Effect of Silica Moduli on the Thermal Degradation Mechanisms of Fly Ash–Based Geopolymer Mortars
Publication: Journal of Materials in Civil Engineering
Volume 33, Issue 5
Abstract
This study investigates the effect of silica moduli ( ratio) of alkaline activators on the degradation mechanisms of fly ash–based geopolymer (FAG) mortars that are exposed to elevated temperatures of up to 1,000°C. The evolution of the mechanical properties, microstructure, mineralogy, and atomic structure of the FAG with three different silica moduli after the thermal treatment are studied. The results show that silica modulus affects the compressive strength and crack development of geopolymer mortars. Geopolymer mortars with the highest silica modulus have the best thermal stability and volume stability after exposure to high temperatures, as confirmed by the latest cracking initiation and lowest cracking intensity. The mechanism of decreased strength in geopolymer mortars with low silica moduli (owing to crack development) is different from that of increased strength in geopolymer mortars with high silica moduli (owing to further geopolymerization) before 400°C. The crystalline phases of nepheline and albite were observed to appear in the specimen at 800°C and 1,000°C, respectively, which was possibly due to entering into the crystal lattice of mullite and promoting the change of mullite into new crystal phases. Heating processes cause varying degrees of destruction of FAG and form a highly porous and weak structure owing to the sintering process above 800°C. Silica moduli are not an important factor for the gel phase structure of FAG at 1,000°C, which may be related to the same content of .
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China, under Grant Nos. 51778570 and 51879230, and from the Fundamental Research Funds for the Central University of China, under No. 2019QNA4044.
References
Abdulkareem, O. A., A. M. M. A. Bakri, H. Kamarudin, I. K. Nizar, and A. A. Saif. 2014. “Effects of elevated temperatures on the thermal behavior and mechanical performance of fly ash geopolymer paste, mortar and lightweight concrete.” Constr. Build. Mater. 50 (Jan): 377–387. https://doi.org/10.1016/j.conbuildmat.2013.09.047.
Álvarez-Ayuso, E., et al. 2008. “Environmental, physical and structural characterisation of geopolymer matrixes synthesised from coal (co-)combustion fly ashes.” J. Hazard. Mater. 154 (1–3): 175–183. https://doi.org/10.1016/j.jhazmat.2007.10.008.
Ao, Y. 2019. “Study on elevated temperature resistance and shrinkage properties of geopolymer.” [In Chinese.] M.A. thesis, College of Civil Engineering and Architecture, Zhejiang Univ.
ASTM. 2008. Standard specification for coal fly ash and raw or calcined natural pozzolan for use in concrete. ASTM C618. West Conshohocken, PA: ASTM.
Bakharev, T. 2006. “Thermal behaviour of geopolymers prepared using class F fly ash and elevated temperature curing.” Cem. Concr. Res. 36 (6): 1134–1147. https://doi.org/10.1016/j.cemconres.2006.03.022.
Baščarević, Z., M. Komljenović, Z. Miladinović, C. Nikolić, N. Marjanović, and R. Petrović. 2015. “Impact of sodium sulfate solution on mechanical properties and structure of fly ash based geopolymers.” Mater. Struct. 48 (3): 683–697. https://doi.org/10.1617/s11527-014-0325-4.
Bernal, S. A., J. L. Provis, B. Walkley, R. S. Nicolas, D. G. Gehman, D. G. Brice, A. R. Kilcullen, P. Duxson, and J. S. J. van Deventer. 2013. “Gel nanostructure in alkali-activated binders based on slag and fly ash, and effects of accelerated carbonation.” Cem. Concr. Res. 53 (Nov): 127–144. https://doi.org/10.1016/j.cemconres.2013.06.007.
Bignozzi, M. C., S. Manzi, M. E. Natali, W. D. A. Rickard, and A. van Riessen. 2014. “Room temperature alkali activation of fly ash: The effect of ratio.” Constr. Build. Mater. 69 (Oct): 262–270. https://doi.org/10.1016/j.conbuildmat.2014.07.062.
Chandrasekhar, S., and P. N. Pramada. 2001. “Sintering behaviour of calcium exchanged low silica zeolites synthesized from kaolin.” Ceram. Int. 27 (1): 105–114. https://doi.org/10.1016/S0272-8842(00)00049-3.
