Design, prototyping and tests of a rollable ramp for temporary use

Experimental investigations were conducted to examine the behavior of concrete sandwich composites under compressive and tensile loads. 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 with experimental data. All specimens had facing thicknesses of 1 in. (25.4 mm), core thicknesses of 1, 2 and 3 in. (25.4, 50.8 and 76.2 mm); core-cell size of 1/8 and 3/8 in. (3.2 and 9.5 mm); while four different core foil gages were considered for each size. The facings were either plain concrete mortar or reinforced with steel wires. The large-core-cell-size specimen displayed better bond characteristics and produced more consistent experimental data. The ultimate strengths of both compressive and tensile specimens were not affected by the core-cell size, core thickness, or core density. Axial compressive loads were carried by the facing area while tensile loads were by the reinforcements in the facings. The buckling waves were developed due to the wrinkling of the facings. The buckling waves in the two facings were independent of each other and the overall wave pattern was antisymmetrical.

Effect of axial loads on concrete-mortar 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.

M. K. S. Phang

Papers

Flexural behavior of reinforced-concrete sandwich composites