Mechanical properties and meso-structure of concrete under the interaction between basalt fiber and polymer

Insufficient adhesion of the fibers to the concrete matrix causes the fibers to be pulled out under load, making the fiber concrete unable to meet the support requirements of deep roadways. Basalt fiber (BF) and polymers were selected for the design of mechanical experiments and studied using CT scanning, scanning electron microscopy (SEM) and discrete element simulation. The results show that the fiber mainly affects the compressive and flexural strength of concrete, and the polymer has an effect on the splitting tensile strength of the fibers. From the fine viewpoint, the increase in BF admixture resulted in the conversion of medium pores to small pores within the concrete. Incorporation of polymers results in a smooth polymer film inside the concrete matrix and more hydration products on the surface of the BF to enhance the adhesion of the BF to the concrete matrix. In the discrete element simulation, the fracture evolution can be divided into three stages and the angle of the microscopic fracture is mainly distributed in the range of 60°∼130°. Under loading, BF shares the stress of the matrix and presents itself as a tensile force at its tip, and the increase in BF doping improves the integrity of the specimen at damage.