Experimental assessment of functionally graded reinforced concrete (FGRC) slabs under drop weight and projectile impacts

• Experimental impact tests executed on FGRC slabs.
• More efficiency obtained for FGRC slabs under projectile impact.
• A linear relationship found between fiber content, penetration, and destroyed area.

The present paper investigates impact resistance of functionally graded reinforced concrete (FGRC) without conventional reinforcement under drop weight and projectile impact. Architecture of reinforced layers and the content of fiber volume fraction used through the thickness were considered as the main variables of the proposed slabs. Some functionally graded reinforced concrete slabs were proposed to consider the effects of architecture of reinforced layers. Therefore, in order to indicate impact resistance of functionally graded reinforced concrete slabs under low velocity impacts, nine slabs were cast and tested in the first stage of the present study. The experimental results showed high efficiency of the proposed functionally graded reinforced concrete slabs under drop weight impact. Additionally, using tensile strength and compressive strength of reinforced concrete, a nonlinear regression modeling was developed to predict the failure blow number. The nonlinear regression modeling showed good agreement with experimental results. In the second stage of the present study, eighteen slabs were studied under impact loading with high velocity. The gathered results revealed that employing functionally graded reinforced concrete leads to more reduction in penetration depth, and destroyed front and back area, compared to entirely reinforced concrete cross section slabs with equal fiber volume fractions.