Assessment of the Physical and Mechanical Properties of Autoclaved Aerated Concrete (AAC) Incorporated with Sisal Fibers and Nano-Aluminum Particles

Introduction Autoclaved Aerated Concrete (AAC) is a lightweight, thermally insulating, and fire-resistant building material that has gained popularity in sustainable construction due to its lower energy requirements during production and minimal environmental impact. AAC is composed of cement, sand, lime (CaO), water, and nano-aluminum powder. Despite its excellent physical properties, its mechanical resistance remains low. This study aims to examine the effect of sisal fibers and nano-aluminum on the physical and mechanical properties of autoclaved aerated concrete blocks. Methods The experimental program involved adding Sisal fibers to the AAC mix; additionally, the aluminum in AAC was replaced with nano-aluminum. Three samples were produced and labeled A, B, and C, with sisal fiber contents of 0.1%, 0.2%, and 0.3% by total volume, each sample consisting of three specimens for each test. The total number of samples are 36. Results The results show that AAC reinforced with nano-aluminum and sisal fibers improved compressive and flexural strength. However, the density increased to between 734 kg/m 3 and 752 kg/m 3 , while the thermal conductivity reached 0.19 W/m.K. According to the ASTM C 1693-11 specifications, which define the density as 400 to 800 kg/m 3 , compressive strength as 2 MPa to 8 MPa, and thermal conductivity as 0.09 to 0.18 W/m.K. Discussion The improvement in mechanical performance is attributed to the reinforcing effect of sisal fibers, which bridge micro-cracks, and the high reactivity of nano-aluminum. SEM analysis confirmed the formation of well-developed tobermorite structures, which are responsible for the increased strength. While the thermal conductivity (0.19 W/m.K) slightly exceeded the standard range (0.09-0.18 W/m.K), it remains within an acceptable range for structural efficiency. Conclusion The incorporation of sisal fibers and nano-aluminum transforms AAC into a stronger material. This modified AAC is suitable for lightweight structural units and low-rise load-bearing walls in residential buildings, providing a balance between sustainability and structural integrity.