Study on the fatigue life and toughness of recycled aggregate concrete based on basalt fiber

This paper studies the influence of basalt fibers on the mechanical properties, fatigue life, and toughness of Mechanically Recycled Aggregate Concrete (MRAC). Basalt fibers of varying volume fractions and lengths, along with quantified amounts of mineral powder and fly ash, are incorporated into MRAC to prepare Basalt Fiber Mechanically Recycled Aggregate Concrete (BFMRAC). The results of basic mechanical tests and fatigue tests showed that mineral powder and fly ash reduce cement consumption, achieve the effect of green construction, and basalt fibers improve the mechanical properties and toughness of concrete. The results of the response surface method (RSM) model indicate that the volume fraction of basalt fibers has a greater influence on the mechanical properties of BFMRAC compared to fiber length. The fatigue test results indicate that under different fiber volume fractions and lengths, the uniaxial compressive fatigue life (N) of specimens for each mix proportion is consistently improved. When the length of basalt fibers is 12 mm and the volume fraction is 0.3 %, the uniaxial compressive fatigue life of BFMRAC reaches its maximum (231638), which is twice that of MRAC. When the survival rate (P) is set to 0.5, with a basalt fibers volume content of 0.3 % and a length of 12 mm, the fatigue limit strength (Se) attains its maximum (0.8648 fc). When stress levels (S) reach 0.75 and the basalt fibers length is 12 mm, the relative CI Intensifying Coefficient achieves its maximum (1.133), resulting in optimal fatigue toughness. When the basalt fibers length is 6-12 mm, Se generally increases with the increase of fiber length, and the enhancement effect is best at 12 mm.