TAN 31- STONEMASONRY MATERIALS AND SKILLS

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TAN 31:STONEMASONRY SKILLS AND MATERIALS: A methodology to survey sandstone building facades

TYPICAL EXAMPLES OF STONE DECAY CLAS 1. Ashlar walls

a) Surface crustformed (tooling on surface is still intact) but the loss of sandstone cementfrom thegrains below the suface has led to granular disaggregation in the su@ce zone for more than 20 mm depth. ClassiJication: Immediate replacement

d) Granulation: Serious loss ofbinding cement in the blonde sandstone. Possibly associated with salt action and hard pointing. Classijcation: Immediate replacement

b) Cnrsr yl~rsgranulation: Edge erosion: similar action to illustration a) e) Flaking: Pre-existing decay accelerated by a covering ofcement and decay is accelerated by loss of pointing in both the drip moulding, mortar plastic repair. and in the stonework generally, and/or use ofhard mortar. Classijcation: Immediate replacement Classijcation: Immediate replacement

c) Loss ofstone su@ce. Primary cause is dijkult to determine but the facade has been cement plastered and painted resulting in entrapped moisture. Maintenance will be required on thisfacade to remove the cement plaster within the next twenty years. ClasJiSIcation: Immediate replacement of decayed stone and maintenance of plastered areas within twenty years

f) Partial loss ofstonefrom drip moulding leading to su@ce runs of rainwater but someJicnction still retained. Classijication: Replacement within twenty years


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