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Clegg impact hammer: an equipment for evaluation of the strength characteristics of pavement materials, turf, and natural and artificial playing surfaces: a review

The Clegg impact hammer (CIH) was developed by Baden Clegg for engineering purposes in 1976. The CIH was designed to measure and control the mechanical properties of road materials during construction. Nowadays, the device is used all around the world for a wide range of applications ranging from road applications to sports surfaces. The objective of this study is to review the various types of CIH and their current applications in geotechnical engineering and the control of stiffness of natural and artificial playing surfaces. Many relationships including the correlations between the Clegg impact value (CIV) and other soil parameters, such as the California bearing ratio (CBR) and resilient Modulus (Mr), with a range of R2 values, have been reviewed and discussed. It is concluded that the Clegg impact hammer is a valuable item of equipment and provides a simple method for estimation of the density, strength, and behaviour of materials under dynamic repeated loads. However, correlations developed specifically for different types of material and condition are recommended for more reliable results.