Influence of two polymer-based superplasticizers (poly-naphthalene sulfonate, PNS, and lignosulfonate, LS) on compressive and flexural strength, freeze-thaw, and sulphate attack resistance of lime-metakaolin grouts
Keywords: 
Lime-based grouts
Metakaolin
Polymer-based superplasticizers
Freeze-thaw cycles
Magnesium sulphate attack
Issue Date: 
26-Jul-2018
Publisher: 
MDPI AG
ISSN: 
2073-4360
Editorial note: 
From the January 2016 issue, MDPI journals will use article numbers in place of the traditional method of continuous pagination through the volume. This step helps us to maintain a rapid, efficient production process by being able to define pagination as soon as a paper is accepted. We have recently made a number of improvements to article layout and production procedures, of which article numbers is just one component. You can read more about the changes at http://blog.mdpi.com/2015/12/01/a-new-look-for-mdpi-papers/. For papers that use article numbers the page number will start from 1 and the citation needs only list the article number, e.g., Holmes, L.; LaHurd, A.; Wasson, E.; McClarin, L.; Dabney, K. Racial and Ethnic Heterogeneity in the Association Between Total Cholesterol and Pediatric Obesity. Int. J. Environ. Res. Public Health 2016, 13, 19 (article number: 19. http://www.mdpi.com/1660-4601/13/1/19).
Citation: 
Duran A, Gonzalez-Sanchez JF, Fernández JM, Sirera R, Navarro-Blasco I, Álvarez JI. Influence of Two Polymer-Based Superplasticizers (Poly-naphthalene Sulfonate, PNS, and Lignosulfonate, LS) on Compressive and Flexural Strength, Freeze-Thaw, and Sulphate Attack Resistance of Lime-Metakaolin Grouts. Polymers 2018; 10(8): 824
Abstract
A new range of grouts prepared by air lime and metakaolin (MK) as a pozzolanic admixture has been obtained by using as dispersing agents two polymers, namely poly-naphthalene sulfonate (PNS) and lignosulfonate (LS), with the aim of improving the fluidity of the fresh grouts. Fluidity and setting times of the grouts were assessed. Differences in the molecular architecture and in the anionic charge density explained the different adsorption of the polymers and the different performance. The higher anionic charge of PNS and its linear shape explained its better adsorption and effectiveness. The pozzolanic reaction was favoured in grouts with PNS, achieving the highest values of compressive strength (4.8 MPa after 182 curing days). The addition of PNS on lime grouts slightly decreased the frost resistance of the grouts (from 24 freeze-thaw cycles for the polymer-free samples to 19 or 20 cycles with 0.5 or 1 wt % of PNS). After the magnesium sulphate attack, grouts were altered by decalcification of hydrated phases and by formation of hexahydrite and gypsum. A protective role of portlandite against magnesium sulphate attack was clearly identified. Accordingly, the polymer LS, which preserves a significant amount of Ca(OH)2, could be an alternative for the obtaining of grouts requiring high sulphate attack resistance.

Files in This Item:
Thumbnail
File
polymers-10-00824.pdf
Description
Size
6.66 MB
Format
Adobe PDF


Items in Dadun are protected by copyright, with all rights reserved, unless otherwise indicated.