We demonstrate that a scanning acoustic microscope (SAM) operating in the f
requency range 100-400 MHz can detect cracks at the aggregate/paste interfa
ce and subsurface cracks in aggregates with high sensitivity. A complete in
terpretation of the obtained results has been made by combining high and lo
w frequency acoustic microscopy, SEM, optical microscopy, and energy disper
sive (X-ray) spectroscopy. (C) 2000 Elsevier Science Ltd. All rights reserv
ed.