Experimental study on dynamic mechanical properties of the basalt fiber reinforced concrete after the freeze-thaw based on the digital image correlation method

- This paper studies the effect of basalt fibers and FTCs on the concrete impact resistance.
- Adding fibers could significantly improve the impact resistance of the concrete.
- The FTCs made the basalt fibers lose its enhancement effect.

This paper studies the effect of the basalt fibers and the freeze thaw cycles on the concrete impact failure mechanism through the concrete beam fall ball impact test. The experiment used the digital image correlation method to measure the full field strains and then make a real-time analysis of them. Based on the number of impacts and the strain curves of the starting crack points, the impact times respectively for initial cracking and eventual damaging were determined. The test results show that with the basalt fiber content increasing, the impact times for the concrete specimens' initial cracking and final failure were also raised because adding fibers formed a three-dimensional system which could enlarge the transmission range of the impact stress waves and thus improved the concrete's elastic deformation performance, that is, improved the concrete's initial cracking capability to impact resistance. On the other hand, as the number of freeze-thaw cycles increased, the impact times for the initial crack and the final failure declined in that the freeze-thaw damage reduced the elastic deformation performance of the concrete specimens. The impact energy in the early freeze-thaw period lost the fastest and the most, indicating that the freeze-thaw cycles would produce damage and defect in the fiber/matrix interface and therefore made the fiber's three-dimensional system gradually lose its enhancement effect. The experimental study provides a new approach to understanding the effect of the fibers and the freeze-thaw cycles on the impact resistance performance of the concrete.