Chindaprasirt, P., and U. Rattanasak. 2018. “Fire-resistant geopolymer bricks synthesized from high-calcium fly ash with outdoor heat exposure.” Clean Technol. Environ. Policy 20 (5): 1097–1103. https://doi.org/10.1007/s10098-018-1532-4.
Chindaprasirt, P., U. Rattanasak, and C. Jaturapitakkul. 2011. “Utilization of fly ash blends from pulverized coal and fluidized bed combustions in geopolymeric materials.” Cem. Concr. Compos. 33 (1): 55–60. https://doi.org/10.1016/j.cemconcomp.2010.09.017.
Cho, Y. K., S. W. Yoo, S. H. Jung, K. M. Lee, and S. J. Kwon. 2017. “Effect of content, molar ratio, and curing conditions on the compressive strength of FA-based geopolymer.” Constr. Build. Mater. 145 (Aug): 253–260. https://doi.org/10.1016/j.conbuildmat.2017.04.004.
Colangelo, F., R. Cioffi, G. Roviello, I. Capasso, D. Caputo, P. Aprea, B. Liguori, and C. Ferone. 2017. “Thermal cycling stability of fly ash based geopolymer mortars.” Composites, Part B 129 (Nov): 11–17. https://doi.org/10.1016/j.compositesb.2017.06.029.
Criado, M., A. Fernández-Jiménez, and A. Palomo. 2007a. “Alkali activation of fly ash: Effect of the ratio. Part I: FTIR study.” Microporous Mesoporous Mater. 106 (1–3): 180–191. https://doi.org/10.1016/j.micromeso.2007.02.055.
Criado, M., A. Fernández-Jiménez, A. Palomo, I. Sobrados, and J. Sanz. 2008. “Effect of the ratio on the alkali activation of fly ash. Part II: 29Si MAS-NMR survey.” Microporous Mesoporous Mater. 109 (1): 525–534. https://doi.org/10.1016/j.micromeso.2007.05.062.
Criado, M., A. Fernández-Jiménez, A. G. D. L. Torre, M. A. G. Aranda, and A. Palomo. 2007b. “An XRD study of the effect of the ratio on the alkali activation of fly ash.” Cem. Concr. Res. 37 (5): 671–679. https://doi.org/10.1016/j.cemconres.2007.01.013.
Davidovits, J. 2008. Geopolymer chemistry and applications. 2nd ed. Saint-Quentin, France: Institut Geopolymere.
De Vargas, A. S., D. C. C. Dal Molin, A. C. F. Vilela, F. J. da Silva, B. Pavao, and H. Veit. 2011. “The effects of molar ratio, curing temperature and age on compressive strength, morphology and microstructure of alkali-activated fly ash-based geopolymers.” Cem. Concr. Compos. 33 (6): 653–660. https://doi.org/10.1016/j.cemconcomp.2011.03.006.
Dombrowski, K., A. Buchwald, and M. Weil. 2007. “The influence of calcium content on the structure and thermal performance of fly ash based geopolymers.” J. Mater. Sci. 42 (9): 3033–3043. https://doi.org/10.1007/s10853-006-0532-7.
Duan, P., C. Yan, W. Zhou, W. J. Luo, and C. H. Shen. 2015. “An investigation of the microstructure and durability of a fluidized bed fly ash–metakaolin geopolymer after heat and acid exposure.” Mater. Des. 74 (Jun): 125–137. https://doi.org/10.1016/j.matdes.2015.03.009.
Duxson, P., G. C. Lukey, and J. S. J. van Deventer. 2007. “Physical evolution of Na-geopolymer derived from metakaolin up to 1000°C.” J. Mater. Sci. 42 (9): 3044–3054. https://doi.org/10.1007/s10853-006-0535-4.
Fernandez-Jimenez, A., F. Puertas, I. Sobrados, and J. Sanz. 2002. “Structure of calcium silicate hydrate formed in alkali activated slag cement pates.” In Proc., Int. Symp. of Non-Traditional Cement and Concrete, edited by V. B. Brno, and Z. Kersner, 29–41. Brno, Czech Republic: BRNO Univ. of Technology.
