Concrete Admixtures – Types and Uses

Proprietary mixture of chemicals added at the mixing stage to concrete to alter or improve the properties of fresh or hardened concrete, is known as Admixtures. Concrete admixture is a material other than cement, water and aggregate. Admixtures change properties of the concrete such as colour, curing temperature range and setting time.

 

 

WHEN TO USE ADMIXTURES:

 

• When properties cannot be made by varying the composition of basic material


• To produce desired effects more economically


• Unlikely to make a poor concrete better


• Not a substitute for good concrete practice


• Required dose must be carefully determined and administered

 

HOW TO USE ADMIXTURES

 

• Check job specification


• Use the correct admixture
  
  
  
  • Never use one from an unmarked container.
  
  
  • Keep containers closed to avoid accidental contamination.
  
  
  
  

• Add the correct dosage.
  
  
  
  • avoid adding ‘a little bit extra’
  
  
  • use a dispenser
    
    
    
    • wash thoroughly at the end the day
    
    
    
    
  
  
  
  


• Best if added to the mixing water


• Manufacturer’s recommended dosage is usually adequate


• Trial mixes are important to determine most effective dosage