What is geopolymer concrete?

At all times, scientists conducted experiments and experiments, which investigated mixtures that combine natural and artificial components. Such a tandem made it possible to obtain materials with higher performance characteristics, since elements of artificial origin enhanced all the indices of those components that nature gave. The materials obtained in this way were called composite or polymeric materials. One of them is geopolimeric concrete, which is the newest environmentally friendly and safe building material. Prefix "geo" (in Greek - "earth") is a confirmation that the new material contains only natural ingredients.

An innovative concrete mix is not something new - it was already known to man in ancient times: when building pyramids in Egypt, this kind of building material was used. Unfortunately, its exact formulation remained a mystery to modern man, but thanks to the introduction of the latest technology, scientists were able to restore the approximate composition, technology and get almost the same analog as the geopolymeric concrete in antiquity. But this fact is only historical and to modern construction it concerns only partially.

Description of the innovative solution

One of the most important properties of an innovative concrete mix is a set of maximum strength in a short time: it only takes a week to completely harden, whereas a traditional solution requires exactly 4 times as much time.

Geopolymer concrete, like portland cement, consists of several components, but their composition varies considerably. The new solution consists mainly of ash and slag - waste from various industries. Previously, such wastes were not processed at all and only polluted the environment. Of course, the release of innovative building materials will not solve this problem at once, but ash and slag will become a significant source of raw materials for their production.

Benefits of application

According to experts, geopolymer concrete - a product with a great future: unlike Portland cement, it is used in the manufacture of lightweight structures. But this is not all: in terms of its heat-saving characteristics, the new concrete mix is much superior to other building materials that are used in the construction of buildings. For example, a wall made of this geopolymer, only 30 cm thick, retains heat in the same way as a brick, but 1.25 m thick.

Accordingly, using an innovative solution for construction, you can significantly save money:

1. You can build buildings using a smaller number of building materials.
2. Due to the low thermal conductivity of the geopolymeric building materials, the costs for heating the rooms in them will be reduced.

Main characteristics

According to experts, geopolymer concrete is the building material of the future, since it has excellent operational characteristics, such as:

1. Small shrinkage.
2. High compressive strength.
3. Resistance to acids.
4. Low permeability. This figure is almost equal to that of granite.
5. Excellent resistance against high temperatures - up to + 1300 °. Scientists conducted an experiment: for 120 minutes, exposed panels were made of geopolymer concrete and portland cement to very high temperatures. After that, the products from the innovative mixture remained completely intact, while on the Portland cement panels there appeared many cracks and chips.

But the most valuable property of the solution we are considering is that it releases a minimum of greenhouse gases.

If we compare the structure of a new construction material, it resembles that of a natural stone, due to which it has higher properties than a conventional solution. But the most important thing is that you can prepare geopolymer concrete yourself, because it is not difficult at all. It is only necessary to prepare the components necessary for the work.

Feature of composition

The recipe is simple enough, and the components are available: fly ash, water, potassium hydroxide, water glass and slag. The last ingredient is needed to give strength and durability. But he alone can not protect the finished products from the cracking that is inevitable during shrinkage. This disadvantage eliminates the presence of fly ash. Moreover, both components strengthen the concrete mix, and it will be able to withstand any negative factors.

Why is it fly ash? Because even this component itself possesses high technological and physical properties, so its introduction into the structure helps to improve the strength indexes of finished products (to the level of granite).

Strengthen the strength of the building material called for in the aluminum silicates. They, reacting with alkali in the reaction, polymerize. Due to this, a solid monolith is formed. It was this reaction of the components that triggered the appearance of another name for the material - it is called a slag-alkaline concrete mixture.

Preparation for work

Before you get started, you need to prepare:

1. Capacities.
2. Instruments.
3. Overalls.
4. Respirator.
5. Glasses.
6. Gloves.
7. Scales to control the proportions.
8. Formwork or form, where the finished solution will be cast.

An important detail: for stirring, you need to take a shovel from a material that will not react with alkalis. The best tool is made of wood.

What is important: mixing, the components produce heat, so for mixing, you need to take a container that is resistant to high temperatures. If it is necessary that the finished solution is more quickly frozen, it is possible to lay electrolytes in the formwork. In this case, they must also be prepared in advance.

