Fitness for Purpose is fundamental to the successful use of stone, but how do we evaluate a stone to ensure its suitability for a particular use or location? In this article we will discuss four basic keys to assist in the selection and specification of the right stone for the job. The keys are relevant to all stone users and specifiers, and they provide a useful starting point for choosing the right stone. The four keys are:  Stain Resistance  Strength  Resistance to Abrasion  Durability

1. 4 Basic Keys to Successful Stone Selection Jim Mann Stone Consultant www.stonemtg.com.au

4. Stain Resistance A stone’s ability to absorb stains is directly related to its water absorption. C629 C568 C616 C503 C615 ASTM Spec. 0.45 12 (LD) 7.5 (MD) 3.0 (HD) 8 (S) 3 (QS) 0.20 0.40 Standard Requirement 6 – 0.3 Slate 26 – 0.08 Limestone 12 – 0.3 Sandstone 0.8 – 0.04 Marble 0.8 – 0.01 Granite Water Absorption Typical Range (weight %) Stone Type

6. Stain Resistance Note: Impregnating sealers are not effective in protecting acid-sensitive materials from etching Limestone and calcite marbles are particularly sensitive to acid attack and etching. Be wary of using polished marble in entertaining areas!

8. Stain Resistance Spot the chewing gum!

9. Strength Stone installations must have adequate strength to withstand both live and static loads that may be encountered in service.

10. Compressive Strength Unconfined Compressive Strength – ASTM C170

11. Compressive Strength Compressive strength results can be useful for comparing likely performance of different stones. - C629 200 - 25 Slate 12 (LD) 28 (MD) 55 (HD) C568 150 - 4 Limestone 27.6 (S) 68.9 (QS) C616 120 -10 Sandstone 52 C503 150 – 80 Marble 131 C615 300 – 100 Granite Standard Requirement ASTM Spec. Typical Compressive Strength (MPa) Stone Type

12. Measuring Flexural Strength Flexural strength ASTM C880 – 4 point loading Modulus of Rupture – 3 point loading

13. Flexural Strength Adequate flexural strength is essential for satisfactory performance of stone used for paving or ‘dynamic’ wall cladding 49.6 (MoR) C629 50 - 15 Slate 2.9 (LD) - MoR 3.4 (MD) - MoR 6.9 (HD) - MoR C568 21 – 2 Limestone 2.4 (S) – MoR 6.9 (QS) - MoR C616 15 – 3 Sandstone 7 C503 22 – 6 Marble 8.3 C615 30 – 6 Granite Standard Requirement ASTM Spec. Typical Flexural Strength (MPa) Stone Type

14. Flexural failure of paving under load

16. Resistance to Abrasion ASTM C1353 “Standard Test Method for Determining Abrasion Resistance of Dimension Stone

17. Resistance to Abrasion Typical Values – higher numbers indicate greater wear resistance 8 C629 4 - 20 Slate 10 C568 <1 – 20 Limestone 2(S) 8 (QS) C616 4 – 24 Sandstone 10 C503 15 – 50 Marble 25 C615 50 – 150 Granite Standard Requirement ASTM Spec. Typical Abrasion Index (Ha) Stone Type

24. Durability Suitable only for use in sheltered locations free from exposure to salt attack. Additional engineering practices may be required to protect stone. D > 10 Exposed to infrequent wetting and drying or low level salt attack C 6 – 10 Exposed to intermittent wetting and drying or moderate level salt attack B 1- 5 Exposed to continual wetting and drying or moderate salt attack A 0.1 – 1 Aggressive environments, constant wetting and drying and exposure to salt attack AA < 0.1 Environment Suitability Grade Weight Loss (%)

26. Choose stone that’s “fit for purpose” Jim Mann Stone Consultant www.stonemtg.com.au