How to Properly Mix Concrete
Tips for Mixing Quality Concrete Products that Last
Mixing concrete may seem pretty straightforward. But there are certain mixing techniques that will ensure you get the most out of your concrete products.
Properly mixing concrete gives you a strong finished product and saves you from frustrating problems in the future. Too much water will weaken the concrete, while too little will prevent the concrete mix from sticking together.
If you’re doing a small job, bagged concrete mix should be enough. But for larger concrete projects, you’re better off ordering ready-mix concrete delivered in a mixing truck. This will ensure your concrete is mixed thoroughly and with expertise.
To use strong, durable concrete products that will last a lifetime, follow these mixing and curing tips.
If you plan to hand mix small batches of concrete, wear the proper safety gear and use sturdy tools.
Tools and Supplies You’ll Need
For ease of use, mix concrete in a wheelbarrow if you have one. If not, a large plastic tub will do. Along with a mixing container, you will need:
- Waterproof (i.e. rubber) gloves;
- Safety glasses;
- A dust mask;
- A sturdy hoe;
- A large bucket;
- A plastic sheet or piece of plastic; and,
- A stiff-bristle scrub brush.
Step 1: Add Water to the Concrete Mix
Place the bag of concrete mix in a wheelbarrow (or other mixing container) on one end, and slice open with the hoe. Dump out the mix into your mixing container while pulling out the bag. Scoop out a few cups of dry mix and set aside.
Measure out the specified amount of water into a bucket. You will find the recommended amount on the mix bag. Pour most of the water (except for about 4 cups) into the end opposite the concrete mix in the wheelbarrow.
Using the hoe, pull a small amount of the dry mix into the water, mixing it completely. Keep pulling dry mix into the water and mixing well until all the dry mix is wet and piled on the water side of the wheelbarrow.
Go to the other end of the wheelbarrow, and start pulling the mix back toward you, mixing completely as you go.
Tip: When mixing in a wheelbarrow, brace it with your knee to keep it sturdy.
Step 2: Mix to the Perfect Consistency
Pull the hoe through the mix to create a trench. If the sides of this trench crumble and the concrete falls in chunks, then the mix is too dry. Or, if the mix sags into the trench and is soupy, then the mix is too wet.
The mix will have the right consistency when the sides of the trench stand, the mix is thoroughly wetted, and the concrete has a slight shiny surface when patted with the hoe.
For a mix that is too dry, add one cup of water, mix, and repeat if needed.
If the mix is too wet, add more dry concrete and mix well until it achieves the right consistency.
Step 3: Clean the Equipment
Once you’ve poured the concrete, clean the wheelbarrow, hoe, and any other mixing tools with a scrub brush and water. The longer you leave the residual concrete to dry, the harder it will be to clean.
Before cleaning the wheelbarrow, scrape off any leftover concrete and place it on a plastic sheet or a piece of plastic. For a large pile of excess concrete, break it up into chunks before it hardens so it will be easier to move.
Use a hose and a brush to wash your wheelbarrow (or mixing container) and hoe. Since the rinse water can kill grass, dump the water in a hidden spot on your property. Or dig a hole, pour the water in, wait for it to drain, and then cover with soil.
After placing concrete, you must cover it, keep it moist, and allow it time to cure. The curing process is how concrete develops strength. Through a chemical reaction with water called hydration, the concrete aggregates bind together, becoming stronger, harder, and denser. But the concrete must stay covered and moist to prevent evaporation and prematurely halting the hydration process.
Freshly poured concrete is very porous, which makes it more vulnerable to rapid evaporation and stopping hydration. But as the concrete becomes denser with time, it will become less porous. Since it can take months for concrete to fully hydrate and cure, you will only let it cure for as long as needed to attain the required compressive strength.
If you use bagged concrete mix for your project, follow the manufacturer’s instructions for curing. And if you order ready-mixed concrete from a local supplier, the concrete experts will inform you of the curing process for your specific mix. Expect to wait between 2 to 28 days for the concrete to cure, depending on the mix.
Keep the following tips in mind to ensure your concrete hydrates well and cures to a durable strength:
- Keep it covered with a moist curing blanket—made of canvas or burlap;
- Keep the curing blanket moist at all times;
- If it’s very hot out and the concrete is in the direct sun, mist spray the concrete with water, or sprinkle with water using a watering can or sprinkler; and,
- Cold concrete cures (gains strength) slower than warm concrete, so if you want your concrete project to cure faster, wait until the warmer months to complete your concrete project.
Why Curing And The Water-Cement Ratio Are So Important
Both the water-cement ratio and curing will affect the strength and lifespan of concrete. Concrete with too much water will be weaker since the particles in the mix will be diluted and further apart from each other, making it harder to bond together and form a strong concrete matrix. Instead, the concrete will take longer to cure and will have a lower strength. As a result, weak concrete will be at risk of cracking and curling.
Properly curing concrete ensures the concrete strengthens. It also prevents drying shrinkage. Once the concrete cures well and is strong enough, it will be more resistant to cracking and curling from drying shrinkage.
A properly mixed and cured concrete will improve its strength, durability, water tightness, and resistance to wear. Contact your local concrete suppliers for professionally mixed concrete and curing advice. With a strong concrete and proper care, your concrete products can last a lifetime.