Autogenous Shrinkage Mitigation in HVFA Mixtures with Internal Curing

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Title: Autogenous Shrinkage Mitigation in HVFA Mixtures with Internal Curing

Author(s): I. De la Varga, J. Castro, and J. Weiss

Publication: Special Publication

Volume: 290

Issue:

Appears on pages(s): 1-12

Keywords: Chemical shrinkage, cracking, early age shrinkage, fly ash, high volume fly ash, internal curing,

Date: 9/14/2012

Abstract:
This paper reports results from a series of experiments performed in an ongoing FHWA research program that is investigating the potential for using more fly ash in transportation structures. The paper focuses on test results from five mortar mixtures: a water-to-cement ratio (w/c) of 0.30 and water-to-cementitious materials ratio (w/cm) of 0.30 with 40% and 60% fly ash by volume with and without internal curing. A reduction in early age autogenous shrinkage is observed for HVFA mixtures. While initial autogenous shrinkage is reduced in HVFA mixtures, they are more prone to higher rates of shrinkage and cracking at later ages (after seven days). This can be related to pore size distribution as well as continued effects of hydration and the pozzolanic reaction. Chemical shrinkage and isothermal calorimeter results are shown to describe the rate of fly ash reaction at early ages. Internal curing can reduce the propensity for cracking.