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INFORMATION
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What is Ferrocement?
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It is a structured construction material constituted by a thin layer of portland cement mortar
reinforced with steel wire meshes of small diameter, transversally and equally distributed across
its layers.
A cement mortar of 37 pounds/cubic feet (600 Kg/m3) is used in order to obtain better results than reinforced
concrete. From a structural point of view, ferrocement resistance is given by the geometrically
folded shape parts.
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Technical Characteristics
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Ferrocement exceptional resistance is due to its framework. It is made by a stell skeleton
structure and several wire meshes or unfolded metal overlapped and slightly distributed
among the different layers.
The concrete, this material is made of, suffers considerable deformation in the proximity of the
framework surface, without breaking its structure. That is why we can speak of a flexible
concrete.
Ferrocement mechanical perfomance has better results than traditional materials because of
its framework specific surface and its tensile strength that exceeds sensibly the reinforced
concrete strength. Ferrocement also keeps its elastic qualities until it cracks slightly on
the surface.
Te total resistance to compression is given by the concrete compression resistance. This is not
modified by the steel skeleton.
We use steel meshes with a minimun weight of 0.33 pounds/square feet (1.6 Kg/m2) and 2.844 pounds/square inch (200 kg/cm2) of elastic limit.
The adopted steel quantity is 11/15 pounds/cubic feet (180/250 kg/m3). The used concrete has a compression resistance of
about 5.688 pounds/square inch(400 kg/cm2).
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Historical Background
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Although descontinously used on the market, ferrocement is a contemporary material of reinforced
concrete.
According to Shah's published works, the Lambot was the first small boat made of Ferrocement in
1849. Incredibly, this boat was still afloat in 1949, that is to say a hundred years after it
was constructed. Since then, it has been exhibited in te Brignoles museum.
Pier Luigi Nervi, who considered ferrocement as a boatbuilding material, started using it in
Italy during the last century. He also built ships, due to the flexibility and exceptional
resistance of this material. One of these ships called "Irene", had 165 ton of displacement
and her hull had 1.38 inch (35 mm) of thickness. According to Nervi, the ship was 5% lighter and 40% cheaper
than an similar hull made of wood.
Nervi also build a shed with a span of 321.64 feet (98 m) for the Turin Exhibition in 1949. This shed had
1,58 inch (40 mm) thickness ferrocement prefabricated ribbed assembled shells.
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