Researchers have developed a new type of concrete that is environment friendly and cheaper than Portland cement. They have used sugar cane straw ash (SCSA), a crop residue – typically discarded as waste – as the substitute.
A project on assessment of SCSA conducted at Polytechnic University of Valencia (UPV) in collaboration with San Paolo State University (UNESP) revealed that it can replace 15 to 30 percent of Portland cement and yet achieve good mechanical properties in mortars.
Jordi Paya, one of the researcher at the UPV explains, “The harvester strips the cane, discarding the tops and leaves as waste. This is the raw material we work with, sugar cane straw.”
In total around 650 million tons of sugar cane are harvested in Brazil every year. Of this, between 15 and 20 percent corresponds to sugar straw, which is left on the field and is either burnt or left to decay naturally.
Speaking about the cement, Paya mentions that the cement itself is the most expensive and most polluting ingredient of concrete, which makes the benefits of this new method as much economic as environmental. They also intend to make use of other by-products that are currently unexploited, with all the benefits that this entails.
To burn the waste, the researchers designed a modified combustion burner, into which the raw material must be fed following a strict procedure. Further Paya explains that through this process they can obtain ashes that are very reactive to the cement – a quality very important to the mechanical performance of the resulting concrete.
The work was primarily focused on the microstructural analysis of the concrete. “In the lab we analyze the chemical compounds of the ashes and of the compounds produced during the reaction with the cement, in order to assess their performance in the final product,” intoned Paya.
Future work will include studying indicators related to the durability of mass and reinforced concrete. The research team also intends to study the use of other agricultural wastes like bamboo leaf as a cement substitute.
Image Credits: Investigacion y Desarrollo