olny consider admixtures when other methods dont work or not economical

Air-Entrainer

1. Formation of small stable discrete bubbles
2. Improved workability ( higher slump )
3. Increases resistance to frost action
4. Reduction in bleeding and water gain
5. Use for road any runway construction
6. Adverse effect : some reduction in strength
7. The incorporation of voids space within concrete decreases its crushing strength by 6% for every offset by using lower water content