Shoddy materials

[Hagbard Celine]

The parapet on this overbridge on the Borders Railway was raised in case the line is ever electrified. The new parapet is less than ten years old but a large percentage of the bricks are already badly spalled. The same is happening on the outside of the parapets, from where any debris could land on a passing train.



The bricks below are still in pristine condition despite being at least 50 years older.

Is it normal for such shoddy materials to be used in railway construction? How long is it likely to be before this has to be replaced?

 

[The exile]

Is it normal for such shoddy materials to be used in railway construction?

Seems to be about par for the course everywhere - not just on the railway. When comparing with “the good old days”, one shouldn’t forget that we don’t see the worst examples of really old shoddy work as it’s long been replaced. We only see what was built well enough to survive!

 

[snowball]

To look on the bright side, this has had at least one good outcome - I've learned that there is a place called Plenploth.

 

[randyrippley]

If that parapet was raised ten years ago then they used second hand bricks.
To be honest it looks like all they did was (badly) repoint the existing brickwork and fit new capstones. But even that was done incorrectly as you've got water seepage and smeared mortar around some of the joints.
Besides that, the masonry isn't even level - there's a half inch or so drop in the middle.
You're right it's a mess, but not for the reasons you think.

 

[Hagbard Celine]

Streetview image from the A7, April 2011 -



Streetview image from the A7, August 2014 -



2014 picture shows the masonry bridge with a darker line of the old brick parapet and the contrasting yellow brick of the heightened and lengthened parapet. AFAIK this is the only original masonry overbridge on the Borders line that had a brick rather than masonry parapet, so it may not have been original.


Close up of some of the worst bricks -



They look very second hand now!!
It doesn't show up in my photo but some of the 'pointing' is 10mm proud of the crumbling brickwork.

 

[John Webb]

I wonder if the darker original brickwork was put together with lime mortar and the new brickwork with cement mortar. If so, then possibly the older brickwork, able to move a little, has set up stresses in the newer brickwork which has lead to the spalling?

 

[WAO]

The lime mortar, as well as being slightly elastic, also is porous and so allows moisture to diffuse out and evaporate. Portland cement mortar does not. The glazed brick will also be impervious to moisture, so freezing of trapped moisture, then frost heave and spalling will damage the brickwork. The pointing is "proud" probably because it has been pushed out by expanding ice behind.

What do they teach architects (and builders) today?

WAO