In uganda we have a couple of possible pozzoloanic sources :
1) Sugar baggase Ash & Filter Cake :
The sugar factories are generally not very willing to part with the ash & filter cake, one was convinced of what we are doing and are co-operating. I have a couple of issues 1) a sample of ash obtained was really dark, to me indicating lots of carbon , so is it useable to make CP or does it have to be subjected to further heating or treated in a specific way to ensure we get good quality CP?
2) Other sources we are exploring are :
a) Burnt Tile & Brick rejects are plentiful in Uganda ( Surkhi binder)- I await your experiences and advice on this.
b) Clay & Sugar Straw Waste fuel Ash ( we are thinking of introducing this,do you have any experience with this ? Please advise.
c) Wood Ash - There are lots of bakeries burning wood and have lots of Wood Ash ? Can this work, does anyone have any experience with this ?
3)General Questions :
What is the appropriate mesh size for Pozzolanic material ?
4) CVBT Rod Mill :
Your notes indicate an output of 16 kg per 30 mins, how can you possibly increase the output to at least 50 Kg ? I got a source willing to sell me some old use carbon steel balls, could this do the magic instead of the steel rods ?
Thanks
Godfrey , ECO-LIFE UGANDA
1)Bagase. I don't have direct experience with this. Please check with Practical Action and the Asian Institute of Technology. With rice husk ash, dark ash does not necessarily mean carbon; the ash is over 90% silica.
2)a. Burnt clay bricks and tiles are a source of pozzolana.
b. Clay and sugar straw waste fuel ash. Could you clarify this please?
c. Wood ash. I have never heard of wood ash being pozzolanic.
3) Pozzolanic materials, like cement, must be finely ground to make them reactive. The finer the particles, the higher the total surface area and therefore the higher the reactivity. To test a pozzolana we use a fine sieve. We recommend a standard of 85% passing an ASTM #325 sieve (45 micrometer hole size). To do this test an accurate scale is needed. This test is a wet sieve test; the ash will not pass through the sieve by shaking. It must be washed through with water. The dried residue weight is subtracted from the initial weight to get the weight of the material passing.
4) The output of the CVBT rod mill is 16 kg. This is enough to combine with 34 kg of cement to make 50 kg of pozzolana cement. I believe that we can add the 34 kg of cement after the ash has been ground fine. Then we run the mill for a few minutes to get good mixing. For our size mill it is not possible to grind 50 kg of ash at one time. The rods will become tangled. We do not have experience with balls; I believe rods are much cheaper. If you have a good source of cheap steel balls then I think it is possible to use them instead of rods. We can develop larger capacity mills if there is a need for them.