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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

Material Sampling Protocols (MS)

FLD-DC-MS-001, Wet Coring of Concrete Decks

FLD-DC-MS-002, Compressive Strength and Static and Dynamic Elastic Moduli of Concrete Cores

FLD-DC-MS-003, Resistance of Concrete to Chloride Ion Penetration (Permeability)

FLD-DC-MS-004, Sampling and Testing for Chloride Profiles

Long-Term Bridge Performance Program Logo

Wet Coring of Concrete Decks
LTBP Protocol #: FLD-DC-MS-001


1.

Data Collected

 
1.1 Concrete heterogeneity and consolidation.  
1.2 Reinforcing steel depth, size, and condition.  

2.

Onsite Equipment and Personnel Requirements

 
2.1 Equipment:  
2.1.1 PRE-PL-LO-004, Personal Health and Safety Plan.  
2.1.2 Concrete pachometer (cover meter).  
2.1.3 Permanent marker.  
2.1.4 Temporary chalk marker.  
2.1.5 Water-cooled core drilling machine (portable or vehicle based) for nominal 4-inch diameter core.

NOTE— Electricity may not be available at the bridge.
 
2.1.6 Water (for cooling).  
2.1.7 Diamond-impregnated coring bit(s) of appropriate diameter.  
2.1.8 Wrapping materials.  
2.1.9 Approved patching materials.  
2.1.10 Hammer.  
2.1.11 Chisel or flathead screwdriver.  
2.1.12 Core extraction tool.  
2.1.13 Three-point caliper.  
2.1.14 Digital camera.  
2.1.15 Pencil, sketch pad, and clipboard.  
2.1.16 Tape measure.  
2.1.17 6-ft folding rule.  
2.1.18 Push broom or hand broom.  
2.1.19 Ground penetrating radar (GPR); if necessary.  
2.2 Personnel: PRE-PL-LO-005, Personnel Qualifications.  

3.

