Effect of admixture on the pore structure refinement and enhanced performance of alkali-activated fly ash-slag concrete

Journal Article (2018)
Author(s)

A. Keulen (Van Gansewinkel Minerals, Eindhoven University of Technology)

Q. L. Yu (Eindhoven University of Technology)

S. Zhang (TU Delft - Materials and Environment)

S. Grunewald (TU Delft - Concrete Structures, CRH Sustainable Concrete Centre)

Research Group
Materials and Environment
Copyright
© 2018 A. Keulen, Q. L. Yu, Shizhe Zhang, S. Grunewald
DOI related publication
https://doi.org/10.1016/j.conbuildmat.2017.11.136
More Info
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Publication Year
2018
Language
English
Copyright
© 2018 A. Keulen, Q. L. Yu, Shizhe Zhang, S. Grunewald
Research Group
Materials and Environment
Volume number
162
Pages (from-to)
27-36
Reuse Rights

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Abstract

This paper investigates the influence of a plasticizing admixture on the pore structure refinement of alkali-activated concrete and paste mixtures and the consequently enhanced performance. Alkali-activated fly ash-slag concrete and paste are designed using a polycarboxylate-based admixture with different dosages. The pore structure and porosity are analyzed using mercury intrusion porosimetry (MIP). The workability, compressive strength, chloride migration resistance and electrical resistivity of alkali-activated fly ash-slag concrete and paste are determined. The results show that significantly improved workability and strength development are obtained at an increased admixture content. The admixture improves the gel polymerization product layer most likely around the GGBS particles, densifying the matrix. The 28-day Cl-migration coefficient of admixture (1–2 kg/m3) modified concrete is equal to the reference mixture, while at the highest admixture content the Cl-ingress is increased. At the later ages (91-days), the Cl-migration coefficients of all concretes, non- and admixture-containing samples, are comparable and low (about 2.6 × 10−12 m2/s). The MIP analyses show a significant decrease of the total and effective capillary porosity over time at an increased admixture content. The relationships between the porosity and other properties are discussed, at varying admixture contents.

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