Building Materials, Third Edition

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Ferrocement is used in thin-walled structures where strength and rigidity are developed
through form or shape. It has the distinct advantage of being moldable and of one piece
construction. Other major advantages are its low cost and its non-flamability and high corrosion
resistance characteristics. The advantages of ferrocement are:

1. Easy availability of raw materials.


2. Reduction in weight consequent of thin section.


3. Moulding can be done without any formwork.


4. No machinery or sophistication is required in construction.

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Ferrocement, a homogeneous composite material, contains a high percentage of ductile steel
wire mesh with a high surface area to volume ratio in a brittle cement-mortar matrix, enables
the matrix to assume the ductile characteristics of the reinforcement. The strength of ferrocement,
as in ordinary concrete, is commonly considered as the most valuable property, although in
many practical cases other characteristics, such as durability and permeability may in fact be
more important. Nevertheless, strength always gives an overall picture of the quality of
ferrocement, as strength is directly related with the properties of its hardened cement paste and
reinforcement. Some of the properties of steel were meshes and rainforcement are given in
Table 20.4.

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Ideally, ferrocement acts as a homogeneous material in the elastic range and the stress of the
composite is obtained from the laws of mixture. When a ferrocement specimen is subjected to
increasing tensile load, three stages of behavior are observed. These stages are classified
according to the width of cracks. Experimental studies on the behavior of ferrocement specimens
in tension show a typical stress strain curve as shown in Fig.20.4. An idealized curve of a
ferrocement section in tension is also shown in Fig. 20.4. A brief description of the stress-strain
curve of ferrocement at different stress levels are described as follows:

i— ™2‚— The stress-strain curve is essentially linear in this stage. Elastic deformations
occur at this stage in both metal and crystalline grids as well as in colloids. There is no evidence
of crack formation even when observed with magnification. The limit of elasticity of ferrocement
is also higher than that of unreinforced concrete.
With a further increase of stress, ferrocement become quasi-elastic. The relatively small
plastic strains of the colloids are restrained by the elastic deformation of metal wires. The micro
cracks are invisible to the naked eye and are difficult to observe even when optical instruments