Sulfuric Acid Resistance of Pumice Based Geopolymer Mortars with Fly Ash and Calcium Aluminate Cement Additives

Öz

In this study, pumice based geopolymer (PGP) mortars were produced by replacing 10, 20, and 30 wt.% of the pumice with fly ash and/or calcium aluminate cement. After curing at ambient temperature and 60 °C, the mortars were placed in a 5% sulfuric acid (H2SO4) solution on the 28th day and kept for 120 days. The change in appearance, weight loss and residual compressive strength of the PGP samples due to the effect of sulfuric acid were determined on the 60th and 120th days and compared with the Portland Cement based reference mortar. The study showed that the reference samples underwent a weight loss of 25.6% at the end of 60 days by dissolving of hardened cement paste in the sulfuric acid medium. However, it was observed that the PGP mortars did not undergo any visual change in sulfuric acid solution, except for the samples containing 20 and 30% calcium aluminate cement (for ambient curing). In addition, it was determined that the PGP samples cured at ambient temperature and 60 °C had a maximum weight loss of 6.5% and 4.1, respectively, at the end of 120 days. PGP mortars underwent compressive strength losses of up to 70% in the 120-day sulfuric acid solution. However, with sufficient fly ash and calcium aluminate cement substitution, the compressive strength of PGP mortars increased significantly as well as the sulfuric acid resistance.

Anahtar Kelimeler

• Geopolymer
• pumice
• fly ash
• calcium aluminate cement
• heat curing
• sulfuric acid resistance

Uçucu Kül ve Kalsiyum Alüminat Çimentosu Katkılı Pomza Esaslı Geopolimer Harçların Sülfürik Asit Direnci

Öz

Bu çalışmada, uçucu kül ve/veya kalsiyum alüminat çimentosu ağırlıkça toplam toz bağlayıcının %10, 20 ve 30’u kadar pomza ile ikame edilerek pomza esaslı geopolimer (PGP) harçlar üretilmiştir. Ortam sıcaklığı ve 60 °C’de kür edilen bu harçlar, 28. günde %5 derişime sahip sülfürik asit (H2SO4) çözeltisine konularak 120 gün bekletilmiştir. PGP numunelerde sülfürik asit etkisiyle oluşan görsel değişim, ağırlık kaybı ve kalan basınç dayanımı, 60 ve 120. günde ölçülmüş ve Portland Çimentosu esaslı referans harçla kıyaslanmıştır. Çalışma, referans numunelerinin sülfürik asit ortamında çözünerek 60 günün sonunda %25.6 ağırlık kaybı yaşadığını buna karşılık %20 ve 30 oranında kalsiyum alüminat çimentosu içeren karışımların ortam sıcaklığında kür edilmiş numuneleri hariç PGP harçlarda (görsel açıdan) bir çözünme olmadığını göstermiştir. Ayrıca ortam sıcaklığı ve 60 °C’de kür edilen PGP numunelerin 120 günün sonunda sırasıyla en fazla %6.5 ve 4.1 ağırlık kaybına uğradıkları tespit edilmiştir. PGP harçlar, sülfürik asit çözeltisinde 120 günün sonunda %70’e varan basınç dayanım kayıpları yaşamıştır. Ancak yeterli miktarda uçucu kül ve kalsiyum alüminat çimentosu ikamesi ile PGP harçların basınç dayanımı önemli derecede arttığı gibi sülfürik asit direnci de iyileşmiştir

Anahtar Kelimeler

• Geopolimer
• pomza
• uçucu kül
• kalsiyum alüminat çimentosu
• ısıl kür
• sülfürik asit direnci

Kaynakça

1. Agrawal VM, Savoikar PP, 2022. Sustainable use of normal and ultra-fine fly ash in mortar as partial replacement to ordinary Portland cement in ternary combinations. Materials Today: Proceedings, 51: 1593-1597.
2. Aiken TA, Kwasny J, Sha W, Soutsos MN, 2018. Effect of slag content and activator dosage on the resistance of fly ash geopolymer binders to sulfuric acid attack. Cement and Concrete Research, 111: 23-40.
3. Ariffin M, Bhutta M, Hussin M, Tahir MM, Aziah N, 2013. Sulfuric acid resistance of blended ash geopolymer concrete. Construction and Building Materials, 43: 80-86.
4. Bakharev T, 2005. Resistance of geopolymer materials to acid attack. Cement and Concrete Research, 35(4): 658-670.
5. Balun B, Karataş M, 2021. Influence of curing conditions on pumice-based alkali activated composites incorporating Portland cement. Journal of Building Engineering, 43: 102605.
6. Celik K, Hay R, Hargis CW, Moon J, 2019. Effect of volcanic ash pozzolan or limestone replacement on hydration of Portland cement. Construction and Building Materials, 197: 803-812.
7. Davidovits J, 2005. Geopolymer, green chemistry and sustainable development solutions: proceedings of the world congress geopolymer 2005. Geopolymer Institute.
8. Djobo JNY, Elimbi A, Tchakouté HK, Kumar S, 2016. Mechanical properties and durability of volcanic ash based geopolymer mortars. Construction and Building Materials, 124: 606-614.

