Case Of Damage - Reinforced Concrete Deck -

Deterioration process of RC Deck

  • Cracks in one direction
    Cracks in one direction
  • Cracks in two directions
    Cracks in two directions
  • Crack density is high
    high-density cracks

Reinforcement of Concrete decking

drilling
drilling
smoothing
smoothing
Setting steel plate
Setting steel plate
Putting resin
Putting resin
Painting
Painting
Completion
Completion

Case Of Damage - ASR -

ASR (Alkali-Silica Reaction)

In 1980's, Alkali-Silica Reaction was identified in Japan

Hanshin expressway
  • 1982: ASR was identified on Reinforced Concrete-Pier
  • 1985: Maintenance Manual for ASR
  • 1989: Surface Coating Manual
Deterioration by ASR

ASR is a reaction between highly alkaline cement paste and reactive silica in aggregates.

Concrete Core Observation

  • Black color edges formed on aggregate surface Formed on Aggregate Surface
    Black color edges formed on aggregate surface
    Formed on Aggregate Surface
  • Gel Formed after Alkali Silica Reaction
    Gel Formed after Alkali Silica Reaction

ASR forms a swelling gel that grows in volume in contact to water.
It exerts an expansive pressure inside the material and causes strength loss of concrete.

Reinforcement by Lining Steel Plate

Reinforcement by Lining Carbon Fiber Sheet

Case Of Damage Fatigue of steel structures

Preventive Measures against Crack Failure

We repair them with various proper methods.

Preventive Measures against Crack Failure