Methodology

 
3.1 Select equipment for coring that meets the requirements of section 2.1 of this protocol.  
3.2 Site cleaning and preparation:  
3.2.1 Clean debris from the deck area(s) using the push broom or hand broom.  
3.2.2 Follow PRE-OP-SP-001, Site Preparation.  
3.3 Unique core identifier:  
3.3.1 Create a unique identifier for each core. The identifier has three components: the two-letter State code; the NBI structure number; and a sequential number. For example: VA-0102030-1 is the first core on a bridge in the Commonwealth of Virginia having an NBI number of 0102030.  
3.3.2 The sequential number component of the unique core identifier is determined as follows: core number VA-0102030-1 is the core nearest to the deck origin in the x direction; core number VA‑0102030-2 is the next closest core to the deck origin in the x direction; core number VA‑0102030-N is the core farthest from the deck origin in the x direction.  
3.4 Determining locations and sizes of cores:  
3.4.1 For locations, number, and sizes of cores for reference bridges, follow PRE-PL-LO-001, Reference Bridge Testing.  
3.4.2 For locations, number, and sizes of cores for cluster bridges, follow PRE-PL-LO-002, Cluster Bridge Testing.  
3.4.3 Consult as-built plans for reinforcing steel (rebar) locations to avoid cores with rebar in them.  
3.4.4 Use the concrete pachometer (cover meter) to confirm the location of the reinforcement and avoid cores with rebar in it. Indicate longitudinal and transverse (or skewed) reinforcement in the vicinity of the core location. Record the depth of reinforcement detected. If the pachometer cannot confirm the reinforcing bar locations, use GPR (if available) to confirm the locations.  
3.4.5 Use the results of visual inspection and NDE testing of the deck (if available) to identify possible locations of cores in sound concrete that is determined to be free of cracks, delaminations, and spalls.  
3.4.6 Use the temporary chalk marker to mark the location of the core on the deck.  
3.4.7 Measure the x-coordinates and y-coordinates of the core location using the grid from section 3.3 of this protocol, and record these values in the data collection table.  
3.4.8 Use a permanent marker to clearly mark the top of the core so that physical orientation in relation to the deck is known.  
3.4.9 Mark the location of each core and the respective unique core identifier on a sketch of the bridge deck.  
3.5 Obtaining the core(s):  
3.5.1 Determine the ideal core length (depth)—this is at least two times the core diameter. Refer to sections 7.1 and 7.1.1 of AASHTO T 24-07 (2011), Standard Method of Test for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete, for further guidance on permissible core lengths.  
3.5.2 Mark the intended core length (depth) on the coring bit with a permanent marker. Most concrete cores will not break off evenly at the bottom of the cored depth, so add an inch of penetration to the desired core length, if possible.  
3.5.3 Obtain the core(s) following AASHTO T 24-07 (2011).  
3.6 Extracting samples:  
3.6.1 When the desired depth is reached, stop coring.  
3.6.2 When coring at a location where delaminations exist, the top portion of the concrete core comes loose in the core barrel once delamination depth is reached. Stop coring immediately, remove the loose top section, retain the loose concrete, and then continue coring.  
3.6.3 Insert a screwdriver, chisel, or other suitable lever instrument into the annular space of the core, and gently tap with a hammer. Repeat tapping along different sectors of the core until the bond at the bottom of the core is broken.  
3.6.4 Use the core extraction tool to grab the core and pull it out of the hole.  
3.6.5 Using the permanent marker, mark the core with unique labeling. Identify this unique label on the sketch of coring locations.  
3.7 Determine and record the core’s diameter and length following AASHTO T 24-07 (2011). Record any necessary correction factors from section 7.1.1 of AASHTO T 24-07 (2011).  
3.8 Using the three-point caliper, determine (in the data collection table) the length of the core(s) following AASHTO T 148-07 (2011), Standard Method of Test for Measuring Length of Drilled Concrete Cores.  
3.9 Storing samples:  
3.9.1 Within 1 hour of extracting the core, wrap the specimen in four layers: 4-mil polyethylene sheet or similar, aluminum foil, 4-mil polyethylene sheet, and duct tape.  
3.9.2 Clearly label the external wrapping with the unique identifier.  
3.9.3 Before wrapping the specimen, note important characteristics, such as maximum aggregate size, presence and location of reinforcing steel in the specimen, cracking, and voids.  
3.9.4 To preserve the “as-is” condition of the concrete and prevent net moisture gain or loss, allow the cores to air dry only long enough for visible water (from coring) on the core perimeter to evaporate.  
3.10 Repairing sample locations:  
3.10.1 Before leaving the site, repair each location where physical sampling resulted in a hole in the concrete element. Coordinate with and obtain approval from the bridge owner/agency concerning the material used in the repair and the method of repair.  
3.10.2 Repairs to overlays or membranes should be compatible with the base material and approved by the owner.  
3.10.3 Allow deck repair materials time to reach adequate strength before reopening deck to traffic.  
3.11 Documenting cores: Take photographs of core locations before testing, after locating reinforcement, and after coring is completed, using FLD-DC-PH-002, Photographing for Documentation Purposes, and create a photo log.  
3.12 Storing data, documents, and images:  
3.12.1 FLD-DS-LS-001, Data, Document, and Image Storage—Local, for local storage.  
3.12.2 FLD-DS-RS-001, Data, Document, and Image Storage—Remote, for remote storage.  
3.13 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 was collected
Text
Exact date
 
mm/dd/yyyy
Green
8 Coring equipment name
Text
 
 
 
Green
9 Coring equipment manufacturer
Text
 
 
 
Green
10 Coring equipment model name and number
Text
 
 
If available
Green
11 Equipment comments
Text
 
 
 
Orange
12 Span number
Text
 
 
 
Blue
13 Location of core
(x-, y-coordinates)
Number
1
in.
 
Blue
14 Test location description
Text
 
 
Descriptive location of core on the bridge (e.g., slow (right) lane, fast lane (left lane), right or left shoulder, etc.)
Blue
15 Ambient temperature during testing – High
Number
1
ºF
 
Blue
16 Ambient temperature during testing – Low
Number
1
ºF
 
Blue
17 Unique core identifier
Text
 
 
 
Blue
18 Core length measurement
Number
0.05
in.
See AASHTO T 148-07 (2011)
Yellow
19 Core diameter
Number
0.1
in.
 
