Q: We often find water trails on the surfaces of walls when the forms are removed. Is there a way to avoid this?
A: The condition you describe is called sand streaking, and it's caused by excessive bleeding. As bleedwater moves upward along the form in long channels, it washes away some of the paste and exposes sand. Sand streaks can be avoided by reducing bleeding. You can do this by taking one of the following steps.
- Reduce water content
- Add an air-entraining admixture
- Add a water-reducing admixture
- Increase cement content
- Add fly ash to the concrete as a supplementary cementing material, or use a blended cement
- Blend a fine sand to increase the amount of material passing the No. 50 and No. 100 screens.