Effects of Basalt Fiber on the Mechanical and Frost Resistance of Geopolymer-Stabilized Aeolian Sand Gravel

Abstract To address the challenges of road construction aggregate scarcity and cost control in desert regions, this study utilized solid wastes (steel slag powder, fly ash) to prepare geopolymer for stabilizing aeolian sand and gravel mixtures as road base materials. The feasibility of applying fibre-reinforced geopolymer stabilized aeolian sand gravel (FGSG) mixture was demonstrated through systematic investigation of its mechanical properties, frost resistance and micro-mechanisms. The results showed that the alkali content had the most significant effect on the compressive strength of geopolymer paste. The optimal mix ratio was a slag-to-fly ash ratio of 3:7, an alkali content of 8%, and a water glass modulus of 1.4. Furthermore, the incorporation of basalt fibre at a dosage of 0.15 v% and a length of 12 mm significantly enhanced the mechanical strength of the mixture and improved the frost resistance. The compressive strength of FGSG gradually decreased with the increase in freeze-thaw cycles; however, it remained over 80% of its original compressive strength after 12 cycles. Microstructural analysis revealed that polymerization reaction occurred around the basalt fibres, effectively filling gaps and connecting cracks. This reaction enhanced the connectivity within the mixture, thereby increasing overall strength and reducing both mass and strength losses. Notably, freeze-thaw cycles induced fatigue damage within FGSG, leading to structural deterioration and ultimately resulting in strength reduction.