20 kg Clegg Impact Soil Tester

A universal instrument for the assessment of soil compaction, surface stiffness, and impact characteristics.

Dynamic Test

The basic principle behind the Clegg Impact Soil Tester is to obtain a measurement of the deceleration of a free falling mass (hammer) from a set height onto a surface under the device. The impact of the hammer produces an electrical pulse, which is converted into a Clegg Impact Value (CIV). Four successive blows of the hammer on the same spot constitutes one test with the peak CIV output to the digital display. The CIV is displayed in units of tens of gravities. This value correlates to the California Bearing Ratio, Texas Class Number, Elastic Modulus, and PSI. Reference ASTM test methods D5874 and F1702.

The Clegg offers the convenience of rapidly scanning compaction variation over large areas. In research studies, 250 tests were performed with the Clegg in a half-day.

Durability

The Clegg is constructed to be extremely durable and easy to operate. The hammer has a hardened strike face, and comes in weights of 0.5 kg, 2.25 kg, 4.5 kg, and 20 kg. The guide tube is metal and will provide years of reliable, accurate service. The control box features a digital display and is powered by a standard 9-volt battery. During operation, the control box may be hand held or mounted to the guide tube.

Simple and Quick Test Procedure

The test procedure is very rapid and can easily be performed by site personnel with minimal training. Each test can be completed in less than 30 seconds. The results are immediate.

• Select a level surface. (If needed, lightly scuffing surface with a foot to level the strike area.)
• The guide tube is set into position, secured by placing a foot on the tube base flange and steadied with the lower leg and knee.
• The On / Reset Button on the control box is pressed and released to activate the circuitry.
• The hammer is raised to the drop height indicator mark.
• The hammer is released allowing it to fall freely and cleanly.
• Without moving the guide tube or repressing the On / Reset button, the Hammer is raised to the mark and released three more times.
• The value (CIV) displayed after the fourth blow is recorded and the display automatically powers down 30 seconds after activation.
• Move to next test site.

Versatility

The Clegg may be transported and operated by one person, allowing for low cost, rapid field and laboratory testing, as well as direct readout of the test results.

The Clegg can test a full range of soils and stone as encountered in the construction of flexible pavement and earthworks. It is useful for quickly checking variations during construction and monitoring changes over time due to seasonal environmental changes or road traffic as well as testing natural and "as constructed" conditions.

The Clegg can test a full range of natural and artificial athletic surfaces where hardness / impact characteristics need to be controlled for safety or playability.