Transmission loss simulations for floor systems with composites of scrap tire rubber particles and adhesive mortar

This work aims to evaluate the transmission loss (TL) of a three-layer floor system with a porcelain finishing layer, a mortar fixation layer and a concrete structural layer by simulation using the visualTMTX software [1]. Fixation layer was exchanged between pure mortar, and composites of mortar and scrap tire rubber particles with two different granulometries (between 18-35 mesh and between 35-60 mesh named here as M35 and M60, respectively), and containing 15% (in mass) of rubber particles. TMTX code simulates a multilayer system with a finite thickness in the Z axis and infinite dimensions in X and Y axes where plane waves are propagated. First and last layers represent the incident and the receptor medium, in this case, air. The simulation software uses the material properties to find the continuity relations in a border point in order to obtain the incident and transmitted wave amplitudes, and thus calculate the energy transmission coefficient. Hence, the elasticity modulus of pure mortar and mortar/rubber composites were determined through a compression test with cylindric samples of 21 mm diameter and 55 mm length. Poisson's ratio was calculated by the ratio of the dynamic shearing modulus obtained from Dynamic Mechanical Analysis (DMA) and the elasticity modulus. Results showed a decrease from approximately 6 MPa for the pure mortar to 2 MPa in the composites elasticity modulus. The critical frequency for the system with M35 composite (near of 600 Hz) decreased regarding the critical frequency of a system with pure mortar (approximately 1000 Hz); for the mass controlled region, the TL values for both systems were almost the same (56 dB and 60 dB for M35 and pure mortar, respectively). An increment of approximately 10 dB was obtained in the damping controlled region for M35 composite system compared to the pure mortar. For the system with M60 composite, the critical frequency (near of 1500 Hz) increased regarding the system with pure mortar. In this case, the transmission loss in the mass controlled region was very close to that observed for the system with pure mortar. In the damping controlled region, for the system with M60 composite TL was lower compared to the system with pure mortar.