Investigating impact sound insulation in cross-laminated timber (CLT)-concrete composite floors with embedded mechanical fastening: Experimental analysis and statistical energy analysis

CLT-concrete composite (CCC) floors are increasingly used in modern timber buildings for their superior strength and fire resistance over traditional cross-laminated timber (CLT) floors. However, their impact sound insulation remains problematic, potentially causing noise-related disputes. To investigate the impact sound insulation performance of CCC floors with varying structural design parameters and floating constructions, this study conducted laboratory tests on twelve full-scale floors. Impact sound insulation class was determined using single number indexes, primarily the normalized impact sound pressure level (L_n,w). The test results indicated that structural design parameters showed minor influence on the impact sound insulation performance of CCC floors (ΔL_w ≤10 dB), while floating constructions significantly enhanced the impact sound insulation performance (ΔL_w ≥21 dB). In contrast, a 31-mm-thick floating construction achieved an L_n,w value of 59.0 dB, elevating the impact sound insulation class to Level 4—outperforming previously reported results. Furthermore, a simplified statistical energy analysis (SEA) model was developed for the CCC floor system with a floating floor. The predicted L_n,w values aligned well with the test results, with errors below 6 dB. This study provides a research foundation for the design of sound insulation solutions and performance prediction of CCC floor systems in practical engineering applications.