Impurities in Mixing Water for Cement and Concrete

Impurities in Mixing Water for Cement and Concrete

Introduction

• Mixing water quality is crucial for the performance of cement and concrete.
• Impurities in water can affect the setting time, strength, and durability of concrete.

Types of Impurities

1. Dissolved Salts
   • Chlorides
   • Sulfates
   • Carbonates
2. Suspended Solids
   • Silt
   • Clay
   • Organic matter
3. Dissolved Gases
   • Carbon dioxide
   • Oxygen
   • Hydrogen sulfide

Effects of Impurities

• Chlorides: Can cause steel reinforcement corrosion.
• Sulfates: May lead to sulfate attack, compromising the integrity.
• Carbonates: Affect setting time and reduce strength.
• Suspended Solids: Hinder concrete strength and workability.
• Organic Matter: Adversely affects setting time and strength.
• Dissolved Gases: May result in excessive porosity or softening of concrete.

Standards and Testing

• Adherence to standards such as ASTM C1602, EN 1008 to ensure permissible impurity levels.
• Regular testing of mixing water to maintain quality control.

Mitigation Measures

• Water Treatment: Use of filtration, sedimentation, and chemical treatment to remove impurities.
• Substitute Water Sources: Use of potable water or other treated water acceptable for mixing.
• Regular Monitoring: Consistent monitoring and testing of water quality.

Conclusion

• Ensuring the quality of mixing water is essential for achieving desired concrete strength, durability, and longevity.
• Implementing proper water treatment and regular testing can help in maintaining the required standards.

These notes should serve as a comprehensive overview of the critical aspects related to impurities in mixing water for cement and concrete.