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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

Sampling and Testing for Chloride Profiles
LTBP Protocol #: FLD-DC-MS-004


1.

Data Collected

 
1.1 Testing of concrete cores to estimate the permeability to chloride ingress and the density and voids characteristics of the concrete.  

2.

Onsite Equipment and Personnel Requirements

 
2.1 Equipment:  
2.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
2.1.2 Sampling plan with sample locations marked.  
2.1.3 Test specimens.  
2.1.4 Apparatus specified in AASHTO T 260-97 (2011).  
2.1.5 Tape measure.  
2.1.6 Digital camera.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications.  

3.

Methodology

 
3.1 Test preparation:  
3.1.1 Use a 2.5-inch diameter core that has been properly obtained, prepared, and stored using
FLD-DC-MS-001, Wet Coring of Concrete Decks.
 
3.1.2 Record the unique core identifier, and note any damage to the wrapping.  
3.1.3 Unwrap the core, removing all four layers of wrapping. Compare sample number and other descriptive information on the wrapping with the similar data on the unwrapped core.  
3.1.4 Weigh and record the weight of the core as-received uncut sample.  
3.1.5 Photograph the sample (top, bottom, and sides at four quadrants), and create a photo log following FLD-DC-PH-002, Photographing for Documentation Purposes.  
3.2 Core sampling: For each core, if conducting both the permeability test and the chloride profile test, use the top 3 inches of the core for the chloride profile and the remainder of the core for the permeability test.  
3.3 Laboratory testing:  
3.3.1 To minimize the potential for cross-contamination of titrated samples, specimens should be tested in order of anticipated increasing chloride concentration, typically taken from deepest depth increment to shallowest increment. Conduct titration of all specimens from a given sample location in one group, and calculate and analyze results (as outlined below) before proceeding with titration of specimens from the next sample location.  
3.3.2 To determine the profile of chloride concentrations as a function of depth at each sample location, determine the diffused chloride contents for depth increments as shown in table 1. The surface chloride value is the chloride content determined for the 0.25–0.75-inch depth range for concrete bridge decks.  

Table 1. Chloride Profile Depth Increments.

Increment # Base unit (U.S. Customary) Metric Equivalent (S.I.)
Nominal Depth
(in.)
Depth Range
(in.)
Nominal Depth
(mm)
Depth Range
(mm)
1 0.5* 0.25–0.75 13 6–19
2 1.0 0.75–1.25 25 19–32
3 1.5 1.25–1.75 38 32–44
4 2.0 1.75–2.25 51 44–57
5 2.5 2.25–2.75 64 57–70
6 3.0 2.75–3.25 76 70–83
* Concentration at this depth is to be used as driving chloride concentration, Co, for diffusion calculations.

3.3.3 Determine and record the chloride concentration of the powdered sample from each depth increment following AASHTO T 260-97 (2011), Sampling and Testing for Chloride Ion in Concrete and Concrete Raw Materials, procedure A.  
3.4 Retain for reference, but do not report, detailed titration records, to include all of the following: the identification and amount of sample, the calibration standards of titrant, the endpoint values of required blank samples, the detailed log of incremental titrant addition and resulting reference voltage readings, and the calculation of endpoint values using the second derivative analysis for each powdered concrete sample. Such information can be captured and stored by automated titration systems and should be archived.  
3.5 Take photographs to document the core features using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.6 Storing data, documents, and images:
3.6.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.6.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.7 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 (e.g., Route 15 SB over I–66)
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 collected
Text
Exact date
 
mm/dd/yyyy
Green
8 Test site
Text
 
 
Location of data collection on the bridge (e.g., span number, lane number, right or left shoulder, substructure unit, etc.)
Green
9 Equipment name
Text
 
 
 
Green
10 Equipment manufacturer
Text
 
 
 
Green
11 Equipment model name and number
Text
 
 
Include model number if available
Green
12 Equipment comments
Text
 
 
 
Orange
Core Information
Pink
13 Unique core identifier
Text
 
 
 
Blue
14 Sample location on structure (x-coordinate)
Number
1
in.
Transverse distance from grid origin
Yellow
15 Sample location on structure (y-coordinate)
Number
1
in.
Longitudinal distance from grid origin
Yellow
16 Core length
Number
0.1
in.
 
Yellow
17 Core diameter
Number
0.1
in.
 
Yellow
18 Presence of reinforcement
Predefined list
 
 
Yes
No
Yellow
19 Overlay depth
Number
0.1
in.
 
Yellow
20 Weight of core
Number
0.1
lb.
 
Yellow
21 Reinforcement depth
Number
0.05
in.
 
Yellow
Chloride Concentration Results
Pink
22 Nominal depth of 0.5 in.
Number
0.05
%
Chloride concentration expressed as percent chloride per concrete mass
Yellow
23 Nominal depth of 1.0 in.
Number
0.05
%
Chloride concentration
Yellow
24 Nominal depth of 1.5 in.
Number
0.05
%
Chloride concentration
Yellow
25 Nominal depth of 2.0 in.
Number
0.05
%
Chloride concentration
Yellow
26 Nominal depth of 2.5 in.
Number
0.05
%
Chloride concentration
Yellow
27 Nominal depth of 3.0 in.
Number
0.05
%
Chloride concentration
Yellow
28 Comments
Text
Unlimited
 
 
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 Precision, bias, and repeatability of the individual tests outlined herein are addressed in the respective ASTM standards that govern the laboratory tests being conducted.  

6.

Commentary/Background

 
6.1 The purpose of this protocol is to describe the laboratory test methods to determine the indication of permeability to chloride ingress and density and voids characteristics.  
6.2 Corrosion of the reinforcement due to chloride ingress is a primary cause of damage to reinforced concrete structures. Sources of chloride in concrete include internal chloride, which refers to chloride added to the concrete at the time of mixing (calcium chloride accelerators for rapid hardening concrete, salt contaminated aggregates, sea water, or other saline contaminated water) and external chloride, which refers to chloride ingress into the concrete from the environment (typically deicer salt and marine salt).  
6.3 Ions, such as chloride, penetrate into the concrete by various processes, most notably diffusion, eventually reaching the reinforcing steel where chloride accumulates to sufficient concentration to induce corrosion. At such concentrations, chloride destroys the naturally occurring protective film on the reinforcing steel that forms in the highly alkaline environment of concrete. This depassivation leads to severe corrosion when sufficient oxygen and moisture are present at the steel–concrete interface.  
6.4 Corrosion of mild steel produces oxide products that consume more volume than the original reactants, which causes expansive pressures and subsequent cracking of the surrounding concrete. Therefore, chloride attack could be very critical for the concrete structure.  
6.5 Identification of chloride attack may be conducted via a combination of visual characterization of the environment and the concrete element condition, as well as chemical and electrochemical testing of the environment and reinforced concrete materials.  

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 FLD-DC-MS-001, Wet Coring of Concrete Decks.  
7.1.4 FLD-DC-PH-002, Photographing for Documentation Purposes.  
7.1.5 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.6 FLD-DS-RS-001, Data, Document, and Image Storage—Remote.  
7.2 External:  
7.2.1 AASHTO T 260-97 (2011), Sampling and Testing for Chloride Ion in Concrete and Concrete Raw Materials, American Association of State Highway and Transportation Officials, Washington, DC, 2011.  

 

 

 

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