Acoustic modelling of textile fibre reinforced mortars and their sound absorption performance

This study focuses on the acoustic behaviour of fibre-reinforced mortars incorporating polyester, nylon, cotton, and elastane fibres. Micro-computed tomography was employed to estimate key acoustic pore characteristics, including open porosity, flow resistivity, and tortuosity. These parameters served as initial inputs for inverse estimation using the Johnson-Champoux-Allard acoustic model. The model's accuracy was validated through impedance tube measurements of the sound absorption coefficient and surface acoustic impedance. The model demonstrated strong predictive accuracy, with an average root mean square error of 0.0025 ± 0.0012 within the 500–1500 Hz frequency range, corresponding to the typical range of traffic noise. This suggests that the model can be effectively used to predict the sound absorption of textile fibre-reinforced mortars for traffic noise mitigation applications, eliminating the need for laboratory testing. Sensitivity analysis showed that open porosity and flow resistivity have a significant influence on acoustic performance, while tortuosity has a moderate impact. Good agreement was observed between micro-computed tomography-derived porosity and inverse-estimated porosity for all fibre-reinforced mortars. However, the limited resolution of micro-computed tomography, along with assumptions of the Johnson-Champoux-Allard model, such as homogeneous and isotropic pore geometry led to discrepancies in the predicted flow resistivity and tortuosity of specific mortars. Correlation analysis of micro-computed tomography derived pore characteristics with the average sound absorption revealed a strong relationship between open porosity and the sound absorption average. Based on this, a linear regression model was proposed to predict the sound absorption average using open porosity values. This work represents one of the first comprehensive studies to acoustically model textile fibre-reinforced mortars by combining microstructural analysis with theoretical predictions, supporting the development of sustainable, sound-absorbing cementitious materials. • Sound Absorption Coefficient (SAC) of fibre-reinforced mortars was measured and predicted. • The Johnson-Champoux-Allard model closely matches experimental SAC values. • Open porosity, flow resistivity, and tortuosity are key influencing parameters. • A linear model predicts sound absorption average based on open porosity. • Predicted surface impedance showed ≤10 % error for elastane mortars at 600-1400 Hz.