Desempenho acústico de sistemas de pisos com a utilização de lajes pré-fabricadas nervuradas de vigotas protendidas

Abstract

Precast beam-and-block floor systems of prestressed beams and inert filling elements are a frequent used technical solution in residential buildings, where normative requirements of acoustic performance are applicable. Despite this context, there is still a considerable gap in knowledge regarding the acoustic performance of this constructive system. This study evaluated the behavior of beam-and-block systems, with prestressed beams and ceramic hollow blocks towards air and impact sound, analyzing the influence of different blocks and different layers complementary to the structural layer. The study conducted experimental (laboratory) and numerical (computational estimate, with software SONarchitect®) analysis in 21 distinct slabs compositions, with 2 of these compositions replicated in a building for experimental analysis in the field. The use of higher thick blocks, although it did not reflect on better performance when analyzed slabs composed only by its structural layer, influenced the behavior of the systems when added complementary coating layers, and greater efficiency assigned by the coating layers was observed in the systems of greater rigidity (with the most thick blocks). The results showed that solutions that give greater efficiency to the floor systems in relation to airborne sound do not necessarily constitute the most efficient solutions to impact sound. For airborne sound, the increase of mass from the addition of complementary layers has little impacted systems efficiency, unlike expected on homogeneous constructive systems, reinforcing the thesis that sound means of transmission in heterogeneous slabs are more complex. Regarding impact sounds, the successive addition of layers provided greater efficiency to the analyzed floor systems, with significant gains when applying a laminate floor finish layer, reinforcing the strong influence of the elastic characteristics of the floor system surface. In all systems evaluated in this study, the resonance effect was observed within the cavities of the hollow blocks, either in experimental analyzes in laboratory and field, eather in the computational numerical analysis. However, the installation of suspended plasterboard lining compensated part of the reduced loss of sound transmission resulting from this phenomenon, both in the laboratory samples and in the field analysis. Still, in the field, the impact pressure levels observeds indicate that the presence of a suspended plasterboard lining was able to minimize the effects of a probable failure on the damping system (resilient layer), possibly due to executive inconsistency in the floating floor (resilient layer). Differences observed between estimated and field values may indicate that variables not considered in statistical energy analysis methods, such as beams direction and floor system linking with adjacent structural elements, influence at sufficient scale the results to change system classification before the requirements of NBR 15575-3.