Ceramics-Silikáty 69, (3) 477 - 486 (2025)

In this paper, basalt-polypropylene hybrid fibre concrete (BPHFC) was prepared, and the effects of different fibre contents on its mechanical properties, permeability and pore structure were systematically studied. Two methods (Jin and Menger Models) were used to calculate the fractal dimension of the concrete, and the correlation between the fractal dimension and mechanical properties with the chloride ion permeability coefficient is thoroughly discussed. The research results indicate that there is an optimal dosage of mixed fibres in concrete. When the basalt fibre (BF) and polypropylene fibre (PF) are 0.05% and 0.1%, respectively, the compressive strength and splitting tensile strength increase the most, reaching 7.13% and 9.68%, respectively. Meanwhile, the chloride ion permeability coefficient, electrical flux, and porosity decreased by 77.85%, 36.40%, and 49.52%, respectively. The incorporation of an appropriate amount of fibres significantly improves the pore structure by reducing the volume fraction of the large pores while increasing that of the small pores. However, an excessive fibre addition has adverse effects on the concrete, manifested by a decrease in the mechanical properties, and an increase in the chloride ion permeability coefficient and electrical flux. The correlation analysis shows that the fractal dimension of BPHFC has a significant positive correlation with the mechanical properties and a negative correlation with the chloride ion permeability. In addition, the grey correlation degree analysis of the pore structure and mechanical properties of the concrete show that the medium pore content is the most correlated with the mechanical properties of BPHFC.