Cement, or some form of cementing
material is an essential ingredient in
most forms of building construction.
Cement is the vital binding agent in
concretes, mortars and renders, and is
used for the production of walling
blocks and roofing tiles.
Since its invention in the first half of
the 19th century, Portland cement has
become the most widely available
cementitious material. Its dominance
over alternative cements has been in
part, due to successful, aggressive
marketing. This is despite its clear
technical disadvantages for certain
Figure 1: Participants at a workshop in Uganda
visiting a very small traditional lime plant photo:
Practical Action/Simon L'epine Ekless..
applications. In addition Portland cement is relatively expensive to produce and is often in
short supply in many developing countries. Typically, a rural African labourer may need to
work for up to two weeks to earn enough money to buy one bag of cement. In comparison
alternative cements can be produced locally, on a small scale and at much lower cost.
Alternative cements are not capable of replacing Portland cement totally, but they can be
used in the many construction applications where they have advantages. These are as
mortars, renders and non-structural concretes. Alternative cements are not normally
considered suitable for structural applications such as reinforced concrete beams and
The most common of these so-called ‘alternative’ binders is lime, to which other materials,
known as pozzolanas, can be added to enhance strength and water resistance. Other binders
such as gypsum, sulphur, bitumen, mud and animal dung have also been used.
Binding systems from history
The simplest, and possibly the earliest, binding material used was wet mud, and there are
records of its use in ancient Egypt. Another example of a binder from the distant past is the
use of naturally occurring bitumen by the Babylonians and Assyrians in their brick and
alabaster (gypsum plaster) constructions.
Lime was known to the Greeks and was widely used by the Romans. The Roman architect and
engineer Vitruvius published the first specification for the use of lime in building in his
celebrated work De Architectura. The Romans also knew how to make a lime-pozzolana
cement by adding materials such as volcanic ash or powdered bricks, tiles and pottery to
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