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Show Miniature Ocean, Artificial Sea Water, Controlled Tides, Used to Test Concrete A miniature ocean with artificial sea water and electrically controlled con-trolled tides is an important part of the equipment in a research laboratory lab-oratory in Chicago as a means of studying the effects of continuous exposure of concrete to sea water. The apparatus includes two 11-foot 11-foot tanks of concrete filled with water of the same chemical composition com-position as sea water, except that it is four times as concentrated. Electric Elec-tric pumps circulate the water and give the effect of tides. Every twenty-four hours it's 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 in the tanks and daily observations made of their behavior. The depth of penetration of the salt water is checked by daily tests with extremely ex-tremely delicate electronic meters. Each test specimen contains many electrodes in pairs. An electric elec-tric current of the intensity of one niillidiiii-'cie 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 of the test speci mens. That shows the penetration of the salt water. The tests will continue for years. The concentration of the water and the longer period of alternate immersion im-mersion and drying out afforded by the twenty-four-hour tide cycle instead in-stead 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 re-search engineer in charge of these tests says. "These tests will give us more precise data on the factors fac-tors which promote a longer life to concrete exposed to sea water." |