5. Quality evaluation index for concrete patch repair materials

  • RTRI proposed a coefficient of permeability for the interface between concrete and repair materials as an index to evaluate the quality of patch repair materials.
  • Using this index in maintenance management increases durability after reinforcement work and helps avoid re-deterioration.

Although patch repair materials are widely used to repair concrete structures (Fig. 1), by and large evaluation to date was only aimed at individual repair materials, and as such no general index existed to evaluate the overall durability of repaired sections after completion of repair work on structures (Table 1). Accordingly, focus was placed on the interface between concrete and repair materials to make it possible to evaluate post-repair durability.

RTRI prepared test objects by spraying various patch repair materials onto the lower face of the concrete, and allowed water to permeate from the rear. Repeated observations were made of water leaching from the interface over short periods of time (Fig. 2). The coefficient of permeability ascertained from the results of these test objects indicated that water permeation was up to 100 times higher than with single concrete. In actual structures, steel corrosion is often seen as a result of water permeation through interfaces. Since this phenomenon cannot be evaluated using individual repair materials, focus was placed on the water flow resistance at the interface to provide a new approach to quality evaluation, and a coefficient of permeability at the interface was proposed as an index.

Quality control using this index enables substrate treatment to be designed according to material characteristics and materials themselves to be improved, and also makes it possible to increase the durability of concrete structures after repair work by means of patch repair materials as well as preventing re-deterioration.

  • fig 1
    Fig. 1 Example of concrete structure repair work

    table 1
    Table 1 Main test method for patch repair materials
  • fig 2
    Fig. 2 Moving resistivity of water at the interface between concrete and repair material