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A strain gauge is constructed by bonding a fine electric resistance wire or photographically etched metallic

resistance foil to an electrical insulation base using an appropriate bonding materials , and attaching gauge

leads.

-1 STRAIN GAUGE

Other types :

2- Ultrasonic Concrete tester

3- Waterproof strain gauge

4- Bolt strain gauge

5- Joint-Meter

These models are used to measure joint opening displacement of mass concrete

6- Shear Displacement Transducer

The KU-A shear displacement transducer is used to measure the shear displacement of a joint between

tunnel bedrock and concrete lining or the shear displacement between two concrete layers of a concrete

structure (concrete placed first and that placed next). This transducer is installed on the anchor bolt driven

into tunnel bedrock or first-placed concrete, then concrete lining or another layer of concrete is laid to

sandwich the transducer for shear displacement measurement.

The micro-creep meter is used to measure the displacement in underground concrete tanks

or tunnels. Specifically, it measures microscopic displacements by measuring the distance

between two points set at an interval of 1 m to 10 m. The micro-creep meter is set at one

point and a super-invar wire fixing bracket is set at the other point, each secured using anchor

bolts. A super-Invar wire is then set up between these two points to measure the distance.

This meter is mainly used to control the conditions of work execution.

7- micro-creep meter

8- Center-hole type Load Cell

The KCE-NA load cell is a center-hole type load cell designed to use in tension

measurement of anchoring strand. It can deliver stable measurement performance under somewhat eccentric load.

9- Soil Pressure Gauge

The soil pressure gauges each 200 mm in outside diameter. They are widely used at construction sites.

They are designed with a dual-diaphragm structure that can minimize the displacement of a sensing area

and thereby can keep the stress distribution in soil undisturbed under pressure. With the KDA-PA, the

Input / Output cable comes from the side of body. With the KDB-PA, the cable comes from the back of

body. The KDA-PA is used to measure the pressure in soil and to monitor the behavior of embankments.

The KDB-PA is used to measure the pressure in earth retaining walls or the pressure on wall surfaces of structures.

10- Temperature Gauge

The temperature gauges use a special temperature gauge as an internal sensor device. It has a

waterproof structure and is suitable for being embedded in concrete or soil. Because it is designed

with the full bridge method, actual temperature can be measured using a measuring instrument that supports entry of initial values.

11- Concrete free water transducer Index

For quality control of concrete, seizing variation in the water content of concrete directly is rational and

very effective method. The concrete free water transducer continuously monitors water variation in the

concrete from fresh concrete to hardened concrete just after placement in electrical and non-destructive

way to let the user estimate the amount of concrete free water (vapor-possible water at 105°C). Thereby

curing state, the time of form removal and the time of surface finish can be judged. Also, the transducer

can be used for versatile applications such as the study on the hydration of concrete closely related to moisture in concrete, durability and maintenance control.

12- Caisson skin-friction meter

The is a transducer to measure skin friction bearing force with the ground acting on the wall of

concrete caisson. The transducer is installed so that the sensing area of the transducer faces

the caisson's wall and measures skin friction bearing force with the ground when settled and fixed.

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