Construction without Cement
A Korean research team consisting of a college student and a professor has succeeded in developing a technology to make a new material that can replace cement. The material is made from industrial by-products, and thus it can reduce environmental pollution. On top of that, it is economical.
Jeon Dong-ho, a senior in the School of Unban and Environmental Engineering at the Ulsan National Institute of Science and Technology (UNIST), and his adviser Oh Jae-eun announced on Jan. 15 that they have successfully developed a technique to produce a cement-free binding material with high compressive strength. It is possible by adding chemical activators Ca(OH)2 and Na2CO3 to fly ash, a by-product of burning coal in thermoelectric power plants.
Currently, the most widely-used cement is Portland cement. Around 0.9 tons of CO2 is emitted when one ton of Portland cement is produced. As a result, about 7 percent of the total CO2 around the world occurs from the manufacturing process of cement each year.
So far, research on cement-free binding materials has been actively done to replace existing cement. However, most technologies have been unsuccessful in making a cheaper material than Portland cement. In some cases, highly corrosive solutions with over a pH of 14 have been used, which is dangerous.
The newly-developed material can reduce the amount of CO2 at the 15 percent level of existing cement by using as much as 85 percent fly ash. In addition, the price of the material amounts to only 80 percent of that of Portland cement. It is also possible to put the power-like material in a sack for sale like Portland cement by improving its safety using Ca(OH)2 and Na2CO3. They are less corrosive than exiting agents that help with hardening.
However, the cement-free binding material easily solidifies. To address the problem, another method to control the time needed for solidification was developed as well, which was patented in the country.
Jeon said, “The use of the cement-free binding material enables people to build concrete structures without utilizing Portland cement.” He added, “When it comes to countries in Central Asia like Mongolia and Kazakhstan, which mostly import cement, it will be possible to make and supply a cement replacement material from a by-product abandoned in thermoelectric power plants. So, it would be like killing two birds with one stone.”
The City of Ulaanbaatar in Mongolia and the Mongolian University of Science and Technology already suggested establishing a joint venture firm, which is being discussed. The research team is also working on a building project for production facilities of a cement-free binding material in partnership with a local builder in Dhaka, Bangladesh.
The research findings were published online in the January issue of Cement and Concrete Research, a scientific journal published by Elsevier B.V., and two patents were filed for the technology with the Korean Intellectual Property Office.