Admixture

• Such as water - reduces or plasticisers improve workability 
• Used for 3 purposes : 

1.  To achieve higher strength by decreasing w/c ratio at the same worability as an admixture - free mix 
2. To avhieve the same workability the decreasing cement content to reduce heat of hydration in mass concrete . 
3. To increase workability to ease placing in inaccessible location .