Experimental investigation of (FRSC) cementitious composite functionally graded slabs under projectile and drop weight impacts

The purpose of this study was to investigate the impact strength of functionally graded reinforce concrete (FGRC) slabs made with self-compacting cementitious composites. To this end, 60 slabs measuring 40 x 40 x 7.5 cm which had been reinforced with 1% fixed volume of steel and nylon fibers were made. Some of them were entirely reinforced concrete slabs, and their constituent fibers were uniformly distributed in them. Others were FGRC slabs, and their constituent fibers were non-uniformly distributed in them. Non-uniform distribution in the present study means that the fibers were increased in the peripheral layers and they were decreased in the inner layers, although the whole volume of fibers were equally used in all the slabs. Projectile impact tests (high speed) and drop weight impact tests (low speed) were performed on the slabs. The results of these tests showed the considerable effects of steel fibers, and insignificant effects of nylon fibers, on the impact strengths of slabs. The non-uniform distribution of fibers in the FGRC slabs led to their behavior improvement. The FGRC slabs had lower penetration depths and destroyed volume in the projectile impact tests, and they had higher failure strength and energy absorption in the drop weight impact tests, as compared to the entirely reinforced slabs. (C) 2019 Published by Elsevier Ltd.