Fernández-Jiménez, A., J. Y. Pastor, A. Martín, and A. Palomo. 2010. “High-temperature resistance in alkali-activated cement.” J. Am. Ceram. Soc. 93 (10): 3411–3417. https://doi.org/10.1111/j.1551-2916.2010.03887.x.
Fernández-Jiménez, A., A. Palomo, J. Y. Pastor, and A. Martin. 2008. “New cementitious materials based on alkali-activated fly ash: Performance at high temperatures.” J. Am. Ceram. Soc. 91 (10): 3308–3314. https://doi.org/10.1111/j.1551-2916.2008.02625.x.
Gao, K., K. L. Lin, D. Y. Wang, C. L. Hwang, H. S. Shiu, Y. M. Chang, and T. Cheng. 2014. “Effects molar ratio on mechanical properties and the microstructure of nano- metakaolin-based geopolymers.” Constr. Build. Mater. 53 (Feb): 503–510. https://doi.org/10.1016/j.conbuildmat.2013.12.003.
Guerrieri, M., and J. G. Sanjayan. 2010. “Behavior of combined fly ash/slag-based geopolymers when exposed to high temperatures.” Fire Mater. 34 (4): 163–175. https://doi.org/10.1002/fam.1014.
Guo, X., H. Shi, and W. A. Dick. 2010. “Compressive strength and microstructural characteristics of class C fly ash geopolymer.” Cem. Concr. Compos. 32 (2): 142–147. https://doi.org/10.1016/j.cemconcomp.2009.11.003.
Habert, G., and C. Ouellet-Plamondon. 2016. “Recent update on the environmental impact of geopolymers.” RILEM Tech. Lett. 1 (Apr): 17–23. https://doi.org/10.21809/rilemtechlett.2016.6.
Hajimohammadi, A., J. L. Provis, and J. S. J. van Deventer. 2008. “One-part geopolymer mixes from geothermal silica and sodium aluminate.” Ind. Eng. Chem. Res. 47 (23): 9396–9405. https://doi.org/10.1021/ie8006825.
Hajimohammadi, A., and J. S. J. van Deventer. 2017. “Solid reactant-based geopolymers from rice hull ash and sodium aluminate.” Waste Biomass Valorization 8 (6): 2131–2140. https://doi.org/10.1007/s12649-016-9735-6.
Hamilton, J. P., S. L. Brantley, C. G. Pantano, L. J. Criscenti, and J. D. Kubicki. 2001. “Dissolution of nepheline, jadeite and albite glasses: Toward better models for aluminosilicate dissolution.” Geochim. Cosmochim. Acta 65 (21): 3683–3702. https://doi.org/10.1016/S0016-7037(01)00724-4.
Industry Standard of People’s Republic of China. 2009. Standard for test method of performance on building mortar. [In Chinese.] JGJ/T70-2009. Beijing: Industry Standard of People’s Republic of China.
Jeon, D., Y. Jun, Y. Jeong, and J. E. Oh. 2015. “Microstructural and strength improvements through the use of in a cementless -activated Class F fly ash system.” Cem. Concr. Res. 67 (67): 215–225. https://doi.org/10.1016/j.cemconres.2014.10.001.
Jin, M. T., M. Y. Liao, Z. D. Zheng, and Z. F. Jin. 2017. “Effects of ratio on thermal properties of fly ash-straw-metakaolin composite geopolymers.” [In Chinese.] J. Chem. Eng. Chin. Univ. 31 (1): 211–221. https://doi.org/10.3969/j.issn.1003-9015.2016.00.045.
Khedmati, M., H. Alanazi, Y. R. Kim, G. Nsengiyumva, and S. Moussavi. 2018. “Effects of molar ratio on properties of aggregate-paste interphase in fly ash-based geopolymer mixtures through multiscale measurements.” Constr. Build. Mater. 191 (Dec): 564–574. https://doi.org/10.1016/j.conbuildmat.2018.10.024.
Kong, D. L. Y., and J. G. Sanjayan. 2010. “Effect of elevated temperatures on geopolymer paste, mortar and concrete.” Cem. Concr. Res. 40 (2): 334–339. https://doi.org/10.1016/j.cemconres.2009.10.017.
