Influence of different fiber types on properties of biocemented calcareous sand

Within recent years, microbial induced calcium carbonate precipitation (MICP) technology has been widely applied to ground improvement. The addition of fiber has a great improvement on properties of biocemented sand. This paper studied the influence of three fiber types on properties of biocemented calcareous sand by using MICP technology and discovered the influence mechanism of three fiber types on biocemented calcareous sand. Unconfined compressive strength (UCS) test, tensile strength test, and calcium carbonate content were carried to estimate properties of biocemented calcareous sand. The microstructures of biocemented calcareous sand with fibers and surface of three fiber types were observed under the scanning electron microscope. The test results showed that the ductility, the bridging role, and calcium carbonate content of biocemented calcareous sand with carbon fiber were better, followed by basalt fiber and glass fiber. The UCS, tensile strength, and calcium carbonate content of biocemented calcareous sand increased with the increasing fiber content. The optimum fiber content of biocemented calcareous sand was found to be 1%. Compared with biocemented calcareous sand without fiber, the unconfined compressive strength of biocemented calcareous sand at optimum glass fiber, basalt fiber, and carbon fiber content increased by 458%, 784%, and 1133%, respectively. Meanwhile, the tensile strength of biocemented calcareous sand at optimum basalt fiber, glass fiber, and carbon fiber content increased by 115%, 129%, and 317%, respectively. Therefore, the properties of biocemented calcareous sand with carbon fiber are better than basalt fiber and glass fiber.