Paved Paradise

It isn't pretty but it's a subject I looked at this week: cement. Mostly it's not very aesthetic to look at, but sometimes it can be pleasing to the eye, like the arches on the Annandale aqueduct.

I found out more about some wayfinding aids (mentioned last week in 'Australia, Street'). When town planners 'set them in stone' on concrete footpaths, they clearly thought the designations would last forever. Little did they know the 'municipality' and council areas would be constructed, deconstructed and amalgamated many times.
  

A blink in time: 1906 to 1948. But the footpath sign lives on in 2019.

'Municipality of Petersham' was created in 1906, born out of the 'borough' created in 1871 from townlets Stanmore, Petersham and others. The 'municipality' lasted until 1948, when it merged and fell under the name of Marrickville Municipality. They were happy enough together for nearly 70 years - until 2016 when the 'forced merger' with two other municipalities created Inner West Council.

I'm trying hard not to discuss 'politics' in this blog. But it wants to creep in.

Back to concrete 'standing the test of time'. Its discoverers knew that. It is similar to ceramics: if you use very high heat to cook certain materials - types of mineral dust - they change and can be bound together almost forever. In some archaeological sites, pot sherds or shards are found more than anything else. 

The Annandale aqueduct has a plaque explaining it was made in 1896 from a revolutionary material: reinforced concrete. A royal commission investigated its use; and the builders were forced to post a large 'surety' and guarantee maintenance for three years. More than 120 years later it's fine.

At a California mission site I worked at years ago, we found fired-clay roof tile pieces by the bucket load. 

(The adobe blocks which made the buildings were only sun-dried, and 'melted' when exposed to rain.) Fragments of plates also made up great quantities, especially from dates closer to the present; the California Indians who lived in the area and were recruited to the mission did not make pottery as a rule since they had an incredible range of baskets that could cover almost any task.

I went down a research hole to understand the origins of pottery and porcelain. Travelling to England's Staffordshire District I visited pottery factories and the home of Wedgwood. Even while in England seeds of doubt were being sown, about whether this was the job for me. I thirstily went to exhibitions and free archaeology lectures. Sitting in one lecture about medieval shoes... the speaker droning about minutiae... something snapped in me and I lost momentum. I don't doubt the usefulness of all kinds of arcane subjects; I just found that even I had a limit.

Bowls and plates made from pottery or china last a very long time, or at least pieces of them do.

Photo by Louis Hansel on Unsplash.com

Another limit I brushed against was digging up bones. Some archaeologists dream of a day they could be privileged to uncover a human skeleton. I dreaded it, and luckily was never asked to do so. I believe in science but also feel unseen connections from past to present and person to person and I didn't want to cross that. I did shake a lot of bone fragments through screens, and tried to learn from experts to identify them, so as not to unwittingly handle human ones. (So many cow bones, fish bones, deer bones, bird bones.) 

I love handling a cool stone arrowhead, or glassy obsidian flake, or smooth grinding stone as much as anyone. But over time for a number of reasons I veered away from archaeology and into 'interpretation'. There is plenty of stuff already dug up, and more to come, and maybe I could be of use helping spread understanding of material objects.

This homeowner built their front fence from homemade concrete

 instead of buying shaped sandstone forms and pillars like everyone else in the street.

Regarding concrete: in our 'throwaway' societies with great pockets full of money, we are able to finance the wholesale destruction of previous concrete buildings. I first saw a stadium demolished in San Francisco. In 1989 they tore down Kezar Stadium, standing since the 1920s on the edge of Golden Gate Park. In my walks, I would gape at trucks being filled with endless piles of white concrete rubble. I simply couldn't figure it out. Couldn't quite believe what I was seeing and hearing.

Kezar opened as a 50,000 seat stadium, where famous football teams played, and concerts. But it was superceded when Candlestick park opened in 1971. Reading this week to see if I could find why Kezar was demolished, I found this: "Cramped bathrooms, minimal concession stands, and most of all no parking were all problematic for Kezar." * 

(There is a rebuilt sporting ground there now, much smaller.)

The knocking down of stadiums has been in the news lately as a political subject, but as I said, not going there...

I used to not understand the material very well. Doing some home handy-work and wanting to patch holes in a driveway, I bought a bag of 'cement' and mixed it with water and poured it in. Later I was told by others wiser than me, 'you can't just use cement, you have to mix it with something to make concrete' - hence the bags of 'sand and cement' for sale that I'd overlooked. Plain cement sort of works, but isn't as solid as concrete.

They put this concrete around metal bars. That's usually what 'reinforced' concrete means.

Cement has been in the news recently, with growing awareness of its high carbon cost. Says someone who knows more about it than me, 'Cement is made of gypsum and lime. You heat them very hot by burning coal.' This makes white cement powder. Add water and it magically turns hard. (But first add sand or pebbles to make concrete.)

High fuel usage is needed to make the lime by burning limestone, or burning crushed shells. 

In early Sydney a lot of mortar for joining bricks into house walls came from Darling Harbour (Cockle Bay) shells. Researchers have pointed out that the shell piles there were middens from Indigenous living sites. Colonists desecrated these 'easy picking' places and when they were gone, people turned to the harder work of prising shells off rocks. If you've ever had an oyster cut, you know how awful this job would be. 

Modern lime for cement is often made from limestone instead of shells. In either case, pits or kilns are where it is burnt. Some old historic areas have interesting looking 'lime kilns'.

'If it were a country, the cement industry would be the third largest in the world, its emissions behind only China and the U.S.', John Vidal said in The Guardian, 26 February 2019. Making cement creates around 8% of global emissions. 

I think we all need to look at the materials we use and ask is there a way to 'reduce, reuse, recyle'? If something no longer suits our purposes, can we 'repurpose' it somehow? I wonder perhaps not how but why things like Roman-built stadiums and aqueducts still stand. We know the materials can last, but it's the will to continue using them that seems to fade so easily now.

* Website by Bob Busser. https://ballparks.smugmug.com/Kezar