SHOTCRETE

Causes of concrete failure — when we use shotcrete:

• Corrosion caused by the loss of alkalinity around reinforcement steel
  
  Typical causes:
  • Acid rains
  • Carbon dioxide, sulphur dioxide and other air pollutants
  Other factors:
  • Poor quality or insufficient thickness of concrete cover
  • Inadequate care or lack of care
  • Location and age of the structure
  • Weather conditions
• Corrosion of reinforcement steel caused by chlorides
  Typical causes:
  • Marine environment Direct contact with sea water or airborne chloride
  • Anti-icing salts
  • Chlorides introduced into concrete as a result of adding contaminated water, contaminated aggregate or improper use of additives
  Other factors:
  • High porosity, low concrete quality
  • Concrete condition, e.g. scratches
  • Prevalent wind direction, location of the facility and length of impact time
• Other causes of concrete failure
  Typical causes:
  • Reactions in aggregate in alkaline environment
  • Insufficient concrete care
  • Inadequate or excessive vibrations during concrete laying, causing segregation, patches
  • Shaking or displacement of reinforcement during concreting
  • Lack of sufficient design details
  • Activation of aggressive chemicals such as acids or sugars, or soft water
  • Biological aggression in the sewage system
  • Corrosion caused by stray currents or bimetallic corrosion
  Other factors:
  • Low quality, alkali-sensitive aggregate
  • Location and environment
  • Temperature, concentration and duration of action of chemical agents
  • Change in the method of use or load conditions in relation to the designed conditions
  • Quality of structural concrete and selection of protective coatings