FEFU scientists developed brand-new rapid strength eco-concrete
The compressive strength of concrete — is achieved 28 days after pouring — has increased by 2.7 – 3.3 times (B60) compared with traditional concrete mixtures of similar components. Frost-resistance is increased three times up to F600 from F200. Water-resistance (the pressure under which water permeate a concrete) increased more than four times — W18 instead of W4.
New concrete is more environmentally friendly compared with traditional samples. When pouring, steam-heat treatment is not required, so there is no extra heat emission to the atmosphere associated with this stage of construction. Energy costs go up to 70 percent down.
The technology for the manufacturing of the new concrete could be implemented at the plants with minimum spending.
‘When designing the composition of new concrete, we applied the fundamental principles of modern science called geonics (geomimetics). It studies the similarity of construction materials to the natural ones, their nature-likeness. Professor Valery Lesovik from the Belgorod State Technological University, a corresponding member of the Russian Academy of Architecture and Building Sciences conceived the foundation for this science. Currently, engineers failed to achieve the same concrete strength as mountain conglomerates and sandstones. The strength of these natural stones is ten times higher, although they have almost the same composition and structure as concrete has. Our task is to improve the strength of new building materials bringing up their characteristics closer to natural ones via using new technologies. Right now we are capable of creating concrete several times stronger than one obtained using old technologies’, told Lieutenant Colonel Roman Fediuk, associate professor of the Training Military Center of FEFU, the winner of the XIII All-Russian contest “Engineer of the Year 2018”.
Fediuk went on that for the production of new concrete the components were selected in terms of similarity of their chemical composition, physical and mechanical characteristics. According to the principles of geonics, this similarity can be achieved through the stone, sand, cement, and water – all traditional components of concrete – are obtained in the same geographical area. Thus, it is cost-effective to produce components for the concrete mixture in the region where the very concrete will be produced.
Engineers abandoned the excessive use of water in the production of new concrete. Usually, water the fluidity of the concrete mix. However, when dried, water provokes cracks decreasing the strength of concrete. In the new composition, all additional water is replaced with fifth-generation superplasticizers. These substances make the molecules of the concrete mixture to push off from each other which results in increasing fluidity, workability and other concrete qualities useful for construction engineering.
Next important step in the manufacturing of new concrete is mechanochemical activation, i.e. the concrete components are mixed and grind at high speed in a rotary pulsation apparatus – a special concrete mixer. Due to the fine grinding of concrete particles, a greater amount of artificial stone is obtained from a volume unit of the mixture.
The rapid strength of the new concrete is the quality which makes it possible to remove the formwork from the embedded structures in three to seven days instead of 28 as it usually takes and apply them at new stages of pouring. It still takes 28 days for the new concrete to achieve its brand strength.
Roman Fediuk summed up that at the present time it’s possible to design rapid-strength concrete akin to the new one using traditional methods, but there will be drawbacks as cost-inefficiency and harm to the environment. To achieve the same rapid strength with traditional methods, one should use a larger amount of expensive higher-quality cement while the cement manufacturing occupies world number two position in terms of greenhouse gas contamination.
The composition of the new concrete was brought up during FEFU and KGASU inter-university collaboration. Ruslan Ibragimov, Head of the Department of Construction Technology, KGASU, took part in the project.published on www.eurekalert.org