In the surrounding rural region of Hawassa village houses are constructed by using soil, wood, teff straw, and water which is called chika in the local name, although its degradable materials prompt a shift to adobe brick for durability. Adobe brick, prevalent in rural locales, offers social, economic, and cultural advantages. However, its inherent flaws include brittleness, low compressive, and tensile strength, along with moisture sensitivity. This research aims to enhance the native soil attributes of Hawassa villagers by integrating sisal fiber for brick production. The investigation employed soil, water, and sisal fiber to create enhanced adobe bricks. A displacement controlled uniaxial testing machine was utilized to evaluate the compressive strength of the bricks. Findings indicated that a 0.9% sisal fiber inclusion achieved a maximum compressive strength of 13.44 MPa, outperforming conventional samples by 3.4 times, alongside a flexural strength of 0.097 MPa, exceeding conventional results by 3.34 times. The study includes a comparative analysis of mechanical properties and a cost evaluation between traditional and enhanced approaches.

In this research, a soil reinforcement approach was explored by introducing a polyvinyl acetate polymer treatment along with sisal fiber material, considering two mean particle sizes (D50 = 0.63 and 2.00 mm). The sand specimens were mixed with varying sisal fiber contents (Fs = 0 to 0.8%) and polyvinyl acetate polymer contents (PVAc = 6%, 9%, and 12%). A series of unconfined compression tests were performed to evaluate the compressive strength of the tested materials. The experimental findings indicate a positive correlation between the concentration of polyvinyl acetate polymer and the unconfined compressive strength within the tested range. The shear strength and of the sand initially increases with rising sisal fiber contents and then decreases with further increments in sisal fiber, peaking at a maximum value when the fiber content reaches a threshold of 0.6%. The findings validate the significance of the strain energy parameter as a reliable indicator for elucidating and forecasting the mechanical characteristics of soil reinforcement. New correlations have been developed to predict variations in unconfined compressive strength and peak strain energy based on the studied parameters (Fs, PVAc, and D50). The agreement between predicted and measured characteristics validates the effectiveness of these established relationships in accurately predicting UCS and strain energy factors.

In response to escalating environmental concerns, this study explored the use of sisal fiber as a sustainable alternative to traditional cement or synthetic fibers for soft soil stabilization. An optimal selection test was conducted to determine the optimal sisal fiber characteristics and their impact on the mechanical performance of cemented soil. The findings indicated that incorporating sisal fibers into cemented soil inhibits crack propagation, thereby enhancing its strength and ductility. A significant improvement was achieved by incorporating optimal fiber parameters (content = 0.4 %, length = 11 mm) into the cemented-soil, the compressive strength reached 4.4 MPa (by 29.4 %). In addition, to further improve the work performance of sisal fibercemented soil (SFCS), alkaline and acetylation treatments were applied, respectively, to prevent volume instability and degradation of sisal fiber. The study also evaluated the effects of these modification methods on the physical properties of sisal fiber and the strength of sisal fibercemented soil (SFCS). The results showed that a 6 % NaOH treatment was determined to be the most effective modification method, reducing the moisture affinity of sisal fiber, improving fiber-matrix bonding, and consequently enhancing the mechanical properties of SFCS (by 18.7 %). However, it should be noted that an excessively high concentration may adversely affect fiber properties, negatively impacting the strength of SFCS (by up to 11.59 %).

As one of the world's most fragile and sensitive ecological regions, Xizang risks significant environmental damage from using traditional materials, including cement and lime, to improve and reinforce loose accumulated sandy soil slopes. To address this issue, this study utilized a low-concentration biodegradable polyvinyl alcohol (PVA) solution combined with sisal fibers (SFs) to stabilize loose accumulated sand in southeastern Xizang. A series of physical, mechanical, and microscopic analyses was conducted to evaluate the properties of the treated sand. The results indicated the following. 1) The stress-strain curves of the improved samples exhibited an elastic-plastic relationship. Failure was observed in two stages. At a strain of 3% or less, the samples demonstrated elastic deformation with a linear increase in stress, whereas the deviator stress increased rapidly and linearly with an increase in axial strain. Once the strain exceeded 3%, the deformation became plastic with a nonlinear increase in the stress-strain relationship, and the growth rate of the deviator stress gradually decreased and leveled off. 2) Under varying confining pressure conditions, the relationship curve between the maximum (sigma 1-sigma 3)max similar to sigma 3 for both untreated loose accumulated sandy soil and soil improved with the PVA solution, and the sisal fiber was approximately linear. 3) The SFs created a skeletal-like network that encased the soil particles, and the hydroxyl functional groups in the PVA molecules bonded with both the soil particles and the fiber surface, thereby enhancing the interfacial properties. This interaction resulted in a tighter connection between the soil particles and SFs, which improved the stability of the structure. 4) The incorporation of a PVA solution and SFs significantly enhanced the mechanical strength and deformation resistance of the loose accumulated sandy soil. The optimal ratio for the improved soil was SP = 3% and SL = 15 mm, which increased the cohesion from 24.54 kPa in untreated loose accumulated sandy soil to 196.03 kPa. These findings could be applied in engineering practices to improve and reinforce loose accumulated sandy soil slopes in southeastern Xizang and provide a theoretical basis for such applications.