EM - Escola de Minas

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Enhancing the eco-efficiency of concrete using engineered recycled mineral admixtures and recycled aggregates.
(2020) Carvalho, José Maria Franco de; Fontes, Wanna Carvalho; Azevedo, Carlos Felipe de; Brigolini, Guilherme Jorge; Schmidt, Wolfram; Peixoto, Ricardo André Fiorotti
Non-conventional densely packed concrete mixtures are proposed and evaluated in this paper using engineered recycled mineral admixtures and recycled aggregates obtained from steel slag, quartz mining tailings, and quartzite mining tailings. High fines content sand-concretes containing coarser- and finer- than-cement recycled powders were designed to obtain blends with broader particle-size ranges and improved packing density. As a result, compressive strength up to 99 MPa, cement intensity up to 2.33 kg/m3 /MPa, and consumption of recycled material up to 95 vol% were obtained. Compressive strengths up to 66 MPa and cement intensity up to 2.34 kg/m3 /MPa were also obtained with the addition of coarse aggregates to such sand-concrete mixtures, with consumption of recycled material up to 96.5%. The results launch new insights on the role of recycled admixtures and aggregates on the mixture design of cement-based composites regarding efficiency improvement and technological performance.
Mechanical and durability performance of concretes produced with steel slag aggregate and mineral admixtures.
(2022) Costa, Laís Cristina Barbosa; Nogueira, Marcela Aguiar; Andrade, Humberto Dias; Carvalho, José Maria Franco de; Elói, Fernanda Pereira da Fonseca; Brigolini, Guilherme Jorge; Peixoto, Ricardo André Fiorotti
The steel slag is a residue for the steel industry that is already applied in many cement-based composites, although there is a lack of studies on the durability of this material in aggressive environments. This work evaluated the durability against chloride attack of concrete produced using steel slag as aggregate and mineral admixture, called steel slag powder. For comparison purposes, reference concretes using conventional aggregates and commercial mineral admixtures (silica fume and metakaolin) were produced. The concretes produced with steel slag aggregates and steel slag powder had lower chloride penetration depths compared to conventional ones. The steel slag powder presented an ability similar to silica fume of forming Friedel salt. The concrete produced with steel slag aggregates also presented a smaller water absorption and a higher compressive/tensile strength compared to the reference one. In general, this research observed that steel slag concretes are techni- cally feasible options for the construction sector.
Reuse of iron ore tailings from tailings dams as pigment for sustainable paints.
(2018) Galvão, José Lucas Barros; Andrade, Humberto Dias; Brigolini, Guilherme Jorge; Peixoto, Ricardo André Fiorotti; Mendes, Júlia Castro
In order to minimise the environmental, social and economic impacts caused by the mining activity, this work proposes the use of iron ore tailings from tailings dams (IOT) as pigment in the production of a paint for buildings e the Sustainable Paint. The waste originates from the mining activity in the state of Minas Gerais. For this work, it was used in its raw state, subjected only to drying and lump breaking. In addition to IOT and water, four types of binders were tested: polyvinyl acetate (PVA) resin (in the form of ordinary white glue), acrylic resin, hydrated lime for painting and high early strength Portland cement. Binder contents ranged from 0% to 50% over the mass of IOT. For the evaluation of the mixtures, four main parameters were used: cost, colour homogeneity, abrasion resistance, and durability to external exposure, using the colour difference methodology DE (Delta-E). The results of binder evaluations were compared among themselves and with conventional paints from a brand recognised by the Brazilian Association of Paint Manufacturers. The Sustainable Paint presented reddish colour; suitable opacity; satisfactory results regarding durability at a significantly lower cost. In general, the blends with IOT, especially those using PVA as binder, have proved to be promising alternatives for paintings prepared in situ. It is noticeable the wide potential of use of this pigment by communities affected by iron ore tailings dams throughout Brazil and worldwide.
Ladle furnace slag as binder for cement-based composites.
(2017) Marinho, Ana Luiza Borges; Santos, Carina Miranda Mol; Carvalho, José Maria Franco de; Mendes, Júlia Castro; Brigolini, Guilherme Jorge; Peixoto, Ricardo André Fiorotti
In recent years, the environmental facet of industrial waste management has become imperative. The recycling of these residues in the civil construction sector is growing, since both industries have developed an increasing concern for the exhaustion of natural resources. In this scenario, one example is the ladle furnace slag (LFS), a by-product of the secondary refining of steel. It is mainly composed of calcium and calcium magnesium silicates. Thus, this research aims to develop a sustainable binder obtained from LFS as a substitution of hydraulic lime. In this sense, an extensive characterization of the LFS was carried out in its raw and processed forms. Subsequently, all the requirements for hydrated lime and hydraulic lime were verified according to Brazilian and Portuguese standards. Finally, mortars for coating and laying were produced with portland cement, lime, and the sustainable binder, and their main properties were evaluated in the fresh and hardened states. The chemical and mechanical properties of the sustainable binder were closer to those of the hydraulic limes. The obtained results indicate the technical feasibility of the use of LFS as binder for mortars in the replacement of lime.

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