Effects of Bio-Based Plasiciers, Made From Starch, on the Properties of Fresh and Hardened Metakaolin-Geopolymer Mortar: Basic Investigations

  • Conventional superplasticizers based on polycarboxylate ether (PCE) show an intolerance to clay minerals due to intercalation of their polyethylene glycol (PEG) side chains into the interlayers of the clay mineral. An intolerance to very basic media is also known. This makes PCE an unsuitable choice as a superplasticizer for geopolymers. Bio-based superplasticizers derived from starch showedConventional superplasticizers based on polycarboxylate ether (PCE) show an intolerance to clay minerals due to intercalation of their polyethylene glycol (PEG) side chains into the interlayers of the clay mineral. An intolerance to very basic media is also known. This makes PCE an unsuitable choice as a superplasticizer for geopolymers. Bio-based superplasticizers derived from starch showed comparable effects to PCE in a cementitious system. The aim of the present study was to determine if starch superplasticizers (SSPs) could be a suitable additive for geopolymers by carrying out basic investigations with respect to slump, hardening, compressive and flexural strength, shrinkage, and porosity. Four SSPs were synthesized, differing in charge polarity and specific charge density. Two conventional PCE superplasticizers, differing in terms of molecular structure, were also included in this study. The results revealed that SSPs improved the slump of a metakaolin-based geopolymer (MK-geopolymer) mortar while the PCE investigated showed no improvement. The impact of superplasticizers on early hardening (up to 72 h) was negligible. Less linear shrinkage over the course of 56 days was seen for all samples in comparison with the reference. Compressive strengths of SSP specimens tested after 7 and 28 days of curing were comparable to the reference, while PCE led to a decline. The SSPs had a small impact on porosity with a shift to the formation of more gel pores while PCE caused an increase in porosity. Throughout this research, SSPs were identified as promising superplasticizers for MK-geopolymer mortar and concrete.show moreshow less

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Metadaten
Document Type:Article
Author: Adrian TutalORCiD, Stephan PartschefeldGND, Vertr.-Prof. Dr.-Ing. Jens Schneider, Prof. Dr.-Ing. Andrea OsburgORCiDGND
DOI (Cite-Link):https://doi.org/10.1007/s42860-020-00084-8Cite-Link
URN (Cite-Link):https://nbn-resolving.org/urn:nbn:de:gbv:wim2-20210804-44737Cite-Link
URL:https://link.springer.com/article/10.1007%2Fs42860-020-00084-8
Parent Title (English):Clays and Clay Minerals
Publisher:Springer
Place of publication:Heidelberg
Language:English
Date of Publication (online):2021/08/02
Date of first Publication:2020/10/13
Release Date:2021/08/04
Publishing Institution:Bauhaus-Universität Weimar
Institutes and partner institutions:Fakultät Bauingenieurwesen / Professur Bauchemie und Polymere Werkstoffe
Volume:2020
Issue:volume 68, No. 5
Pagenumber:15
First Page:413
Last Page:427
Tag:Metakaolin; Superplasticizer
GND Keyword:Geopolymere
Dewey Decimal Classification:500 Naturwissenschaften und Mathematik / 540 Chemie
BKL-Classification:51 Werkstoffkunde / 51.60 Keramische Werkstoffe, Hartstoffe
Licence (German):License Logo Creative Commons 4.0 - Namensnennung (CC BY 4.0)