Alkaline activation of blast furnace slag with red mud: monitoring of chemical reaction and mineralogical changes
| Reference | Presenter | Authors (Institution) | Abstract |
|---|---|---|---|
| 04-044 | Heitor Montefusco Bernardo | Bernardo, H.M.(University of São Paulo); Romano, R.C.(University of São Paulo); Pileggi, R.G.(University of São Paulo); Cincotto, M.A.(University of São Paulo); | It
is estimated that the generation of red mud (RM) in Brazil is around 8 Mt per
year, being around 100% disposed in the lakes of mud. This can to result in a
considerable environmental impact. At the same time, the slag generation in the
steel industry is estimated at around 20 Mt per year, with about 43% being
equivalent to ground blast furnace slag (BFS). The strategy proposed in this
work is to associate red mud and blast furnace slag to evaluate the alkaline
activation due to its high pH and considerable amount of soluble alkalis. In
this first stage the chemical reaction and formation of the hydrated products
are being evaluated. It is expected obtaining products with application in the
civil construction sector with no need to use Portland cement ensuring
adequate performance and durability parameters. Therefore, it would also be
possible to reduce the environmental impact caused during the production of
cement: currently the cement plants account for about 7% of CO2 total
emissions in the world, and there is an estimative that up to 2050 these emissions
will increase around 30%. This work was carried out using red mud, made São
Luis – Brazil northeastern, and ground blast furnace slag – Mizu, made Espirito
Santo – Brazil southeastern. The products were molded with different proportions
of RM and BFS and cured at 23°C and 98% relative humidity. The hydration
reaction of slag was monitored for 72 hours and the crystalline phases formed
was accompanied up to 56 days made by X-ray diffraction (XRD) and thermogravimetric
analyses. The results indicate that the chemical reaction of the slag is very
slow using more than 80% of red mud, and the best ratio between the materials
was 40RM:60BFS, resulting in higher heat release during the chemical reaction
and formation of high amount of hydrated products over time.<!--[if gte mso 9]> |