Ballistic impact resistance of UHPC plates made with hybrid fibers and low binder content

Abstract

This study assesses the ballistic impact strength of thin plates made of ultra-high-performance concrete (UHPC) with low cement content (250 kg/m3) and volumes of 80% steel and 20% polypropylene (PP) hybrid fibers. The plates were prepared with thicknesses of 30, 50, and 70 mm and fiber volume ratios of 1.5% and 3.0%. Compressive strength, flexural tensile strength, residual strength, and ballistic impact strength were determined using experimental methods. Test results showed that regardless of fiber content, the UHPC specimens prepared with the hybrid fibers showed similar performance against ballistic impact, exerting relatively low impact energy below 1000 J. The UHPC3.0 mixture made with 3.0% hybrid fiber content exhibited the best performance in terms of energy absorption and spalling resistance at impact energy levels greater than 4000 J. Plate sections with thicknesses of 7 mm showed class III performance (highest level), as recommended for military-based applications.