Effect of Water Immersion on Mechanical Properties of Epoxy/basalt Fiber Reinforced Composites: New Perspectives

FRPs composites are currently used for several civil, marine and industrial applications due to their interesting specific properties, such as low weight, high stiffness resistance to weight ratio and high chemical resistance. In general, their mechanical performance, especially for conventional composites based on synthetic fibers (i.e. glass or carbon) under common environmental conditions are known to the scientists and engineers. However, there is a lack of knowledge on the mechanical properties and durability of novel composites, based on mineral or natural fibers, exposed to harsh environmental conditions. Among innovative FRPs, basalt-based composites are attracting the attention of researchers as potential substitutes for glass fibers composites, that overcome the corrosion problems of metals and are currently adopted for many marine applications where the water intake can lead to swelling and plasticization of the polymer matrix, fiber/matrix interface deterioration and debonding. In this work, epoxy/basalt twill woven fabric composites have been manufactured by vacuum infusion process and experimentally characterized to investigate the effect of fresh and saline water on their mechanical performance. In particular, to reduce the water absorption, after infusion and curing, the external lower and upper surfaces of composite laminates were covered with polylactic acid (PLA) layers, while an acrylic coating was applied along the cut edges of the samples. Then, both uncoated and coated composites were immersed for 30, 60, and 120 days in freshwater and a proper salt solution at environmental temperature. Five samples of each batch were regularly weighed and used to perform flexural tests.