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PRESERVATION
15 BRIEFS
Preservation of Historic Concrete
Paul Gaudette and Deborah Slaton
National Park Service
U.S. Department of the Interior
Introduction to Historic Concrete mixed with water, was placed between wooden forms,
tamped, and allowed to dry in successive layers. Tabby
Concrete is an extraordinarily versatile building material was later used by the English settlers in the coastal
used for utilitarian, ornamental, and monumental southeastern United States.
structures since ancient times. Composed of a mixture
The early history of concrete was fragmented,
of sand, gravel, crushed stone, or other coarse material,
with developments in materials and construction
bound together with lime or cement, concrete undergoes
techniques occurring on different continents and in
a chemical reaction and hardens when water is added.
various countries. In the United States, concrete was
Inserting reinforcement adds tensile strength to
slow in achieving widespread acceptance in building
structural concrete elements. The use of reinforcement
construction and did not begin to gain popularity until
contributes significantly to the range and size of
the late nineteenth century. It was more readily accepted
building and structure types that can be constructed
for use in transportation and infrastructure systems.
with concrete.
The Erie Canal in New York is an example of the
While early twentieth century proponents of modern
early use of concrete in transportation in the United
concrete often considered it to be permanent, it is,
States. The natural hydraulic cement used in the canal
like all materials, subject to deterioration. This Brief
construction was processed from a deposit of limestone
provides an overview of the history of concrete and
its popularization in the United States, surveys the found in 1818 near Chittenango, southeast of Syracuse.
The use of concrete in residential construction was
principal causes and modes of concrete deterioration,
and outlines approaches to repair and protection that
are appropriate to historic concrete. In the context of this
Brief, historic concrete is considered to be concrete used
in construction of structures of historical, architectural,
or engineering interest, whether those structures are old
or relatively new.
Brief History of Use and Manufacture
The ancient Romans found that a mixture of lime putty
and pozzolana, a fine volcanic ash, would harden
under water. The resulting hydraulic cement became
a major feature of Roman building practice, and was
used in many buildings and engineering projects
such as bridges and aqueducts. Concrete technology
Figure 1. The Sebastopol House in Seguin, Texas, is an 1856 Greek
was kept alive during the Middle Ages in Spain and
Revival-style house constructed of lime concrete. Lime concrete
Africa. The Spanish introduced a form of concrete to or "limecrete" was a popular construction material, as it could be
the New World in the first decades of the sixteenth made inexpensively from local materials. By 1900, the town had
century, referred to as "tapia" or "tabby." This material, approximately ninety limecrete structures, twenty of which remain.
a mixture of lime, sand, and shell or stone aggregate Photo: Texas Parks and Wildlife Department.
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