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ASTM Stone Testing

The American Society for Testing and Materials (ASTM) developed several methods for testing and comparing the physical properties of natural building stones.  The most basic stone testing methods analyze the characteristics shown below.  Although these three tests are typically run as a suite with modulus of rupture and flextural strength, for practical purposes the absorption and density are usually the most relevant to modern stone construction methods, at least for the types of projects represented on this web site.

 

Explanation of ASTM test results

Density

In the United States, density is measured in pounds per cubic foot.  The density of a stone is determined by the density of the individual minerals that compose the stone and the porosity or open space between the grains.  Densities of common masonry stones range from about 130 lbs/cf for porous limestones and sandstones to 195 lbs/cf for dark granites.  Most limestones are in the 135 – 155 lbs/cf range, while most sandstones are  over 140 – 165 lbs/cf.  Some examples are shown below.

Frontier Sandstone 160 lbs/cf

Berea Sandstone 134 lbs/cf

Desert Blonde Sandstone 155 lbs/cf

Cottonwood Limestone 146 lbs/cf

Corinthian Granite 172 lbs/cf

Summit Granite 180 lbs/cf

Absorption

The absorption test measures the degree to which water will penetrate a stone, measured at a weight percentage.  A stone sample is cut to specified size, kiln dried, and then weighed accurately.  The dry sample is then immersed in water for a specified period of time and then weighed again.  The difference in weight (as a percentage) is the amount of water that penetrated the stone sample.

Measured absorption typically ranges from less than a percent for granites and crystalline rocks up to 10-12 percent for the more porous sedimentary rocks (like sandstones and limestones).  For sandstones and limestones, an absorption of less than 5 percent is preferable, and in most cases, the lower the better.  Crystalline rocks like granite and quartzite typically have absorptions of less than 1%.  A few examples are:

Frontier Sandstone 1.05%

Berea Sandstone 6%

Desert Blonde Sandstone 1.67%

Pilgrim Limestone 5.12%

Cottonwood Limestone 3.93%

Corinthian Granite 0.17%

Summit Granite 0.076%

Compressive Strength

Compressive Strength is the stress, in pounds per square inch (psi) that will rupture a stone sample.  Very rarely is the compressive strength of a stone much of a factor in stone selection.  A column of stone with a density of 160 lbs/cf that is 100 feet tall exerts a compressive stress of only 110 pounds per square inch.  As you can see below, typical masonry stones have compressive strengths that are commonly two orders of magnitude larger than this.

Frontier Sandstone 15,271 psi

Berea Sandstone 11,576 psi

Desert Blonde Sandstone 15,200 psi

Pilgrim Limestone 8,329 psi

Cottonwood Limestone 6,832 psi

Corinthian Granite 15,770 psi

Summit Granite 24,660 psi

Related Information:

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