*Article* **Application of the Acoustic Emission Method and Artificial Neural Networks to Assess the Damaging Effect of High Temperature on the Structure of Fibre-Cement Boards**

**Tomasz Gorzela ´nczyk \*, Krzysztof Schabowicz and Mateusz Szymków**

Faculty of Civil Engineering, Wrocław University of Science and Technology, Wybrzeze Wyspia ´ ˙ nskiego 27, 50-370 Wrocław, Poland

**\*** Correspondence: tomasz.gorzelanczyk@pwr.edu.pl

**Abstract:** This article shows the results of research into the damaging effect of high temperature on the structure of fibre-cement boards. Samples of fibre-cement boards were exposed to high temperatures over various lengths of time and then they were investigated under the three-point bending and acoustic emission methods. In this way, the critical temperature and the duration of its influence on the structure of a fibre-cement board were determined. An artificial neural network was used to analyse the results obtained using the acoustic emission method. The investigations showed a marked fall in the number of registered AE events for the tested series of boards exposed to high temperature in comparison with the reference boards. Moreover, in the boards exposed to high temperature, a marked increase in the energy of AE events occurs during the bending test, whereby the registered events, by and large, come down to a single pulse induced by a brittle fracture. It is also demonstrated that the determination of the damaging effect of high temperature on the structure of fibre-cement boards solely on the basis of bending strength (*MOR*) is inadequate.

**Keywords:** artificial neural networks; non-destructive testing; fibre-cement boards; acoustic emission; SEM
