Silbury Hill forum 180 room
Image by juamei
Silbury Hill

Silbury updates lock

close
more_vert
nigelswift N
nigelswift Jul 21, 2007 08:02:36
Replying to Littlestone

One thing that should be emphasised is that the concrete lintel will not last forever

Well it probably would except in certain circumstances when it definitely wouldn't. We now have no tower blocks remaining from the 1960s because with the type of concrete used in that era where it contained steel reinforcement the process of carbonation caused the concrete to become porous and water got to the steel which rusted and expanded and cracked the concrete....

I'm sure it will have been fully checked and there are means to chemically analyse for carbonation if steel is suspected to be present but it would be nice to know it had been. External clues are spalling, patches of discoloration and particularly orange colouring. Any photos? ;)

M Mr Hamhead
Mr Hamhead Jul 21, 2007 09:39:07
Replying to nigelswift

If you want to know how concrete can decompose within a short time, once water gets to it, look up Mundic on google...

Mr H

L Littlestone
Littlestone Jul 21, 2007 10:24:55
Replying to nigelswift

I'm sure it will have been fully checked and there are means to chemically analyse for carbonation if steel is suspected to be present but it would be nice to know it had been.
Perhaps someone could ask English Heritage's Ask the Experts ;-)

The most recent photo I've seen of the lintel shows what appears to be a vertical join to the right of the 1968 plaque. That would imply that the lintel is reinforced. Bottom edge of plaque shows some spalling. Orange hue to the concrete, though that might be discoloration from the earth covering (if it was covered with earth and not chalk). Green patina on the Superman door suggests copper.

None of this belongs in Silbury, any more than a commemorative plaque nailed to a Stonehenge trilithon would.