Abstract :
Strength of concrete much be affected by materials properties such as water, cement and aggregate. Then in specially a concrete also be affected by the environment condition. The water is one of materials that very important within mix concrete and additive if needed to occur chemical process which be shaping a pasta as aggregate binding. Besides choose several kinds of water, one of way to get the best quality concrete is curing. This research has aim to know effects of fresh water, sea water and peat water as using water and curing the concrete and also to knows difference strength of each kinds water for concrete. This research used experiment method by type curing was soaking sample. Testing used was compressive strength and flexural strength test with concrete quality fc 30 MPA for in curing 7, 14, 28 and 56 days. The quality concrete this research was fc 30 MPa, comparation percent of compressive strength concrete with sea water had decrease strength on 7, 14, 28 and 56 days of 6%, 6%, 19% and 21%. While to peat water of 24%, 26%, 24% and 25% toward used fresh water. To flexural strength test, comparation percent with used sea water had decrease strength on 7, 14, 28 and 56 days of 7%, 5%, 5% dan 4%. While to peat water of 13%, 15%, 13% and 13% toward used fresh water. From test result, we could look that so important to choose using and curing be done for getting the best result and agreeable in quality.