Retarder

• Delay onset of setting and hardening i.e extending the time between initial mixing and final compaction 
• Use in hot weather where large concrete pour 
• Frequently used in ready - mixed concrte 
• Uses influenced by aggregates type and grading 
• Do not adversely affect 28 days strength 
• Adverse effect : increase bleeding with some type , increase drying shrinkage , reduction of early - strength development