Well why not? He's got the dirt. How tough could it be?
Back in March, Elon Musk announced that he was getting into the brick business. On the Boring Company's FAQ page they noted that moving excavated dirt was expensive and time consuming and they would do better, perhaps making bricks out of the dirt and building the tunnels out of them.
The Boring Company is investigating technologies that will recycle the earth into useful bricks to be used to build structures. This is not a new concept, as buildings have been constructed from Earth for thousands of years including, according to recent evidence, the Pyramids. These bricks can potentially be used as a portion of the tunnel lining itself, which is typically built from concrete. Since concrete production accounts for 4.5% of the world’s greenhouse gas emissions, earth bricks would reduce both environmental impact and tunneling costs.
I thought this was a great idea, and have been impressed with their progress. But new a new tweet shows that he has bigger plans:
The Boring Company will be using dirt from tunnel digging to create bricks for low cost housing— Elon Musk (@elonmusk) May 7, 2018
This is such a wonderful gesture, showing such concern for the underprivileged, given that he is digging these tunnels because he thinks public transit is full of "a bunch of random strangers, one of which might be a serial killer."
According to Sarah McBride in Bloomberg,
A company spokesman confirmed the plans, saying the bricks will come from the "excavated muck," and that "there will be an insane amount of bricks.” Musk has also suggested he has plans to sell them, and the company said future Boring Co. offices will be constructed from the company’s own bricks.
Now I do not know much about building tunnels, but thanks to previous lives as an architect and real estate developer, I do know something about building housing.
Yes, it’s definitely the bricks that make housing expensive 🙄 https://t.co/dBYAEy2c1q— Amanda Kolson Hurley (@amandakhurley) May 8, 2018
As Amanda correctly notes, there is a lot more to building housing than bricks; the main problem is where to put the housing. Construction materials are a small portion of the cost compared to land. Bricks traditionally are labor intensive and in California need sigificant reinforcement, and light buildings perform better in earthquakes than heavy ones. (Musk claims that his bricks will go together like LEGO bricks and will be rated for California seismic loads.)
Another issue is that bricks are usually made of clay, or they are faked out of concrete, which is made from clean sand and aggregate. We have shown rammed or compressed earth blocks on TreeHugger and also these Watershed sorta rammed earth, sorta concrete blocks. But it is not so easy and you need some consistency.
According to Glen Creason in Los Angeles magazine,
This surprisingly engaging map relies heavily on data produced in a thorough soil survey completed in 1903. The variety and complexity of the ground under our feet is amazing. While the colors shown in the legend border describe variations of loam (sandy loam, silt loam), sand, adobe, riverwash, tidal marsh, clay, and even peat, there are 50 soil classifications in L.A. County alone.
Looking at the cross-section, it seems to be a mix of everything. But when you look at where bricks come from, they are usually big deposits of consistent clay. They are rarely made from just stuff dug out of the ground at random, it's too inconsistent.
But then again, this is a guy who can fire sports cars into space, and made ten million bucks selling flamethrowers, so it is hard to dismiss what he says. And as Juan Matute of the the University of California, Los Angeles, told Bloomberg:
That doesn't mean the Boring Company can't buy some land and build a few low-cost houses, with a partner like Habitat for Humanity, and say, "Look what we did."
We will wait and see.