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What Makes Concrete, Well, Concrete


I was racking my brains for an interesting and readable blog idea, when I realized that I had never done the ridiculously obvious. What IS concrete? What is it made of? Where does it come from? How well do we actually know it? What’s its personality? Is it a Virgo? Does it like dogs? Will it call me after the second date? Okay, step too far.

Here are the important facts:

1. Concrete is not just a lonely substance–it is the cookie that you pull out of the oven after you impulse bought four bags of ingredients. It requires a mixture to make it come into the state that we know it as. It requires two things: a filler and a binder.

2. The filler. When I think filler, I think Toaster Strudel and the strange not quite jelly, not quite anything else filler that goes inside. This, thankfully, is not the same and will not do questionable things to your pearly whites. A filler in this case would be “coarse aggregate” which is maybe the fanciest way of saying sand, gravel, tiny pebbles, and other similar things. I always wonder why they decide to name things with words that would never come up in a daily conversation. I mean I guess if you were talking concrete on the daily. “Hey, so Tina, I’m in the third coarse aggregate driveway from the left.” Yeah, no. Not feeling it. Moving on.

3. The binder. Not the three-pieces-of-cardboard-covered-in-some-ridiculous-plastic-that-will-eventually-peel-off-rendering-it-useless binder, but a binder that, combined with the filler, makes the concrete. The binder is, drumroll, cement paste. Hello, Portland Cement, where have you been all my life. Well, everywhere. Literally. In 1824, Joseph Aspdin found himself the inventor of the most sought after cement of today’s modern age: Portland Cement, a very key ingredient in the makings of concrete. Cement and Portland cement are different in what their composed of. Portland is mostly ground limestone which allows it to act as a more generic cement for more things. Joe’s so reliable. Hydraulic or Portland Cement and water are mixed together to create the binder.

4. Adding them together. We have the binder. We have the filler. The filler said, “Hey, binder, looking good tonight.” The binder replied, “Not as rock solid as you.” Okay, bad pun. We’ll work past it. Together, they are concrete (two halves of a whole–how romantic). Bringing it back to the “aggregate” can come from very fine (sand) to very coarse (gravel, etc.) and will affect the concrete. The finer the aggregate, the smoother the surface and vice versa.

I’ve said this before, I’ll say it again. It’s the most used man-made material on the planet. And now, you know all there is to know about it. From the beginning when filler and binder had never even met, all the way up to when they discovered they were soul mates.

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