At all times, scientists conducted experiments and experiments on which mixtures combining natural and artificial components were studied. Such a tandem made it possible to obtain materials with higher performance, since elements of artificial origin strengthened all the indicators of those components that nature gave. The materials obtained in this way were called composite or polymeric. One of them is geopolymer concrete, which is the latest environmentally friendly and safe building material. The prefix "geo" (in Greek - "earth") is a confirmation that the new material contains only natural ingredients.
The innovative
concrete mix is not something new - it was already known to man in antiquity: a similar building material was used in the construction of the pyramids in Egypt. Unfortunately, its exact recipe remained a mystery to modern man, but thanks to the introduction of the latest technologies, scientists were able to restore the approximate composition, technology and get almost the same analogue as the geopolymer concrete in antiquity. But this fact is only historical and it relates only partially to modern construction.
Description of innovative solution
One of the most important properties of an innovative concrete mix is the set of maximum strength in a short time: to fully harden, it takes only a week, while a traditional mortar will need exactly 4 times more time.
Geopolymer concrete, like Portland cement, consists of several components, but their composition varies greatly. The new solution consists mainly of ash and slag - waste from various industries. Previously, such wastes were not recycled at all and only polluted the environment. Of course, the release of innovative building materials will not solve this problem immediately, but ash and slag will become a significant raw material base for their manufacture.
Application benefits
According to experts, geopolymer concrete is 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 far superior to other building materials that are used in the construction of buildings. For example, a wall from this geopolymer with a thickness of only 30 cm retains heat in the same way as a brick, but with a thickness of 1.25 m.
Accordingly, using an innovative solution for construction, you can significantly save money:
- You can erect buildings using fewer building materials.
- Due to the low thermal conductivity of the geopolymeric building material, the cost of heating the premises in them will decrease.
Main characteristics
According to experts, geopolymer concrete is the building material of the future, because it has excellent performance characteristics, such as:
- Small shrinkage.
- High compressive strength.
- Resistance to acids.
- Low permeability. This figure is almost equal to that of granite.
- Excellent resistance to high temperatures - up to + 1300 °. Scientists conducted an experiment: for 120 minutes they exposed panels made of geopolymer concrete and Portland cement to very high temperatures. After this, the products from the innovative mixture remained completely intact, while many cracks and chips appeared on the panels of Portland cement.
But the most valuable property of the solution we are considering is that it emits a minimum of greenhouse gases.
If we compare the structure of the new building material, then it resembles that of natural stone, due to which it has higher properties than ordinary mortar. But the most important thing is that you can make geopolymer concrete with your own hands, since it is not at all difficult. It is only necessary to prepare the components necessary for the work.
Composition feature
The recipe is quite simple, and the components are affordable: fly ash, water,
potassium hydroxide, water glass and slag. The last ingredient is needed to give strength and durability. But he alone cannot protect finished products from cracking that is inevitable during shrinkage. This drawback eliminates the presence of fly ash. Moreover, both components strengthen the concrete mix, and it can resist any negative factors.
Why exactly fly ash? Because even this component itself has high technological and physical properties, therefore, its introduction into the composition helps to increase the strength characteristics of finished products (to the level of granite).
The aluminum silicates included in the composition are also called to strengthen the strength of the building material. They react with alkali and polymerize. Due to this, a solid monolith is formed. It was this reaction of the components that triggered the emergence of another name for the material - it is called slag-alkali concrete mixture.
Preparation for work
Before starting work, you need to prepare:
- Capacities.
- Instruments.
- Overalls.
- Respirator.
- Glasses.
- Gloves.
- Scales to control proportions.
- Formwork or form where the finished solution will be cast.
An important detail: for mixing, you need to take a spatula from a material that will not react with alkalis. A wood tool is best.
What is important: when mixed, the components emit heat, so for mixing you need to take a container that is resistant to elevated temperature. If you want the finished solution to solidify faster, you can lay electrolytes in the formwork. In this case, they must also be prepared in advance.
Recipe
Home craftsmen who decided to make geopolymer concrete with their own hands are primarily interested in the exact composition of the mixture. There is no ready-made recipe on the Web, 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 almost unchanged.
