Site application of biopolymer-based soil treatment (BPST) for slope surface protection: in-situ wet-spraying method and strengthening effect verification

Durability and strength degradation of xanthan gum based biopolymer treated soil subjected to severe weathering cycles

“…Because of its cost-effectiveness, combinations of ST and other biopolymers are being investigated for use as soil binding materials 36 . For example, this study used corn ST, which has approximately 25% amylose, to prepare XG and ST compounds (XS) as strengthening materials for levee slope surfaces 9 .…”

“…Subsequently, the dried soil was uniformly mixed with the biopolymer solution at m w / m s (mass ratio of water to soil) = 25%, resulting in biopolymer to soil contents in mass ( m b / m s ) of 2% with an initial water content of 25%. This initial water content (i.e., water mixing ratio to soil) is the same for all biopolymer-treated soil samples in this study, based on previous research regarding the compaction test of KRS soil and a case study of field application for XS-treated soil 9 , 41 . In the same way, pure XG-treated soil samples were prepared at m b / m s of 1% and 2% for sand.…”

“…When biopolymer-treated soil is implemented in a field slope as surface protection layer (i.e., 5–10 mm thickness), it is typically exposed to air and dried out via evaporation. To focus on how cyclic weathering environments degrade the dry strength of biopolymer-treated soil after the biopolymer treatment has provided sufficient strengthening effects through air drying; all specimens were equivalently dried at room temperature (23 °C) for 28 days until the soil sample weight was no longer changed 9 . The PVC mold was removed after 7 days to ensure adequate drying in all directions.…”

“…Improved geotechnical engineering properties allow BPST to be an environmentally friendly ground improvement method for soil erosion/scouring prevention and slope surface protection 9 , 10 . However, climate-related weathering processes such as cyclic wetting–drying (W–D) and freezing–thawing (F–T) are suspected to reduce the strength of BPST-reinforced soils 11 .…”

“…Therefore, the main objectives of this study were to investigate whether BPST is affected by cyclic W–D and F–T weathering conditions and suggest a more effective BPST composition as a slope reinforcement material. In detail, this study assessed the durability of xanthan gum (XG) and xanthan gum-starch (XS) biopolymer-treated soils, which were applied via wet spraying to embankment slope construction with different fines contents 9 . The durability of XG and XS BPST samples exposed to repetitive W–D and F–T cycles was assessed based on q u , weight loss.…”