The Clegg Hammer is the industry standard instrument used for impact testing, primarily on soils, roading base course materials and sports turf surfaces.

Below outlines a brief history and basic explanation of the Clegg, the CIV "Clegg Impact Value" and the models available in New Zealand.


CLEGG Hammer history
The Clegg Hammer was developed by Dr Baden Clegg in the Department of Civil Engineering at the University of Western Australia in the 1970s.

In 1993, Dr Clegg formed the company that carries his name with the aim of providing a world-wide information service regarding the Clegg Impact Test and to assist in marketing and ongoing R&D work concerning the Clegg Impact Soil Tester and associated soil testing procedures.

Today the CLEGG hammer is used around the world in the determination of soil compaction.

CLEGG Impact Value (CIV)
Four successive blows of the hammer on the same spot constitutes one test, called a Clegg Impact Test (CIT). The CIT provides a soil strength/stiffness - or "hardness" - parameter known commonly as Clegg Impact Value (CIV), also known as Impact Value (IV).
(refer to ASTM Standard D5874)

CLEGG Hammer
Available in various models, the Clegg Impact Soil Tester provides a means for measuring and controlling soil strength and consolidation levels in various construction applications. Simplified the CLEGG consists
of a compaction hammer operating within a vertical guide tube. When the hammer is released from a fixed height it falls through the tube and strikes the surface under test, decelerating at a rate determined by the stiffness of the material within the region of impact.
A precision accelerometer mounted on the hammer feeds its output to a hand held digital readout unit which registers the hammer deceleration.

Clegg CIST883 display

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Clegg 4.5kg Professional

CODE: CLEGG HAMMER

The 4.5kg Professional Clegg Impact Soil Tester is New Zealand's most popular Clegg.
It is used primarily in the roading and re-course/re-instatement industries.
One major benefit of the CIST/883 display is it's large clear viewing as well as it's ability to be removed and be used handheld.
The readout is clamped to the guide tube and the displayed reading is viewed from the top during use.
The Readout Unit displays readings of Impact Value (IV) and also shows the number of times that the hammer has been dropped during each test operation.

Another key feature of the CIST/883 controller is that the inferred %CBR calculated from the drops is displayed.
CIV is similar in concept to the CBR (California Bearing Ratio).
CIV may be used as an alternative to CBR in both laboratory and field samples.

For ease of use, the Clegg Professional has single button operation.

The Clegg Professional Impact Soil Tester features a durable very rugged design, suitable for prolonged use in dirty and harsh site environments.
The CIST/883 readout unit is made from high strength alloy that has been proven to last for decades.

This model runs on 2 x AA batteries, typically giving up to 12 months operation.

The Clegg Professional Impact Tester is available for HIRE.

Standand Package includes:
4.5kg Clegg Professional with T handle, guide tube & locating pin, CIST/883 controller readout unit with side clamps, 2x AA alkaline batteries, connecting cable, operational check ring, instruction manual, test calibration certificate, hard carry case.

Clegg CIST883 display






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Clegg 4.5kg Bluetooth

CODE: CLEGG HAMMER BT

The 4.5kg Bluetooth Clegg Impact Soil Tester is based on the popular Professional model (see above).

The Bluetooth Clegg features the same CIST/883 display with is it's large clear viewing as well as it's ability to be removed and be used handheld.

The major difference between the Clegg Professional and Clegg Bluetooth is the Data Logging feature.
The Bluetooth model features on board data logging and data storage with wireless data transfer facilities.
Users can download their test results from site to a Windows based PC, wirelessly, using the PC software supplied with the instrument.
This cable-free operation greatly enhances system reliability compared to cabled systems.
To transfer the data, Bluetooth wireless data transfer is used.
This cable free transfer is applicable to Microsoft based PC or laptops.
Note: Windows operating system limitations.
A Bluetooth USB Dongle provided.
The file transferred is a Comma Separated Variable (CSV) file with data for manipulation in third party packages such as Excel.
Up to 10000 x 5-drop test jobs can be stored for output.


The Clegg Professional Impact Soil Tester features a durable very rugged design, suitable for prolonged use in dirty and harsh site environments.
The CIST/883 readout unit is made from high strength alloy that has been proven to last for decades.

This model runs on 2 x AA batteries, typically giving up to 12 months operation.

Standand Package includes:
4.5kg Clegg Bluetooth with T handle, guide tube & locating pin, CIST/883 controller readout unit with side clamps, 2x AA alkaline batteries, software disk, connecting cable, operational check ring, instruction manual, test calibration certificate, hard carry case.

Clegg CIST882 display




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Clegg 4.5kg Basic

CODE: CLEGG HAMMER BASIC

The 4.5kg Basic Clegg Impact Soil Tester is the economical model in the Clegg roading range of testers.
It is designed as a low cost alternative to the Professional model (see above).

It is used primarily in the roading and re-course/re-instatement industries.

Compared with the Professional and Bluetooth models above, the Clegg Basic utilises the CIST/882 display controller instead of the 883.
The CIST/882 Readout Unit displays readings of Impact Value (IV) and also shows the number of times that the hammer has been dropped during each test operation.

There are several differences in the 882 and 883 display controllers.
The 882 has the display on the side of the unit instead of the top (883).
The 882 does not display the inferred %CBR calculated from the drops is displayed.
The 882 does not have the added facility of data transfer.
The 882 operates on a 9V battery.

For ease of use, the Clegg Basic has single button operation.

The Clegg Basic Impact Soil Tester features a durable very rugged design, suitable for prolonged use in dirty and harsh site environments.
The CIST/882 readout unit is made from high strength alloy that has been proven to last for decades.

This model runs on 1 x 9V battery.

Standand Package includes:
4.5kg Clegg Basic with T handle, guide tube & locating pin, CIST/882 controller readout unit, 1x 9V alkaline battery, connecting cable, operational check ring, instruction manual, test calibration certificate, hard carry case.

Clegg CIST883 turf display

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Clegg 2.25kg Turf

CODE: CLEGG HAMMER SPORT

The 2.25kg Turf Clegg is a Impact Soil Tester designed and manufactured for an easy and straightforward means for measuring the hardness condition of sports surfaces.

This model Clegg hammer provides good prediction of ball bounce for cricket surfaces and football pitches. Also used for equestrian surface checks, the instrument is used to confirm uniform surface characteristics over play areas and horse tracks.
The impact tester provides a quick and accurate method for monitoring variations in strength and for helping to determine the uniformity of an area. An example of its simplest application is to help determine soft spots or hard areas.
The CIST/883 display, similiar to the roading units above, registers the hardness values in units of Gravities (Gm). The Gm value is an indication of soil strength.

The Clegg Turf Impact Soil Tester features a durable very rugged design, suitable for prolonged use in dirty and harsh site environments.
The CIST/883 readout unit is made from high strength alloy that has been proven to last for decades.

This model runs on 2 x AA batteries, typically giving up to 12 months operation.

Standand Package includes:
2.25kg Clegg Turf with T handle, guide tube & locating pin, CIST/883 controller readout unit with side clamps, 2x AA alkaline batteries, connecting cable, operational check ring, instruction manual, test calibration certificate, hard carry case.