Bagged concrete easy to work with, improve
Tim Carter
Q: I have a few outdoor projects that involve pouring small amounts of concrete. I've seen bags of concrete in stores. Is it any good? Have you used it? Can I modify the mix to increase the strength?
A: I clearly remember my first experience working with this material. I formed and poured a large set of steps that led up to the front door of the first house I remodeled.
The good news is the bagged concrete you can buy at hardware stores is a fantastic product. The man who invented it built his first plant just a few miles from my childhood home in Cincinnati.
It's important to realize that basic concrete contains only four ingredients: small rocks, sand, Portland cement and water. The cement is the glue or binder that holds the sand and rocks together. When water is added to the other three ingredients, it starts a chemical reaction. Countless invisible Portland cement crystals start to form and interlock all the sand and rock together.
I've used bagged concrete for years and had great success with it. A caution: It’s important to use the right amount of water to mix the concrete. Add too much water and you'll ruin the concrete.
You can add more Portland cement to bagged concrete to make it stronger. You can also add some hydrated lime. To make the strongest concrete, the sand should be sourced from volcanic lava that has a high silica content. This is not easy to locate, and I'd not worry about it. But you should get a bag of pure Portland cement and a bag of lime and add some of those two things. Both ingredients are inexpensive.
Most bagged concrete comes in standard-sized bags. To make it stronger, take an old kitchen measuring cup and add 16 ounces of Portland cement and 8 ounces dry measure of hydrated lime to each bag of concrete.
You want to blend the extra cement and lime with the bagged concrete in dry form. Use a newer plastic mixing bag and roll around the dry ingredients before adding the needed water. The concrete should have the consistency of stiff applesauce when you add the correct amount of water.