Heavy metals in construction

Various heavy metals are used and have been used during the years, in construction for different applications, being the most common ones: lead, cadmium, chrome, copper, zinc, tin, mercury, and arsenic.

Copper, zinc, and tin products are perfectly recyclable and/or reusable materials. So, to achieve the goals of a circular economy in construction, in demolitions, remodel, or any other activities related, in which potential waste of this type appear, they should always be carefully separated and classified to manage them correctly to allow their recycling or reusing.

But this is not the case with chrome, lead, mercury, arsenic, and cadmium. These heavy metals are hazardous substances so to remove them decontamination must be done, and they must be treated and landfilled with special precautions, which will depend on the type of metal to deal with.

In these cases, it is indispensable to identify the materials containing the hazardous heavy metal before the beginning of the works to plan the decontamination in advance.

Otherwise, not only, the health of the workers will be compromised, but all the surrounding materials may be contaminated, making them unable to be reused or recycled, going then against the principles of a circular economy.

Below there is a table that includes some of the key information about these hazardous heavy metals:

SubstanceDefinitionApplications
LEADLead is a heavy metal represented with the symbol Pb.

Its principal characteristics are that it is a soft and malleable material, as well as it has a relatively low melting point.

These properties combined with its relative abundance and low cost have made it a really used material for centuries, for very various applications.

·          Paint

·          Ceramics

·          Pipes and plumbing materials

·          Solders

·          Gasoline

·          Batteries

·          Ammunition

·          Cosmetics

MERCURYMercury is a heavy, silvery d-block element, and it is the only metallic element that is liquid at standard conditions for temperature and pressure.

Mercury exists in various forms: elemental (or metallic) and inorganic (to which people may be exposed through their occupation); and organic (e.g., methylmercury, to which people may be exposed through their diet).

However, it is a substance that occurs naturally in the earth’s crust. It is released into the environment from volcanic activity, weathering of rocks, and because of human activity.

Once in the environment, mercury can be transformed by bacteria into methylmercury, which is a substance that bioaccumulates.

·          Button cells

·          Paint pigments

·          Seed dressers

·          Medical and pharmaceutical equipment,

·          Industrial processes: coal combustion, natural-gas scrubbing, and metallurgy

·          Consumer goods: antiques, appliances, automotive parts, barometers, batteries, dental amalgam, electronics, jewellery, light bulbs, skin cream, sporting equipment, thermometers, thermostats

·          Mining applications

CHROME VIChrome VI, also known as hexavalent chromium, is the second most stable oxidation state of chromium. Rarely occurring naturally, most chrome VI compounds are manufactured by industrial processes.·          Pigment for textile dyes

·          Paints

·          Inks

·          Plastics

·          Corrosion inhibitors

·          Wood preservatives

·          Metal finishing and chrome plating

·          Leather tanning (ammonium dichromate).

·          As an impurity in Portland cement

ARSENICArsenic is a naturally occurring element that is widely distributed in the Earth’s crust.

It is classified as a metalloid and in its elemental form, it is a steel grey solid material.

However, in the environment, arsenic is combined with other elements such as oxygen, chlorine, sulphur, or organic elements, being two general forms of arsenic: organic and inorganic:

·                     Industrial processes: It is used as an alloying agent, and in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives, and ammunition.

·                     Pesticides

·                     Pharmaceutical activities and products

·                     Food

·                     Drinking water

·                     Tobacco

CADMIUMCadmium is a natural element in the earth’s crust. It is usually found as a mineral combined with other elements such as oxygen (cadmium oxide), chlorine (cadmium chloride), or sulphur (cadmium sulphate, cadmium sulphide).

All soils and rocks, including coal and mineral fertilizers, contain some cadmium. It is a metal that does not corrode easily, having many uses for that reason.

·          Industrial paints

·          Pigments

·          Anti-fouling or anti-rust

·          Electroplated onto steel, nuts, bolts, and rivets

·          Batteries

·          Alloys

·          Silver solders

·          Metal coatings

·          Plastics

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