Mechanical Strength of Peat Soil Treated by Fiber Incorporated Microbial Cementation.

Abstract

Peat soil is an accumulation of partially decayed vegetation, formed under the condition of nearly permanent water saturation, which makes the high moisture and compressibility as two main features of peat. In recent years, lack of construction lands diverts the attention of researchers to make use of marginal grounds, like peatland, after some improvements. The past decade has witnessed a growing interest towards microbial induced carbonate precipitation (MICP) due to its reliability, wide application and potential contribution to sustainable and green development. There are two primary aims of this study: (i) investigating the feasibility and effectiveness of MICP in peat soil combined with bamboo fiber reinforcement, and (ii) ascertaining the mechanism of bamboo fiber incorporated MICP. Bamboo fiber possesses some unparalleled advantages owing to its fast growth and ability to survive in diverse climates. This study differs from previous researches in the use of native bacteria isolated from the peat soil, while most of them were conducted using exogenous bacteria which might pose a threat regarding adaption and microbial pollution. Different concentration of cementation resources (1-3 mol/L) and proportion of fibers (0-50%) were studied, and each case was well designed. Treated samples were subjected to fall cone test at certain time intervals to estimate the undrained shear strength. The results revealed that the samples with higher fiber content gained higher strength than others did, whereas high initial cementation resources in soil could contribute to the decline of strength. Microscale observations were also performed on treated samples to clarify the mechanism of MICP incorporated with fiber.