Effect of Purposive Distribution of Fibers to Prevent the Penetration of Bullet in Concrete Walls

Abstract

In this study, 10 different types of walls were made by fiber reinforced self-compacting concrete. The concrete walls were reinforced with steel and nylon fibers. The results of rheological tests showed that the steel and nylon fibers have a negative effect on flowability of self-compacting concrete, which the negative effect of steel fibers was more significant in this regard. On the other hand, the results of mechanical tests indicated that the steel fibers have a slight effect on the compressive strength and considerable effect on tensile and flexural strength, whereas, nylon fibers have no significant effect in these cases. In this study, two methods, including uniform distribution and targeted distribution of fibers, were used to reinforce the concrete walls. In the uniform distribution method, all the used fibers were uniformly distributed in the wall, while in the targeted distribution method the used fibers were distributed in the wall, with a more volume of fibers in the surrounding layers and a fewer volume of fibers in the middle layer of the wall. The concrete walls were tested by bullet fire. The results of this test showed that steel fibers could significantly decrease the penetration depth of bullet in concrete walls, while nylon fibers had a much lower effect. By comparing the penetration depth of the bullet in the walls, it was observed that the targeted distribution of fibers was effective to decrease the penetration depth of the bullet.