Zinc works

The present work refers to the technology of application of zinc and copper in the external envelope of buildings. For this purpose, a bibliographical research was carried out based, in its majority, on technical norms and publications edited by producers and applicators of these two materials.
We tried to frame some solutions that are common in other European countries, mainly France and Germany, with the existing practices and legislation in Portugal. The approach begins with a brief historical reference on non-ferrous metals over time, their discovery and evolution to the present day. The indication of its main characteristics, manufacture and transformation, are important data to understand its behavior when applied on site.
The theme of application technology in the external environment of buildings, is associated with roofs and facades. The basic principles for the application of systems in buildings are mentioned, highlighting the slopes, compatibility with other materials, fixing methods, relationship with rainwater flow, thermal insulation, physical and mechanical behavior. The work includes the study of one of the most common cladding systems in Portugal, the stapled joint system, including indications on permissible lengths and widths, dimensioning of fixings, on-site assembly and construction details.
In the final part of the work, the advantages of using these systems in the restoration and rehabilitation of buildings are mentioned, as well as a brief explanation of the costs involved in the use of these materials in the coating of the external envelope of buildings.

About zinc

The first known zinc ornaments date back to 2500 years ago. Their analysis allows us to conclude that they are quite impure, since zinc only accounts for 80 to 90% of their composition. These archaeological finds are considered to be zinc alloys with lead, containing iron and antimony impurities. At that time, zinc was always combined with other elements, forming alloys, with copper for example, thus obtaining brass. These metal alloys have been used for centuries.
There are brass finds dating back to 1000-1400 BC that have been found in Palestine and Transylvania. Due to its low melting point and chemical reactivity, the metal tends to evaporate so that the true nature of zinc is not understood at that time.
The manufacture of brass was dominated by the Romans since 30 BC. This process was described by obtaining aurichalum (brass) by heating a mixture of cadmia (calamine) with copper in a crucible. The material obtained was later cast or forged to manufacture objects.
In 1374 zinc was recognized in India as a new metal – the eighth metal known to man to date. In Zawar, India, zinc, used as a metal, and zinc oxide, used in medicines, were produced between the 12th and 16th centuries. In Europe it was only in the 16th century that zinc was considered a metal [13]. After several centuries of use in the manufacture of bronze, discoveries have been made that make it possible to indicate zinc as an element with characteristics different from other metals.
Giorgios Agrícola, considered the father of geology as a science, observed, in 1546, that a silvery white metal was formed condensed on the walls of kilns in which zinc minerals were fused, pointing out in his studies that a similar metal, called zincum, was produced in Silesia. Paracelsus, a physician dedicated to physics, astrology and alchemy, was the first to suggest that zincum was a new metal and that its properties were different from known metals, without, however, giving any indication of its origin. In documents, treatises and later studies, references to zinc are frequent.
In 1743 was founded in Bristol, Great Britain, the first establishment for metal smelting on an industrial scale. This event gave new impetus to interest in the production of metals in large quantities. Its production was no longer seen as something rudimentary, with basic and low-capacity ovens.
In 1746, chemist Andreas Sigismund Marggraf isolated the element zinc by reducing calamine with charcoal. With regard to the production and transformation of metals in general, but zinc in particular, the evolution of production techniques was slow. Production increases with improvements made to the manufacturing line. Until the 19th century, zinc was widely used in the form of an alloy, combining with copper to form brass, or joining copper with tin to form bronze. Each metal or alloy has its own advantages and applications. Brass, for example, is appreciated for its resistance to oxidation, the ease with which it is worked and its shiny appearance. Bronze and brass metallurgy has developed in the center of Europe, in the area that is now occupied by Belgium, since Celtic times.
The birth of a non-ferrous metals industry in central Europe is linked to the existence of metal deposits (there are important deposits of lead and zinc concentrated 6 in the Vesdre region of Belgium). It is estimated that, in the district of Vesdre alone, approximately 1 100 000 tonnes of zinc metal and 130 000 tonnes of lead have been extracted over the centuries. Other metals are present in neighboring areas. Although numerous, the existing deposits in Europe were, in general, quite limited. But they were valued early on and played an important role in the region’s economic development. In the early 19th century, Jean-Jaques Daniel Dony (Figure 1) [20] developed an industrial procedure for metal extraction, building the first factory on the European continent.

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