Ultrasonic characterization of GRC with high percentage of fly ash substitution

• Glass-fibre reinforced cements with high percentages of fly ash were characterized.
• Microstructural, mechanical and ultrasonic analyses have been correlated for GRC.
• Ultrasonic frequency sweep has been carried out for GRC characterization.
• Signal attenuation was larger for highest water/binder ratio.
• Ultrasonic velocity changed with the variation of water/binder ratio.

New applications of non-destructive techniques (NDT) with ultrasonic tests (attenuation and velocity by means of ultrasonic frequency sweeps) have been developed for the characterization of fibre-reinforced cementitious composites. According to new lines of research on glass-fibre reinforced cement (GRC) matrix modification, two similar GRC composites with high percentages of fly ash and different water/binder ratios will be studied. Conventional techniques have been used to confirm their low Ca(OH)2 content (thermogravimetry), fibre integrity (Scanning Electron Microscopy), low porosity (Mercury Intrusion Porosimetry) and good mechanical properties (compression and four points bending test). Ultrasound frequency sweeps allowed the estimation of the attenuation and pulse velocity as functions of frequency. This ultrasonic characterization was correlated successfully with conventional techniques.