Infrasense Performs Nondestructive Evaluations of Tunnels and Bridges in VA, PA, WI
Posted: 2013-6-4
Source:
PR Web
Infrasense, Inc., a national leader in detecting subsurface conditions, recently is
currently conducting condition investigations of tunnel floor slabs in Virginia and
bridge decks in Wisconsin and Pennsylvania using advanced nondestructive
scanning methods. In Wisconsin, each bridge deck investigation performed by
Infrasense consists of a ground penetrating radar survey, infrared thermography
evaluation, and impact echo testing.
These tests provided a condition assessment of the reinforced concrete bridge
decks without requiring any cores or exposed rebar, and with minimal disruption
to traffic flow. In Pennsylvania, Infrasense engineers focused on infrared
thermography to locate and map near-surface delaminations in the bridge decks.
In Virginia, Infrasense used ground penetrating radar to survey and analyze the
floor slabs of two tunnels using the bridge deck investigation methodology. The
objective of the project is to determine quantities and areas of unsound concrete
slab below the asphalt roadway.
Ground Penetrating Radar (GPR) data is collected to estimate rebar depth and
identify corrosion. The GPR data is collected in a series of lines spaced 3 feet
transversely across the width of the deck, with each line representing a cross
sectional slice of the deck at a particular offset. Decks in good condition consist
of strong and uniform radar reflections from the rebar. GPR data with weak and
inconsistent reflections indicate rebar-level bridge deck deterioration.
The infrared data is collected in a series of passes across each deck, with each
pass covering a deck width of between 12 and 15 feet. For a typical interstate
deck with 2 lanes and left and right shoulders, the survey is carried out in four
passes – one in each lane and one in each shoulder. The survey produces a series
of infrared images collected every foot of vehicle travel. During the survey,
selected areas that appear delaminated in the IR image are manually sounded to
confirm the presence of delamination. Because many of these decks have
overlays, the reinforcing can be 4-5 inches from the surface, and sounding is not
always capable of detecting delamination at this depth. For those locations where
the delamination cannot be confirmed by sounding, testing is carried out using
the Impact-Echo method. By analyzing wave frequencies through the concrete,
the impact-echo equipment is capable of detecting delamination at any depth
throughout the thickness of the deck.
Since 2007, Infrasense has surveyed more than 300 bridge decks across
Wisconsin using its multi-phase approach. After completing a quick and simple
preliminary (Level 1) bridge deck analysis, many are found to be in good
condition and require no further analysis. Those found to have more significant
deterioration levels are mapped in detail (Level 2), providing data to accurately
plan, program, and budget maintenance and rehabilitation.
Many agencies apply GPR and IR separately as tools for bridge deck assessment,
or use only one preferred method. Each method has specific strengths and
weaknesses, and Infrasense uses a combination of both to create a more
effective bridge deck condition assessment. By combining IR and GPR surveys
and using a two level analysis approach, the maximum amount of information
can be obtained for the least cost.
About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied the most current technologies to the
most difficult challenges in subsurface scanning. Infrasense’s engineers are able
to nondestructively extract critical information from a diverse range of
structures. The firm has conducted research to advance the field of subsurface
detection, while also providing valuable information to clients across the country.
Learn more about Infrasense, Inc. and its services at http://www.infrasense.com.
currently conducting condition investigations of tunnel floor slabs in Virginia and
bridge decks in Wisconsin and Pennsylvania using advanced nondestructive
scanning methods. In Wisconsin, each bridge deck investigation performed by
Infrasense consists of a ground penetrating radar survey, infrared thermography
evaluation, and impact echo testing.
These tests provided a condition assessment of the reinforced concrete bridge
decks without requiring any cores or exposed rebar, and with minimal disruption
to traffic flow. In Pennsylvania, Infrasense engineers focused on infrared
thermography to locate and map near-surface delaminations in the bridge decks.
In Virginia, Infrasense used ground penetrating radar to survey and analyze the
floor slabs of two tunnels using the bridge deck investigation methodology. The
objective of the project is to determine quantities and areas of unsound concrete
slab below the asphalt roadway.
Ground Penetrating Radar (GPR) data is collected to estimate rebar depth and
identify corrosion. The GPR data is collected in a series of lines spaced 3 feet
transversely across the width of the deck, with each line representing a cross
sectional slice of the deck at a particular offset. Decks in good condition consist
of strong and uniform radar reflections from the rebar. GPR data with weak and
inconsistent reflections indicate rebar-level bridge deck deterioration.
The infrared data is collected in a series of passes across each deck, with each
pass covering a deck width of between 12 and 15 feet. For a typical interstate
deck with 2 lanes and left and right shoulders, the survey is carried out in four
passes – one in each lane and one in each shoulder. The survey produces a series
of infrared images collected every foot of vehicle travel. During the survey,
selected areas that appear delaminated in the IR image are manually sounded to
confirm the presence of delamination. Because many of these decks have
overlays, the reinforcing can be 4-5 inches from the surface, and sounding is not
always capable of detecting delamination at this depth. For those locations where
the delamination cannot be confirmed by sounding, testing is carried out using
the Impact-Echo method. By analyzing wave frequencies through the concrete,
the impact-echo equipment is capable of detecting delamination at any depth
throughout the thickness of the deck.
Since 2007, Infrasense has surveyed more than 300 bridge decks across
Wisconsin using its multi-phase approach. After completing a quick and simple
preliminary (Level 1) bridge deck analysis, many are found to be in good
condition and require no further analysis. Those found to have more significant
deterioration levels are mapped in detail (Level 2), providing data to accurately
plan, program, and budget maintenance and rehabilitation.
Many agencies apply GPR and IR separately as tools for bridge deck assessment,
or use only one preferred method. Each method has specific strengths and
weaknesses, and Infrasense uses a combination of both to create a more
effective bridge deck condition assessment. By combining IR and GPR surveys
and using a two level analysis approach, the maximum amount of information
can be obtained for the least cost.
About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied the most current technologies to the
most difficult challenges in subsurface scanning. Infrasense’s engineers are able
to nondestructively extract critical information from a diverse range of
structures. The firm has conducted research to advance the field of subsurface
detection, while also providing valuable information to clients across the country.
Learn more about Infrasense, Inc. and its services at http://www.infrasense.com.
