# Experimental Study on the Shear Strength of Silt Treated by Xanthan Gum during the Wetting Process
Inanimate microbial technology can also produce hydrogel colloid and promote the transport of heavy metals in contaminated soil to improve the soil and protect the environment [14]. Numerous suitable biopolymers for soil improvement have emerged in recent years, and biopolymers have become popularized in engineering. For example, the commercial, large-scale production of composite fiber polymer has been applied [15], and the polymer lignin is widely used in manufacturing industries [16; 17]. Polyacrylamide polymers have been widely used in the United States to irrigate land and control sand erosion and runoff protection, as well as to construct helicopter landing pads to reduce dust pollution [10]. Recent studies showed that gellan gum and agar gum could significantly improve soil durability [18], that xanthan gum can maintain water for vegetation growth in the soil to prevent desertification [19], and that both xanthan gum and gellan gum can improve the dynamic characteristics of sand [20]. Adding a small amount of biopolymer can greatly improve the soil strength, and guar gum is more advantageous for treating collapsible soil and clay using the wet mixing method, but xanthan gum is superior when treating silty fine-grained soil [21; 22; 23]. Xanthan gum can be used as a stabilizer for slope protection in geotechnical engineering. Xanthan gum also has a low application cost and very competitive price compared with other biopolymers [24]. In the late 20 th century, [PERSON] and [PERSON] pointed out that xanthan gum is more capable of absorbing water than other polysaccharide polymers [25; 26]. Xanthan gum can be used to effectively improve the water retention capacity of engineering soil, such as through hydraulic seepage barriers and underground pollution stabilization [14; 24; 27]. [PERSON] et al. [28] verified that xanthan gum significantly enhances the water retention of soil. Because xanthan gum can separate soil particles and fill soil pores, the pores of sand become larger [29], and its water retention performance is very strong [30], thus improving the water retention capacity of the soil. [PERSON] and [PERSON] et al. [21; 31] indicated that the addition of xanthan gum could improve the collapsibility resistance of collapsible soil, as well as the water disintegration resistance and strength of sandy soil. [PERSON] et al. [32] showed that the compaction degree, viscosity, and strength of clays treated with xanthan gum were enhanced at low water content. [PERSON] et al. [33] found that the unconfined compressive strength (UCS) of drying soil tended to stabilize upon increasing the xanthan gum content to a certain range. According to the UCS test results of [PERSON] [34], stability can be achieved by adding xanthan gum to bentonite and kaolinite at low water content. [PERSON] et al. [35] found that the strength of soil with 2% xanthan gum content is close to the maximum at low water content. [PERSON] and [PERSON] et al. [36; 37] indicated that water content is an important factor affecting soil strength and that the strength of silty sand and silt treated with xanthan gum is greatly improved at low water content. Engineering soil must usually be cured for a few days to reach a low water content state. Because the water content of engineering soil is low, the soil strength is generally high but easily affected by rainfall infiltration, which can reduce the soil strength and stability. Most soil treatment studies conducted strength tests in the range of high suction, but few tests have focused on soil strength over the entire range of water content of soil treated by xanthan gum. Recent studies showed a significant decrease in the wetting strength of sand after treatment with biopolymergur gum [38]. However, for sand treated with xanthan gum, the wetting strength was greater than the initial strength [39].