Influence of Fiber Content and Length on Engineering Properties of MICP-Treated Coral Sand

Abstract

Microbially induced calcite precipitation (MICP) can improve the engineering properties of coral sand. The dry density, permeability, unconfined compressive strength (UCS), tensile strength, and microstructure were measured to investigate the effect of fiber addition on the engineering properties of MICP-treated coral sand and determine the corresponding microstructure. Apart from reducing the permeability and improving the dry density as well as UCS of the MICP-treated coral sand, the added fibers could improve the ductility, failure strain, and tensile strength of the MICP-treated coral sand. The added fibers increased the dry density of the MICP-treated coral sand from 1.38 g/cm³ to 1.70 ∼ 2.01 g/cm³, reduced the permeability by 2 ∼ 3 orders of magnitude, and improved the UCS to 2.78 ∼ 21.65 MPa, whereas the tensile strength varied from 0.79 to 2.29 MPa. The fiber content affected the engineering properties of MICP-treated coral sand more significantly than the fiber length. The optimal content of fiber addition was 0.2%, whereas the optimal fiber length was 9 or 12 mm. The improvement of the engineering properties of MICP-treated coral sand with fiber addition can be interpreted by the coating, bonding, and interlacing effects observed in scanning electron microscopy (SEM) images.

Keywords:

• Coral sand
• fiber
• microbially induced calcite precipitation (MICP)
• dry density
• mechanical strength
• microstructure

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The present work was financially supported by the National Natural Science Foundation of China [51978103 and 41831282].