olny consider admixtures when other methods dont work or not economical

Air -Entrainer

1. Formation of small stable discrete bubbles
2. improved workability ( high slump )
3. Increase resistance to frost action
4. Reduction in bleeding and water gain
5. Use for road and runway construction
6. Adverse effect : some reduction in strength
7. The incorporation of void space within concrete decreases its crushing sttrength by 6% for every 1% of air -entrained . However , it is partially offset by using lower water content .