Construction engineering in coastal areas is facing the challenge of a shortage of fresh water for mixing and curing. The quality of water places an important role in the setting and strength development of concrete structures. This research aims to study the feasibility of using seawater to cast and curing plain concrete for non-structural uses. Samples were cast using tap water or seawater and then cured using tap water or seawater up to testing ages. Concrete properties were studied in terms of compressive, tensile, flexure, and bond strengths at 7, 28, and 56 days of age. Test results showed that the self-curing concrete with Polyethylene Glycol 400 performed better in its main mechanical properties compared to conventional concrete. The compressive strength and subsequently the other related strengths of concrete were shown to increase for specimens mixed and cured with seawater at early ages up to 7 days, while a definite decrease in the respective strengths was observed for ages more than 28 days and up to 56 days. The reduction in strength increases with an increase in exposure time, which may be due to salt crystallization formation affecting the strength gain.