Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes.
Influence of Shrinkage-Reducing Admixtures on Early-Age
Properties of Cement Pastes.
Bentz, D. P.
Journal of Advanced Concrete Technology, Vol. 4, No. 3,
423-429, October 2006.
cements; cement pastes; shrinkage; equations;
experiments; motor; admixtures; surface tension; drying
Because most shrinkage-reducing admixtures (SRAs)
significantly reduce the surface tension of a cement
paste pore solution, they will naturally influence all
physical properties and processes that are dependent in
some way on surface tension. Such properties include
internal relative humidity, capillary stresses, and
freezing point depression, all via the Kelvin equation
and its variants (Kelvin-Laplace, Gibbs-Thomson).
Processes that will thus be strongly influenced by the
presence of SRAs include drying, autogenous stress and
strain development, and freezing. In this paper,
experimental measurements of these processes in cement
pastes and mortars with and without SRA additions will
be presented in light of the Kelvin equation. The
experimental measurements that are applied to early-age
specimens include X-ray absorption measurements to
quantify drying profiles, bulk mass loss measurements,
measurements of internal relative humidity, assessments
of autogenous deformation under sealed curing
conditions, and low temperature calorimetry scans to
quantify freezable water content. The results indicate
that SRAs can provide benefits in several new
applications beyond their conventional usage to reduce