ASTM Standards

Did you know that ASTM C1799 states that test results for stone should not be more than three years old? One of the most important resources for the design professional is the set of standards and testing procedures developed by ASTM International and the American National Standards Institute (ANSI). These standards guide the natural stone industry and help protect end users; in fact, most architectural specifications require that stone meet certain specified ASTM or other testing standards before it will be accepted for use.

ASTM publishes about 25 documents related to natural stone. These are organized into four categories: Standard Guides, Standard Materials Specification, and Standard Test Methods. Standard Guides documents provide basic information and definitions of terms used in the stone industry. The Standard Materials Specifications are specific to each of the commercially defined groups of dimension stone—marble or travertine, for example. (Note: There is no Materials Specification for onyx or soapstone.) These documents define the acceptable range of values for the physical and mechanical properties for these products and explain which test methods should be used to evaluate these properties.

Standard Test Methods describe the test protocols that are used to evaluate certain properties of a stone material—compressive strength and abrasive hardness, for example. We will be looking at these tests in greater detail soon, but for now, let’s look at a simple example that shows the relationship between the Materials Specifications and Standard Test Methods.

If we look at the Standard Materials Specification for limestone, we see that limestone is classified into three types based on density. The standard sets minimum or maximum values for several ASTM tests for each type of limestone. For example, a type II or medium-density limestone should have an abrasion resistance of at least 10 and compressive strength of at least 4,000 psi. Later we will look at how these test results help specifers.

A number of ASTM test standards pertain to natural stone; above all, these test standards help ensure an acceptable level of safety and quality for a given application. However, if you are new to this area, it can be intimidating if not overwhelming to determine which tests are applicable to your project.

Fortunately, design professionals have many helpful resources at their disposal, starting with the accredited quarry, material supplier, or fabricator. Not only will the supplier have test data, they will have anecdotal and historical information about the performance of a given material. They often can point to specific projects that have used the same stone in a similar application.

The Dimension Stone Design Manual is the “bible” of the natural stone industry. This invaluable resource is a one-stop reference manual that includes a comprehensive Illustrated Glossary of Stone Industry Terms, descriptions and technical data for individual stone varieties, and installation guidelines.

The Natural Stone Resource Library is a resource created for architects, designers, and contractors. This free online database includes documents on all varieties of natural stone, including suggested uses and applications for both residential and commercial settings. Users can refine their searches by using filters such as the type of stone, application, and document type.

The Role of the Design Professional

It is important to understand the roles and responsibilities of each of the key players in the process of specifying, installing, and maintaining a natural stone product. These include the design professional, general contractor, materials supplier, installing contractor, and end user.

As the specifier, the design professional is responsible for material selection based on aesthetics and performance criteria. He or she must obtain visual and physical samples and also acquire the test results that back up claims about the material’s performance for that particular application. It is the design professional’s responsibility to choose which tests are included in the specification, and it should include everything necessary to obtain an informed bid.

The material supplier furnishes the material to the installing contractor. Most suppliers hold test data from a standard series of tests for their main products. They must be able to obtain material that meets or exceeds the performance parameters outlined in the specification. They should also provide specimens and perform testing to document that the material meets those parameters. Realistically, the supplier will not always have the full spectrum of test results required on hand.

The general contractor oversees construction and coordinates with the installing contractor. The installing contractor must be able to install the material as prescribed. Often it is up to the installer to obtain testing if it is required, though this task may also fall to the specifier or general contractor.

The end user also has a role to play. The person must understand the material and his/her role in its maintenance; ideally, this will be established early in the design process so the client is not caught off guard.

There are several situations where you might have to seek testing. Perhaps you are introducing a new stone for which testing has not been conducted. You might have outdated technical data—test results that are more than three years old. Or you might have a special project that requires specific testing not included in the usual scope of tests.

You have several options for seeking the required tests. You may request the quarry or representative company to conduct them, but be prepared to encounter some resistance, depending on the quarry or provider, as they can sell directly to homeowners and residential projects that do not require performance testing. Independent labs also can perform the tests. If you anticipate that the stone product you are specifying may require additional testing, be sure to account for this in the specification, as these tests involve a cost, both in terms of time and money, and must be considered during the bid.