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Stone Legend

Stone Legend

Question

What is the water absorption rate that is acceptable in the spec? How do you achieve it with such porous materials like those used in the thin set veneer? It has been my experience that it is difficult to have low water absorption and relative low PSI material as you call out in the ASTM spec mentioned here. It may be considered a secrete formulation but i am curious what additives you are using to get both light weight and lower your water absorption.

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Unfortunately, there is no 'magic' mix design to produce a given set of properties for manufactured stone. Nearly all manufactured stone is produced using lightweight aggregate to lower the weight of the installed product, however, there are slight variations in lightweight aggregate depending upon whether one is using a manufactured lightweight aggregate (expanded clay or shale for example) or a natural lightweight aggregate (such as pumice or scoria). These aggregates themselves may have varying densities and absorption characteristics that impact the properties of the finished product.
 
Dialing in on a specific set of targeted properties includes some trial and error. Admixtures such as plasticisers will aid in not only the molding of the stone units, but removing removing voids within the stone that can lead to increased absorption. Some producers have found that in order to achieve their targeted absorption levels they need to increase the compressive strength of the mix above the minimum compressive strength requirements of ASTM C1670.
 
That all said, ASTM C1670 does not stipulate a maximum absorption for manufactured stone units, only that it be tested for during routine quality control assessment.

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3 hours ago, NCMA said:
Unfortunately, there is no 'magic' mix design to produce a given set of properties for manufactured stone. Nearly all manufactured stone is produced using lightweight aggregate to lower the weight of the installed product, however, there are slight variations in lightweight aggregate depending upon whether one is using a manufactured lightweight aggregate (expanded clay or shale for example) or a natural lightweight aggregate (such as pumice or scoria). These aggregates themselves may have varying densities and absorption characteristics that impact the properties of the finished product.
 
Dialing in on a specific set of targeted properties includes some trial and error. Admixtures such as plasticisers will aid in not only the molding of the stone units, but removing removing voids within the stone that can lead to increased absorption. Some producers have found that in order to achieve their targeted absorption levels they need to increase the compressive strength of the mix above the minimum compressive strength requirements of ASTM C1670.
 
That all said, ASTM C1670 does not stipulate a maximum absorption for manufactured stone units, only that it be tested for during routine quality control assessment.

 

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Interesting to know that there are no expectations on the absorption in the cultured stone. I suppose sealing must be included in the installation?

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