Gökhan GÖRHAN

Geopolimer Harç Özelliklerine Metakaolin Kalsinasyon Sıcaklığının Etkisi

Yapılan bu çalışmada kaolin kili farklı sıcaklıklarda metakaoline dönüştürülmüş ve ardından bumalzemeler kullanılarak metakaolin esaslı geopolimer harç örnekleri üretilmiştir. Elde edilen bulgularagöre farklı sıcaklıklarda kalsine edilen metakaolin malzemesinin örnek özelliklerinde gösterdiğideğişimler incelenmiştir. Metakaolin esaslı geopolimer harçların hazırlanmasında alkali aktifleştiriciolarak 9M konsantrasyonlu NaOH çözeltisi ve sodyum silikat solüsyonu kullanılmıştır. Harçlar, 40 mm x40 mm x 160 mm metal kalıplarda vibrasyon yöntemiyle şekillendirilmiştir. Ardından numuneler termalkür prosesinin gerçekleştirilmesi için laboratuvar tipi etüve yerleştirilmiş ve 24 saat süre ile 90 oC’de küredilmiştir. Sonuç olarak, tüm örnek grupları içerisinde en yüksek basınç dayanım değeri 700 oC’dekalsine edilen metakaolin esaslı geopolimer harçlarda 59.7 MPa olarak elde edilirken, en düşük basınçdayanım değeri 27.8 MPa ile 900 oC’de elde edilen metakaolin esaslı geopolimer harçlarda eldeedilmiştir. Bununla birlikte metakaolin kalsinasyon sıcaklığının basınç dayanım değerleri üzerindeetkisinin net olmadığı ve nispeten daha yüksek kalsinasyon sıcaklıklarında, metakaolin malzemesininamorf yapısının bozulması nedeniyle basınç dayanım değerlerinin belirgin bir şekilde azaldığıbelirlenmiştir.

Effect of Calcination Temperature of Metakaolin on the Properties of Geopolymer Mortar

In this study, the kaolin clay was transformed into metakaolin at different temperatures and then metakaolin based geopolymer mortar samples were produced. According to the findings, the changes in sample properties because of metakaolin material calcined at different temperatures were investigated. 9M NaOH solution and sodium silicate solution were used as alkali activator in preparation of metakaolin based geopolymer mortars. The mortars are shaped by vibration method in 40 mm x 40 mm x 160 mm metal moulds. Then, the samples were placed in the oven for the thermal curing process and the samples were cured at 90 °C for 24 hours. As a result, the maximum compressive strength value in all sample groups was obtained as 59.7 MPa in the metakaolin-based geopolymer mortar obtained by calcined at 700 oC, while the lowest compressive strength value was obtained in the metakaolinbased geopolymer mortar obtained at 27.8 MPa and 900 oC. However, the effect of the calcination temperature of metakaolin on the compressive strength values is not clear, and at relatively higher calcination temperatures, the compressive strength values are markedly reduced due to the deterioration of the amorphous structure of the metakaolin material.

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ASTM C 618 - 17a, 2017. Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete, ASTM-USA.
Castelein, O., Soulestin, B., Bonnet, J.P., Blanchart, P., 2001. The influence of heating rate on the thermal behaviour and mullite formation from a kaolin raw material. Ceramics International. 27, 517–522.
Cioffi, R., Maffucci, L., Santoro, L., 2003. Optimization of geopolymer synthesis by calcination and polycondensation of a kaolinitic residue. Resources, Conservation and Recycling. 40, 27–38.
Curcio, F., DeAngelis, B.A., Pagliolico, S., 1998. Metakaolin as a pozzolanic microfiller for highperformance mortars. Cement and Concrete Research. 28, 803–809.
Elimbi, A., Tchakoute, H.K., Njopwouo, D., 2011. Effects of calcination temperature of kaolinite clays on the properties of geopolymer cements. Construction and Building Materials. 25, 2805– 2812.
He, J., Zhang, J., Yu, Y., Zhang, G., 2012. The strength and microstructure of two geopolymers derived from metakaolin and red mud-fly ash admixture: A comparative study. Construction and Building Materials. 30, 80–91.
Ozer, I. and Soyer-Uzun, S., 2015. Relations between the structural characteristics and compressive strength in metakaolin based geopolymers with different molar Si/Al ratios. Ceramics International. 41, 10192–10198.
Kaya, K., Soyer-Uzun, S., 2016. Evolution of structural characteristics and compressive strength in red mud-metakaolin based geopolymer systems. Ceramics International. 42, 7406–7413.
Kenne Diffo, B.B., Elimbi, A., Cyr, M., Dika Manga, J., Tchakoute Kouamo, H., 2015. Effect of the rate of calcination of kaolin on the properties of metakaolin-based geopolymers. Journal of Asian Ceramic Societies. 3, 130–138.
Kong, D.L.Y., Sanjayan, J.G., Sagoe-Crentsil, K., 2007. Comparative performance of geopolymers made with metakaolin and fly ash after exposure to elevated temperatures. Cement and Concrete Research. 37, 1583–1589.
Logesh Kumar, M. and Revathi, V., 2016. Metakaolin bottom ash blend geopolymer mortar - A feasibility study. Construction and Building Materials. 114, 1–5.
Kuenzel, C., Neville, T.P., Donatello, S., Vandeperre, L., Boccaccini, A.R., Cheeseman, C.R., 2013. Influence of metakaolin characteristics on the mechanical properties of geopolymers. Applied Clay Science. 83–84, 308–314.
Marín-López, C., Reyes Araiza, J.L., Manzano- Ramírez, A., Rubio Avalos, J.C., Perez-Bueno, J.J., Muñiz-Villareal, M.S., Ventura-Ramos, E., Vorobiev, Y., 2009. Synthesis and characterization of a concrete based on metakaolin geopolymer. Inorganic Materials. 45, 1429–1432.
Pacheco-Torgal, F., Moura, D., Ding, Y., Jalali, S., 2011. Composition, strength and workability of alkali-activated metakaolin based mortars. Construction and Building Materials. 25, 3732– 3745.
Rovnaník, P., 2010. Effect of curing temperature on the development of hard structure of metakaolin-based geopolymer. Construction and Building Materials. 24, 1176–1183.
van Jaarsveld, J.G., van Deventer, J.S., Lukey, G., 2002. The effect of composition and temperature on the properties of fly ash- and kaolinite-based geopolymers. Chemical Engineering Journal. 89, 63–73.
Tchakouté, H.K., Rüscher, C.H., Kong, S., Kamseu, E., Leonelli, C., 2016. Geopolymer binders from metakaolin using sodium waterglass from waste glass and rice husk ash as alternative activators: A comparative study. Construction and Building Materials. 114, 276–289.
TS EN 196-1, 2016. Methods of testing cement - Part 1: Determination of strength, TSE-Turkey.
TS EN 771-1, 2015. Specification for masonry units - Part 1: Clay masonry units, TSE-Turkey.
TS EN 772-4, 2000. Methods of test for masonry units - Part 4: Determination of real and bulk density and of total and open porosity for natural stone masonry units, TSE-Turkey.
Villa, C., Pecina, E.T., Torres, R., Gómez, L., 2010. Geopolymer synthesis using alkaline activation of natural zeolite. Construction and Building Materials. 24, 2084–2090.
Zibouche, F., Kerdjoudj, H., d’Espinose de Lacaillerie, J.-B., Van Damme, H., 2009. Geopolymers from Algerian metakaolin. Influence of secondary minerals. Applied Clay Science. 43, 453–458.