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benkampot 09-04-2008 01:44 AM

Motar Issuses
I Have recently began construction on my WFO, but when i mixed the cement today i seem to have run into problems.
The Cement comes from china and is called CA-50 cement, It has 50% alumina, 2.5% iron oxide and SiO2 8%.
Initally i mixed this with three parts sand and water but this seemed to turn out like soil and have no motaring ability. I tried with no sand and it was little stickier but not like normal portland.
Has anybody come accross this product and know how to use it.

benkampot 09-04-2008 07:36 AM

Re: Motar Issuses
Sorry That should be Mortar above, spelling errors, possibly no binding agent in the cement??. Could this be mixed with normal portland??
thanks again

james 09-04-2008 06:06 PM

Re: Motar Issuses
Yikes. This is new to me. Anyone?

Did the mortar ever set? Is it possible that it is similar to Lumnite? Calcium aluminate cement.


Dutchoven 09-04-2008 06:27 PM

Re: Motar Issuses
Ben, James From what I have been able to find out this CA-50 is a calcium aluminate many cases these types of cements are what might be called "spec" mixes and therefore already has the specified amount of sand in reacts to hydration very differently than portland seems mixing it without adding sand and lightly hydrating it until you find the right ratio to create a workable mortar. Also mix in smaller batches because it tends to set faster and does not re-hydrate well.
Hope this helps!
P.S. Ben...the calcium aluminate cement will make an excellent refractory mortar as it is used for it's acid resistance and thermal benefits and it also has a high early strangth

Johnny the oven man 09-04-2008 07:41 PM

Re: Motar Issuses
It's also known as A 500 cement, high alumina, we have it in Oz and its called cement fondue. Most likely will be ok.

benkampot 09-04-2008 11:24 PM

Re: Motar Issuses
Thanks for the replies johnny james and dutch. All indications are that this is high alumina cement, that is what it is described as, unfortuately all in vietnamese and chinese. Searching the internet i can find references to items with the same composition, although different packaging, but the photos of the powder are the same colour. And i found one mixing description to do the same as with normal portland.
However,having tried all manner of combinations the best performance is to set like clay after 24 hours. It hardens but still lacks any binding ability. when i tap it,it crumbles to dust!! Whereas it seems calcium alumina should have super binding strenght?? as if i am right you dont use portland at all in homemade calcium alumina cement???
I have also been unable to locate lime for homemade refactory mortar, but i have see recipies on this site that do not call for lime! How important is lime in the mixture. I have lots of left over fire bricks, could i crush these down mix with portland and sand at the 1:1:3 (fireclay, portland, sand) ratio? would i need hundreds of bricks to make enough mortar?
I would rather do what has been done before, than mix my cement with normal portland to help it bind.
Thanks again for your time in responding to me and sorry to be asking more questions, unfortuately difficult to find someone who speaks chinese or vietnamese to ask the manufactorers or suppliers.
Thanks again

Dutchoven 09-05-2008 05:21 AM

Re: Motar Issuses
you are correct in that you would not use portland in a home-made CalAlum cement...both materials do basically the same thing...

there are some who feel that lime in the mortar mix is not necessary and those who think the portland cement is not necessary...and also Frances built here oven using only fireclay and sand as mortar for the oven there a chance you could get something like a Type N mortar mix? is a blended portland cement and lime mixture(1:1) so that you could just mix from there...the lime in the mortar makes it stickier and aids in the workability of the mortar...can you get fireclay? or some other type of powdered clay

Mojoe 09-05-2008 11:00 AM

Re: Motar Issuses
Not sure how phone numbers work over there but here's the number to the Thailand office of the #3 Cement Manufacturer in the World: 66-2-718-0252. Company's official language is English, not sure whether all coutries abide by that though. Website shows a Portland Type-I, Mixed Cement-Red, and a Dry Mortar-Green..specifications are in an unfamiliar language to me but I'd guess you'd be looking at the Red or Green: CEMEX

If the Thailand office is set up like one of the ones here in the States you won't be able to order/pick up at the plant but will have to go through a distributor. Distributor typically being a privately owned Mom and Pop building materials shop.

benkampot 09-08-2008 06:50 PM

Re: Motar Issuses
Hi guys,
Thanks for all the information regarding my mortar. Having got a translater i was told that i had to mix this CA 50 with normal portland and sand.
This sounds very bizzare to me - Why do i have to add cement to Cement, very confusing.
However mixing this at 3:1:1 Ca50, sand, cement it seems to set very well and have tried heating it and cooling it and it seems to last.
But when i bought this Ca 50 i was given a white powder to mix with this and when i do add one part of this the mortar seems to remain water soluable, after 24hrs the monsoons hit and washed it all out of the joints, but the mix without the white powder remained solid. So i will have to go with this cement, but i am worried that i will not know if it is high heat mortar till it is too late, just got to hope that as it came from a refactory shop that it will be ok. Some good irish logic there.
Thanks again, and i will keep you updated.

james 09-08-2008 06:59 PM

Re: Motar Issuses
I'm glad this has a happy ending. This sounds like something designed to give Portland-based mortar better resistance to the expansion/contraction, heat-up/cool-down cycle.

We need photos! I think you are the first builder from Cambodia.

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