Flexural behavior and durability of reinforced concrete beams with seawater, sulfate-resistant cement, and glass fiber-reinforced polymer reinforcement

Seawater has recently been proposed for concrete manufacturing as a sustainable alternative to fresh water. However, seawater degrades the concrete properties at later ages. Accordingly, this study experimentally and analytically investigated the flexural behavior and durability of 9 concrete beams reinforced with glass fiber-reinforced polymer (GFRP) reinforcement and made with 3 seawater replacement ratios (0 %, 50 %, and 100 %), 2 types of cement (ordinary Portlandite and sulfate-resistant cement), and 2 types of curing water (fresh water and seawater). The beams were prepared with dimensions of 200 x 500 x 2200 mm and tested after exposure to seawater for 6 months. The results demonstrated that incorporating seawater and sulfate-resistant cement simultaneously improved the 28-day mechanical properties of concrete by about 16 % compared to those made entirely with fresh water. Likewise, beams made with 100 % seawater and sulfate-resistant cement recorded an improvement of 23 % in the load-carrying capacity and 80 % in the energy absorption compared to beams with fresh water. In addition, the beams made with seawater and sulfate-resistant cement showed no difference in the failure mode and flexural properties after conditioning in seawater for 180 days as compared to the reference beam. Analytically, ACI 440.11-22 achieved the best moment capacity prediction of the tested beams with an average, standard deviation, and coefficient of variance of experimental-to-predicted moment ratios of 1.26, 0.11, and 8.75 %, respectively.