Blast Response of Additively Constructed Concrete (2024-09)¶

As the adoption of additive construction (AC) (ISO/ASTM 52939:2023) increases for building components and the threat of terrorist activity remains high, the need to evaluate the dynamic response of AC structural components to blast loads becomes important. Since 2014, the U.S. Army Engineer Research and Development Center (ERDC) Construction Engineering Research Laboratory (CERL) has researched the use of AC for expeditionary structures [1-4]. In 2023, ERDC began investigating the response of partially reinforced AC panels to airblast loads using the 2.4 m (8-ft.) compressed gas driven Blast Load Simulator (BLS) at the Geotechnical and Structures Laboratory (GSL) in Vicksburg, MS, USA. This limited research project follows previous BLS studies to determine if AC has any clear weaknesses that would exclude this construction method for structures potentially subjected to blast loads. One of the advantages of AC is the ability to construct unique complex wall geometries. Two shapes were selected for evaluation and additively constructed at CERL: the flat and chevron wall (Figure 1). Extrusion based AC was used with a concrete mixture of nominal maximum aggregate size of 9.5 mm meeting requirements outlined in Negrón-McFarlane et al. [4]. Three 2.2 m wide by 2 m tall samples of each wall with a slenderness ratio of 9 were selected for evaluation. The wall samples used in the evaluation were constructed with 34.5 MPa (5-ksi) concrete, horizontal ladders every 20.3 cm (8-in.) and fully grouted vertical Grade-60 rebar, similar to European Grade 420, on the outer edges of the specimen and at the center line. To ensure a one-way response, the panels were supported along the top and bottom and free to deform along the sides. Measured properties included center-span deflection and the reflected pressure and impulse.