Title:
Hardening and Shrinkage Kinetics of Geopolymers
Author(s):
Hugo Thuilliez, Christophe Lanos, Annabelle Phelipot-Mardelé, Gérard Mauvoisin
Publication:
Symposium Paper
Volume:
362
Issue:
Appears on pages(s):
487-498
Keywords:
3D scanner, alkali activated binder, alternative material, drying shrinkage, geopolymer, macroindentation, shrinkage
DOI:
10.14359/51741005
Date:
6/14/2024
Abstract:
Geopolymers are amorphous mineral materials manufactured from aluminosilicates and a strongly basic alkaline solution. One of their advantages is a lower carbon footprint than conventional cementitious binders. However, they are subject to significant drying shrinkage. In this study, geopolymer samples are produced from metakaolin, silica fume, and a potash solution. The mixture proportions are selected to reach the molar ration Si/Al=1.8, K/Al=1.15, and H2O/K=5.3 leading to satisfactory rheology while mixing. Cylindrical samples (70 mm diameter, 40 mm height) are exposed to various curing conditions (temperature and relative humidity). A protocol including 3D scanning and instrumented macroindentation is used to monitor the drying shrinkage and hardening kinetics. Sample volume change and hardness are measured periodically until sample mass stabilization. It appears that the hardest samples are also the most cracked. Covering the sample for 5 days at 23°C or 24 hours at 40°C limits the shrinkage to ~1% but leads to a large decrease of the hardness compared to the hardest samples. An optimal geopolymerization requires a minimal amount of water which decreases with the progress of the reaction. Optimal curing conditions are identified. Thus, covering the sample for 3 days at 23°C allows to limit the shrinkage to 3% without cracking while reaching satisfactory mechanical properties.
Related References:
1. Sbahieh, S., McKay, G., Al-Ghamdi, S.G., 2023, “Comprehensive Analysis of Geopolymer Materials: Properties, Environmental Impacts, and Applications”, Materials, 16, 7363
2. Duxson, P., Provis, J.L., Lukey, G.C., Van Deventer, J.S.J., 2007, “The role of inorganic polymer technology in the development of ‘green concrete”, Cement and Concrete Research, 37, 1590–1597. doi: 10.1016/j.cemconres.2007.08.018
3. Zuhua, Z., Xiao, Y., Huajun, Z., Yue, C., 2009, “Role of water in the synthesis of calcined kaolin-based geopolymer”, Applied Clay Science, Volume 43, Issue 2, 218-223
4. Pouhet, R., Cyr, M., Bucher, R., 2019, “Influence of the initial water content in flash calcined metakaolin-based geopolylmer”, Construction and Building Materials, 201
5. Kuenzel, C., Vandeperre, L.J., Donatello, S., Boccaccini, A.R., Cheeseman, C., 2012, “Ambiant Temperature Drying Shrinkage and Cracking in Metakoalin-Based Geopolymers”, The American Ceramic Society, 95(10)
6. Ye, H., Cartwright, C., Rajabipour, F., Radlińska, A., 2017, “Understanding the drying shrinkage performance of alkaliactivated slag mortars”, Cement Concr. Compos., Volume 76, 13-24
7. Si, R., Dai, Q., Guo, S., Wang, J., 2020, “Mechanical property, nanopore structure and drying shrinkage of metakaolinbased geopolymer with waste glass powder”, Journal of Cleaner Production, 242:118502
8. Yang, T.; Zhu, H.; Zhang, Z., 2017, “Influence of fly ash on the pore structure and shrinkage characteristics of metakaolinbased geopolymer pastes and mortars”, Constr. Build. Mater. 2017, 153, 284–293
9. Zhang, B., Zhu, H., Feng, P., Zhang, P., 2022, “A review on shrinkage-reducing methods and mechanisms of alkaliactivated/geopolymer systems: Effects of chemical additives”, Journal of Building Engineering, 49, 104056
10. Liu, X.; Liu, E.; Fu, Y., 2023, “Reduction in Drying Shrinkage and Efflorescence of Recycled Brick and Concrete Fine Powder–Slag-Based Geopolymer”, Appl. Sci., 13, 2997
11. Trincal, V., Multon, S., Benavent, V., Lahalle, H., Balsamo, B., Caron, A., Bucher, R., Diaz Caselles, L., Cyr, M., 2022, “Shrinkage mitigation of metakaolin-based geopolymer activated by sodium silicate solution”, Cement and Concrete Research, 162, 106993
12. Collins, F., Sanjayan, J.J.C., 2000, “Effect of Pore Size Distribution on Drying Shrinking of Alkali-Activated Slag Concrete”, Cement and Concrete Research, 30, Issue 9, 1401-1406
13. Thomas, R.J., Lezama, D., Peethamparan, S., 2017, “On drying shrinkage in alkali-activated concrete: Improving dimensional stability by aging or heat-curing”, Cement and Concrete Research, 91, 13-23
14. Bartier, O., Hernot, X., Mauvoisin, G., 2010, “Theoretical and experimental analysis of contact radius for spherical indentation”, Mechanics of Materials, 42, 6, 640–656
15. Collin, J.M., Mauvoisin, G., Bartier, O., El Abdi, R., Pilvin, P., 2009, “Experimental evaluation of the stress–strain curve by continuous indentation using different indenter shapes”, Materials Science and Engineering A, 501, 140-145
16. Chicot, D., Mercier, D., 2008, “Improvement in depth-sensing indentation to calculate the universal hardness on the entire loading curve”, Mechanics of Materials, 40, Issue 4–5, 171-182
17. Oliver, W.C., Pharr, G.M., 1992, “An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments”, Journal of materials research, 7, 1564–1583
18. NF EN ISO 14577-1, 2015, “Metallic materials — Instrumented indentation test for hardness and materials parameters Part 1: Test method”, AFNOR, 12 September 2015
19. Rowles, M., O’connor, B., 2003, “Chemical optimization of the compressive strength of aluminosilicate geopolymers synthetized by sodium silicate activation of metakaolinite”, Journal of Materials Chemistry, 13, 5