Self-consolidating concrete is an emerging
technology that utilizes flowable concrete
that eliminates the need for consolidation.
Apart from regulation considerations, the growth of the SCC market share
depends to a great extent on the robustness of the mixtures.
Robustness depends on a number of different
attributes including the mix design, shear energy, shear rate, and
application. It implies that a given mixture can be regarded as robust
for a lateral flow application, such as garage floor, but might
segregate once it cast into tall columns. Similarly, because of
thixotropy considerations, a robust mix that is successfully cast into
columns might turn out to be a non-robust mix if it has a different
mixing history.
From all practical considerations (and in
analogy to the flow requirements), it is the opinion of the authors that
robustness should be evaluated according to the application. For
example, for most lateral flow applications, the VSI method mentioned
above is sufficient for rating the robustness of the mix. In more
demanding applications, other quantitative methods listed above should
be used. Robustness issues can be overcome if a greater attention is
paid to the moisture variations in aggregate and carefully metering of
all ingredients, especially chemical admixture and water. Higher
robustness is achieved by increasing the viscosity of the mixture via
materials selection and incorporation of more VMA and/or powder. In
regard to the latter, incorporation of supplementary cementitious
materials of high specific gravity, such as slag, dolomite, or limestone
increases the robustness considerably.