Interaction of cement and admixtures and its influence on rheological properties

Dispersing admixtures play an important role in today¿s concrete
technology. Around eight billion cubic metres of concrete are
made each year and most of it contains dispersing admixtures.
These chemical compounds, added at low dosages during concrete
mixing, make fresh concrete more liquid and improve its workability.
A precise way to determine the workability of concrete is to measure
its rheological values yield stress and plastic viscosity. From
ready mixed concrete plants and concrete element plants it is known
that rheological values of mortar and concrete can sometimes vary
when a new cement batch (i.e. a new production date) is used. The
aim of this study is threefold. Firstly, to measure and evaluate the
effect of variations during routine cement production on the rheology
of mortar and concrete. Secondly, to identify the constituents
in cement which lead to fl uctuations in rheology. Thirdly, to quantify
the changes in rheology due to variations in cement properties.
These questions are essential for cement and concrete producers
to guarantee a homogeneous concrete production, but also for the
scientifi c community to reach a deeper understanding of cementadmixture
interactions.