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REPORT
This report is an archived publication and may contain dated technical, contact, and link information
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Publication Number:  FHWA-HRT-16-007    Date:  January 2016
Publication Number: FHWA-HRT-16-007
Date: January 2016

 

Long-Term Bridge Performance (LTBP) Program Protocols, Version 1

Long-Term Bridge Performance Program Logo

Concrete—Sulfate Attack
LTBP Protocol #: FLD-DC-VIC-007


1.

Data Collected

 
1.1 Description and location of areas affected by sulfate attack on concrete bridge elements.  

2.

Onsite Equipment and Personnel Requirements

 
2.1 Equipment:  
2.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
2.1.2 Ladder, access platform, snooper, bucket truck, man lift, and/or high-reach equipment (if necessary).  
2.1.3 Tape measure.  
2.1.4 6-ft folding rule.  
2.1.5 Sounding hammer.  
2.1.6 Wire brush or hand brush.  
2.1.7 Crack comparison card (gage).  
2.1.8 Measuring wheel.  
2.1.9 Waders or a boat (if necessary).  
2.1.10 Slide caliper.  
2.1.11 Laser measuring device (optional).  
2.1.12 Temporary marker.  
2.1.13 Digital camera.  
2.1.14 Pencil, pad, and clipboard.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications.  

3.

Methodology

 
3.1 Use the data collection grid (FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks) to locate defects on the deck.  
3.2 Use the segmentation and numbering system (FLD-OP-SC-002, Structure Segmentation and Element Identification System) to locate and document defects by the unique element identifier. Establish the two relevant coordinate axes for each face of each element being evaluated.  
3.3 Use FLD-OP-SC-003, Determination of Local Origins for Elements, to establish a local origin on each element of the superstructure and substructure.  
3.4 Cleaning: Use the wire brush or hand broom to clean the concrete element by brushing away any debris so that any defects are visible.  
3.5 Identification: Identify probable sulfate attack through visual inspection.  
3.6 Measuring, recording, and evaluating characteristics of areas of the concrete exhibiting signs of sulfate attack:  
3.6.1 For each area of suspected sulfate attack, strike the concrete surface with a sounding hammer and remove any concrete that is loose. Measure and record each spall and/or delamination following FLD-DC-VIC-003, Concrete Deck—Spalls and Delamination, or FLD-DC-VIC-004, Concrete Superstructure and Substructure—Spalls and Delamination.  
3.6.2 Mark the limits of each area of suspected sulfate attack on the element with a temporary marker and mark the corners of a rectangle that encompasses the maximum length and maximum width of the area of suspected sulfate attack.  
3.6.3 Measure and record the dimensions of each area of suspected sulfate attack at its maximum length and width.  
3.6.3.1 If the area of suspected sulfate attack is on the deck, determine and record the coordinates of the fourcorners of the rectangle using x and y coordinates from the rectangular grid system created using FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks.  
3.6.3.2 For each area of suspected sulfate attack on other concrete elements, document on which superstructure or substructure element and on what area of the element the sulfate attack is located. Using the element local origin as point (0,0,0), determine and record the coordinates of the four corners of the rectangle.  
3.6.4 Measure and record any cracks following FLD-DC-VIC-005, Concrete—Cracking.  
3.7 For each instance of exposed steel reinforcement and tendons or strands:  
3.7.1 Record the type and unique element identifier of the superstructure element where the steel reinforcement and/or tendons or strands are exposed.  
3.7.2 Mark the length of the exposed steel reinforcement and tendons or strands with a temporary marker and photograph the damage.  
3.7.3 Measure the length of the exposed steel reinforcement and/or tendons or strands.  
3.7.4 Document the location of exposed steel reinforcement and tendons or strands by determining and recording the coordinates of the beginning and the end of the affected portion of the element.  
3.7.5 Clean with a wire brush, and measure and record the amount of section loss in the exposed steel reinforcement and/or tendons or strands (if applicable). If necessary, obtain the original cross‑section from the existing documentation for the bridge (PRE-ED-BD-001, Plans and Specifications for Bridge Design and Construction).  
3.8 Documenting defects:  
3.8.1 Take photographs of defects using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.8.2 Use sketches as needed to document spalls and delaminations and supplement the photographs.  
3.9 Storing data, documents, and images:  
3.9.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.9.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.10 Reporting: Transfer all metadata, data, documents, and images to Federal Highway Administration (FHWA), and/or upload all metadata, data, documents, and images into the Long-Term Bridge Performance (LTBP) Bridge Portal.  

