Complex adverse weather conditions such as rain erosion and frost are frequently encountered in practical construction projects, particularly in the Inner Mongolian region of China. In this study, a new biopolymer (GGPAM) with an interpenetrating crosslinked network structure was developed by chemically modifying GG to address the poor resistance of soil to rainwater erosion, frost, and other complex environmental conditions in open-air construction buildings. First, GG-PAM was synthesized by chemically modifying guar gum (GG) through graft copolymerization, and thermogravimetric (TG) analysis confirmed its favorable thermal stability. Subsequently, experiments were conducted to investigate the mechanical properties and microstructural characteristics of GG-PAM-solidified soil. Then, using GG as a control, dry-wet cycle and freeze-thaw cycling tests were performed to compare the changes in unconfined compressive strength (UCS) of GG- and GG-PAM-solidified soil. Finally, water erosion, crack propagation, and permeability tests were conducted to evaluate the resistance of GG-PAM-solidified soil to external forces. The results indicated that the mechanical strength, durability, and erosion resistance of the GG-PAM-solidified soil were significantly superior to those of GG. When the GG-PAM content reaches 1 %, both the mechanical strength and erosion resistance of the solidified soil are significantly improved. These findings provide a theoretical basis for the construction and maintenance of roadbeds.

Nowadays, biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide attentions. However, the feasibility of using biopolymer as a green additive of cementstabilized dredged sediment (CDS) with high water content is still unknown. In this study, guar gum (GG) and xanthan gum (XG) were adopted as typical biopolymers, and a series of unconfined compressive strength (UCS), splitting tensile strength (STS) and scanning electron microscopy (SEM) tests were performed to evaluate the mechanical and microstructural properties of XG- and GG-modified CDSs considering several factors including biopolymer modification, binder-soil ratio and water-solid ratio. Furthermore, the micro-mechanisms revealing the evolutions of mechanical properties of biopolymermodified CDS were analyzed. The results indicate that the addition of XG can effectively improve the strength of CDS, while the GG has a side effect. The XG content of 9% was recommended, which can improve the 7 d- and 28 d-UCSs by 196% and 51.8%, together with the 7 d- and 28 d-STSs by 118.3% and 42.2%, respectively. Increasing the binder-soil ratio or decreasing the water-solid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of CDS. Adding XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement (OPC)-XG-stabilized DS (CXDS). The micro-mechanism models revealing the interactions of multiple media including OPC cementation, biopolymer film bonding and bridging effects inside CXDS were proposed. The key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).