Enhancing the floor impact sound insulation of reinforced steelmaking slag concrete slab utilizing lightweight aggregate and steel fiber for modular construction

With the growing emphasis on carbon neutrality, the concrete industry is increasingly focusing on cement replacement technologies and modular construction. Reducing the weight of floor concrete slabs is critical in modular construction; however, this can exacerbate floor impact sound, potentially compromising acoustic performance. This study investigates the effect of lightweight aggregate and steel fiber incorporation on the mechanical and acoustic performance of steelmaking slag concrete, where 15 % of the cement was replaced with steelmaking slag. The combination of lightweight aggregates and steel fibers facilitated pore interconnectivity, forming extensive pore channels within steelmaking slag concrete. As a result, the fiber-reinforced lightweight steelmaking slag concrete (LSSCF) exhibited the highest continuous porosity among all mixtures. While such porosity could potentially weaken mechanical performance, the bridging effect of steel fibers mitigated this issue, limiting the reduction in compressive strength to just 1 MPa (final strength: 64 MPa). Furthermore, the increased continuous porosity enhanced sound absorption, leading to the highest sound absorption area ratio (SAAR) of 0.34 and the greatest reduction in sound pressure level (SPL) of lightweight floor impact sound (LFIS). However, the inherent weakness of lightweight aggregates reduced the elastic modulus, adversely affecting the SPL of heavyweight floor impact sound (HFIS). Notably, the addition of steel fibers counteracted this effect, improving stiffness and reducing the single number quantity (SNQ) of fiber-reinforced steelmaking slag concrete (LSSCF, NSSCF) slabs by 1 dB compared to non-fibrous counterparts (LSSC, NSSC). These findings highlight the potential of hybrid lightweight aggregate-steel fiber incorporation in optimizing both the acoustic and mechanical performance of steelmaking slag concrete while offering economic benefits. This strategy is particularly advantageous in applications demanding enhanced structural integrity and superior sound insulation.