Kong, D. L. Y., J. G. Sanjayan, and K. Sagoe-Crentsil. 2007. “Comparative performance of geopolymers made with metakaolin and fly ash after exposure to elevated temperatures.” Cem. Concr. Res. 37 (12): 1583–1589. https://doi.org/10.1016/j.cemconres.2007.08.021.
Krivenko, P. V., and G. Y. Kovalchuk. 2007. “Directed synthesis of alkaline aluminosilicate minerals in a geocement matrix.” J. Mater. Sci. 42 (9): 2944–2952. https://doi.org/10.1007/s10853-006-0528-3.
Kuenzel, C., L. J. Vandeperre, S. Donatello, A. R. Boccaccini, and C. Cheeseman. 2012. “Ambient temperature drying shrinkage and cracking in metakaolin-based geopolymers.” J. Am. Ceram. Soc. 95 (10): 3270–3277. https://doi.org/10.1111/j.1551-2916.2012.05380.x.
Lahoti, M., K. K. Wong, K. H. Tan, and E. H. Yang. 2018. “Effect of alkali cation type on strength endurance of fly ash geopolymers subject to high temperature exposure.” Mater. Des. 154 (Sep): 8–19. https://doi.org/10.1016/j.matdes.2018.05.023.
Lee, W. K. W., and J. S. J. van Deventer. 2003. “Use of infrared spectroscopy to study geopolymerization of heterogeneous amorphous aluminosilicates.” Langmuir 19 (21): 8726–8734. https://doi.org/10.1021/la026127e.
Li, J., M. F. Du, B. Yan, and Z. X. Zhang. 2008. “Quantum and experimental study on coal ash fusion with borax fluxing agent.” J. Fuel Chem. Technol. 36 (5): 519–523. https://doi.org/10.1016/S1872-5813(08)60032-8.
Li, J., M. F. Du, Z. X. Zhang, R. Q. Guan, Y. S. Chen, and T. Y. Liu. 2009. “Selection of fluxing agent for coal ash and investigation of fusion mechanism: A first-principles study.” Energy Fuels 23 (2): 704–709. https://doi.org/10.1021/ef800784k.
Li, Y. L., X. L. Zhao, R. S. Raman, and S. Al-Saadi. 2018. “Thermal and mechanical properties of alkali-activated slag paste, mortar and concrete utilising seawater and sea sand.” Constr. Build. Mater. 159 (Jan): 704–724. https://doi.org/10.1016/j.conbuildmat.2017.10.104.
MacKenzie, K. J. D., and M. E. Smith. 2002. Multinuclear solid-state nuclear magnetic resonance of inorganic materials. Amsterdam, Netherlands: Elsevier.
National Standard of People’s Republic of China. 1999. Method of testing cements–Determination of strength. [In Chinese.] GB/T 17671-1999. Beijing: National Standard of People’s Republic of China.
Niklioć, I., S. Marković, I. Janković–Častvan, V. V. Radmilović, l. Karanović, B. Babić, and V. R. Radmilović. 2016. “Modification of mechanical and thermal properties of fly ash-based geopolymer by the incorporation of steel slag.” Mater. Lett. 176 (Aug): 301–305. https://doi.org/10.1016/j.matlet.2016.04.121.
Pan, Z., J. G. Sanjayan, and F. Collins. 2014. “Effect of transient creep on compressive strength of geopolymer concrete for elevated temperature exposure.” Cem. Concr. Res. 56 (Feb): 182–189. https://doi.org/10.1016/j.cemconres.2013.11.014.
Pan, Z., J. G. Sanjayan, and B. V. Rangan. 2009. “An investigation of the mechanisms for strength gain or loss of geopolymer mortar after exposure to elevated temperature.” J. Mater. Sci. 44 (7): 1873–1880. https://doi.org/10.1007/s10853-009-3243-z.
Park, S. J., and H. J. Yim. 2016. “Evaluation of residual mechanical properties of concrete after exposure to high temperatures using impact resonance method.” Constr. Build. Mater. 129 (Dec): 89–97. https://doi.org/10.1016/j.conbuildmat.2016.10.116.
