Mechanical Properties, Failure Mode, and Microstructure of Soil-Cement Modified with Fly Ash and Polypropylene Fiber

Abstract EN

In order to investigate the effects of fly ash and polypropylene fiber on mechanical properties, failure mode, and microstructure of soil-cement, the unconfined compression test, splitting tension test, and scanning electron microscopy (SEM) test of soil-cement with different polypropylene fiber contents (0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% by weight of dry soil) and fly ash contents (0%, 4%, 8%, and 12% by weight of dry soil) were carried out.

The compressive and tensile strengths, deformation characteristics, failure mode, and microstructure of soil-cement modified with fly ash and polypropylene fiber were analyzed.

The results show that the unconfined compressive strength and splitting tensile strength of soil-cement show a trend of increasing first and then decreasing with the increase of polypropylene fiber and fly ash content.

Under the condition of 0.4% polypropylene fiber and 8% fly ash, the unconfined compressive strength and the splitting tensile strength are 4.90 MPa and 0.91 MPa, respectively, which increased by 32.79% and 51.67% as compared with the plain soil-cement, respectively.

When 8% fly ash was used in the experiment, the unconfined compressive peak strain and the splitting tensile peak strain of the inclusion of 0.4% polypropylene fiber were 0.0410 and 0.0196, respectively.

The corresponding peak strains were increased by 20.94% and 68.97% as compared with non-fiber-stabilized soil-cement, respectively.

The stress-strain curve of fly ash soil-cement modified with polypropylene fiber can be divided into compaction phase, linear rise phase, nonlinear rise phase, and failure phase.

Polypropylene fiber constrains the lateral deformation of fly ash soil-cement, which improves the peak strain and the failure mode of soil-cement.