A novel approach to polyaluminosialates curing process using electric boosting and temperature profile investigation by DSC
The curing procedures of polyaluminosialates mixtures at elevated temperature are widely involved in preparation of geopolymer systems. This paper deals with design and characterization of a novel curing process by electric boosting, where electric power, current and voltage were controlled in relation to the curing temperature of geopolymer binder based on concentrated potassium silicate solution. Two types of specimens were prepared, namely beam-shaped specimens with a volume of 96 cm3 to study the flexural strength and apparent porosity development and plates with a volume of 352 cm3 to investigate the changes in electric parameters in relation to the elevated temperature during the curing process in increased volume specimens. The evolution of curing temperature was controlled by manually adjusting the electric power, depending on the specimen type, so as not to exceed 80 °C. An analysis of the curing mechanism is presented for highly filled geopolymer paste with angular particles of ceramic grog. The mechanical tests revealed no differences in flexural strength (>5 MPa) and apparent porosity (~26 %) between electrically and normally cured specimens. The curing regime for experimental mixture was studied systematically by the effects of heat evolution using DSC, indicating acceleration of structural changes in the temperature range 60–80 °C. The results showed that proposed procedure provides a good alternative for traditional curing methods using dry oven facilities.
KeywordsGeopolymer Curing Electric boosting Flexural strength DSC
The result was developed within the CENTEM project, Reg. No. CZ.1.05/2.1.00/03.0088, cofunded by the ERDF as part of the Ministry of Education, Youth and Sports OP RDI programme and, in the follow-up sustainability stage, supported through CENTEM PLUS (LO1402) by financial means from the Ministry of Education, Youth and Sports under the National Sustainability Programme I. This action is realized by the project EXLIZ—CZ.1.07/2.3.00/30.0013, which is co-financed by the European Social Fund and the state budget of the Czech Republic. The authors wish to thank DiS. Vladimír Kriška for drawings and design of the moulds.
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