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Defective tesserae applied to a concrete parapet. Both the background render as well as the tile finish have failed, possibly because of lack of key and water ingress via the parapet capping. |
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This panel of tesserae was repaired about 10 years before this photograph was taken. Vacuum grouting was used to secure the background render to the concrete substrate. The repair appears to be performing satisfactorily. |
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The various layers of construction can be seen: individual tile detachment around the perimeter of the damage, separation of layers of render and poor adhesion to the background concrete. |
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Sulphate attack has caused the mortar joints in the brick background to expand and cause cracking in the tesserae, the render background has begun to spall off. |
