Since this is a cleaning-up period at the end of the year, I’ll feature a couple of photos I’ve had for a long time and get them off my mind.
If you’ve been to the Quad at Stanford University, you may have noticed the excellent concrete walkways there. They date from the construction of the buildings in 1890 and were made by the same George Goodman, of San Francisco, whose lovely escutcheon stamp I featured here the other month.
Goodman listed himself in the business directory as a specialist in the Schillinger Patent method, which wasn’t really about concrete per se but about making sidewalks in a way that would help keep them from breaking up. The next photo, though, is about concrete itself.
If you’ve been to the Conservatory of Flowers in Golden Gate Park, you must have noticed the vintage pavement there. Its age is uncertain, but probably from before 1900. The Granolithic Paving Company was listed in the 1887 business directory at 422 Montgomery Street, San Francisco.
Peter Stuart, a Scot, invented granolithic concrete in the 1830s. It’s an extremely strong material, the Gorilla Glass of concrete, made by an ingenious method that lays down a surface layer, or screed, of concrete densely packed with finely crushed granite or similar rock. At the correct point in curing, an absorbent blanket is placed on the concrete to reduce the water content, raising its strength. (Low water content was one reason ancient Roman concrete was so strong.) Stuart’s granolithic method was patented in this country, as the stamp says, in 1882. The company that bore his name stayed in business until 2012.
While you’re there, walk south to John F. Kennedy Drive and visit the Alvord Lake Bridge, the first reinforced concrete bridge built in America.