Waterproofing Concrete Tanks

Horowhenua Chronicle, 12 May 1911, Page 4

Waterproofing Concrete Tanks

The following method is given by Mr Albert Mover for making impervious concrete tanks or vats for butter-milk, wine, oil, pickles, sauerkraut. etc. After the forms are removed, grind off with a carburnndum stone, any projections due to the concrete seeping through the points between the boards. Keep the surface damp for two weeks from the placing of the concrete. Wash the surface thoroughly," and allow to dry. Mix a solution of one part water glass (sodium silicate). -100 Baume, with four to six parts of water—total five to seven parts—according to the density of the concrete surface treated." The denser the surface the weaker should be the solution. Apply the water-glass solution with a brush. After f our hours, and within twentv-four hours, wash off the surface with clear water and allow to dry. When dry apply another coat of the waterglass solution. After four hours and within twentv-four hours, again wiash off the surface with a clear water and allow to dry. "Repeat this process for three or four coats, which should be sufficient to close up all the pores. The water-glass (sodium silicate) which has penetrated _ the pores has come in contact with the alkalies in the cement an 3 concrete and formed into an insoluble hard material, causing the surface to become very hard to a depth of | to Jin. according to the density of the concrete. The excess sodium silicate which has remained on the surface not having come in contact with the alkalies, is soluble; therefore is easily washed 1 off with water. The reason for washing off the surface between .each coat and allowing the surface to dry is to obtain a more thorough penetration of the sodium silicate.