Drying shrinkage of alkali-activated cements: effect of humidity and curing temperature

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Abstract

Alkali-activated concrete (AAC) is a recycled and low-CO2 alternative to ordinary portland cement (OPC) concrete. One challenge with AACs is their propensity to shrinkage and cracking. In this work, drying shrinkage of four different structural-grade AACs was studied, namely: an activated class F fly ash, an activated slag, and two activated fly ash/slag blends. All four binders and a control OPC binder had the same (liquid/solid)vol and initial porosity. Drying shrinkage and mass loss of paste prisms were monitored as a function of time, relative humidity (RH), and the preceding moist-curing temperature. The results show that all AACs moist cured at 23 °C (73 °F) showed high shrinkage in comparison with the OPC binder and the shrinkage increased with higher proportions of fly ash. Steam curing at 60 °C (140 °F) substantially reduced the shrinkage of fly ash-rich mixtures, but it was less effective for slag-rich mixtures. Slag mixtures showed a significant time dependent response (creep), where the pastes continued to shrink after their mass loss had reached equilibrium.

Original languageEnglish (US)
Article number118
JournalMaterials and Structures/Materiaux et Constructions
Volume52
Issue number6
DOIs
StatePublished - Nov 1 2019

All Science Journal Classification (ASJC) codes

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science(all)
  • Mechanics of Materials

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