Freeze-thaw attack aggregate

Freeze-thaw Alkali-aggregate reactions Fire Acid attack... 

Concrete may deteriorate if adequate precautions are not exercised to protect it from adverse effects that could result from exposure to natural or artificial conditions. Several physical, chemical, and electrochemical processes are known to induce cracking of concrete. Concrete can have durability problems as a consequence of its exposure to seawater, sulfates, chlorides, freeze-thaw action, carbon dioxide, etc., or when it is attacked by artificially induced processes such as exposure to acids and salts in chemical plants or to fire. In recent years, a new type of durability problem was encountered that involved use of steam cured concrete products. The distress was caused by the formation of delayed ettringite. If the raw materials in concrete are not carefully controlled, there may be an eventual failure of concrete elements, eg., the presence of excess alkali in concrete that promotes alkali-aggregate expansion reaction, harmful impurities in the aggregates, or the presence of excess amounts of dead-burnt MgO. Thermal techniques in combination with others have been employed with success to examine the raw materials as well as the failed concrete. The knowledge gained from such work has been applied to produce more durable concrete. 

Besides corrosion-induced rebar damage, there are three other commonly cited forms of concrete degradation, namely, alkali-aggregate reaction, freeze-thaw damage, and sulfate attack. 

---