Assessment of Destruction Processes in Fibre-Cement Composites Using the Acoustic Emission Method and Wavelet Analysis

In recent years, there has been a growing interest in fibre-cement boards as a finishing material for facades, internal walls and roofs. These panels, used in construction for over one hundred years, are made of natural ingredients such as cement, cellulose fibres and polyvinyl alcohol fibres (PVA), water and mineral fillers. It should be emphasized that due to the method of use, these elements carry loads of significant value as a result of wind pressure and suction. In addition, the boards are exposed to long-lasting atmospheric conditions such as rainfall, significant temperature fluctuations. The threatening factors also include the possibility of exceptional conditions, including fire. Long-term exposure to various types of conditions results in a significant reduction of the material's durability after only a few years of use. In connection with the above, it is considered that it is recommended to conduct research to assess the state of fibrous - cement elements exposed to the conditions, for which they will be exposed to during operation. The article presents the possibility of using the acoustic emission method (AE) and time-frequency analysis as tools for monitoring the state of cement-fibre boards. Three-point bending tests were carried out on air and dry samples, soaked for 1 h and 24 h. Acoustic emission signals were acquired during the tests. The obtained results allowed to follow the mechanisms of destroying the examined elements and to observe the influence of the conditions and their duration on changing the way of destroying the elements.