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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


Appears on pages(s): 297-308

Keywords: alkali-activated slag, polycarboxylate, dispersion, solubility

DOI: 10.14359/51736083

Date: 7/1/2022

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.