Evolution of the optimum ultrasonic testing frequency of alkali-activated soil-ash

• Type: Article in International Scientific Journal
• Date: 2021-08-27

Authors

Cristiana Ferreira (Author) FEUP; Sara Rios (Author) FEUP; N. Cristelo (Author) Other; António Viana da Fonseca (Author) FEUP

Journal

Title: Geotechnique Letters

Vol. 11

Pages: 158-163

ISSN: 2049-825X

Publisher: ICE Publishing

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-00V-HM8

DOI: 10.1680/jgele.21.00041

Abstract (EN): Monitoring the curing process of mixtures produced by soil, fly ash and alkaline solution can be effectively performed by ultrasonic measurements of compression and shear wave velocities. These measurements detect the evolution of stiffness with time, as a result of alkali-activated ash reactions. Conventionally, ultrasonic testing relies on the use of a fixed input frequency, corresponding to the nominal frequency of the transducer, for which a maximum response is expected from the transducers. This procedure, however, has shown some limitations especially when applied to materials under curing, in which stiffness is changing with time. To overcome these limitations, a wide range of frequencies, from 24 to 200 kHz, was used at each of the selected curing periods for determining wave travel time, instead of a single frequency reading. The results show a clear increase in the optimum frequency with curing time, indicating that the ultrasound testing frequency should be adjusted to account for the stiffness increase due to curing. Additionally, the use of frequencies other than the nominal frequency of the ultrasonic transducers generated clearer signals, particularly at early curing periods.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 6