10 things to know about stone testing

Testing is the starting point for determining the suitability of a specific stone for a particular application. This can include testing the strength of the stone by determining its resistance to crushing and bending; testing the stone’s wear resistance and slip resistance, particularly for flooring applications; and analytical testing such as petrographic examination, to determine the stone’s mineralogical and chemical characteristics.

Stone testing is important because it can help to avoid product failures, and offers information that allows you to work with the strengths and minimise the weaknesses of your product.

Here are 10 things to know about stone testing:

1. Stone is a natural product. Every piece has its own unique story to tell, and understanding its strengths, weaknesses and any variability is important if you want to select the right stone for your job. This is why it’s best to test from a batch proposed for use in your project, at a thickness and finish that is relevant to that project.

2. Stone can be a durable, longstanding building material when selected, installed and maintained properly. The Appian Way, built circa 300 BC, is a prime example and a testament to the durability and timeless nature of stone as external paving. This ancient roadway has withstood the forces of nature and countless wars for over two thousand years, with parts of the road still carrying vehicular traffic. Understanding the strength, durability and load capacity of your stone paving is the starting point to producing a pavement that is fit for purpose.

3. There are four basic keys to selecting and specifying the right stone for your project (as a starting point). These are stain resistance, strength, resistance to abrasion, and durability. These keys are relevant whether the stone is to be used as a kitchen bench top or for cladding a multi-storey building, although the relevance and ‘weighting’ of each key will vary depending on the proposed use and location.

4. Stone testing reports are about more than numbers. It’s one thing to have paperwork full of test results, but the real value comes from our experts working with clients to ensure they understand what the results mean. This allows them to work with the strengths and minimise the weaknesses of their product.

5. Accidents never happen! Pedestrian surfaces can be litigation minefields following falls on all kinds of surfaces, from polished stone to linoleum and bitumen roadways. There is a need for everyone – from the architect to the maintenance supervisor – to keep in mind the potential hazard of all pedestrian surfaces. Appropriate and timely slip resistance testing can help to prevent falls and keep surfaces safer for users.

6. Not all tests can be carried out on site. While in some cases product evaluation testing such as skid and slip resistance can be performed on the project floor, many analytical and physical tests must be performed in our NATA-accredited lab, such as resistance to salt attack, water absorption and compressive strength testing, and petrographic examination.

Stone testing can include petrographic analysis, slip resistance testing, stain resistance testing and failure investigation, among other tests.

7. The right sealer can improve stain resistance significantly. Stain resistance is determined by a combination of the stone’s properties, colour, texture and composition. Stone types that are acid soluble or have a mid-tonality (e.g. mid-grey) are often very sensitive to staining. Textured finishes also have a tendency to entrap grime.

8. Asbestos and silica are naturally occurring minerals that can be present in dimension stone and pose a risk to health. Awareness and appropriate protection are key for anyone working with natural stone, in order to reduce the risk of exposure to these potentially harmful fibres and micro-particles. Prevention includes appropriate analysis and identification by qualified technicians.

9. Information is key in heritage conservation. The ad-hoc and ill-informed use of consolidants, sealers, coatings and cleaning methods on historical material can result in irreversible damage to our cultural heritage. Determination of the material’s characteristics and physical properties allows the conservation plan to be based on informed decisions, minimising the risk of damage or unnecessary deterioration. 

10. Testing and analysis can tell us fascinating stories. This is especially true when it comes to heritage conservation projects and the analysis of historical stone, mortar products and other building materials. Layers of history can be unravelled and we can learn surprising lessons from what the discoveries tell us.

Types of stone testing

Whether you require stone testing for building and architectural projects, product manufacturing, heritage restoration or litigation issues, it’s important to understand which tests are right for your job. Various tests can be carried out on site at a project, while others are performed in the lab, to determine both physical and chemical properties. Stone testing services include (but are not limited to) the following:

Basic physical tests:
Water Absorption
Bulk Specific Gravity
Compressive Strength
Flexural Strength
Modulus of Rupture
Resistance to Salt Attack
Resistance to Acid Attack

Analytical testing:
Petrographic Examination
Whole Rock Chemical Analysis
Moisture Content
pH Determination
Microscopic Examination by Polished Section
Total Dissolved Salt (Conductivity)

Product evaluation:
Slip Resistance
Skid Resistance
Accelerated Wear Testing
Stain Resistance
Sealer Evaluation
Impact Resistance
Chemical Resistance

Heritage services:
Identification and Matching of Historical Stone
Analysis of Mortar and Render Samples
Analysis of Historical Paint and Wash Coatings
Dilapidation Surveys
Rising Damp Surveys
Consolidation Trials
Cleaning Trials

For more tests, see the summary of our capabilities, or get in touch to discuss your testing requirements.

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