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, since elements of artificial origin enhanced all the indicators of those components that nature gave. Materials obtained in this way were called composite or polymer. 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.
Innovative concrete mixture is not something new - it was already known to man in ancient times: similar building materials were 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 geopolymer concrete was in antiquity. But that's just a facthistorical and only partially applies to modern construction.
Description of the innovative solution
One of the most important properties of an innovative concrete mix is that it reaches maximum strength in a short time: it takes only a week to fully harden, while traditional mortar will take exactly 4 times longer.
Geopolymer concrete, like Portland cement, consists of several components, but their composition varies significantly. The new solution consists mainly of ash and slag - waste from various industries. Previously, such waste was not recycled at all and only polluted the environment. Of course, the production 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 that's not all: in terms of its heat-preserving characteristics, the new concrete mixture is much superior to other building materials that are used in the construction of buildings. For example, a wall of this geopolymer only 30 cm thick retains heat in the same way as a brick wall, but 1.25 m thick.
Accordingly, using an innovative mortar for construction, you can significantly save money:
- You can build buildings with fewer building materials.
- Thanks to lowthermal conductivity of geopolymer building materials will reduce the cost of space heating in them.
Key Features
According to experts, geopolymer concrete is the building material of the future, as it has excellent performance characteristics, such as:
- Small shrinkage.
- High compressive strength.
- Resistant to acids.
- Low permeability. This indicator is almost equal to that of granite.
- Excellent high temperature resistance up to +1300°. Scientists conducted an experiment: for 120 minutes they exposed panels of geopolymer concrete and Portland cement to very high temperatures. After that, the products from the innovative mixture remained completely intact, while the Portland cement panels showed many cracks and chips.
But the most valuable property of the solution we are considering is that it emits a minimum of greenhouse gases.
When comparing the structure of the new building material, it resembles that of natural stone, due to which it has higher properties than ordinary mortar. But most importantly, you can prepare geopolymer concrete with your own hands, since it is not at all difficult. It is only necessary to prepare the components necessary for work.
Composition feature
The recipe is quite simple, and the components are affordable: fly ash, water, potassium hydroxide,liquid glass and slag. The last ingredient is necessary to give strength and durability. But he alone cannot protect finished products from cracking, which are inevitable during shrinkage. This disadvantage eliminates the presence of fly ash. Moreover, both components strengthen the concrete mixture, and it will be able to resist any negative factors.
Why fly ash? Because even by itself this component has high technological and physical properties, so adding it to the composition helps to increase the strength characteristics of finished products (to the level of granite).
Also, the aluminum silicates included in the composition are called upon to strengthen the strength of the building material. They, reacting with alkali, polymerize. As a result, a solid monolith is formed. It was this reaction of the components that gave impetus to the emergence of another name for the material - it is called slag-alkaline concrete mix.
Preparation for work
Before starting work, you need to prepare:
- Capacities.
- Tools.
- Overalls.
- Respirator.
- Points.
- Gloves.
- Scales to control proportions.
- Formwork or form where the finished mortar will be cast.
An important detail: for mixing, you need to take a spatula made of a material that will not react with alkalis. A wood tool is best.
What is important: when mixed, the components generate heat, so for mixing you need to take a container that is resistant to elevated temperatures. If ait is necessary that the finished solution hardens faster, electrolytes can be laid in the formwork. In this case, they must also be prepared in advance.
Cooking recipe
Home craftsmen who decide 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 main 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 the same amount of slag;
- 110g water;
- 240 g water glass;
- 180g 45% CON.
All components are commercially available and easy to find. Of course, the cost of the resulting products will be higher than analogues from ordinary Portland cement, but their strength far exceeds concrete elements.
Cooking technology
If you have all the necessary components and tools, you can prepare geopolymer concrete yourself. The technology is quite simple, but you only need to strictly follow all the recommendations:
- Humidity must be low in the room where the work is carried out so that the potassium hydroxide does not “float”. Because of this feature, the hydroxide is usually only unpacked before being put into solution.
- KOH israther aggressive material, so you need to work with it using protective equipment - gloves and goggles.
- Liquid glass is also considered hygroscopic and aggressive - you need to be no less careful with it.
- All kneading work must be done quickly.
If a concrete mixer is used, work in the following sequence:
- Pour in water. Do not use cold liquid - it must be warm.
- Pour in slag and ash.
- After everything is well mixed, add polymers.
- Mix again until a homogeneous solution is obtained.
- Pour mixture into molds.
An important detail: fly ash is a substance with a rather dubious environmental reputation, but thanks to its use, the concrete mixture acquires a higher strength, which it retains for a very long time. Therefore, if it is important to obtain a 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.
Product molding
To produce parts of the desired size and shape, you can use the same formwork as for conventional Portland cement. They must be cleaned and lubricated with used or any other (even vegetable) oil in advance. After that, reinforcement is installed (if necessary), and only then the form is filled with concrete mortar. When pouring, care must be taken not to leave voids inside, due to which geopolymer concrete slabs canfuture cracking.
Already in a day, the blanks will harden: a film forms on their surface. Its presence will increase the solidity of materials, and they will be able to withstand higher loads.
Solution options
For lovers of experiments, this material is a wide field for the implementation of any ideas: when making a concrete mix, you can use any organic substances. So, water-soluble resins can serve as astringent components. Another option is to use instead of PVA resins, then the emulsifier will be polyvinyl alcohol, which is in its composition.
Some use shredded wood in their manufacture. It is soaked in water and treated with an ozonizer, after which it is placed in a concrete mixer to be combined with other components to end up with geopolymer concrete. 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 they are then 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.
Purchasing ready mixes
Not every consumer or master likes to experiment - many prefer not to make building concrete, but to purchase ready-made concrete, especially since there are no difficulties in finding the composition: for more than 4 years in Russiageopolymer concretes are produced 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. 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 the speed of solidification.
Products of the following Russian brands are of interest:
- "Stone Flower".
- Sebryakovcement.
- "Eurocement group".
From foreign companies, the materials of such companies are popular:
- German Heidelberger Cement.
- Spanish GRUPOSUBDI.
- French LAFARGE.
Dignity of finished materials
Today you can buy ready-made concrete blanks of different brands. They are made taking into account the following indicators:
- Water resistant - grades 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 ease of use - 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 is replaced by fly ash. Its amount should be equal to the sum of the parts of crushed stone, sand and cement.
