Preliminary study

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PRELIMINARY STUDY OF ADMIXTURES AND TEMPERATURE EFFECT ON WORKABILITY OF MINING WASTE BASED GEOPOLYMER

Luís Vaz 1,a, João Castro-Gomes 1, Luiz Oliveira 1 Alexandre S. Vargas2 1

2

C-MADE, Center of Materials and Building Technologies, Department of Civil Engineering and Architecture, University of Beira Interior, Covilhã, Portugal

Department of Materials Technology and Industrial Processes, University of Feevale, RS 239 nº 2755 Novo Hamburgo RS, Brasil a

luis.filipe.costa.vaz@gmail.com

Keywords: Sustainability, Geopolymer, Mining waste mud, Workability, Admixtures Summary. This work intends to bring a better understanding of the geopolymer properties and potential large-scale benefits associated with the use of geopolymer-based on tungsten mining waste mud. Both sodium silicate and sodium hydroxide were used as activators. The effect of the addition of water, naphthalene-based, and modified polycarboxylates superplasticizers on the workability and strength of geopolymer were studied. The effect of temperature during the mixture process and different ratios between precursors and activators were also analyzed. Properties of geopolymer were characterized by flow table test, rheological behavior measurements, Marsh cone and compressive strength tests. Mortars compressive strength for 14 days was in the range of 17-24 MPa being the higher values for the ones using only water and the lower values to those with naphthalene-based admixture. Superplasticizers did not have a significant improvement in the workability of geopolymeric mixtures, since the alkaline medium might have changed its chemical structure. The maximum torque of 250 Nmm in the rheometer prove to be insufficient to measure the rheological behavior of most of geopolymer mixtures studied. Finally, it was found out that temperature reduces activators viscosity, however is not an adequate method to improve the workability of geopolymer.

1. Introduction Portland cement-based concrete is one of the most versatile materials and one of the highest-volume manufactured construction products. However the production of ordinary Portland cement (OPC) is responsible for large emission of greenhouse gases (GHGs) and dust pollution, although the embodied energy intensity per functional unit remains lower than other available building materials. [1]. The worldwide production of OCP significantly grew for 594 Mton in 1970 to 2284 Mton in 2005. The demand of OCP in 2015 is estimated in 3500 Mton. Due to environmental and energy issues, some authors advocate a


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