Re: Most suitable grog granularity
If you are set on designing your own castable you should also consider the addition of burn out fibres to assist drying the refractory when you begin heating. Proprietary castables usually have these added already.you need fibres that burn out at very low temperatures like polypropylene which melt at 160 C and then burn at not much more leaving a network of tiny pipes. You need less than you would think because they are extremely fine (finer than human hair) but require extensive mixing for adequate dispersal (about double the mixing time that you need to make the mix workable) A proprietary castable mix already has these fibres dispersed through the dry mix in the correct proportions so this is something you don't need to worry about when you buy the correct product (another reason I advised using a proprietary castable)
The castable I use has pretty fine aggregate, about 2mm max.
If you are set on designing your own castable you should also consider the addition of burn out fibres to assist drying the refractory when you begin heating. Proprietary castables usually have these added already.you need fibres that burn out at very low temperatures like polypropylene which melt at 160 C and then burn at not much more leaving a network of tiny pipes. You need less than you would think because they are extremely fine (finer than human hair) but require extensive mixing for adequate dispersal (about double the mixing time that you need to make the mix workable) A proprietary castable mix already has these fibres dispersed through the dry mix in the correct proportions so this is something you don't need to worry about when you buy the correct product (another reason I advised using a proprietary castable)
The castable I use has pretty fine aggregate, about 2mm max.
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