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PLASTIC CRACKING OF CONCRETE
Taken from : Ambuja Technical  Literature Series -22


INTRODUCTION
Concrete by virtue of its physical and chemical properties is prone to cracking. Most of the concrete structures develop cracks. Cracks cannot be eliminated totally but can be restricted or reduced to a great extent. 

Fortunately most of the cracking is on a microscopic scale and does not appear visibly as a fault. The cracking can also be macroscopic and can result in loss of strength, stability and durability. It can also cause decrease in sound insulation and overall efficiency besides affects aesthetics to a great extent.

The main causes of cracking can be attributable to the following:

• Poor workmanship and negligence.
  
• Defects and errors in construction practices.
  
• Poor quality of concrete materials and improper concrete mix.
  
• Movement of concrete arising from physical properties.
  
• Over trowelling and impermeable formwork.
  
• Reduced continuity of the structural member.
  
• Deficiencies in design.
  
• Ageing - Carbonation.
  
• Weathering action.
  
• Foundation Problems.
  
• Improper or modified use of the structure.
  
• Progressive loading.
  
• Poor maintenance. 
  
• Improper structural repairs or modification. 
  
• Chemical attacks by Chlorides and Sulphates.
  
• Differential thermal stress - Heat of Hydration of cement.
  
• Alkali aggregate reaction.
  

It is always preferable to prevent cracking to the extent possible then to think of repairs at a later stage due to various reasons. One of the frequent occurrence of cracking of concrete is due to plastic shrinkage or plastic settlement. This booklet deals with various aspects of these types of cracking explaining the causes and preventive measures necessary.

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