fearghusq
Structural
- Apr 20, 2011
- 14
How do you normally account for pigments in concrete mix design?
Here is my problem. I am working on a project to increase the durability of products manufactured by a precast company. They are having major problems with freeze thaw durability of concrete flags.
To overcome this I am proposing changes to mix design to be in line with BS 8500 (Exposure XF3 - Horizontal, exposed to freeze thaw without deicing salts) which gives:
360 kg/m3 CEM
W/C 0.45
5.5% Target Entrained Air
I have been told by pigment manufacturers to treat the pigment as an aggregate. However they significantly increase the water demand of a mix, so is it acceptable to treat it as an aggregate with high water absorption? (ie 'soaks' up water contained in wet agg). Therefore allowing you to add additional water to mix and remain below the 0.45 W/C limit.
Or do you have to treat it as a binder (even though it will not contribute to strength development) thereby increasing your cement content allowing you to add additional water and maintain the 0.45 W/C ratio.
Any help any more experienced engineers or concrete technologists could give would be greatly experienced.
Thanks for reading!
Here is my problem. I am working on a project to increase the durability of products manufactured by a precast company. They are having major problems with freeze thaw durability of concrete flags.
To overcome this I am proposing changes to mix design to be in line with BS 8500 (Exposure XF3 - Horizontal, exposed to freeze thaw without deicing salts) which gives:
360 kg/m3 CEM
W/C 0.45
5.5% Target Entrained Air
I have been told by pigment manufacturers to treat the pigment as an aggregate. However they significantly increase the water demand of a mix, so is it acceptable to treat it as an aggregate with high water absorption? (ie 'soaks' up water contained in wet agg). Therefore allowing you to add additional water to mix and remain below the 0.45 W/C limit.
Or do you have to treat it as a binder (even though it will not contribute to strength development) thereby increasing your cement content allowing you to add additional water and maintain the 0.45 W/C ratio.
Any help any more experienced engineers or concrete technologists could give would be greatly experienced.
Thanks for reading!
