Unveiling Shielding Effectiveness and Ballistic Resistance of Multifaceted Engineered Concrete

Multifaceted engineered concrete (MFEC) is a concrete that can withstand various forms of attacks such as blast, ballistic, and electromagnetic pulse (EMP) weapons. However, improvement of MFEC performance is required to ensure the comprehensive safeguarding of defense infrastructure. This study pursued an extensive research effort to enhance the shielding effectiveness (SE) and ballistic resistance of MFEC. SE was assessed through various experiments. Conductivity was assessed using a high-performance frequency analyzer and an EMP test chamber (at 1.46 GHz). Ballistic resistance was assessed using a lab-scale gas gun (at 1,945 J) and field experiments using real ammunition (at 3,450 J). MFEC without fibers had exceptional electrical conductivity, surpassing that of ultrahigh-performance concrete (UHPC) without fibers by 3–4 times. Moreover, aggregates such as magnetite, copper slag, and hematite can be used in MFEC, leading to enhanced electrical conductivity. A fiber combination (0.5% 6-mm and 1.5% 13-mm hybrid straight steel fibers, and 0.25% 12-mm carbon fibers) had excellent compressive strength (CpS), flexural strength (FS), and electrical conductivity. Modified MFEC (Version 2) had substantially increased SE, reaching an impressive 63 dB. MFEC exhibited remarkable resistance to ballistic impact; minimal penetration depths were observed even when subjected to real ammunition tests. Reinforcements, such as steel mesh and carbon composite backing, enhanced its impact resilience. In repeated impact tests, the modified MFEC slab withstood multiple impacts without significant damage in laboratory and field testing.