The Strength of Concrete

Mark Miodownik explains our planets dependence on concrete in his book, Stuff Matters, which is an exploration of the built world and the materials that make the world what we see.  Miodownik explains that the first concrete developed on our planet came from the Romans, but the technology was not perfected until more recent times.  He also tells the story of how reinforced concrete came to be when a potter found that he could produce cheap concrete pots and boost their durability by setting the concrete around a steel internal skeleton. The strength provided allowed his pots to hold up to dropping, shipping, and the general wear and tear of the gardening world.
I find Miodownik’s section on concrete fascinating. Prior to reading his book I had never stopped to consider what truly went into producing concrete and concrete structures.  from our sidewalks, to buildings, to dams and barriers, we see concrete everywhere and Miodownik reflects on our perceptions when we see things everywhere.  He writes about our normal tendency to see those common and everyday things as simple and unimportant, when oftentimes, as in concrete, they are complex, crucial, world altering innovations.
While most of us may not appreciate just how important concrete is and we may not understand just how complex concrete is, there is an understanding in our country that our infrastructure needs some TLC.  And it is not just people in the United States who know their structures need some love, “To prevent stone or concrete structures being similarly affected, maintenance of their fabric needs to be carried or every fifty years or so.” In this quote Miodownik is explaining the effect of general wear and tear on concrete.  As materials heat up or cool down, as happens yearly due to the temperature changes of the seasons and days, they expand and contract. Reinforced concrete is a wonderful material in respect to contraction and expansion because the concrete itself and the internal steel skeleton expand and contract at almost identical rates.  This prevents the steel from busting out of the concrete and keeps the steel protected and the concrete free from cracks.  But overtime the concrete does develop micro-fractures, which grow into visible fractures, which allow more water in, and become clear chips and breaks in the concrete.  This erodes and breaks down the concrete structures we build in the same way that nature breaks down the mountains around us (or at least around me living in Reno Nevada at the base of the Sierra Nevada Mountains).
I think what I like about Miodowniks quote is that it shows the impermanence of what feels like our most robust building materials.  We may look at concrete structures and imaging their hulking frames will last forever, but what material science shows us is that they are constantly in a battle to be broken down. Even the mountains which define borders and seem to be natural strongholds of the earth are not permanent as weather batters them down.  If you cannot enjoy the science behind the concrete, hopefully you can at least appreciate the brevity of its existence in the long term life of the planet, or appreciate our perspective on the material, seeing it as an unyielding monolith which ultimately is brought down by some water and wind.
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