Water immersion effect on swelling and compression properties of Eco-Core, PVC foam and balsa wood

Syntactic foam, balsa wood and PVC foams are commonly used as core materials in sandwich structures for weight critical applications such as aircraft and ship structures. Water absorption is highly undesirable in these applications. The present study evaluates the effect of water immersion on three types of core materials, namely, Eco-Core, balsa wood and PVC foam. Eco-Core is a new fire resistant core material under development that utilizes about 83% by weight of fly ash. Designers of naval ships and aircraft commonly specify balsa wood and PVC foam as core materials for sandwich structures. These three core materials were subjected to water immersion to determine the relative resistance to property change. Both tap water as well as seawater was used. Core samples were studied for dimensional change, weight gain and compression properties after water immersion and the results were compared with the test results of dry core samples. Time periods included in the study ranged from 4 h to 500 days. The results showed that Eco-Core is as good as PVC foam in resisting swelling, water absorption and changes in compression properties due to water immersion. Where as balsa wood showed a significant swelling, water absorption and deterioration of compression properties.