Flexural behavior of reinforced-concrete sandwich composites

An experimental investigation was carried out to examine the flexural behavior of rectangular sandwich composites and to determine appropriate structural applications for such constructions. The sandwich cores were composed of nonpermeated, expanded aluminum honeycomb and the facings consisted of concrete mortar. Appropriate theories that predict the behavior of such composites were presented and compared to experimental data. All specimens had facing thicknesses of 1 in., core thicknesses of 1 in., 2 in. and 3 in.; core-cell size of 1/8 in. and 3/8 in.; while four different core foil gages were considered for each cell size. The lower facing was either plain concrete mortar or reinforced with steel wires. The large cell-size specimen displayed better bond characteristics and produced better and more stable experimental data. Reasonable agreement was found between the observed and computed flexural stresses. The deflections at midspan were in good agreement with the theoretically predicted deflections in all of the specimens, with or without reinforcement. Regardless of cell size, density, core thickness or reinforcement, the observed midspan and quarterspan deflections of the top facing were approximately twice the deflections at the corresponding locations on the lower facing. The ultimate loads increased as the core thickness and the core density increased. The influence of flexural rigidity of the core can be neglected.