Sandy Soil Improvement through Biopolymer Assisted EICP
Mohamed Refaei, Mohamed G. Arab, Maher Omar
Abstract
Bio-inspired improvement of soils via enzyme induced carbonate precipitation (EICP) has attracted increasing attention over the past decade. EICP employs the hydrolysis of urea (ureolysis), a process catalyzed by the urease enzyme, to precipitate calcium carbonate (CaCO3) in the presence of calcium ions. This paper describes a preliminary experimental study on improvement of sand shear strength through the use of EICP along with sodium alginate biopolymer for surficial soil applications. In this research, the sodium alginate biopolymer was used to evaluate the ability of the biopolymer hydrogel to improve EICP by holding the reaction substance around the soil particles. Unconfined compression strength (UCS) test of the treated soils was measured to evaluate enhancement in soil strength. Scanning electron microscope (SEM) imaging was conducted to study the microstructure and identify the presence of crystalline materials in treated sand samples. The results indicate that the incorporation mix of EICP and SA significantly improved the UCS compared to the samples treated with only EICP. The improvement is mainly attributed to the inter-particle bonding effect of both carbonate precipitant and biopolymer.