1. STONE IN CITY THE

2. Dr Tim Yates BRE Ltd

3. There’s no such thing as bad stone – only badly used stone Tim Yates, BRE 12 th March 2008, Stone in the City, The Natural Stone Show 2008

4. Where do we begin ? Choosing by appearance – colour, texture, etc Meeting a required performance – strength, durability Performance or prescription? Trial and error? Past performance Testing and assessment

5. How many types of stone are available? Locally – for example Bath Stone –About 6 Nationally – for example UK –Around 250 World Wide – –Over 8000

6. Where do we begin ? Stone properties Project needs Stone properties Project needs Project needs Stone properties Failure! At the limit! Success! Variable Fixed Variable Fixed

7. How do we match a stone to a project? Failure mode effect analysis –What can go wrong? –What can we test for this? –How can we manage the risk? Is it safe? Will it last? Is it strong enough?

8. Specifying by experience Local Stone Trial and errorObservation Experience Measurement Traditional UseTesting Classification Portland Stone in London - observation of balusters on buildings in Whitehall - failure of stone at the Palace of Westminster

9. Performance versus Product specification Example 1: Resistant to 10 m/s wind loading 70mm thick cladding London limestone

10. Performance versus Product specification Example 2: “Durable” for 50 years Weathering rate 2mm per 100 years Class B London limestone (based on tradition)

11. Product specification BS 8298: 1994 Design and installation of natural stone cladding and lining –Use stone like this and it will be alright BS 680: 1971 Specification for roofing slates –Use slates that pass (Now replaced by BS EN123630 BS5385 Part 5 :1994 Wall and Floor Tiling: Design and installation of terrazzo tile and slab, natural stone and composition block flooring –Doesn’t matter what you use as long as you do it right

12. Different types of test (1) Index tests –Petrographic description –Porosity, Density and Water Absorption –Saturation Co-efficient Strength tests –Compressive –Flexural –Modulus of Rupture –Strength around a fixing –Point load

13. Different types of test (2) Durability tests –Freeze-thaw resistance –Salt resistance –Thermal Shock Safety –Slip and skid resistance Component tests –Wind loading –Fire –Impact

14. Deterioration of natural stone Erosion and spalling Large, solid stones Loss of strength Thermal and moisture cycles Biological growths Westminster Abbey, London

15. Deterioration of cladding Bowing and distortion of marble cladding Large, thin panels Loss of strength Thermal and moisture cycles University Library, Göttingen, Germany

16. Deterioration of cladding Bowing and distortion of marble cladding Large, thin panels Loss of strength Thermal and moisture cycles Finlandia Hall Helsinki Amoco Tower Chicago

17. Different uses of stone in construction External Cladding

18. External Cladding

20. Different uses of stone in construction - Flooring and Paving

21. Different uses of stone in construction - Roofing

22. Roofing

26. Roofing - does something always go wrong?

27. Vimy Ridge

29. Will the stone do what I want it to do?

30. Stone in different environments

31. Is the stone what I wanted?

32. A few pointers Select the stone with care –Establish what performance requirements of the project –Recent test results –Assurance that the material is consistent –Extra tests if needed Workmanship –A good contractor –Sorting –Laying Any questions?

33. Some conclusions Performance Life time Realism

34. Thank you for your attention