DEVELOPMENT OF APPARATUS FOR TESTING THE WASHOUT RESISTANCE OF UNDERWATER CONCRETE MIXTURES

Admixtures for concrete to be placed under water are now widely used. The use of such admixtures allows concrete to be placed underwater with much less risk than has been previously possible. However, such concrete has to satisfy several requirements when fresh (workability, washout resistance) as well as when hardened (strength, durability). Workability and washout resistance are particularly important for underwater placing. The paper briefly reviews existing washout tests, assesses the potential of alternative tests and introduces the new test designed by Ceza. The principle of the new test, the apparatus required and the test procedure are described. Results of tests on practical underwater mixtures are shown and effects of UW admixtures are discussed.