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

Kai Yang, Muhammed Basheer, Yun Bai, Bryan Magee, Adrian Long

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)

    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.
    Original languageEnglish
    Pages (from-to)1-17
    Number of pages17
    JournalMaterials and Structures
    Early online date07 Sep 2013
    DOIs
    Publication statusEarly online date - 07 Sep 2013

    Keywords

    • On-site water permeability test
    • Guard ring
    • Steady rate of flow
    • Flow simulation

    ASJC Scopus subject areas

    • Materials Science(all)
    • Building and Construction
    • Mechanics of Materials
    • Civil and Structural Engineering

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