Utilization of Sea Water to Production of Concrete in Terms of Mechanical Behavior

Abstract

Supplies of fresh water in everyday life has increased, but the smaller the potential sources of water so we need to think of alternative uses of water for concrete construction work. This study aims to compare the compressive strength of concrete using sea water and fresh water with water cement ratio of 0.37. An experimental research was conducted by making specimens of concrete cylinder with a diameter of 150 mm and height of 300 mm. The study used specimens of concrete using sea water and fresh water. There were 32 specimens for each kind of concrete. The treatment of each specimen used sea water and fresh water in accordance with the type of mixing water. The immersion periods were 1, 3, 7 and 28 days. Mechanical testing of concrete was conducted by testing the compressive strength and elasticity, while the testing of concrete microstructure was conducted by using X-Ray Diffraction (XRD) and Scan Electron Microscopy (SEM). The results revealed that in the 28-day immersion period. The compressive strength values of the sea water concrete and fresh water concrete were 44.88 MPa and 44.03 Mpa respectively. The difference of compressive strength in the two types of concrete was not significant. The result of microstructure test in the 28-day period revealed that in the sea water concrete, there was a formation of Friedel’s salt (3CaO.Al2O3.CaCl2.10H2O) of 7.71%, tobemorite (3CaO.2SiO2.3H2O) of 58.66% and calcium hydroxide (Ca(OH)2) of 6.18%. In the fresh water concrete, there was a formation of tobermorite (3CaO.2SiO2.3H2O) of 51.35%, and calcium hydroxide (Ca(OH)2) of 22%. There was no formation of Friedel’s salt in the fresh water concrete because there was no mutual reaction between chloride and calcium hydroxide elements. From the regression analysis, showed that the difference of microstructure compressive strength differences caused by differences in the microstructure of the content of the two types of concrete.