4.

Data Collection Table

 
4.1 Table:  
# Field Name Data Type Accuracy Unit Field Description Row Color
1 State
Text
 
 
State Code; e.g., Virginia = VA
Green
2 NBI structure number
Text
 
 
Item 8, structure number; from NBI Coding Guide
Green
3 Structure name
Text
 
 
Descriptive name for the bridge; e.g., Route 15 SB over I–66
Green
4 Protocol name
Text
 
 
Title of the protocol
Green
5 Protocol version
Text
Month and year
 
Month and year the protocol version was published; e.g., May 2015
Green
6 Personnel performing data collection activities
Text
 
 
First name(s) Last name(s)
Green
7 Date data were collected
Text
Exact date
 
mm/dd/yyyy
Green
For Sulfate Attack on the Deck
Pink
8 Location of defect: span number
Text
 
 
Example: Span 1; evaluate each span individually and record data on each individual defect
Blue
9 Location of defect on the deck
Text
 
 
Describe the location of defect on the deck (e.g., lane number, right or left shoulder)
Yellow
10 Location of corner 1
Number
1
in.
(x,y) coordinates of the four corners of a rectangle encompassing the deteriorated area
Yellow
11 Location of corner 2
Number
1
in.
Yellow
12 Location of corner 3
Number
1
in.
Yellow
13 Location of corner 4
Number
1
in.
Yellow
14 Maximum length defect
Number
1
in.
Measured parallel to the x-axis
Yellow
15 Maximum width of defect
Number
1
in.
Measured parallel to the y-axis
Yellow
16 Defect characteristics
List
 
 
Spalls
Concrete crazing
Microcracking
Concrete swelling
Efflorescence
Concrete friability
Other (specify under comments)
Yellow
17 Defect photos and sketches
BLOB
 
 
Document typical corroded areas with photos and/or sketches
Yellow
18 Comments
Text
 
 
 
Orange
For Sulfate Attack on a Superstructure or Substructure Element
Pink
19 Location of the defect: element type and identifier
Text
 
 
Example: Girder 1A; evaluate each element individually and record data on each individual defect data on each individual defect
Blue
20 Location of the defect on the element
Text
 
 
Example: bottom flange of girder
Yellow
21 Pair of coordinates used to locate the defect on element
Text
 
 
(x,y), (x,z), or (y,z)
Yellow
22 Location of corner 1
Number
1
in.
(x,y) coordinates of the four corners of a rectangle encompassing the deteriorated area
Yellow
23 Location of corner 2
Number
1
in.
Yellow
24 Location of corner 3
Number
1
in.
Yellow
25 Location of corner 4
Number
1
in.
Yellow
26 Maximum length of the defect
Number
1
in.
 
Yellow
27 Maximum width of the defect
Number
1
in.
 
Yellow
28 Defect characteristics
List
 
 
Spalls
Concrete crazing
Microcracking
Concrete swelling
Efflorescence
Concrete friability
Other (specify under comments)
Yellow
29 Defect photos and sketches
BLOB
 
 
Document typical corroded areas with photos and/or sketches
Yellow
30 Comments
Text
 
 
 
Orange
For Exposed Steel Reinforcement and/or Tendons/Strands
Pink
31 Location of the defect: element type and identifier
Text
 
 
Example: Girder 1A; evaluate each element individually and record data on each individual defect data on each individual defect
Blue
32 Location of the defect on the element
Text
 
 
Example: bottom flange of girder
Blue
33 Condition of reinforcement and/or prestressing strands/tendons
Text
 
 
Reinforcement and/or prestressing strands or tendons not exposed
Visibly corroded section
Loss of section
Other (specify under comments)
Yellow
34 Location of the beginning of the defect: x-coordinate
Number
1
in.
Measured from the element local origin to the beginning of the defect
Yellow
35 Location of the end of the defect: x-coordinate
Number
1
in.
Measured from the element local origin to the end of the defect
Yellow
36 Length of impact damage
Number
1
in.
 
