PS 200 Ferroscan PS 200 Ferroscan

frizzflowerUrban and Civil

Nov 29, 2013 (3 years and 11 months ago)

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Measuring Systems

PS 200 Ferroscan

PS 200 Ferroscan

Measuring Systems

Measuring Systems

Application Knowledge

Application Knowledge

Measuring Systems

Rebar is added to concrete to increase its tensile strength


Concrete is very strong in compression, but very weak in tension


Loads placed on concrete are tension which may cause the concrete


to break


Rebar can be added to concrete for added strength

Measuring Systems

Rebar placement and coverage information can be critical


Rebar Corrosion


weakening of the concrete


Fire Protection


rebar loses its strength


Rebar Verification for Load Changes


can a structure’s use
be changed?


Safe and Fast Drilling


not hitting statically relevant rebar,
less wear and tear on drills and bits



Knowledge of rebar placement and the amount of concrete coverage
can be critical to insure the integrity of the structure


Factors influencing rebar integrity:

Measuring Systems

Concrete surfaces sprayed repeatedly with salty water from
the ocean or road surfaces during winter

The salts penetrate the surface and soak into the rebar

The rebar corrodes and expands

The structure is weakened by the corroded rebar. In some
instances, the concrete surface may blow off

Rebar corrosion weakens concrete structures

Measuring Systems

Concrete surface is exposed to fire over a long period of time

The heat will penetrate the concrete

Rebar that heats up loses its strength. Almost all strength is
lost at about 932
°
F (500
°
C) and an average building fire
temperature is 1500
-
1800
°
F (815
°
C
-
982
°
C). The deeper
the rebar is in the concrete, the less it will heat up

The rebar loses its strength and the structure can be damaged

Rebar loses is strength in high temperatures, such as fires

Measuring Systems

Changing loads on a structure …

Can the structure’s use be changed?

Knowing rebar placement and size can determine the load placed on it

Measuring Systems

Knowing rebar location aids safe and fast drilling


Prevent cutting of statically relevant
reinforcement


Increase life of drill and core bits


Reduce wear and tear on tool motors


Reduce time spent drilling

Measuring Systems


Corrosion
studies


Fire protection


Change of
loads on a
structure


Safe Drilling


General Contractors


Civil Contractors


Civil Engineers


General Contractors


Diamond Specialists


Road, Bridge and
Tunnel Contractors


Mechanical & Electrical
Contractors

The Issue

Required
Information

Who needs the
information

Application / User / Scan Mode Matrix


Quickscan
Recording


Imagescan


Quickscan
Detection


Imagescan


Blockscan

Scan Mode


General Contractors


Civil Contractors


Civil Engineers

Measuring Systems

Detection Principle

Detection Principle

Measuring Systems

Transmitter

Receiver

Radar waves

Magnetic field

There are 3 main types of detection tools

1. Induction


PS 200

2. Reflection
-

Radar

3. Inflection


X
-
ray

Advantages

Disadvantages


Must be processed in an office


Very difficult to analyze


Very poor depth measurement


The size of the tool determines the
depth it will read


the smaller tools
don’t see very deep


Cannot work in a damp or wet
environment



Can see everything in the
concrete


Can see very deep in the
concrete with large, push
behind equipment


Dangerous
-

the working area
has to be cleared of people


No depth measurement


Must have access to both sides of
the structure


Very slow to process image


Extremely expensive



Can see everything in the
concrete


Very clear, 2
-
D image



Instant, 3
-
D image


Can analyze the image on the
jobsite


Easy operation


Can analyze large areas quickly


Very good depth accuracy


Can use on floors, walls or ceilings


Detects rebar and other ferrous
objects only


Image depth limited to 7.1” (180 mm)
depending on rebar size


Measuring Systems

The distortion creates a current around the 7 sensor
coils and produces a signal the tool can interpret

When the scanner is far away from rebar or ferrous
metal it produces a perfect magnetic field

When the scanner is placed over rebar the magnetic
field becomes distorted

The magnetic field produced by the PS 200 becomes distorted

Measuring Systems

Because the signal that is created around the sensor coils cannot determine
rebar diameter or depth, other factors also have to be considered:


Signal strength alone cannot determine rebar size


-

Two different sized bars can have the same signal strength


-

The signal strength is always strongest at the surface




Additional factors that must be examined


-

Start and end points of the signal


-

Radius


-

Angle


-

Amplitude





The PS 200 is programmed to calculate the depth and diameter based on
US and Canadian rebar standards


Other factors are considered in determining rebar diameter and depth

Start
point

End
point

Radius

Angle

Amplitude

Measuring Systems

A large rebar deeper in the concrete produces the same signal as a smaller bar
near the surface

The amount of signal generated does not indicate rebar size

Two different sized boxes will make the same size shadow depending on the
distance they are away from the light source

Measuring Systems

The software uses
mathematical analysis to
determine the number and
approximate position of the
rebar

Next, it separates the
signals into individual
rebars

Last, the software
determines the bar size
and depth

The software analyzes the data to determine rebar position, depth and diameter

Location, coverage and diameter

Measuring Systems

Based on the magnetic principle of locating, determining
diameter and depth of rebar, there are other factors that
influence what the PS 200 is able to detect:

Other factors also influence what the PS 200 can detect


Rebar Spacing


-

Rebar that is closely spaced together



The Shading Effect



Ferrous Metal Detection


-

The PS 200 is designed to detect ferrous metal,
specifically rebar that meets US and Canadian rebar
standards



Measuring Systems

Rebar Spacing can effect the PS 200’s ability to distinguish rebar

Rebar must be spaced a minimum distance apart for the PS 200 to be
able to distinguish individual bars

C = Coverage S = Spacing

The minimum rebar spacing is defined as the ratio S:C (Spacing:Coverage)
and the bars must be at least 1” in the concrete



For image and depth of rebar, the ratio is
≥ 1:1



To determine diameter, the ratio is
≥ 3:1



Using Quickscan Detection, the ratio is
≥ 2:1



Using Quickscan Recording, the ratio is ≥ 1:1




For example, to determine the image of rebar 4 in
(100 mm) in the concrete, the rebars must be at
least 4 in (100 mm) apart.

Measuring Systems

The Shading Effect



the magnetic field from the first layer of rebar
shades the second layer of rebar preventing detection of second layer.

1st Layer of
rebar

2nd Layer of
rebar

Shading

The Shading Effect can also effect the PS 200’s ability to distinguish rebar