Which sand for foam concrete manufacturing is better to use in the CLC lightweight concrete blocks manufacturing or for the construction from lightweight concretes? In this video, we give an example of what a suitable sand for foam concrete manufacturing can be.
In this article, we will give brief recommendations on which sand is best to use for the lightweight concretes manufacturing.
These recommendations are based on our experience and the experience of our customers. And also on the recommendations of manufacturers of ready-mixed concrete with many years of experience.
In the lightweight concrete or foam blocks manufacturing using BAS series machines, sand should comply with the following simple recommendations:
- sand should not be salty (sea sand and sand from salt marshes is not suitable for the lightweight concrete production)
- sand must be sifted (sand must not contain small stones and other inclusions)
- sand for foam concrete manufacturing should not contain clay (the content of clay can lead to stratification of the homogeneous mass and loss of quality of foam concrete)
Salty sand is bad
For the lightweight concrete production or for foam concrete blocks manufacturing, as well as for the production of other building materials, it is not recommended to use salted or sea sand. Salted sand interferes with the foam generation during mixing. In addition, it negatively affects the quality of the final product. It can show through on the surface of foam concrete blocks and even reduce their strength over time. Therefore, the sand should be free of salt and other mineral additives. In no case should you use sea sand or sand from the ocean.
Sand for foam concrete manufacturing should not contain clay
The clay content in sand negatively affects the quality of foam concrete. It leads to the formation of so-called microlenses. These are small inclusions of clay in a foam concrete mortar. When the mortar dries and the foam concrete matures, material stratification is formed in these areas. And cracks appear. Therefore, the presence of clay in the sand for the of foam concrete manufacturing should not be allowed.
Sand must be sieved
Before using sand for foam concrete manufacturing, it must be cleaned of mechanical impurities and stones. It’s no secret that the quality of sand is different. And sometimes there are foreign impurities in it in the form of small stones or debris. For this, sand is sieved through a fine sieve before use. There are many different ways to do this. We will not dwell on them. It is only important to know that the size of the sieve should be not more than 3 mm.
We do not give clear recommendations down to hundredths of a millimeter on the size of grains of sand for foam concrete manufacturing. But the smaller the sand fraction, the better the quality of the resulting foam concrete.
Is quartz sand good or bad?
Quartz sand has certain characteristics that you need to know when producing foam concrete. It’s heavy enough. Therefore, it can settle during mixing. It is also for this reason that silica sand particles can destroy air bubbles while the mortar is mixing. This destroys the foam. As a result, there is an increased foaming agent consumption, since it is necessary to add more of it.
Ash instead of sand
Sometimes fly ash is used instead of sand for foam concrete manufacturing.
This is a good solution in places where there is no sand, and this material can be used as a mortar filler. This material is often free. Since it is a waste of some kind of production. But when using ash, it is necessary to adjust the formulation of the mixture and the ratio of additives in each case on the manufacturing place.