If you have ever made your own concrete you will no doubt have been told that you need to use some Ballast, but what is Ballast?
What is Concrete Ballast?
Ballast is a mix of sand and gravel that is then mixed with cement in order to make concrete.
The gravel usually consists of limestone or other stone, this is often recycled stone from other manufacturing procedures.
Why use ballast for concrete?
When mixed with cement ballast creates concrete. But why do we use it, after all, you could just add sand and be done with it, without the need for the stones in ballast.
Adding ballast helps to strengthen concrete, that is why it is added. The aggregate in the ballast helps bind the concrete together and as such increases the overall strength.
Why not use ballast?
Ballast is often left out of screed concretes. The reason for this is to allow the finish to be as smooth as possible, which is obviously seriously hindered when you have big chunks of gravel in there.
For these screeding mixtures is it common to just use sharp sand without the gravel.
This mix is weaker than regular concrete, which is why it is either applied just as a screed or other reinforcement, such as metal rebar is added.
Buying Pre Mixed Bags
While it is obviously possible to mix up your own Ballast, after all, it is just sharp sand and gravel, it is commonly sold as a premade product.
This is because mixing the right ratio requires a bit of knowledge, so it is often easier for the DIY’er to just buy it ready to go.