Sound Insulation Performance of Sustainable LC<sup>3</sup> Mortars with Barite and Waste Rubber Aggregates

This study investigates the potential of limestone calcined clay cement (LC3) as a sustainable binder for developing a single-layer composite material incorporating barite and rubber aggregates, hypothesized to achieve enhanced sound insulation performance compared to conventional multi-layered wall systems. Mortars were prepared using LC3 with 55% clinker, 30% metakaolin, 15% limestone, substituting 45% of cement clinker. Hybrid mixtures of barite and rubber aggregates (barite-to-rubber volume ratios of 2:1 and 1:2) were tested at aggregate-to-binder ratios of 2.0, 2.75, and 3.5 to evaluate their combined mass and damping effects on acoustic performance. Experiments were conducted to determine physical, mechanical, and acoustic properties of the developed composites. Airborne sound transmission loss (STL) and Ravg (single-number descriptor derived from STL data) were measured with an impedance tube. Rsim (single-number descriptor derived from STL data) measured with INSUL in 1/3 octave bands. Results revealed that the mortar with an aggregate-to-binder ratio of 2.75 and a 2:1 barite-to-rubber combination (2B1R) achieved the highest Ravg (30.18 dB) value at 90 mm thickness and Rsim (50 dB) at 120 mm thickness, exceeding those of mixtures with ratios of 2.0 and 3.5. INSUL software simulations extended the experimental findings and provided predictions about room-scale result values, unlike impedance tubes.