Comparative evaluation of hybrid flax fiber reinforced normal and foamed mortar using five aggregates for sustainable and acoustically enhanced non-load-bearing applications

Abstract

As the use of cement-based materials which are lightweight, thermally and acoustically efficient is becoming popular, there is growing research into alternative aggregates and natural fibers for use in construction. Whereas each material individually has been explored, the potential impact of these materials together in normal and foamed mortars is not well understood. This research involved the production of twenty composites, which were made using five aggregates that included crushed sand, expanded clay, pumice, expanded vermiculite, and recycled rubber combined with normal and foamed mortars both with and without flax-fiber reinforcement. This was done by means of testing such as dry unit weight, porosity, compressive strength, ultrasonic pulse velocity, thermal conductivity, and sound absorption. Results revealed that the performance of the mortars depends on aggregate morphology, porosity, and matrix material. The maximum strength was recorded for the normal crushed sand aggregate sample with compressive and flexural strength of 49.9 MPa and 10.6 MPa, respectively. The minimum density and thermal conductivity values were recorded for the flax-fiber-reinforced foamed-mortar mixture containing expanded vermiculite sample with values of 562 kg/m³ and 0.198 W/m.K, respectively. In contrast, the flax-fiber-reinforced foamed-mortar mixture containing waste rubber had the maximum sound absorption coefficient with a NRC of about 0.5740 for the thickness of 5 cm due to viscoelastic damping ability of rubber particles. Therefore, considering its low density, high sound absorption, and moderate thermal-insulation performance, F-KAU-KL can be considered a promising material for protected non-load-bearing applications, such as interior acoustic linings, insulation layers, lightweight infill, and sandwich-panel cores.