With ready-mixed concrete, you hardly seem to be able to go wrong: add water and the concrete is ready. But that's not right. Proper mixing is definitely essential for good quality concrete. How to do it right, and what to use for it, is what you will learn in this post.
In order for concrete to achieve its planned strength, the so-called water-cement ratio must be right in any case. It describes the ratio of water to the cement present in the concrete mix. Neither too much nor too little water must be added, and the water-concrete mixture must be as uniform as possible so that the correct water-cement ratio is achieved.
- Also read - precast concrete or mix it yourself?
- Also read - correctly process precast concrete
- Also read - An overview of mixing concrete: manual, compulsory mixer and ready-mixed concrete
In any case, this requires precise mixing - in addition to the exact addition of water, in the amount as prescribed by the manufacturer. Incidentally, this also applies to mixing mortar (7.79 € on Amazon *) s and screeds, but due to their consistency, it is often easier there.
Depending on the amount of concrete you need, you can use different mixing devices. The easiest option if you only need a little concrete is to mix by hand with a shovel, which is best done on a tarpaulin or in the largest possible tub.
With a special mixer you can also mix smaller amounts of concrete in the tub - the process is generally faster than by hand and is less strenuous. The mixing result is also often better than mixing by hand. But that always depends on the practice you have in it.
Concrete mixers are also suitable for larger quantities. Again, it's about using the right mixing technique. First you put two thirds of the required amount of water into the mixer, then the concrete mixture, and then gradually the remaining third of the amount of water. The concrete must not stay in the mixer for too long. But it has to stay in it long enough that it is sufficiently well mixed. That always requires some experience.
Proper mixing by hand
If you only need a small amount of concrete for home improvement, simply use a shovel to work with. Mixers are possible if they are sufficiently powerful, but most of them are usually overwhelmed with the tough concrete mass. They can burn out or become unbalanced.
Use the shovel to spread the concrete mixture a little on the tarpaulin or in the tub. Then pour the first liter of water over the mixture. Now turn the scoop with the curved side towards you and pierce the mixture.
Push a small pile forward and push it back with the shovel blade. You can do this in as many places as possible on your precast concrete (€ 15.69 at Amazon *). Every now and then, slide the scoop into the mixture from below and turn it over completely.
Then pour another liter of water over the entire mixture and repeat the process until you have added all the water you need by the liter. So the concrete is exactly mixed and evenly.