Biopolymer-biocement composite treatment for stabilisation of soil against both current and wave erosion

Abstract

Increased frequency of extreme weather events has made the conservation of riverbanks and coastlines a global concern. Soil stabilisation via microbially induced calcite precipitation (MICP) is one of the most eco-suitable candidates for improving resilience against erosion. In this study, the erosion characteristics of soil treated with various levels of biocementation are investigated. The samples were subjected to hydraulic flow in both tangential and perpendicular directions in a flume to simulate riverbank and coastal situations. Soil mass loss, eroded volume, and cumulative erosion rates of the treated soil against the applied hydraulic energy density have been reported. Post erosion exposure, the residual soil has been assessed for its properties using needle penetration resistance, precipitated calcium carbonate content and microstructure. It was observed that soil erosion declined exponentially with the increase in calcium carbonate content against the perpendicular waves. However, biocementation leads to brittle fracture beyond a threshold, limiting its efficacy, especially against the tangential waves. Additional composite treatment with a biopolymer was found to improve the resilience of the soil specimens against erosion. The composite treatment required half of the quantity of the biocementing reagents in comparison to the equally erosion-resistant plain biocemented sample. Therefore, stoichiometrically the composite treatment is likely to yield 50% lesser ammonia than plain biocement treatment. This investigation unravels a promising soil conservation technique via the composite effect of biocement and biopolymer.

Biopolymer Stabilization of Highly Plastic Silty Soil for Rammed Earth Construction Materials

“…In previous studies, it has been established that the biopolymer treatment for sandy soil is not suitable due to the hydrophilic nature of XG and the lack of the chance of Thermal conductivity (W/m*K) TH-02-069 formation of stable cationic bonds due to the scarcity of clay particles [9,12,24]. However, studies on fine-grained soils have established that the clayey soils treated with XG are substantially more stable [8,16,17,26].…”

“…Recent studies reported that the addition of biopolymers such as Xanthan Gum (XG) to soil could improve the strength and erosion resistance significantly [8][9][10][11][12][13][14][15][16][17]. However, the application of biopolymers in view of preparing an ECM has not been well explored yet.…”

Experimental Study on Silt Soil Improved by Microbial Solidification with the Use of Lignin

“…In the field of geotechnical engineering, the research results of MICP on soil improvement can be used for foundation reinforcement [ 57 , 58 , 59 ], earth dam reinforcement [ 60 ], wind prevention, sand fixation [ 61 ], reservoir bottom anti-seepage, and anti-seepage curtains [ 42 ]. In the field of agricultural production and construction, MICP technology also plays a beneficial role in improving soil mass, such as water and soil conservation, the prevention of water and soil loss [ 62 ], and stability improvement in agricultural water conservancy projects [ 63 ] and agricultural buildings [ 64 ], which is conducive to planting and production activities and also ensures safety. Testing the mechanical properties of the cemented samples can not only measure the quality of the cementation effect but can also determine the feasibility of using the MICP technology based on urea hydrolysis to improve the soil.…”