Desempenho acústico de laje com vigota e lajota: isolamento ao som aéreo e de impacto

Abstract

Resumo Considerando o uso expressivo no cenário nacional de lajes pré-fabricadas de concreto com elementos inertes de preenchimento do tipo cerâmico, este trabalho contém a avaliação do comportamento do sistema frente a ruídos aéreos e de impacto, em diferentes composições. Foram realizados ensaios em câmara reverberante vertical, conforme a ISO 10140-5:2010. As variações empregadas nos sistemas foram contrapiso, camada resiliente, revestimentos de laminado de madeira e porcelanato, reboco de argamassa e forro suspenso. Os resultados evidenciaram que o desempenho acústico ao som de impacto da laje pré-fabricada de concreto com lajota cerâmica é afetado pelo efeito da ressonância nas cavidades das lajotas e que a adição de contrapiso pode compensar o menor isolamento acústico em comparação à laje de concreto maciço, em razão do consequente aumento na massa do sistema. Os resultados também mostraram que, para o isolamento ao ruído aéreo, não existem diferenças significativas entre os revestimentos de porcelanato e piso laminado e que a instalação do forro compensou a reduzida perda de transmissão sonora da laje vigota/lajota em relação à laje de concreto maciço.

Floor impact noise performance of prefabricated prestressed joists and block slabs with wooden laminate floors

“…Thus, in samples from S3 to S7, it was observed that the addition of a laminate flooring in the system improved sound insulation at medium and high frequencies, noting that the increase in mass caused by the addition of laminate flooring was negligible when considering the total mass of the system (mass + subfloor). This phenomenon was also observed in the work by Oliveira et al (2021), in which the addition of 4 cm of subfloor and porcelain tile coating reduced sound levels from the 400Hz band, but there was no change in the graphic profile because it is a system that is a damping resource.…”

“…This was also confirmed in the study by Oliveira et al (2021) who studied the acoustic performance of t-beam and hollow-block slabs: airborne and impact noise insulation and concluded that with the progressive addition of layers in the slab, it resulted in lower L 'nT values. Thus, it is denoted that when adding more mass to the system, due to the mass law, L' nTw tends to improve.…”

“…The performance of Sample 3, comparing the reference values of the bare slab (Sample 1) and slab with subfloor (Sample 2), presents a curve with an inverse behavior, that is, descending. This behavior is inextricably linked to the damping and surface density found in the wooden laminate floor coverings (OLIVEIRA et al, 2021), which shows the highest performance values at low frequencies (68 dB) and the lowest values at high frequencies (37 dB). The value of L' nT,w is 60 dB, which in the performance standard is the intermediate category, even without using insulation.…”

“…In both samples with (S3 to S7) or without subfloor (S8 to S12) and in samples with floating floor (S13 to S39), there was a decay in sound levels from 400 Hz. It is noteworthy that the composition with only wooden laminate floor cannot be conceptualized as a floating floor because it does not have enough mass in the upper layer and also because it does not have a characteristic damping in the elastic layer (OLIVEIRA et al, 2021).…”

“…Moreover, studies show that T-beam/hollow-block slabs present most of the sound transmission in the spaces of the ceramic tiles because they allow the internal reverberation of sound and amplify the sound waves in some central frequency bands (HOPKINS, 2012). Other studies show that adding subfloors can compensate for the lower sound insulation compared to solid concrete slabs due to the mass law which increases the mass of the entire set (OLIVEIRA et al, 2021).…”