NONDESTRUCTIVELY DELINEATING CHANGES IN MODULUS PROFILES OF ROAD CONSTRUCTIONS

The spectral-analysis-of-surface-waves (SASW) method is a nondestructive seismic method which has been used in situ to determine the elastic moduli of soils and pavements at low levels of strain and the variation of these moduli with depth. In this method, the applicability of the SASW method to the identification of (1) changes in stiffness profiles during road construction, (2) the quality of the road construction, and (3) possible alkali-silica-reactions (ASR) was investigated. Results are presented from experimental laboratory studies on a small scale concrete road and a full scale test site where the modulus profile of every construction phase of a reinforced concrete road, starting with the embankment, surface compaction, foundation and top layers was evaluated. Falling weight deflectometer (FWD) test results on an asphalt pavement were compared with the elastic moduli out of the SASW test and structural stiffness changes by ASR were measured on a parking lot.