, W.G. 

(1992). “A Critique of the ACI 318 Chloride 

Limits.” PCI Journal, March–April, pp. 68–71, 

Precast/Prestressed Concrete Institute, 

Chicago, IL.

22. Taylor, P.C., Nagi, M.A., and Whiting, D.A. 

(1999). Threshold Chloride Content for 

Corrosion of Steel in Concrete: A Literature 

Review, PCA R&D Serial No. 2169, Portland 

Cement Association, Skokie, IL. 

23. Li, L. and Sagues, A.A. (2001). Metallurgical 

Effects on Chloride Ion Corrosion Threshold 

of Steel in Concrete, University of South 

Florida Final Report for Florida Department of 

Transportation, Tampa, FL.

24. Powers, R.G., Sagues, A.A., and Virmani, Y.P. 

(2002). “Corrosion of Post-Tensioned Tendons 

in Florida Bridges.” Technical Memorandum 

of Public Works Research Institute, No. 3843, 

pp. 579–594.

25. Wang, H.B., Sagues, A.A., and Powers, 

R.G. (2005). “Corrosion of the StrandAnchorage System in Post-Tensioned Grouted 

Assemblies.” NACE International Corrosion 

Conference Paper No. 05266, Houston TX.

26. Azuma Y., Miyazato, S., Niitani, K., Yamada, K., 

and Tokumitu, S. (2007). “Influence of Chloride 

Ion Content and Stress on Steel Corrosion in 

Cement Paste Grout.” The 32nd Conference on 

Our World in Concrete & Structures, Article ID 

100032017, Singapore.

27. Angst, U., Elsener, B., Larsen, C.K., and 

Vennesland, Ø. (2009). “Critical Chloride Content 

in Reinforced Concrete—A Review.” Cement 

and Concrete Research, 39, pp. 1122–1138.

28. Trejo, D., Hueste, M.B., Gardoni, P., Pillai, 

R.G., Reinschmidt, K., Im, S.B., Kataria,  S., 
16

Hurlebaus, S., Gamble, M., and Ngo, T.T. 

(2009). Effect of Voids in Grouted, PostTensioned Concrete Bridge Construction: 

Volume 1 — Electrochemical Testing and 

Reliability Assessment, Report 0-4588-1, 

Texas Transportation Institute, Texas A&M 

University, College Station, TX.

29. Trejo, D., Pillai, R.G., Hueste, M.B., Reinschmidt, 

K., and Gardoni, P. (2009). “Parameters 

Influencing Corrosion and Tendon Capacity 

of Post-Tensioning Strands,” ACI Materials 

Journal, March–April, pp. 144–153.

30. Whiting, D., Stejskal, B., and Nagi, M. (1993). 

Condition of Prestressed Concrete Bridge 

Components Technology Review and Field 

Surveys, Report No. FHWA-RD-93-037, Federal 

Highway Administration, McLean, VA.

31. Parsons Brinckerhoff Quade & Douglas, 

Inc. (2002). Sunshine Skyway Bridge PostTensioned Tendons Investigation, Final Report 

to Florida Department of Transportation 

District Seven, Tallahassee, FL. 

32. Corven Engineering Inc. (2001). Mid-Bay 

Bridge Post-Tensioning Evaluation, Final 

Report to Florida Department of Transportation 

District Three, Tallahassee, FL.

33. Hartt, W.H. and Venugopalan, S. (2002). 

Corrosion Evaluation of Post-Tensioned 

Tendons on the Mid Bay Bridge in Destin, 

Florida, Final Report to Florida Department of 

Transportation, Tallahassee, FL.

34. FIGG Bridge Engineers, Inc. (2010). I-295 

Varina-Enon Bridge Tendon Replacement, 

Final Report to Virginia Department of 

Transportation, Richmond, VA.

35. Stark, D. (1984). “Determination of Permissible 

Chloride Levels in Prestressed Concrete.” PCI 

Journal, July–August, Precast/Prestressed 

Concrete Institute, Chicago, IL.

Researchers—This study was performed under FHWA LTBPP (Long-Term Bridge Performance 

Program) by Dr. Seung-Kyoung Lee, a Research Associate at the Center for Advanced Infrastructure 

and Transportation, Rutgers University. For more information about this research, contact 

Dr. Paul Y. Virmani, HRDI-60, 202-493-3052, paul.virmani@dot.gov or Dr. Hamid Ghasemi, 

HRDI-60, 202-493-3042, hamid.ghasemi@dot.gov 

Distribution—This summary report is being distributed according to a standard distribution. 

Direct distribution is being made to the Divisions and Resource Center. 

Availability—This summary report may be obtained from the FHWA Product Distribution Center 

by email to report.center@dot.gov, fax to 814-239-2156, phone to 814-239-1160, or online at 

http://www.fhwa.dot.gov/research.

Key Words—Post-tensioned bridge, 7-wire strands, Corrosion, Grout, Prestressed concrete, 

Water-soluble chloride, Acid-soluble chloride, LTBP, and Chloride threshold.

Notice—This document is disseminated under the sponsorship of the U.S. Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no liability 

for the use of the information contained in this document. The U.S. Government does not endorse 

products or manufacturers. Trademarks or manufacturers’ names appear in this summary report 

only because they are considered essential to the objective of the document.

Quality Assurance Statement—The Federal Highway Administration provides high-quality 

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November 2012 FHWA-HRT-12-067

HRDI-60/11-12(600)E