Scientists: Environmentally friendly as usual

Scientists of Kaunas University of Technology (KTU), Lithuania is developing methods for the production of cement without using industrial waste – fly ash. The final product is as strong as the traditional concrete, is more resilient to damaging effects of acid, and more stable in cases of exposure to extreme heat and cold.

In order to produce 1 metric ton of Portland cement, a basic ingredient of concrete and most commonly used carbon dioxide (CO2) is released. It is estimated that the global cement industry is responsible for 7 percent of annual carbon dioxide emissions into the atmosphere. KTU researchers have been investigating methods of substituting Portland cement with other materials.

"At first, the idea that concrete can be produced without success." Now, after several years of intensive work we succeed to develop alkali activated concrete, which compressive strength is 55 MPa. We are using alkali activated industrial waste products – fly ash, bottom ash biofuel, AlF3 production waste – silica gel etc. ", says Vytautas Bocullo, researcher at KTU Faculty of Civil Engineering and Architecture.

According to the researcher, the largest advantage of this type of binder is that in its production of industrial waste, containing active form of silicon and aluminum compounds can be used. Theoretically, any material containing silicon and aluminum compounds could be used, such as blast furnace slag or metakaolin, material derived from clay mineral kaolitin modification.

Treated with special alkaline solution These materials start melting and binding similarly to traditional cement. Depending on the composition, the final product can be either geopolymer or alkali-activated material. Alkali activated concrete is much more resilient to the effects of fire and acid. Also, due to its higher pH this concrete is protecting armature against corrosion.

Bocullo maintains that alkali activated concrete can be used instead of traditional concrete in many fields, and is becoming a globally popular alternative to traditional concrete. Precisely solid materials and the activating solution, such concrete is solidifying in usual (+200) temperature. However, in this case, it is recommended to use local materials.

"We are trying to use such materials as aluminum fluoride production waste – silica gel and biofuel ash." The preparation of the substance for the material itself. Biofuel: The need for the final product, several substances, but their chemical composition and additives need to be investigated for their impact on the environment. on the compressive strength of the concrete ", says Bocullo.

###

The research groups working in the KTU are also experimenting and developing other types of concrete mixtures, such as ultra-high performance concrete, which is used for safe production, self-renewing concrete and others.