Title:
Influence of HPEG-Based Polycarboxylate on the Flow Properties of Alkali-Activated Slag: Sodium Hydroxide and Sodium Carbonate Activated Systems
Author(s):
Hsien-Keng Chan, Lei Lei
Publication:
Symposium Paper
Volume:
354
Issue:
Appears on pages(s):
297-308
Keywords:
alkali-activated slag, polycarboxylate, dispersion, solubility
DOI:
10.14359/51736083
Date:
7/1/2022
Abstract:
Slag cement as a potential replacement for ordinary portland cement (OPC) could solve the global CO2 emission problem from cement productions. However, such slag-based binders provide poor workability and require activation by alkali solutions. Unfortunately, so far no sufficiently performing superplasticizer has been identified for these alkali-activated slag (AAS) systems. In this study, a series of α-methallyl-ω-hydroxy poly (ethylene glycol) ether (HPEG)-based polycarboxylate polymers possessing different anionic charge density or side chain lengths was synthesized. Then, the solubility and dispersing performance of these polymers were tested in both sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) activated slag systems. Specific HPEG-based PCE polymers with higher anionicity, shorter side chain length, and higher Mw were identified which provide outstanding dispersing performance in a NaOH activated slag system while none of polymers were able to increase fluidity in a Na2CO3 activated slag system. The possible reasons for such poor results in a Na2CO3 system are the solubility issue and the almost complete removal of calcium cations from the pore solution stemming from precipitation by the carbonate ions.
Related References:
1. Andrew RM, "Global CO2 emissions from cement production," Earth System Science Data, V. 10, No. 1. 2018, pp. 195.
2. Panesar DK, "Supplementary cementing materials," Developments in the Formulation and Reinforcement of Concrete, Mindess S, ed., Woodhead Publishing, 2019, pp. 55–85.
3. Bernal SA, Provis JL, "Durability of alkali‐activated materials: progress and perspectives," Journal of the American Ceramic Society, V. 97, No. 4. 2014, pp. 997-1008.
4. Bakharev T, Sanjayan JG, Cheng YB, "Resistance of alkali-activated slag concrete to acid attack," Cement and Concrete Research, V. 33, No. 10. 2003, pp. 1607-11.
5. Wang S-D, Scrivener KL, "Hydration products of alkali activated slag cement," V. 25, No. 3. 1995, pp. 561-71.
6. Shi C, Qu B, Provis JL, "Recent progress in low-carbon binders," Cement and Concrete Research, V. 122. 2019, pp. 227-50.
7. Gartner E, Sui T, "Alternative cement clinkers," cement and concrete research, V. 114. 2018, pp. 27-39.
8. Shi C, Jiménez AF, Palomo A, "New cements for the 21st century: The pursuit of an alternative to Portland cement," Cement and concrete research, V. 41, No. 7. 2011, pp. 750-63.
9. Alonso M, Gismera S, Blanco M, Lanzón M, Puertas F, "Alkali-activated mortars: Workability and rheological behaviour," Construction and Building Materials, V. 145. 2017, pp. 576-87.
10. Li N, Shi C, Zhang Z, "Understanding the roles of activators towards setting and hardening control of alkaliactivated slag cement," Composites Part B: Engineering, V. 171. 2019, pp. 34-45.
11. Puertas F, González-Fonteboa B, González-Taboada I, Alonso M, Torres-Carrasco M, Rojo G, et al., "Alkaliactivated slag concrete: Fresh and hardened behaviour," Cement and Concrete Composites, V. 85. 2018, pp. 22-31.
12. Gong C, Yang N, "Effect of phosphate on the hydration of alkali-activated red mud–slag cementitious material," Cement and Concrete Research, V. 30, No. 7. 2000, pp. 1013-6.
13. Collins F, Sanjayan JG, "Effect of pore size distribution on drying shrinking of alkali-activated slag concrete," Cement and Concrete Research, V. 30, No. 9. 2000, pp. 1401-6.
14. Tong S, Yuqi Z, Qiang W, "Recent advances in chemical admixtures for improving the workability of alkaliactivated slag-based material systems," Construction and Building Materials, V. 272. 2021, pp. 121647.
15. Brough A, Holloway M, Sykes J, Atkinson A, "Sodium silicate-based alkali-activated slag mortars: Part II. The retarding effect of additions of sodium chloride or malic acid," Cement and Concrete Research, V. 30, No. 9. 2000, pp. 1375-9.
16. Chang J-J, "A study on the setting characteristics of sodium silicate-activated slag pastes," Cement and Concrete Research, V. 33, No. 7. 2003, pp. 1005-11.
17. Berke N, Dallaire M, Hicks M, Kerkar A, "New Deveopments in Shrinkage-Reducing Admixtures," Special Publication, V. 173. 1997, pp. 973-1000.
18. Palacios M, Puertas F, "Effect of superplasticizer and shrinkage-reducing admixtures on alkali-activated slag pastes and mortars," Cement and concrete research, V. 35, No. 7. 2005, pp. 1358-67.
19. Plank J, Sakai E, Miao C, Yu C, Hong J, "Chemical admixtures—Chemistry, applications and their impact on concrete microstructure and durability," Cement and concrete research, V. 78. 2015, pp. 81-99.
20. Schröfl C, Gruber M, Plank J, "Preferential adsorption of polycarboxylate superplasticizers on cement and silica fume in ultra-high performance concrete (UHPC)," Cement and Concrete Research, V. 42, No. 11. 2012, pp. 1401-8.
21. Palacios M, Houst YF, Bowen P, Puertas F, "Adsorption of superplasticizer admixtures on alkali-activated slag pastes," Cement and Concrete Research, V. 39, No. 8. 2009, pp. 670-7.
22. Luukkonen T, Abdollahnejad Z, Ohenoja K, Kinnunen P, Illikainen M, "Suitability of commercial superplasticizers for one-part alkali-activated blast-furnace slag mortar," Journal of Sustainable Cement-Based Materials, V. 8, No. 4. 2019, pp. 244-57.
23. Conte T, Plank J, "Impact of molecular structure and composition of polycarboxylate comb polymers on the flow properties of alkali-activated slag," Cement and Concrete Research, V. 116. 2019, pp. 95-101.
24. Lei L, Chan H-K, "Investigation into the molecular design and plasticizing effectiveness of HPEG-based polycarboxylate superplasticizers in alkali-activated slag," Cement and Concrete Research, V. 136. 2020, pp. 106150.