Yellow
37 Defect photos and sketches
BLOB
 
 
Document typical defects with photos and/or sketches
Yellow
38 Comments
Text
 
 
 
Orange
4.2 Table Key:  
Column Descriptions
#
Sequential number of data item
Field Name
Data field name
Data Type
Type of data, such as text, number, predefined list, binary large object (BLOB), or PDF file
Accuracy
Accuracy to which the data are recorded
Unit
Unit in which a measurement is taken and recorded
Field Description
Commentary on the data or list of items in a predefined list
Row Color Key
Green
Data items only entered once for each protocol for each day the protocol is applied
Pink
Logical breakdown of data by elements or defect types (not always used)
Blue
Data identifying the element being evaluated or the type of defect being identified
Yellow
LTBP data reported individually for each element or defect identified
Orange
Comments on the data collection or data entered

5.

Criteria for Data Validation

 
5.1 Compare measurements with measurements from previous inspections of the same structure to make sure that values make sense.  
5.2 Compare measurements with photo documentation to make sure results shown in photos are consistent with items measured.  
5.3 If an element’s condition is improved when compared to the condition documented in a previous inspection, check with the State department of transportation to determine if any maintenance, repair, and/or bridge preservation actions have occurred. If so, document these maintenance, repair, and/or bridge preservation actions using appropriate protocols.  

6.

Commentary/Background

 
6.1 This protocol provides guidance for identifying, locating, and measuring the extent of sulfate attack.  
6.2 External sulfate attack is the most common type of distress and typically occurs where water containing dissolved sulfate penetrates the concrete. Consequences include extensive cracking, expansion of concrete, loss of bond between the cement paste and aggregate, alteration of paste composition with ettringite formation, and, in later stages, gypsum formation. The effect of these changes is an overall loss of concrete strength.

External sources of sulfate that can cause sulfate attack include seawater, oxidation of sulfide minerals in clay adjacent to the concrete (sulfuric acid formation), and bacterial action in sewers (sulfur dioxide then sulfuric acid formation).
 
6.3 Internal sulfate attack occurs when a source of sulfate is incorporated into the concrete mix. Examples include using sulfate-rich aggregate, an excess of gypsum in the cement, or contamination. External sulfate attack can come from sulfates present in the soil or in the water. See PRE-ED-BD-002, Bridge Construction Records, for mix design properties.  
6.4 Delayed ettringite formation (DEF) is a special case of internal sulfate attack and occurs in concrete that has been cured at elevated temperatures. DEF requires wet conditions to occur, causes expansion of the concrete due to ettringite formation within the paste, and can cause serious damage. If DEF is suspected, check curing records to see if the internal curing temperature of the concrete member ever exceeded 150 °F (PRE-ED-BD-002, Bridge Construction Records).  
6.5 Thaumasite sulfate attack (TSA) can form in concrete and in mortar. The cement hydration products normally present are decomposed as a result of both sulfate attack and of carbonation. Thaumasite typically forms at temperatures between 39 °F and 50 °F and results in severe weakening. As it forms, the concrete or mortar converts to a friable material often described as a “mush.” Concrete severely affected by thaumasite formation is easily broken with the fingers, and the coarse aggregate can be lifted out.  

7.

References

 
7.1 LTBP Protocols:  
7.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
7.1.2 PRE-PL-LO-005, Personnel Qualifications.  
7.1.3 PRE-ED-BD-002, Bridge Construction Records.  
7.1.4 FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks.  
7.1.5 FLD-OP-SC-002, Structure Segmentation and Element Identification System.  
7.1.6 FLD-OP-SC-003, Determination of Local Origins for Elements.  
7.1.7 FLD-DC-VIC-003, Concrete Deck—Spalls and Delamination.  
7.1.8 FLD-DC-VIC-004, Concrete Superstructure and Substructure—Spalls and Delamination.  
7.1.9 FLD-DC-VIC-005, Concrete—Cracking.  
7.1.10 FLD-DC-PH-002, Photographing for Documentation Purposes.  
7.1.11 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.12 FLD-DS-RS-001, Data, Document, and Image Storage—Remote.  
7.2 External:  
7.2.1 FHWA-NHI-12-053, Bridge Inspector’s Reference Manual, Federal Highway Administration, Washington, DC, 2012.  

 

 

 

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