<p>The current study highlights the effectiveness of triangular-shaped polyester fiber in enhancing the geotechnical prospects of lime-treated expansive soil. A series of laboratory tests were conducted on different soil specimen conditions such as unstabilized, stabilized (lime-treated), and reinforced clay. To examine the optimum lime content, clay was mixed with different dosages of lime ranging from 2 to 8% with an increment of 2%. The inclusion of randomly oriented synthetic fiber with the stabilized clay at optimum lime content indicates the reinforced clay condition. The quantity of fiber content was amended as 0.5, 1, 1.5, and 2%. The unconfined compressive strength (UCS), California bearing ratio (CBR), and consolidation tests were conducted. From the results, the UCS and CBR of the clay were improved to a maximum corresponding lime content of 6%, considered an optimum value. Furthermore, the strength and deformability behavior of stabilized clay was enhanced significantly up to the addition of 1% fiber beyond which it becomes insignificant. In the case of reinforced clay, an 8.85 times improvement in the UCS was noticed as compared to the unstabilized clay. The ductility index of stabilized clay was enhanced by 1.85 times with the inclusion of fiber. Similarly, soaked CBR of an unstabilized and stabilized condition was improved by 7 and 2.1 times, respectively, upon the inclusion of fiber reinforcement. Furthermore, volumetric shrinkage and crack propagation of unstabilized clay were reduced significantly. Based on the outcomes, the reinforced clay can be suggested as a potential subgrade material in terms of mechanical strength and ductility properties.</p>