Tuesday, March 19, 2013

Great Wall of MIT Redux

Way back in the olden days of this blog, near the middle of the last decade,  we had some words with Joe Dahmen about his Great Wall of MIT project.


 

Recently we found ourselves strolling the sunny streets of Cambridge, Massachusetts and thought to check in and see how the wall has withstood six cold winters.

 


 
The wall was very thoughtfully designed with steel plates installed to give information about the soil mix at various levels of the wall.


 As you can see the soil ratios are sensible. You can't get too fiddly with your proportions when you're working at such a large scale.

 It reads (in all caps):
Financial support: Office of the Dean, MIT School of Architecture and Planning  MIT Council for the Arts Boston Society of Architects Sasaki Associates Inc.
Material Donations: Modern Continental Construction JF White Contracting Co.
Project Team: Teagan Andres Charles Mathis Omar Rabie Shuji Shuzumori
Project Designer: John Ochsendorf
Designer/Team Leader: Joe Dahmen

If you have environmental concerns about using cement stabilizer in your rammed earth walls, and you have somehow managed to convince All Who Would Thwart You to allow you proceed using regionally available clay, this is likely to be your final surface, unless you go in for plaster (stucco is cement after all) and even more labour.
While you can see bits and pieces of the wall crumbled on the ground, keep in mind that there's been six winters of unsympathetic Massachusetts snow removal against it. It is still a formidable structure despite the surface concerns. Perhaps if you were imprisoned within similar walls you could, with time, scratch your way out, but if you tried to drive a car through them, that would be the end of the car. It would take several generations of cattle to rub those walls away.


As has been mentioned in numerous documents regarding historical rammed earth, the part of the wall closest to the soil and the drip line are the most prone to erosion. It would have been interesting if they had left the roof cap off one section to see how much of this erosion is caused by drips falling from the small over-hang and splashing up from the ground versus how much would be caused by water infiltration from the top wall surface.

 The surface is definitely looking better under the steel cap.

Still pretty bony though. I think if you're going to go to the trouble and expense of ramming a wall with labour costs what they are in the First World, you'll want a more durable surface than what we're seeing here. Still a worthwhile experiment, though.


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