Experimental Testing of CFRP-Strengthened Reinforced Concrete Slab Elements Loaded by Close-In Blast

Strengthening reinforced concrete slab or wall structural elements with carbon fiber-reinforced polymer (CFRP) can improve their blast resistance. However, close-in blasts (blasts with a scaled range of less than 0.4 m/kg1/3) may undermine the effectiveness of the CFRP strengthening. This paper presents an experimental testing program on CFRP-strengthened reinforced concrete slab specimens that utilized fiber anchors. Two CFRP mitigation designs were tested under blast loads with a scaled range of 0.4 and 0.6 m/kg1/3. Tests on unmitigated reinforced concrete slab specimens provided baseline comparisons. The experimental results showed that the use of CFRP strengthening improved the blast resistance of reinforced concrete slab specimens. For a larger scaled range, 0.6 m/kg1/3, the CFRP successfully prevented flying debris and reduced the overall deflections of the slab specimens. However, for the closer scaled range, 0.4 m/kg1/3, the high shock blast pressures shattered the concrete through the thickness of the slab specimen and tore through the back-face CFRP. However, back-face velocity and overall deflections were reduced by about 75% compared to the baseline test slab specimen.