Yellow
20 Correction factor used
Number
0.1
 
Obtain correction factor from Section 7.1.1 of AASHTO T 24 – 07 (2011)
Yellow
21 Overlay depth
Number
0.1
in.
 
Yellow
22 Depth to reinforcement
Number
0.1
in.
 
Yellow
23 Weather during sampling
Text
 
 
e.g., cloudy, sunny, etc.
Yellow
24 Core photos
BLOB
 
 
Document core condition with photos
Yellow
25 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 Where feasible, data will be validated using standard error checking within the Bridge Portal.  

6.

Commentary/Background

 
6.1 The purpose of this protocol is to obtain physical samples of concrete materials for subsequent laboratory evaluation and testing.  
6.2 Physical sampling of the concrete material is often required to evaluate the condition of reinforced concrete bridge decks and other conventionally reinforced concrete elements. Laboratory assessment and testing determines the fundamental physical properties of the material, evaluates construction quality, and identifies evidence of deleterious reactions that may inhibit performance.  
6.3 Coring is often the most convenient method of physical sampling. The cores and the exposed substrate are visually evaluated, and the cores are transported to the laboratory for closer visual evaluation as well as physical and chemical testing. The number, location, size, and depth of cores to be sampled are determined as part of a comprehensive evaluation plan for a given structure or element.  
6.4 Conventional pachometers will not detect stainless steel or other nonferromagnetic elements. In such cases, it may be necessary to use GPR or another method to locate such features.  
6.5 Pachometer and GPR are used to locate top mat or nearest-to-surface reinforcement easily, but it is difficult to identify the lower mat reinforcement location. Take cores to a shallower depth to avoid encountering lower mat if avoiding reinforcement is critical.
Alternatively, probe locations adjacent to the intended core to positively identify reinforcement and bracket the core location. However, this method is time- and labor-intensive and increases intrusion into the structure.
 
6.6 In some cases where reinforcement is taken within the core, particularly where epoxy coating inhibits the bond of concrete to reinforcement, the core may break at the plane of reinforcement rather than at the bottom of the core during extraction of the core. If breakage occurs at the plane of the reinforcement, remove the loose top section and retain, then proceed coring to the desired depth. This situation may be unavoidable.  
6.7 If interference between tests is avoided and tests are performed on appropriate sections of the core, extracted cores can serve for multiple observations and tests. Time between field sampling and laboratory testing may influence the outcome of certain tests and should be considered in advance.  
6.8 Typical materials for repairing core locations are rapid set cementitious repair materials, although gel-type polymer mortars may be used. Consult the State department of transportation for a list of materials on its approved materials list.  

7.

References

 
7.1 LTBP Protocols:  
7.1.1 PRE-PL-LO-001, Reference Bridge Testing.  
7.1.2 PRE-PL-LO-002, Cluster Bridge Testing.  
7.1.3 PRE-PL-LO-004, Personal Health and Safety Plan.  
7.1.4 PRE-PL-LO-005, Personnel Qualifications.  
7.1.5 FLD-OP-SC-001, Data Collection Grid and Coordinate System for Bridge Decks.  
7.1.6 FLD-DC-PH-002, Photographing for Documentation Purposes.  
7.1.7 FLD-DS-LS-001, Data, Document, and Image Storage—Local.  
7.1.8 FLD-DS-RS-001, Data, Document, and Image Storage—Remote.  
7.2 External:  
7.2.1 AASHTO T 24-07 (2011), Standard Method of Test for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete, American Association of State Highway and Transportation Officials, Washington, DC, 2011.  
7.2.2 AASHTO T 148-07 (2011), Standard Method of Test for Measuring Length of Drilled Concrete Cores, American Association of State Highway and Transportation Officials, Washington, DC, 2011.  
7.2.3 FHWA-NHI-12-053, Bridge Inspector’s Reference Manual, Federal Highway Administration, Washington, DC, 2012.  

 

 

 

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