Abstract
Microbial-induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties through the precipitation of calcium carbonate (CaCO3) on the contact and surface of soil particles in recent years. In the present experiment, water absorption and unconfined compressive strength (UCS) tests were carried out to investigate the effects of three different fiber types (glass fiber, polyester fiber, and hemp fiber) on the physical and mechanical properties of MICP-treated calcareous sand. The fibers used were at 0%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, and 0.40% relative to the weight of the sand. The results showed that the failure strain and ductility of the samples could be improved by adding fibers. Compared to biocemented sand (BS), the water absorption of these three fiber-reinforced biocemented sands were, respectively, decreased by 11.60%, 21.18%, and 7.29%. UCS was, respectively, increased by 24.20%, 60.76%, and 6.40%. Polyester fiber produced the best effect, followed by glass fiber and hemp fiber. The optimum contents of glass fiber and polyester fiber were 0.20% and 0.25%, respectively. The optimum content of hemp fiber was within the range of 0.20–0.25%. Light-emitting diode (LED) microscope and scanning electron microscope (SEM) images lead to the conclusion that only a little calcite precipitation had occurred around the hemp fiber, leading to a poor bonding effect compared to the glass and polyester fibers. It was therefore suggested that polyester fiber should be used to improve the properties of biocemented sand.
Highlights
Published: 7 January 2021Calcareous sand is the main foundation soil in the South China Sea
For the GF-biocemented sand (BS), the stress and strain trend of the sample after failure was roughly consistent with that of the BS, as shown in Figure 7a below. It indicated that glass fiber was consistent with that of the BS, as shown in Figure 7a below
Series of water absorption and unconfined compressive strength (UCS) tests and scanning electron microscope (SEM) scanning on three different fiberreinforced biocemented sands were conducted to investigate the effectiveness of three different types of fibers on microbial-induced calcite precipitation (MICP)-treated calcareous sands
Summary
Published: 7 January 2021Calcareous sand is the main foundation soil in the South China Sea. It is a type of special rock and soil medium with irregular shapes, many internal pores, low loadbearing capacity, and ready susceptibility to particle breakage under pressure [1] This soil foundation is prone to destruction due to insufficient tolerance capacity under the action of periodic load [2]. A new soil reinforcement technology has been found to improve the physical and mechanical properties of calcareous sand, known as microbial-induced calcite precipitation (MICP) [4,5]. It was first proposed by Australian geological engineer Whiffin [6]
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