9. Djobo JNY, Elimbi A, Tchakouté HK, Kumar S, 2017. Volcanic ash-based geopolymer cements/concretes: the current state of the art and perspectives. Environmental Science and Pollution Research, 24(5): 4433-4446.
10. Duxson P, Fernández-Jiménez A, Provis JL, Lukey GC, Palomo A, van Deventer JS, 2007. Geopolymer technology: the current state of the art. Journal of materials science, 42(9): 2917-2933.
11. Firdous R, Stephan D, Djobo JNY, 2018. Natural pozzolan based geopolymers: A review on mechanical, microstructural and durability characteristics. Construction and Building Materials, 190: 1251-1263.
12. Hamid MA, Yaltay N, Türkmenoğlu M, 2022. Properties of pumice-fly ash based geopolymer paste. Construction and Building Materials, 316: 125665.
13. Hardjito D, Rangan BV, 2005. Development and properties of low-calcium fly ash-based geopolymer concrete.
14. Kani EN, Allahverdi A, Provis JL, 2012. Efflorescence control in geopolymer binders based on natural pozzolan. Cement and Concrete Composites, 34(1): 25-33.
15. Karaaslan C, Yener E, 2021. The Effect of Alkaline Activator Components on the Properties of Fly Ash Added Pumice Based Geopolymer. Journal of the Institute of Science and Technology, 11(2): 1255-1269.
16. Karaaslan C, Yener E, Bağatur T, Polat R, Gül R, Alma MH, 2022a. Synergic effect of fly ash and calcium aluminate cement on the properties of pumice-based geopolymer mortar. Construction and Building Materials, 345: 128397.
17. Karaaslan C, Yener E, Bağatur T, Polat R, 2022b. Improving the durability of pumice-fly ash based geopolymer concrete with calcium aluminate cement. Journal of Building Engineering, 59: 105110.
18. Mehta A, Siddique R, 2017. Sulfuric acid resistance of fly ash based geopolymer concrete. Construction and Building Materials, 146: 136-143.
19. Mehta PK, Monteiro PJ, 2014. Concrete: microstructure, properties, and materials. McGraw-Hill Education.
20. Nehdi ML, Yassine A, 2020. Mitigating Portland cement CO2 emissions using alkali-activated materials: system dynamics model. Materials, 13(20): 4685.
21. Neville AM, 1995. Properties of concrete (Vol. 4). Longman London.
22. Provis JL, 2018. Alkali-activated materials. Cement and Concrete Research, 114: 40-48.
23. TS EN 196-1, 2009. Çimento deney metotları - Bölüm 1: Dayanım tayini (Methods of testing cement - Part 1: Determination of strength). In. Ankara: Türk Standartları Enstitüsü.
24. Vafaei M, Allahverdi A, 2016. Influence of calcium aluminate cement on geopolymerization of natural pozzolan. Construction and Building Materials, 114: 290-296.
25. Vafaei M, Allahverdi A, Dong P, Bassim N, 2018. Acid attack on geopolymer cement mortar based on waste-glass powder and calcium aluminate cement at mild concentration. Construction and Building Materials, 193: 363-372.
26. Wang Y, Hu S, He Z, 2019. Mechanical and fracture properties of fly ash geopolymer concrete addictive with calcium aluminate cement. Materials, 12(18): 2982.
27. Yener E, Karaaslan C, 2019. Effect of Clinker Additive on Pumice-based Geopolymer Properties. 4th International Conference on Advances in Natural & Applied Sciences,
28. Yener E, Karaaslan C, 2020. Curing Time and Temperature Effect on the Resistance to Wet-Dry Cycles of Fly Ash Added Pumice Based Geopolymer. Cement Based Composites, 1(2): 19-25.