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Post by rnb1989 on Mar 8, 2017 23:59:56 GMT
Hi all, my project is a pizza dome made out of vermiculite/cement mix, my question is how long would you say it would take to dry out in this weather?? I covered it with damp towels for 2 days then have let it sit to dry in my garage, thanks for your advice
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Post by downunderdave on Mar 9, 2017 12:08:06 GMT
Hi all, my project is a pizza dome made out of vermiculite/cement mix, my question is how long would you say it would take to dry out in this weather?? I covered it with damp towels for 2 days then have let it sit to dry in my garage, thanks for your advice A vermicrete mix uses approximately double the amount of water than a standard concrete mix because the grains are so porous. This means that after the hydration process which uses some of the water chemically there's still about 75% of the water added to the mix to eliminate. I did an experiment (attached) to see how long it takes, in ideal drying conditions. You will need to use some fire to push the water out or it will take months to dry in a UK winter. Avoid direct flame impingement on the inside of the dome. Vermicrete insulating slab copy.doc.zip (73.2 KB)
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Post by rnb1989 on Mar 9, 2017 13:13:41 GMT
Hi all, my project is a pizza dome made out of vermiculite/cement mix, my question is how long would you say it would take to dry out in this weather?? I covered it with damp towels for 2 days then have let it sit to dry in my garage, thanks for your advice A vermicrete mix uses approximately double the amount of water than a standard concrete mix because the grains are so porous. This means that after the hydration process which uses some of the water chemically there's still about 75% of the water added to the mix to eliminate. I did an experiment (attached) to see how long it takes, in ideal drying conditions. You will need to use some fire to push the water out or it will take months to dry in a UK winter. Avoid direct flame impingement on the inside of the dome. View AttachmentThanks for the advice I was going to do a few tiny fires to start off with , I need your advice, I have taken the doorway support out today and the doorway is no where near thick enough in places, my own fault really, how would I rectify this! Stick more on now? Or wait till it dries I have a bag of refractory cement I was going to render the dome with
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Post by rnb1989 on Mar 9, 2017 13:27:24 GMT
Hi all, my project is a pizza dome made out of vermiculite/cement mix, my question is how long would you say it would take to dry out in this weather?? I covered it with damp towels for 2 days then have let it sit to dry in my garage, thanks for your advice A vermicrete mix uses approximately double the amount of water than a standard concrete mix because the grains are so porous. This means that after the hydration process which uses some of the water chemically there's still about 75% of the water added to the mix to eliminate. I did an experiment (attached) to see how long it takes, in ideal drying conditions. You will need to use some fire to push the water out or it will take months to dry in a UK winter. Avoid direct flame impingement on the inside of the dome. View Attachment I also have cement and vermiculite mix left
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Post by downunderdave on Mar 9, 2017 19:07:20 GMT
A vermicrete mix uses approximately double the amount of water than a standard concrete mix because the grains are so porous. This means that after the hydration process which uses some of the water chemically there's still about 75% of the water added to the mix to eliminate. I did an experiment (attached) to see how long it takes, in ideal drying conditions. You will need to use some fire to push the water out or it will take months to dry in a UK winter. Avoid direct flame impingement on the inside of the dome. Thanks for the advice I was going to do a few tiny fires to start off with , I need your advice, I have taken the doorway support out today and the doorway is no where near thick enough in places, my own fault really, how would I rectify this! Stick more on now? Or wait till it dries I have a bag of refractory cement I was going to render the dome with The addition of vermiculite to a concrete mix weakens it as well as making it more insulative. Neither of which are desirable qualities for the inner layer IMHO, but you have what you have. Adding another layer of denser material over it will strengthen it, it is also best to do this operation while the initial layer is still moist. Hold off with any fires until it has had a week to cure.
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Post by rnb1989 on Mar 9, 2017 20:11:23 GMT
So do you think I'll be ok adding more vermiculite mix to thicken the doorway, then rendering inside and out with refractory cement
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Post by downunderdave on Mar 10, 2017 2:22:35 GMT
Not quite sure what you've got there. Refractory cement is calcium aluminate cement which needs to be added to some fine aggregate to make a suitable castable mix. Then there is refractory mortar which is premixed calcium aluminate cement mixed with a finer aggregate suitable to use as mortar. Then there is a pre -mixed castable refractory which is calcium aluminate cement, fine and coarse aggregates and other goodies to make a good workable castable mix. All of these mixes are provided dry and require the addition of water. Calcium aluminate mixes achieve their full strength in 24 hrs, so no need for prolonged moist curing.
A coating min thickness of around 10 mm is required otherwise you'll run the risk of it flaking off.
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