Following it, for the manufacture of 1.0 l of geopolymer solution you need to prepare:
- 550 g of fly ash and as much slag;
- 110 g of water;
- 240 g of water glass;
- 180 g 45% KOH.
All components are on sale, and you can find them without any problems. Of course, the cost of the resulting products will be higher than analogues of ordinary Portland cement, but their strength is much superior to concrete elements.
Cooking technology
If you have all the necessary components and tools, you can prepare the geopolymer concrete yourself. The technology is quite simple, but you just have to strictly follow all the recommendations:
- In the room where the work is carried out, there should be low humidity so that potassium hydroxide does not “float”. Because of this feature, hydroxide is usually unpacked only before being put into solution.
- KOH is a fairly aggressive material, so you need to work with it using protective equipment - gloves and glasses.
- Liquid glass is also considered hygroscopic and aggressive - you need to be no less careful with it.
- All kneading work must be carried out quickly.
If a concrete mixer is used, it is necessary to work in the following sequence:
- Pour in water. Do not use cold liquid - it must be warm.
- Pour slag and ash.
- After everything mixes well, add the polymers.
- Stir again until a homogeneous solution is obtained.
- Pour the mixture into molds.
An important detail: fly ash is a substance with a rather dubious environmental reputation, but thanks to its use, the concrete mix acquires higher strength, which it retains for a very long time. Therefore, if it is important to obtain durable material, ash can also be used, but if environmental friendliness is more important, less ash can be taken, and part of it can be replaced with cement.
Shaping Products
To make parts of the right size and shape, you can use the same formwork as for ordinary Portland cement. They must be cleaned in advance and greased with used oil or any other (even vegetable) oil. After this, the fittings are installed (if necessary), and only then the form is filled with concrete mortar. When pouring, you need to make sure that there are no voids inside, because of which slabs made of geopolymer concrete may crack in the future.
After a day, the workpieces harden: a film forms on their surface. Its presence will increase the solidity of materials, and they can withstand higher loads.
Solution Options
For lovers of experiments, this material represents a wide field for the implementation of any ideas: making any concrete mixture, you can use any organic substances. So, water-soluble resins can serve as astringent components. Another option is to use PVA instead of resins, then the emulsifier will be polyvinyl alcohol, which is in its composition.
Some use chopped wood in the manufacture. It is soaked in water and treated with an ozonizer, after which it is laid in a concrete mixer for connection with other components to obtain geopolymer concrete as a result. How to make the resulting solution, having acquired the desired shape, harden faster? To do this, it is poured into the formwork with electrodes, through which then they are exposed to electric current for 60 minutes. Moreover, electricity is not taken directly from the network, but is passed through the converter. After the processed fragment hardens, the formwork is removed from it and the next element is made.
Purchase of ready-made mixtures
Not every consumer or master likes to experiment - many prefer not to make building concrete, but to buy ready-made, all the more so since there are no difficulties in finding the composition: for more than 4 years, geopolymer concrete based on clay raw materials of the Republic of Tajikistan has been produced. Manufacturers offer different brands, the cost of which depends on the number of components and their proportions. You can buy building materials in the form of dry mixes in which there is no hardener.
On sale there are ready-made compositions of both Russian and foreign production. Their differences are the cost and speed of solidification.
The products of the following Russian brands are of interest:
- "Stone Flower".
- "Sebryakovcement".
- Eurocement Group.
From foreign firms are popular materials of such companies:
- German Heidelberger Cement.
- Spanish GRUPOSUBDI.
- French LAFARGE.
Advantages of finished materials
Today you can buy ready-made concrete billets of different grades. They are made taking into account the following indicators:
- Water resistant - brand W 2-W 12.
- Frost resistance - grades from F 50 to F 300.
- Strength - grades from M 50 to M 500.
In addition, in ready-made mixtures, for convenience in work, the volume of parts of each type of filler may vary depending on the desired end result. Cement is also included in geopolymer concrete, but part of it replaces fly ash. Its amount should be equal to the sum of the parts of crushed stone, sand and cement.