ABSTRACT
This paper presents the result and findings of an experimental research on the effect of artificial salt water on compressive strength of concrete. The concrete cubes were cast using fresh water for a design mix of M-30 1:1.7:3.2 by weight of concrete, and 0.5 water-cement ratio.
A total of thirty-nine cubes were cast. Twelve concrete cubes were cast as control (cured in fresh water), nine concrete cubes were cured for 3days in freshwater before curing in artificial saltwater, six concrete cubes were cured for 7days in freshwater before curing in artificial saltwater and lastly twelve concrete samples were cured solely in artificial saltwater. The average compressive strength of the concrete after 3, 7, 14 and 28days curing period, for the purpose of comparison were obtained. The results obtained for the average compressive strength of concrete cured in freshwater were 26.14N/mm2, 30.89N/mm2, 35.7N/mm2 and 41.4N/mm2 ( i.e. 3 cubes each for 3, 7, 14 and 28days respectively). The result for the average compressive strength of the concrete samples cured solely in artificial saltwater are 21.52N/mm2, 24.981N/mm2, 30.591N/mm2 and 26.85N/mm2 (i.e. 3 cubes each for 3, 7, 14 and 28days respectively). The average values for the compressive strength cured in both fresh water and salt water were 28.316N/mm2, 30.307N/mm2 and 33.861N/mm2 (i.e. 3 cubes each for 7, 14 and 28days respectively, with an immersion period of 3days in freshwater before moved into artificial saltwater), 32.981N/mm2 and 34.776N/mm2 (i.e. 3 cubes each for 14 and 28days respectively, with an immersion period of 3days in freshwater before moved into artificial saltwater).
The immersion period of the cubes in saltwater affects the compressive strength of the test cubes. The result shows that the concrete samples with longer period in freshwater before being immersed in saltwater gave a higher compressive strength compared to that with a shorter period in freshwater. This implies that it is good to cure concrete in freshwater for longer periods before exposing them to saltwater.
