ACTIVATE FLY ASH REACTION USING BAUXITE RESIDUE IN BLENDED CEMENT

Reference Presenter Authors
(Institution)
Abstract
04-029 Marcelo Montini Montini, M.(Universidade Federal de São Carlos); Li, X.(Swiss Federal Institute of Technology in Lausanne); Romano, R.C.(Universidade de São Paulo); Rodrigues, J.d.(Universidade Federal de São Carlos); Pileggi, R.G.(Escola Politécnica - Universidade de São Paulo); Scrivener, K.(wiss Federal Institute of Technology in Lausanne); The aluminum industry is responsible for the management of a massive volume of bauxite residue (BR) on a global scale (120 million tons of generation and 3 billons tons of inventory). However, less than 4% of BR has been reused industrially as the high alkalinity of which is harmful for many applications. The most potential way of using the BR is to use it as supplementary cementitious materials in cement. In this study, we tried to use bauxite residue and fly ash blends as SCM to maximize the usage of BR and the benefits of its alkalinity. The objective of the present study is to investigate the activation of fly ash (FA) by bauxite residue. Isothermal conduction calorimetry, XRD, mercury intrusion porosimetry, scanning electron microscopy, compressive strength were carried out to investigate the six Portland blended cements containing different ratio of BR/FA mixture (%w/w): 0/30, 3/27, 7/23, 15/15, 23/7 and 30/0. The results showed that we could use maximum 7% of BR in the blended cement with fly ash. At this BR dosage, the early strength of the blended cement was enhanced and the long term strength didn’t decrease too much. The reaction of fly ash was significantly promoted when BR were added. On the other hand, high BR addition also showed a higher compressive strength at 1 day, but suffered from a considerable reduction on their long-term properties.
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