Evolution of the Mechanical Properties of Concrete Produced with Seawater Under Accelerated Aging

Water is an indispensable natural resource with immeasurable environmental and socioeconomic value. Climate change can directly interfere with water availability, altering the water cycle and causing, e.g., floods and drought, affecting various socioeconomic sectors. In contrast, seawater is a widely available resource that has little explored. Using seawater directly for concrete production can be a relevant solution for saving fresh water, particularly in applications involving reinforced concrete with embedded FRP composite bars. This work compares concrete produced with (i) freshwater and (ii) seawater through mechanical characterization over time. The modulus of elasticity under compression, compressive strength, and tensile splitting strength were evaluated with cylindrical concrete specimens at 28 days exposed to air-curing (unconditioned specimens). The durability of the concrete under investigation was evaluated for up to two years by immersing the specimens in seawater at three different temperatures, namely 20 ℃, 40 ℃, and 60 ℃ (conditioned specimens). The results have shown the lower mechanical performance of unconditioned specimens produced with seawater when compared to the ones produced with freshwater, namely variations of –7% in the modulus of elasticity, -15% in compressive strength, and –34% in tensile splitting strength. On the other hand, when comparing the conditioned specimens with the unconditioned specimens, the compressive strength showed an increase of up to 46% for freshwater concrete, while an increase of about 59% for seawater concrete after 2 years of immersion in seawater at 60 ℃ was observed.