Comparative Experimental Study between Hemp and Pineapple Fiber Wastes as Additional Materials to Improve Acoustic Performance in Concrete Blocks

The sustainability of building materials is receiving increasing attention, particularly through the use of agricultural waste as a low-cost, renewable raw material in concrete mixtures, either as a replacement or an additional component. The additions of hemp and pineapple fibers at 10, 20, and 30% by volume of sand with lengths of 6, 12, and 18 mm were compared for their physical, mechanical, and sound acoustic properties. The results showed that increasing the fiber content decreased the density and led to higher water absorption in concrete containing hemp fiber, while there was a trending decrease in concrete containing pineapple fiber. The optimal fiber was found to be 10% with 12 mm of the highest compressive and tensile strengths. Superior acoustic performance at 1,000–3,150 Hz was detected in pineapple fiber incorporated with concrete, whereas hemp fiber was superior at the higher frequency of 4,000 Hz. For concrete blocks, the density and water absorption were higher than those of plain concrete blocks. Although the compressive strength of concrete blocks mixed with hemp and pineapple fibers decreased, it was still within the range of non-load-bearing concrete blocks. The finding demonstrated that hemp and pineapple fibers incorporated with concrete blocks proved effective for sound absorption on walls.