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Sterile Clay Pozzolans from Phosphate Mining

2015; Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímer; Volume: 18; Issue: suppl 2 Linguagem: Inglês

10.1590/1516-1439.367014

1980-5373

José Afonso de Matos Neto, Domingos Sávio de Resende, João Trajano da Silva Neto, Antônio Maria Claret de Gouveia, Maria Teresa Paulino Aguilar, Augusto César da Silva Bezerra,

Tailings Management and Properties

The work presents the characterization of clays from sterile mining of the concentrated phosphatic materials of Araxá in Minas Gerais as pozzolanic materials. Three clays of distinct tones, namely, yellow (YC), red (RC), and intermediate (IC) clays, were used at different levels of excavation depth. The clays were calcined at three temperatures (680, 760, and 840 °C) in a muffle-type electric oven. The pozzolanic activity levels of the calcined clays was measured through the conductivity change in saturated Ca(OH)2 solutions and also from the result of the compressive failure load achieved by mortars with 35% of the Portland cement replaced with the calcined material. The results indicated that the calcined clays showed a high level of pozzolanic activity and can be used as a partial substitute for Portland cement, thus suggesting the possibility of recovering this sterile material.