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Assessment of the effectiveness of the guard ring in obtaining a uni-directional flow in an in situ water permeability test

Yang, K, Basheer, PAM, Bai, Y and Magee, B.J. (2015) Assessment of the effectiveness of the guard ring in obtaining a uni-directional flow in an in situ water permeability test. Materials and Structures, 48 (1-2). pp. 167-183. [Journal article]

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URL: http://link.springer.com/article/10.1617/s11527-013-0175-5#

DOI: 10.1617/s11527-013-0175-5

Abstract

The non-destructive evaluation of the water permeability of concrete structures is a long standing challenge, principally due to the difficulty of achieving a uni-direction flow for computing the water permeability coefficient. The use of a guard ring (GR) was originally proposed for the in situ sorptivity test, but little information can be found for the water permeability test. In this study, the effect of a GR was carefully examined through the flow simulation, which was verified by carrying out experiments. It was observed that the GR can confine the flow near the surface, but cannot achieve a uni-directional flow across the whole depth of flow. To achieve a better performance, it is essential to consider the effects of the size of the inner seal and the GR and the significant interaction between these two. The analysis of the experimental data has indicated that the GR influences the flow for porous concretes, but there is no significant effect for dense concretes. Further investigation, validated using the flow-net theory, has shown a strong correlation between the water permeability coefficients obtained with the GR (K w-GR) and without it (K w-No GR), suggesting that one dimensional flow is not essential for interpreting data for site tests. Another practical issue was that more than 30 % of the tests with GR failed due to the difficulty of achieving a good seal between the inner and the outer chambers. Based on the work reported in this paper, a new water permeability test is proposed.

Item Type:Journal article
Keywords:On-site water permeability test; Guard ring; Steady rate of flow; Flow simulation
Faculties and Schools:Faculty of Art, Design and the Built Environment
Faculty of Art, Design and the Built Environment > School of the Built Environment
Research Institutes and Groups:Built Environment Research Institute
Built Environment Research Institute > Studies Allied to Built Environment Research (SABER)
ID Code:36897
Deposited By: Dr Bryan Magee
Deposited On:10 Feb 2017 12:14
Last Modified:10 Feb 2017 12:14

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