Inspection and Evaluation of Building Structures - Retrofitting Design of Building Structures - page 23

Fig.2.8 Schematic of rebar detecting instrument.

Currently, there are various kinds of rebar detectors such as PROFOMETER 4 Rebar
Locator (Switzerland). The made-in-China rebar detectors are shown in Table 2.4. The
GBH-1 rebar detector is shown in Fig. 2.9.
The principle of the radar instruments for detecting the reinforcement disposition in con-
crete is as follows: the electromagnetic wave which is transmitted from the radar antenna
is reflected from the interface of the substance, such as rebar, which has different electric
characteristics from concrete, and then return to the antenna located on the concrete surface.

Table 2.4 Detectors of the location and cover thickness of rebar

Name and
model

Weight &
dimension

Display
mode

Technique
parameters

Application Manufacturer

Measuring
range: 5

HBY-84A
detector of
concrete
cover
thickness

60 mm ,
detective error
when cover
thickness less
than 45 mm:
± 3mm

∼

Inspecting
location and
cover thickness
of rebar

Shandong
Sanlian
Electronic
Corporation

250 mm ×
120 mm ×
100 mm

Dial

Measuring range:
12 ∼ 120 mm ,
detective error
when cover
thickness is
20 ∼ 80 mm:
± 3mm

Shantou
Electronic
Devices Factory;
Ultrasonic
Electronic
Devices
Corporation

GBH-1
detector of
concrete
cover
thickness

×
120 mm ×
120 mm ,
weighing 2 . 5kg

220 mm Inspecting

position and
cover thickness
of rebar

Dial

GB-1 smart
detector for
location
and concrete
cover thickness
of rebar

Measuring range
0 ∼ 68 mm , error:
0

Tongji University
(Shanghai
Institute
of Building
Materials)

340 mm ×
120 mm ×
280 mm ,
weighing 2 . 5kg

Inspecting
location and
cover thickness
of rebar

Digital 1 mm;

30 ∼ 50: ± 2 mm;
50

∼ 30: ±

∼ 68: ± 3mm

Measuring range
of rebar diameter:
φ 6

Highway
Scientific
Research
Institute of
Ministry of
Communications ,
Beijing Qingyun
Automation
Technology
Development
Corporation

50 mm
measuring range
of cover
thickness:
0 ∼ 170 mm ,
error: 0 ∼ 60:
± 1 mm; 60 ∼ 170:
±

∼

Inspecting
location ,
diameter and
cover thickness
of rebar

GBY-1
detector
of cover
thickness

220 mm ×
150 mm ×
100 , weighing
3 . 25 kg

Digital

3 mm;
120 ∼ 170 : 10%