Advanced Concrete Technology Properties

Advanced Concrete Technology Properties

Fresh concrete is a transient material with continuously changing properties. It is, however,
essential that these are such that the concrete can be handled, transported, placed, compacted

and finished to form a homogenous, usually void-free, solid mass that realizes the full-
potential hardened properties. A wide range of techniques and systems are available for

these processes, and the concrete technologist, producer and user must ensure that the
concrete is suitable for those proposed or favoured.
Fresh concrete technology has advanced at a pace similar to many other aspects of
concrete technology over the past three decades, and indeed many of these advances have
been inter-dependent. For example, the availability of superplasticizers has enabled workable
concrete to be produced at lower water/binder ratios thus increasing the in-situ strength.

In this chapter, we will start by considering the property known as workability*,
including its definition and common methods of measurement. We will point out the
limitations of these, and show how this leads to the need for a more fundamental scientific
description of the behaviour of fresh cement pastes and concrete. We will then describe
how this has been achieved by applying the principles of rheology, and explain the
development and use of test methods which give a more complete understanding of the
behaviour. We will then discuss the effect on the rheological properties of a range of
constituent materials, including admixtures and cement replacement materials, and how
a knowledge of these properties can be used to advantage. The factors that influence the
loss of workability before setting are then briefly considered.


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