In recent years, biopolymers have been widely used in soil, but few concentration on the application of biopolymers in the organic soil. In this work, the potential using locust bean gum for improving the physical characteristics of the organic soil has been fully evaluated, while the Atterberg limit test, unconfined compressive strength test, and unconsolidated undrained shear test were conducted. In addition, the mineral composition and micro-mechanisms have been analyzed by X-ray diffraction tests, Fourier transform infrared spectra tests, and scanning electron microscopy tests. And we found that locust bean gum could increase the liquid limit and plastic limit of the organic soil, and enchance the compressive strength and shear strength. The increase in soil cohesion with locust bean gum content was more pronounced than the increase in internal friction angle. And as the curing time progresses, locust bean gum gradually transformed from a hydrogel state to a high tensile strength biofilm or flocculent gel matrix, which enhanced the bonding force between soil particles, thus increasing the strength of the specimens, which can be validated by the scanning electron microscopy observations, in which the porosity of soil was significantly reduced. We believed that this work could provide an ecological, economical and practical insight dealing with the engineering project constructions in the organic soil area.

Geopolymer lightweight cellular concrete (GLCC) combines the advantages of geopolymer and LCC but also suffers from the inherent deficiency of low strength, which can be improved by introducing suitable reinforcing materials such as fibers. This paper investigated the mechanical properties and microstructure of fly ash-slag-based GLCC reinforced with glass fibers (GLCCRGF), aiming to reveal the strengthening mechanism of glass fibers. The effects of different fiber contents (0.0, 0.3, 0.6, 0.9, and 1.2%), fiber lengths (3, 6, 9, 12, and 15 mm), and fiber-blending methods (G-R, G-W, and G-S) on the mechanical properties of GLCCRGF were analyzed. The results showed that the fiber incorporation had no significant or even negative effect on the compressive strength but significantly improved the splitting tensile strength. The optimal results of fiber content, fiber length, and fiber-blending method are 0.6%, 9 mm, and G-R, respectively. From the microstructure perspective, optical tests were conducted to explore the evolution rules of pore size, pore shape factor, and fractal dimension of pore distribution of GLCCRGF. The results showed that the incorporation of glass fibers (0.6%, 9 mm, and G-R) improved the pore characteristics and contributed to more uniform pore distribution. Furthermore, scanning electron microscopy (SEM) was employed to observe the micromorphology of the skeleton structure of GLCCRGF. The SEM results showed excellent interfacial bonding between glass fibers and the geopolymer matrix. Due to good bonding quality and crack-bridging effect, the presence of glass fibers enhanced the strength and crack resistance of the matrix.