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Open AccessArticle

Effect of Curing Conditions on Microstructure and Pore-Structure of Brown Coal Fly Ash Geopolymers

1
Civil and Infrastructure Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
2
Civil Engineering Department, Faculty of Computer and Engineering, Universitas Harapan, Medan 20216, Indonesia
*
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(15), 3138; https://doi.org/10.3390/app9153138
Received: 4 July 2019 / Revised: 26 July 2019 / Accepted: 30 July 2019 / Published: 2 August 2019
(This article belongs to the Section Civil Engineering)
This study reports the effect of heat curing at 120 °C on the geopolymeric reaction and strength evolution in brown coal fly ash based geopolymer mortar and concrete. Moreover, an examination of this temperature profile of large size geopolymer concrete specimens is also reported. The specimen temperature and size were observed to influence the conversion from the glassy (amorphous) phases to the crystalline phases and the microstructure development of the geopolymer. The temperature profile could be divided into three principal stages which correlated well with the proposed reaction mechanism for class F fly ash geopolymers. The geopolymerisation progressed more rapidly for the mortar specimens than the concrete specimens with 12 to 14 h providing an optimum curing time for the 50 mm mortar cubes and 24 h being the optimum time for the 100 mm concrete cubes. The 50 mm and 100 mm concrete specimens’ compressive strengths in excess of 30 MPa could be obtained at 7 days. The structural integrity was not achieved at the center of 200 mm and 300 mm concrete specimens following 24 h curing at 120 °C. Hence, the optimal curing time required to achieve the best compressive strength for brown coal geopolymer was identified as being dependent on the specimen size. View Full-Text
Keywords: geopolymer; brown coal fly ash; compressive strength; heat curing; porosity; X-ray computed tomography geopolymer; brown coal fly ash; compressive strength; heat curing; porosity; X-ray computed tomography
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Gunasekara, C.; Dirgantara, R.; Law, D.W.; Setunge, S. Effect of Curing Conditions on Microstructure and Pore-Structure of Brown Coal Fly Ash Geopolymers. Appl. Sci. 2019, 9, 3138.

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