| Show miniature binl ocean artificial sea water controlled tides used to test concrete A miniature ocean with artificial sea water and electrically con trolled strolled tides Is an important part of the equipment in a research laboratory in chicago as a means of studying the effects of continuous exposure ot of concrete to sea water the apparatus includes two 11 foot tanks of concrete filled with water of the same chemical composition as sea water except that it is four times as concentrated electric t pumps circulate the water and give the effect of tides every awen ty four hours its high tide in one tank and low tide in the other the rise and fall Is one foot small reinforced concrete piles of varying quality are placed lacad in the tanks and dally daily observations made of their behavior the depth of penetration of the salt water Is checked by dally daily tests with extremely delicate electronic meters each test specimen contains many electrodes in pairs an electric current of the intensity of one milliampere Is passed between pairs of these electrodes the instrument readings record the amount of resistance to the flow of current in several directions and in various parts odthe of the test sped mens that shows the penetration of the silt salt water the te lesta td will continue for years the concentration of the water and the longer period of alternate ternate ol immersion and drying out afforded by the twenty four hour tide cycle instead of twelve as in the natural ocean gives a more severe test than in actual practice sea walls of concrete have been in service thirty four years and more without deterioration a research engineer in charge of these tests says these tests will give us moro more precise data on the factors which promote a longer life to concrete exposed to sea water |
