One of the things that bugs me is a tendency for many folks to use concrete and cement interchangeably. They are not. Most weeks, I hear at least one person refer to sidewalks as being cement sidewalks or call a concrete mix truck a cement mixer.
Cement is an ingredient in concrete. There is no concrete in cement.
Concrete is made up of cement, water, and aggregate (sand and crushed rock) used in varying proportion to make the sidewalks, driveways, patios, etc. around your home. The differences in proportion affect the strength of the concrete although some concrete has additives that change the concrete and make it more flowable or stronger. Most of the concrete at your house has steel to reinforce it. You would think that also makes concrete stronger and it does, but it also makes it more flexible since wire and steel bars can bend which concrete cannot do.
Cement is a combination of limestone rock, clay, and sand that are crushed, mixed, ground, and baked in a kiln at 2,700 degrees. The baking process is also called sinistering. At some point someone (the cement baker) declares it done; the baked mixture comes out in 1″ to 2″ balls which are called clinkers. They are then ground into a fine powder and mixed with a small amount of gypsum.
This is the kind of information that I love. I like that something that is batched out in huge quantities-30,000# per concrete mixing truck-can be simplified so easily. I also like it because I make little stepping-stones and concrete benches and like to mix my own concrete when possible. The stepping-stones, coasters, and hot pads are easier to make using my own mixture since they use a much smaller quantity.
I’ve learned the hard way that I can’t cut corners on sand and use beach sand for my concrete mix. What I found is that there’s silt in even the prettiest beach sand and the clay makes an unpredictable mixture. I like using a white cement in my mixture because it takes concrete color more completely so I thought the very fine white sand in Ingleside would reinforce that.
My daughter in law MH and I both broke a couple of stones; I found out the clay in that sand made the mix weaker. It takes a lot of work to assemble and place the glass inside the form and to have it break?
I don’t cry about it, but I am glad my backyard is fully fenced since I run around like a crazed eagle, flapping and squawking, until I am composed enough to pick up the pieces, salvage the glass, and start over. Still, it doesn’t feel good.
Now I use a packaged masonry sand. It isn’t white but it has large enough particle size so the stones are less likely to crumble.
I also learned by negative experience that I have to measure my sand, cement, and water by weight and not by volume. The mix for 30 lbs. of my concrete is 2.5 lbs water/5 lbs cement/22.5 lbs sand. My bathroom scale is my scale; I weigh myself with and without the weights. Do I need to add that I generally go on a diet when I’m making concrete since I can’t deny my weight?
I like adding color to the concrete. It usually looks too dark and I’m sure that it won’t turn out right. So far, I haven’t found that to be the case.
I use packaged mixes and need help when I pour benches. Bob plays Igor to my Dr. Frankenstein and helps me out. I find out how unhelpful Home Depot is whenever I’m trying to grapple with a 60 lb. sack of Quikcrete. I’m at that unfortunate age: no longer young and cute but not fragile and old. So, the workers at the lumber company are happy to empower me. I am glad that Bob’s willing to do the heavy lifting.
I’ve been using a standard sealer for the concrete which doesn’t do more than keep mesquite sap and bird poo from penetrating the concrete and discoloring it (theoretically). I’d like to experiment with colored sealer and plan to do so since my next project (big project) is concrete countertops. I’d like to refurb my kitchen counters this winter. Need to learn a little more before then.
Maybe get a little more empowerment from Home Depot.