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This paper presents a method that measures an impact process of a spherical object colliding with on a testing material and, through analytical techniques based on Hertz's theory of impact, deduces the elastic modulus of the tested material. Furthermore, by distinguishing the compress and rebound phrases, and by accounting for the plastic deformation characteristics of the tested material, this method can measure the compressive modulus and rebound modulus simultaneously. This method is suitable for testing various materials, such as steel, concrete, and geomaterials including cement-treated soils. Various deformation parameters can be deduced from this method, including compressive modulus, subgrade soil modulus K30, California Bearing Ratio (CBR) value, and Benkelman Beam Deflection value. This method is shown to be very accurate in a large number of validation tests performed by the authors. Its advantages include broad applicability, high efficiency, and relatively large strain (thus also capable of evaluate material strength). Results from field implementation in actual civil projects show that this method has great potential in many applications, particularly real-time fill materials quality assurance and construction optimization. |
