How to make white concrete floors
What makes white concrete different from ordinary mortar and what gives it this whiteness. After reading this article, you will be able to easily prepare it yourself, as well as choose a suitable dry mixture in the store.
What is white concrete
It differs from gray:
- The technology of manufacture.
Any Portland concrete is extracted from rocks, and different rocks, of course, differ from each other in their mineral composition. First the limestone and clay are heated to make a “semi-finished product” – clinker. This is then ground and a bit of gypsum is added and mixed. This is how concrete is made, consisting of four phases:
Ordinary concrete, in addition, contains impurities: compounds of chromium, manganese, sulfur and other ions (what concrete is made of). Some of the components color it with the familiar gray color.
But white concrete is devoid of these impurities, and in it, in addition, the iron content is reduced. So it turns out due to a choice of raw materials (kaolin and chalk) and a special method of treatment. Clinker is fired at high temperature, and then sharply cooled in water and dried in a drying drum, then milled. At the same time:
A fuel is used for heating that does not produce ash or soot
It also has a much lower degree of grinding than gray concrete.
Of course, all of this affects the characteristics of concrete, in addition to color.
Composition and properties of white concrete
So, the composition will be approximately as follows:
- low-iron clinker;
- mineral additives;
- chlorine salts (bleach the mixture).
The result is a very light, almost white powder.
When the mixture hardens, it becomes a high-strength material. It is also divided into grades (denoted by the letter “M”) – from M400 to M600. The number means how much load it withstands in kg/cm3.
It is worth paying attention to other designations in the marking. Thus, “N” means that from the time of preparation of the concrete mixture and until the end of its laying, there is a reserve of time during which it does not set. Such concrete is usually compatible with most additives. The letter “R”, on the contrary, indicates that it sets quickly. With it, you can noticeably reduce the time for construction work.
Finally, the most important quality just for white concrete – the amount of impurities in percentage – is denoted by the letter D. The maximum permissible value is 20 %. Marking D0 means that there are no impurities.
According to the degree of whiteness (coefficient of light reflection) is divided into:
- Grade 3 (68%);
- Grade 2 (75%);
- Grade 1 (80%);
- “Premium class” (90%).
Advantages of white concrete
There are several advantages over conventional concrete:
- it looks better on its own;
- it also does not hide the color of pigments, which can be added to it;
- the mortar hardens quickly (60% in 16 hours);
- it is more durable due to its fine grinding;
- therefore, also adheres well to other materials;
- allows you to add less chemicals to the composition, and therefore more environmentally friendly;
- sulfate-resistant (it is not corroded by acids in ground water and sediments).
Compared with conventional concrete has no disadvantages, except higher cost. But its advantages allow you to expand the scope of application.
Applications for white concrete
Firstly, the color stability in direct sunlight and resistance to atmospheric moisture make white concrete ideal for outdoor use. It is used as a finishing material for facades – terrazzite plaster, for example, contains mineral particles and looks like natural stone. If desired, it is possible to cover the walls. The mortar, in this case, is not much different from the usual – gray. You can use this instruction: how to dilute plaster for walls at home.
This type of concrete can be part of the white concrete, from which the elements of decor – columns, steps, curbs, vases – are made. By adding pigments, you can achieve saturated colors, create original paving tiles or decorative bricks, the same color plaster or contrasting grout for masonry. The possibilities here are not limited. We have a separate article that will teach you how to make vases out of concrete and sand.
As for the physical properties of the mixture, it is fine-grained, and therefore ideal for grouting and adhesives.
Rules for Making Concrete Mixture
If you are going to manually prepare a small amount of white concrete-based mortar at home, here’s how you can do it.
Pour the dry components (concrete, sand, crushed stone – if necessary) into a clean dry container, measuring the minimum volume with a shovel in the right proportions (usually 1:3:3).
Stir everything thoroughly until the mixture becomes homogeneous.
Add a little water and stir again. Little by little, the mixture should come out creamy rather than crumbly, but not too runny. The volume of water in the mortar should not exceed 15%.
Cement mortar should be used before it hardens, which means you should not make it in large batches. If it is needed more than it turned out, you should add the ingredients in the same order and quantity, stir again and again slowly dilute the mixture with water.
Let’s talk about the ingredients in more detail. Ordinary sand is not suitable here, because it has clay impurities – the same ones that give ordinary concrete a gray color. If you want to get white concrete, then as a fine filler is acceptable to use:
quartz sand (0.1-1 mm), purified at the manufacture;
river sand, washed and sifted (0.5-2 mm);
marble flour (0.1-1.5 mm) – the most expensive filler, but the concrete mortar with it will turn out snow-white.
But even using good building materials, the beautiful white color can easily be spoiled by dirty technical water. It must be clean, as well as all the containers with tools: they should not have grease, alkalis or rust, remnants of mortars or construction dust on them.
It is very important to properly store bags of concrete so that it does not get damp – on pallets, preferably so that they do not touch the outside wall.
Tips for working with white concrete
To protect reinforced white concrete from rusting, you need to follow some simple rules:
The iron elements should be buried to a depth of at least 3 cm from the surface.
Reinforcement bars should be treated with anticorrosion before pouring.
Also, they should be covered in advance with a thin layer of concrete mortar and allow to dry.
For colored compositions based on white concrete, there is also an important condition: the pigment concentration in the solution should be no more than five percent. And you should not add more sand than necessary – it dulls the colors.