Park, S. M., J. G. Jang, and H. K. Lee. 2016. “Physicochemical properties of binder gel in alkali-activated fly ash/slag exposed to high temperatures.” Cem. Concr. Res. 89 (Nov): 72–79. https://doi.org/10.1016/j.cemconres.2016.08.004.
Rees, C. A., J. L. Provis, G. C. Lukey, and J. S. J. van Deventer. 2007. “In situ ATR-FTIR study of the early stages of fly ash geopolymer gel formation.” Langmuir 23 (17): 9076–9082. https://doi.org/10.1021/la701185g.
Ren, W., J. Xu, and E. Bai. 2016. “Strength and ultrasonic characteristics of alkali-activated fly ash-slag geopolymer concrete after exposure to elevated temperatures.” J. Mater. Civ. Eng. 28 (2): 04015124. https://doi.org/10.1061/(ASCE)MT.1943-5533.0001406.
Rickard, W. D. A., J. Temuujin, and A. van Riessen. 2012. “Thermal analysis of geopolymer pastes synthesised from five fly ashes of variable composition.” J. Non-Cryst. Solids 358 (15): 1830–1839. https://doi.org/10.1016/j.jnoncrysol.2012.05.032.
Rickard, W. D. A., R. Williams, J. Temuujin, and A. van Riessen. 2011. “Assessing the suitability of three Australian fly ashes as an aluminosilicate source for geopolymers in high temperature applications.” Mater. Sci. Eng., A 528 (9): 3390–3397. https://doi.org/10.1016/j.msea.2011.01.005.
Rovnaník, P., P. Bayer, and P. Rovnaníková. 2013. “Characterization of alkali activated slag paste after exposure to high temperatures.” Constr. Build. Mater. 47 (Oct): 1479–1487. https://doi.org/10.1016/j.conbuildmat.2013.06.070.
Ryu, G. S., Y. B. Lee, K. T. Koh, and Y. S. Chung. 2013. “The mechanical properties of fly ash-based geopolymer concrete with alkaline activators.” Constr. Build. Mater. 47 (Oct): 409–418. https://doi.org/10.1016/j.conbuildmat.2013.05.069.
Sakulich, A. R., E. Anderson, C. Schauer, and M. W. Barsoum. 2009. “Mechanical and microstructural characterization of an alkali-activated slag/limestone fine aggregate concrete.” Constr. Build. Mater. 23 (8): 2951–2957. https://doi.org/10.1016/j.conbuildmat.2009.02.022.
Sarker, P. K., S. Kelly, and Z. Yao. 2014. “Effect of fire exposure on cracking, spalling and residual strength of fly ash geopolymer concrete.” Mater. Des. 63 (Nov): 584–592. https://doi.org/10.1016/j.matdes.2014.06.059.
Shaikh, F. U. A. 2014. “Effects of alkali solutions on corrosion durability of geopolymer concrete.” Adv. Concr. Constr. 2 (2): 109–123. https://doi.org/10.12989/acc.2014.2.2.109.
Sindhunata, J. S. J., G. C. Lukey, and H. Xu. 2006. “Effect of curing temperature and silicate concentration on fly-ash-based geopolymerization.” Ind. Eng. Chem. Res. 45 (10): 3559–3568. https://doi.org/10.1021/ie051251p.
Środa, M., and C. Paluszkiewicz. 2008. “The structural role of alkaline earth ions in oxyfluoride aluminosilicate glasses—Infrared spectroscopy study.” Vib. Spectrosc. 48 (2): 246–250. https://doi.org/10.1016/j.vibspec.2008.02.017.
Temuujin, J., A. Minjigmaa, W. Rickard, M. Lee, L. Williams, and A. van Riessen. 2009. “Preparation of metakaolin based geopolymer coatings on metal substrates as thermal barriers.” Appl. Clay Sci. 46 (3): 265–270. https://doi.org/10.1016/j.clay.2009.08.015.
Temuujin, J., W. Rickard, M. Lee, and A. van Riessen. 2011. “Preparation and thermal properties of fire resistant metakaolin-based geopolymer-type coatings.” J. Non-Cryst. Solids 357 (5): 1399–1404. https://doi.org/10.1016/j.jnoncrysol.2010.09.063.
