International researchers and students at Polytechnic University of Valencia and San Paolo State University in Brazil have developed a new type of concrete that is cheaper and much less polluting to the environment by swapping in sugar cane straw ash, a crop residue typically discarded as waste, as a substitute for Portland cement. Between 98 and 130 million tons of sugar cane straw is discarded on fields in Brazil annually, left to burn or decay naturally.
So far, the international research team has been able to make concrete using 30 percent less Portland cement, substituting it with the ashes obtained from burning the sugar cane straw.
“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. We are also making use of a by-product that is currently unexploited, with all the benefits that this entails,” says Jordi Payá, researcher at the Concrete Science and Technology Institute (ICITECH).
Researchers have designed a bespoke combustion burner, into which the raw material must be fed following a strict procedure. “Through this process we obtain ashes that are very reactive to the cement, a quality that is very important to the mechanical performance of the resulting concrete, to its resistance to compression, for instance,” Payá says. " We analyzed 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.” explains Payá. Future work includes studying indicators related to the durability of mass and reinforced concrete. ICITECH is also studying bamboo leaves for use as a cement substitute.