Development of Apparatus for Testing the Washout Resistance of Underwater Concrete Mixtures

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Title: Development of Apparatus for Testing the Washout Resistance of Underwater Concrete Mixtures

Author(s): MichalI Ceza and Peter J. M. Bartos

Publication: Special Publication

Volume: 163

Issue:

Appears on pages(s): 111-126

Keywords: admixtures; concretes; tests; underwater structures; workability; Materials Research

Date: 8/1/1996

Abstract:
Admixtures for concrete to be placed underwater 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. Several test methods and related equipment have been designed to evaluate the required properties of the fresh underwater mixtures, including devices to evaluate their washout resistance. One of the problems facing both producers and users of underwater (UW) concrete admixtures up to now has been an absence of a standardized and realistic test method for the assessment of performance of such products in practical concrete construction. This research project aims to develop efficient new tests for the practical evaluation of the washout resistance and nondispersability of fresh concrete mixtures placed underwater. The paper briefly reviews existing washout tests, assesses the potential of alternative tests, and introduces the new tests 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 discussed. The apparatus simulates well the actual washout condition; its performance and design satisfy requirements of a viable test suited for standardization.