Preliminary study on durability of FRP and stainless steel in seawater and sea sand concrete (SWSSC) environment

This paper presents an accelerated aging test of durability of 3 different materials-glass fiber reinforced polymer (GFRP), carbon fiber reinforced polymer (CFRP) and stainless steel (SS) type AISI304-with combined use of seawater sea sand concrete (SWSSC) within ocean environment. Figure (a) and Figure (b) illustrate different exposure environments of Concrete filled tubes (CFST) and Concrete filled double skin tubes (CFDST). The accelerated aging is achieved by elevating temperatures (i.e. 40oC and 60oC). Rectangular coupon and cylindrical tube specimens were immersed in 4 different solutions-alkaline seawater solution (i.e. simulation of SWSSC pore solution), alkaline solution (i.e. simulation of normal concrete (NC) pore solution), saline solution (i.e. simulation of seawater) and distilled water (i.e. reference solution)-for 15, 30, 60, and 90-days. The corrosion rate for stainless steel was calculated based on weight loss while degradation rates of GFRP and CFRP were determined by mass gain and weight loss. In addition, scanning electron microscopy (SEM) test was carried out to examine the surface/microstructure change. The results evidenced that SS AISI304 and CFRP have good durability performance over GFRP especially in SWSSC and NC at elevated temperature. However, in saline environment, no sign of degradation was observed for FRPs and only minimal corrosion was noticed for SS specimens in SEM results.