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Crack repair method

1. Overview

  • Crack repair methods involve injecting a repairing material into the cracks in the concrete in order to prevent corrosive degradation of the steel members inside the concrete, as well as to restore the integrity of the cracked concrete. Crack repair methods include injection methods, filling methods and impregnation material coating methods, and the method chosen will depend upon the width of the cracks and the structure to be repaired.
  • It is essential to choose a material which is suited to the cause and location of the cracking. For progressive cracking caused by factors like alkali‐aggregate reaction, a material with a soft form able to adapt to changing crack width will be used.
  • When combining with some other repair method, it is also necessary to consider the compatibility of the process characteristics. For example, when combining an electrochemical anti-corrosion method with a crack injection method, an inorganic (cement) material will be used as the repair material and an injection device especially for inorganic materials will also be used. This is done because epoxy resin, which is an organic repair material, has insulating properties that inhibit the flow of the electricity that provides anticorrosive effects.


Injection method

Filling method

Impregnation material coating method


2. Key Features

  • For the injection method, a dedicated jig is used which utilizes the resilience, spring, etc., of rubber for the repair material, and injection is performed at a low pressure of 0.4MPa or less and at a low speed.
  • For the filling method, the concrete is cut away along the crack and the space then filled in with a repair material. This method is used for relatively wide cracks of 0.5mm or more.
  • By coating a cracked concrete surface with an impregnating material, it helps prevent intrusion by elements which could cause deterioration as well as prevents rebar corrosion.


3. Our Construction

  • Kitakyushu Ashiya Line (Takasu Bridge) abutment repair work

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