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Use of bottom Ash in shotcrete.

Use of bottom Ash in shotcrete.

Use of bottom Ash in shotcrete.


I am a finisher with a gunite company in Nevada. We are subcontractors for swimming pool builders. I have a friend and associate who is looking into going into the shotcrete business as a subcontractor in the same industry.  He supplies ready mix to several shotcrete companies now but is considering expanding into the application of shotcrete by using the dry mix gunite instead of readymix.

As a cost cutting measure, my friend is considering substituting bottom ash instead of sand as the bulk of his mix. The standard mix for our company is a seven sack mix to a yard of sand for gunite.

A primary concern in our area are the amount of sulfates found in the soil here. We are required to to meet a 4500 psi. standard in our mix because of the sulfate content of the soil. Our standard mix meets and exceeds these requirments.

My friend has also been able to meet this strength standard using this mix of type v portland and bottom ash. However, psi. requirements aren't the only thing to consider in the constuction of a swimming pool shell.

I know that fly ash is often used as an admixture to achieve a high strength product but have never heard of anyone using bottom ash as a primary ingrediant in their mix.

So I am seeking information.
1. Will this product have problems with cracks?  By that I mean both surface cracks as well as shell cracks that can compromise the shell's integrity.
2.How fast would a product like this "set-up" ?  If it sets-up faster than a sand based mix, then my buddy could be in a world of hurt. The high cement content in the desert heat could render a quicker setting material impractical.
3.How would this product react to sulfates? Could it be expected to resist the effects of sulfates and salts found in the soil?
4.Will the tile setters encounter any problems with adhesion?  Will the plaster guys have a problem getting their marble plaster to adhere to a shell constucted with this mix?
5.Would the shell be more or less porous than a shell constructed with a sand based material?
6.What is the likelyhood of encountering problems when adding water to the product. In our dry mix process, water is introduced as the material is exiting the hose through the nozzle. Water content must be consistant and exact in order to achieve the desired standards.

I know am asking a lot here. I didn't really know where to start looking for information. I found this forum while following links from the ASI.

If anyone can help me here or point me in the right direction, I would be very grateful.


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