Laboratory investigation of geopolymer stabilized subgrade soil reinforced with Alkaline binder-coated Natural Jute Sheet

Soft subgrade soils often pose significant challenges in pavement design due to their low bearing capacity and high compressibility, and poor durability under repeated loading. As sustainable alternatives to conventional stabilizers gain attention, alkali-activated materials and natural fiber reinforcements offer promising solutions. This study explores the enhancement of subgrade soil strength through reinforcement with a natural jute sheet coated in a geopolymer-based alkaline binder (AB). The investigation examined the performance of stabilized subgrade soils under varying water-to-binder ratios and curing durations. Subgrade performance was assessed through California Bearing Ratio (CBR) and flexural strength tests, along with resilient modulus evaluation. The CBR value of the treated soil increased from 4.1% in untreated samples to 19.4% in AB-treated jute reinforced specimens. The resilient modulus also improved significantly, rising from 17.3 MPa (untreated) to 81.9 MPa (reinforced). Flexural strength increased by 216% compared to the untreated sample, confirming improved load-bearing capacity. Furthermore, 2D finite element simulations demonstrated a 71% reduction in vertical deformation under wheel load in the reinforced soil. The pressure bulb analysis confirmed more uniform stress distribution and reduced settlement, validating the effectiveness of this sustainable reinforcement method in improving subgrade performance.