This residue would improve the quality of cement even in 20%
The researcher found that by mixing it with cement, the resistance conditons of cement improves in structures.
When examining the resulting liquid, a leachate with heavy metals which is below the established limits in Colombian and international laws. -Unimedios
Palmira, dic. 16 de 2011 - Agencia de Noticias UN- Researchers form Universidad Nacional de Colombia in Palmira analyzed a residue from the petrochemical industry and found that when it is mixed with traditional cement, it improves considerably the mechanic properties.
With the elaboration of gasoline from crude oil, the petrochemical industry generates wastes calculated in 15 thousand tons per year, which go to the ecosystems, affecting the land, fauna and flora located next to the companies, according to a study of the Research Group in Materials and Environment (Gimma) from Universidad Nacional de Colombia in Palmira.
While they were trying to identify its effects and generate a strategy to take advantage and reduce the negative impact, Universidad Nacional de Colombia and the Research Group on Compound Materials from Universidad del Valle found in its composition heavy metals that when mixed with traditional cement could improve the quality of the concrete materials and, likewise, the toxic elements would be encapsulated.
"When evaluating the properties of solid residues, the lab analysis proved that they contain dangerous heavy materials such as zinc, arsenic, lead, cadmium, nickel, among others, which go to waste disposals and can go through the soil and reach subterraneous water," mentioned professor Janneth Torres, director of Gimma.
But in the same way, as results showed dangerous heavy materials, they also showed the presence of silica and alumina (aluminum oxide) in close to 80%, and an acceptable proportion of amorphous material, characteristics that contribute to the hydration reactions and the resistant development of concrete, besides of guaranteeing the compatibility of the compounds.
Mixtures were prepared adding 20% of the petrochemical substance in the amounts of Portland cement (a component of concrete), in order to identify if this union would improve the final quality of the product and the reaction of heavy metals when turning into solid metals.
And, for determining the migration of metals from the waste disposals to the environment, once the mixture is transformed into eight cements blocks, the Synthetic Precipitation Leaching Procedure (SPLP) technique was used, which was developed by the Environmental Protection Agency (EPA) form the USA.
This consisted in reducing the size of the particle of the blocks to mix it with a solution that simulates acid rain. "When examining the resulting liquid, a leachate with heavy metals which is below the established limits in Colombian and international laws, it indicates that the solid residue does not represent any risk," asserted Carolina Martinez, a student of ninth semester of Environmental Engineering at Palmira Campus, who led the study.
Likewise, some evaluations of durability are resistance to compression were performed by putting the material in aggressive environments such as sulphates, chlorides, CO2 , acid, carbonation, corrosion, among others, and it was exposed to water with lime, in periods of one to 360 days.
"Based on these trials, we found that the residue improves substantially the mechanical properties of structures and concrete, it slightly overcomes the resistance characteristics to compression in 20% and optimize its performance in terms of durability," asserted the director of Gimma, who added that the behavior of this material is comparable to that of metakaolin, famous for its high resistance.
Torres concluded that this study opens the possibilities to work with other polluting residues such as residual waters and the battery industry, among others, contributing to its use, with an environmental and productive perspective.
For reading the complete article, please visit:
www.unperiodico.unal.edu.co/dper/article/residuo-petrolero-mejora-calidad-del-cemento/index.html
(Por: End/JCR/whg)
N° 10
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