Recipe

Home craftsmen who decided to make geopolymer concrete themselves, are primarily interested in the exact composition of the mixture. The web does not have a ready-made recipe, as manufacturers keep it secret, and scientists continue to work on improving innovative building materials. You can find many variations of the recipe, but at the same time the initially proposed basic composition remains practically unchanged.

Following him, the production of 1.0 liter of geopolymer solution should be prepared:

• 550 g of fly ash and the same amount of slag;
• 110 g of water;
• 240 g of liquid glass;
• 180 g 45% KOH.

All components are on sale, and you can find them without problems. Of course, the cost of the resulting products will be higher than that of conventional portland cement, but their strength is much greater than the concrete elements.

Technology of preparation

If you have all the necessary components and tools, you can also prepare geopolymer concrete yourself. The technology is fairly simple, but you only need to strictly follow all the recommendations:

1. In the room where the work is done, there should be low humidity, so that potassium hydroxide does not "swim". Because of this feature, the hydroxide is usually unpacked only before being put into the solution.
2. KOH is quite aggressive material, so you need to work with it, using protective equipment - gloves and glasses.
3. Liquid glass is also considered hygroscopic and aggressive - with it you need to be no less cautious.
4. All work on kneading should be done quickly.

If a concrete mixer is used, it is necessary to work in the following sequence:

1. Pour water. You can not use cold liquid - it should be warm.
2. Fall asleep slag and ash.
3. After all is well mixed, add polymers.
4. Mix again until a homogeneous solution is obtained.
5. Pour the mixture into molds.

An important detail: fly ash is a substance with a rather dubious ecological reputation, but thanks to its use, the concrete mix acquires a higher strength, which retains a very long time. Therefore, if it is important to get a strong material, you can use ashes, but if you are more environmentally friendly, the ash can be taken less, and some of it can be replaced with cement.

Molding products

To make the details of the right size and shape, you can use the same formwork as for ordinary portland cement. They must be cleaned beforehand and greased with used oil or any other (even vegetable) oil. After that, the reinforcement is installed (if necessary), and only then the mold is filled with concrete mortar. When pouring it is necessary to watch, so that there are no voids inside, because of which the plates made of geopolymer concrete can crack in the future.

Within a day, the billets will harden: a film forms on their surface. Its presence will increase the monolithic nature of the materials, and they will be able to withstand higher loads.

Variants of solutions

For fans of experiments this material represents a wide field for the introduction of any ideas: when making a concrete mixture, any organic matter can be used. So, water-soluble resins can serve as binders. Another option - to use instead of PVA resins, then the emulsifier will be polyvinyl alcohol, which is in its composition.

Some are used for the production of crushed wood. It is soaked in water and treated with an ozonizer, and then laid in a concrete mixer to mix with other components to get a geopolymer concrete as a result. How to make so that the received solution, having got the necessary form, has quickly hardened? To do this, it is poured into the formwork with electrodes, through which then for 60 minutes they are subjected to an electric current. And electricity is not taken directly from the network, but is passed through the converter. After the workpiece has hardened, the formwork is removed from it and the next element is manufactured.

Purchase of ready mixes

Not every consumer or master likes to experiment - many prefer not to build concrete, but to buy ready-made, especially since there are no difficulties with finding a compound: for more than 4 years, geopolymer concrete has been produced in Russia on the basis of clay raw materials of the Republic of Tatarstan. Manufacturers offer different brands, the cost of which depends on the number of components and their proportions. Buy building materials can be in the form of dry mixtures in which there is no hardener.

On sale there are ready-made compounds of both Russian and foreign production. Their differences - the cost and speed of solidification.

Products of the following trademarks of Russia are of interest:

1. "Stone Flower".
2. "Sebryakovcement".
3. Eurocement Group.

Among foreign companies, the materials of such companies are popular:

1. German Heidelberger Cement.
2. Spanish GRUPOSUBDI.
3. French LAFARGE.

Advantages of finished materials

Today you can buy ready-made concrete blanks of different brands. They are manufactured taking into account the following parameters:

1. The water resistance is W 2-W 12.
2. Frost resistance - grades from F 50 to F 300.
3. Strength - marks from M 50 to M 500.

In addition, in ready mixtures - for ease of use - the volume of the parts of each type of fillers can vary depending on the desired final result. Cement is also included in geopolymer concrete, but its part is replaced by fly ash. Its quantity should be equal to the sum of parts of rubble, sand and cement.