Structural evaluation of pavements

The structural evaluation of pavements is conducted primarily by suitably designed devices and is a non-destructive procedure. However, destructive tests are often necessary to be carried out to confirm the results of the non-destructive structural evaluation of the pavement. On a project level, destructive testing alone may be sufficient for pavement structural evaluation. 

The destructive tests comprise core extraction and trench opening. Core extraction is necessary for the determination of (a) the thickness of the asphalt layers, (b) the degree of compaction, (c) the composition of the asphalt, (d) the mechanical properties of the asphalt and (e) the extension/initiation of cracking within the asphalt layers. 

The non-destructive structural evaluation of a pavement may be carried out by a wide variety of deflection measuring devices. The devices may be classified into three categories (a) static devices, (b) semi-static devices and (c) moving or rolling devices. 

Static devices are those that have to stop to take measurements and the loading is rolling, vibrational or impulse. 

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The FWD was initially developed in France in 1963 (Bretonniere 1963) and then evolved in Denmark (Ullidtz 1987) as an alternative non-destructive device for structural evaluation of pavements. Today, the following FWDs exist on the market Dynatest (Dynatest International A/S 2014), KUAB (ERI2014), PRIMAX (Grontmij A/S) and JILS (JILS) FWD. 

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