Estimating the Acoustic Absorption of Wood-Infused Concretes

Abstract

In architectural design, few materials compare to the degree of use of concrete. Due its high compressive strength and economic efficiency, concrete excels in architectural applications. While impressive, concrete has shortcomings in its acoustic absorption properties and ability to be used sustainably. To address both concerns, the proposed solution is to introduce waste wood fibers into concrete's composition. Due to wood's fibrous nature, acoustic absorption can be bolstered while improving sustainability by recycling waste wood products. While manufacturing wood infused concretes and measuring acoustic absorption is not difficult, it is time consuming and resource intensive. Therefore, a model to estimate acoustic absorption coefficients of fiber-infused concretes is developed to aid in bypassing the need for experimental trial-and-error. The model utilizes the Delany-Bazley (DBz) and Johnson-Champoux-Allard-Lafarge (JCAL) models to predict acoustic absorption coefficients of given fiber-infused concretes. The DBz model provides an estimate of the characteristic impedance and wave number of a sample based on a power-law relationship that considers sound medium and airflow resistivity. The DBz model estimates are then refined by the JCAL model using estimated viscous and thermal properties of the sample. Finally, using these refined acoustic property estimates, the acoustic absorption coefficients are estimated. Using varying wood-infused concrete samples, results are experimentally verified using an impedance tube and absorption coefficients are calculated using the transfer-function method. After comparing estimated and measured absorption values, the current model was found to have the potential of providing a relative comparison of acoustic performance between compositions. However, estimated values were not accurate, nor considered representative of samples. Further, multiple aspects of the model could be improved to better represent different concrete compositions in model estimations.