Compression strength of aqueous media exposed epoxy system containing silane surface bearing fly ash particles

Abstract

Neat epoxy (NE) and epoxy system with different volume fractions of fly ash fillers with their surfaces treated by silane bearing material were made and the responses to exposure by immersion in varying aqueous media, such as plain water (PW), seawater (SW) and seawater containing small amount of dilute hydrochloric acid (SWA) maintained at 80 C, established through weight measurements recorded up to 100 h on the test coupons. Further on, the 100 h exposed samples were subjected to compression tests to evaluate the strength. The results showed that both NE and the silane treated ash bearing composites generally exhibited the highest water absorption in SWA case and the lowest in SW media, with the water absorption level for PW case falling in between. When the ash content in the composite is very large, the water absorption levels tend to be lower for both SW and SWA. The data further showed that unexposed samples recorded less strength compared to the exposed ones. In the case of exposed samples, in all the media employed, as the ash content increases the strength also increases. Further, it was noticed that the samples exposed to SW showed higher strength than the corresponding values noticed with SWA case. Lower strength was found in samples immersed in PW case. Attempts to explain these differing trends are made in this effort by analyzing the features observed on the surface of compression failed samples using fractography technique employing scanning electron microscope (SEM).