MUD AS A MORTAR
Introduction
Clay is the inherent
binder of soils which
are used in building,
including for soil-
based mortars. Such
mortars are generally
used with adobe and
compressed soil block
or, sometimes, fired
clay brick and soft
stone construction.
A mud mortar is
prepared by simply
mixing soil with water
until it is in a plastic
(workable) state. Once
applied, a mud mortar
sets quite rapidly on
drying without the
need for elaborate
curing procedures.
Figure 1: House, Built of stone laid in mud mortar with paving stone
yard of stones in mud mortar. Photo: CRATerre/EAG.
Mud mortars are still
widely used in many
parts of the world and many different types of soil can be used in mortar preparation. Each
type of soil has different characteristics which make it suitable to a greater or lesser extent in
particular applications. However, optimum use can be made of most soils by choosing
particular preparation techniques and construction practices including, sometimes, the
addition of stabilizers or other additives. Recent advances in soil construction practice have
enabled soil-based mortars to be used reliably in a wide variety of construction applications.
Mud mortar applications
The beneficial characteristics of mud mortars including good bond to compatible surfaces,
relatively high compressive strength and ease of preparation allow them to be used in a range
of applications of which the following are common:
Cob walls
Cob walls are built of mortared mud balls in courses 40 to 80 cm high, with a drying period
of several days in-between the courses. Additional soil blocks or stones are often
incorporated.
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