Microstructural, Mechanical, and Durability Related Similarities in Concretes Based on OPC and Alkali-Activated Slag Binders

Kirk Vance, Matthew Aguayo, Akash Dakhane, Deepak Ravikumar, Jitendra Jain, Narayanan Neithalath

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Alkali-activated slag concretes are being extensively researched because of its potential sustainability-related benefits. For such concretes to be implemented in large scale concrete applications such as infrastructural and building elements, it is essential to understand its early and long-term performance characteristics vis-à-vis conventional ordinary portland cement (OPC) based concretes. This paper presents a comprehensive study of the property and performance features including early-age isothermal calorimetric response, compressive strength development with time, microstructural features such as the pore volume and representative pore size, and accelerated chloride transport resistance of OPC and alkali-activated binder systems. Slag mixtures activated using sodium silicate solution (SiO2-to-Na2O ratio or Ms of 1-2) to provide a total alkalinity of 0.05 (Na2O-to-binder ratio) are compared with OPC mixtures with and without partial cement replacement with Class F fly ash (20 % by mass) or silica fume (6 % by mass). Major similarities are noted between these binder systems for: (1) calorimetric response with respect to the presence of features even though the locations and peaks vary based on Ms, (2) compressive strength and its development, (3) total porosity and pore size, and (4) rapid chloride permeability and non-steady state migration coefficients. Moreover, electrical impedance based circuit models are used to bring out the microstructural features (resistance of the connected pores, and capacitances of the solid phase and pore-solid interface) that are similar in conventional OPC and alkali-activated slag concretes. This study thus demonstrates that performance-equivalent alkali-activated slag systems that are more sustainable from energy and environmental standpoints can be proportioned.

Original languageEnglish (US)
Pages (from-to)289-299
Number of pages11
JournalInternational Journal of Concrete Structures and Materials
Volume8
Issue number4
DOIs
StatePublished - Dec 2014

Keywords

  • alkali-activated slag
  • chloride transport
  • durability
  • electrical impedance
  • isothermal calorimetry
  • microstructure

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Ocean Engineering

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