Triaxial mechanical properties and microscopic characterization of fiber-reinforced cement stabilized aeolian sand-coal gangue blends

To understand the mechanical properties of fiber-reinforced cement stabilized aeolian sand-coal gangue blend materials and reveal their failure mechanism, polypropylene fiber was uniformly incorporated into cement stabilized aeolian sand-coal gangue blend materials. Triaxial compression tests were carried out to study the coupling effect of different fiber contents and fiber lengths on the shear strength of the blend materials. The internal physical and chemical mechanisms of structural performance evolution were clearly revealed by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray diffraction (XRD) at the micro level. The results show that adding 2 parts per thousand 12 mm fiber can effectively improve the shear properties of the sample. When the fiber length is 12 mm, the elastic strain energy first increases and then decreases with the increase in fiber content. When the fiber content is 2 parts per thousand, the total energy and elastic strain energy increases steadily with the increase in fiber length. SEM results revealed that the fiber was gradually wrapped with the formation of cement hydration products, which provided both induction and bridging properties. The interface between fiber and granular particles was composed mainly of single fiber grip and fiber network formed by the random distribution of fiber. In the shear process, the fibers in the sample exhibited two failure modes: interface slip and tensile break.