Turner, L. K., and F. G. Collins. 2013. “Carbon dioxide equivalent () emissions: A comparison between geopolymer and OPC cement concrete.” Constr. Build. Mater. 43: 125–130. https://doi.org/10.1016/j.conbuildmat.2013.01.023.
Verdolotti, L., S. Iannace, M. Lavorgna, and R. Lamanna. 2008. “Geopolymerization reaction to consolidate incoherent pozzolanic soil.” J. Mater. Sci. 43 (3): 865–873. https://doi.org/10.1007/s10853-007-2201-x.
Walkley, B., R. San Nicolas, M. A. Sani, J. D. Gehman, and J. S. J. van Deventer. 2016a. “Synthesis of stoichiometrically controlled reactive aluminosilicate and calcium-aluminosilicate powders.” Powder Technol. 297 (Sep): 17–33. https://doi.org/10.1016/j.powtec.2016.04.006.
Walkley, B., R. San Nicolas, M. A. Sani, G. J. Rees, J. V. Hanna, J. S. J. van Deventer, and J. L. Provis. 2016b. “Phase evolution of C-(N)-ASH/NASH gel blends investigated via alkali-activation of synthetic calcium aluminosilicate precursors.” Cem. Concr. Res. 89 (Nov): 120–135. https://doi.org/10.1016/j.cemconres.2016.08.010.
Xue, S., P. Zhang, J. Bao, L. He, Y. Hu, and S. Yang. 2020. “Comparison of mercury intrusion porosimetry and multi-scale X-ray CT on characterizing the microstructure of heat-treated cement mortar.” Mater. Charact. 160 (Feb): 110085. https://doi.org/10.1016/j.matchar.2019.110085.
Yan, D. M., S. K. Chen, C. L. Wu, Q. Zeng, and F. Yang. 2019. “Rate-dependent bonding of steel reinforcement in geopolymer concrete.” ACI Mater. J. 116 (5): 217–219. https://doi.org/10.13140/RG.2.2.19064.90881.
Yaseri, S., V. M. Verki, and M. Mahdikhani. 2019. “Utilization of high volume cement kiln dust and rice husk ash in the production of sustainable geopolymer.” J. Cleaner Prod. 230 (Sep): 592–602. https://doi.org/10.1016/j.jclepro.2019.05.056.
Zhang, H. Y., V. Kodur, S. L. Qi, L. Cao, and B. Wu. 2014. “Development of metakaolin–fly ash based geopolymers for fire resistance applications.” Constr. Build. Mater. 55 (Mar): 38–45. https://doi.org/10.1016/j.conbuildmat.2014.01.040.
Zhang, H. Y., V. Kodur, B. Wu, L. Cao, and F. Wang. 2016. “Thermal behavior and mechanical properties of geopolymer mortar after exposure to elevated temperatures.” Constr. Build. Mater. 109 (Apr): 17–24. https://doi.org/10.1016/j.conbuildmat.2016.01.043.
Zhang, J., C. J. Shi, and Z. H. Zhang. 2019. “Carbonation induced phase evolution in alkali-activated slag/fly ash cements: The effect of silicate modulus of activators.” Constr. Build. Mater. 223 (Oct): 566–582. https://doi.org/10.1016/j.conbuildmat.2019.07.024.
Zhao, M., G. Zhang, K. W. Htet, M. Kwon, C. Y. Liu, Y. Xu, and M. J. Tao. 2019. “Freeze-thaw durability of red mud slurry-class F fly ash-based geopolymer: Effect of curing conditions.” Constr. Build. Mater. 215 (Aug): 381–390. https://doi.org/10.1016/j.conbuildmat.2019.04.235.
Zhuang, X. Y., L. Chen, S. Komarneni, C. H. Zhou, D. S. Tong, H. M. Yang, W. H. Yu, and H. Wang. 2016. “Fly ash-based geopolymer: Clean production, properties and applications.” J. Cleaner Prod. 125 (Jul): 253–267. https://doi.org/10.1016/j.jclepro.2016.03.019.
Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 33 • Issue 5 • May 2021
Copyright
© 2021 American Society of Civil Engineers.
History
Received: May 25, 2020
Accepted: Sep 14, 2020
Published online: Feb 22, 2021
Published in print: May 1, 2021
Discussion open until: Jul 22, 2021
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.