Study on Strength Characteristics and Microcosmic Mechanism of Silt Improved by Lignin-Based Bio-Energy Coproducts

Production of bio-energy from biomass results not only in bio-fuel, but also in coproducts containing lignin, modified lignin, and lignin derivatives. This study was performed to evaluate the feasibility of lignin used to stabilize silt in Jiangsu Province of China and to develop a new soil stabilizer for marine clay. A series of laboratory tests on unconfined compression strength (UCS), pH and electrical resistivity are carried on to study the mechanical properties, environmental effect and electrical properties of silt improved by lignin-based bioenergy coproduct. Scanning electron microscopy (SEM) is also used to analyze the variations of soil microstructure, and the mechanism of silt improved by lignin is preliminarily discussed. With the additive content increased, the unconfined compression strength of improved silt increased at first and then decreased. The optimum additive content should be 10% to 12%. With the curing time increased, the soil pH has a little increase. All the improved silt pH is lower than 10. The electrical resistivity of soil decreased with increasing additive content. The soil content of pore fluid is the control factor for the soil electrical resistivity. Silt improved by lignin-based bioenergy coproduct is carried primarily by filled pores and linked soil particles to form a more compact and stable soil structure. The results indicate that the coproduct lignin is an environmentally friendly, highly promising, new soil stabilizer.