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Chemical Industry

Plastic House

Polymers substitute clay bricks and railway sleepers

EDUARDO CESARPolyvinyl chloride, also known as PVC, was discovered in 1872. Industrial production of this compound began in the 1920’s in the United States and in the 1930’s in Europe. Made from salt and oil byproducts, PVC is one of the most widely used plastics in the world. It is used to manufacture pipes, bathroom couplings and floor mats, toys, and pouches for blood and saline solutions, among other products. The civil construction industry has recently started to use this plastic to replace bricks and other materials. This is illustrated by a technology used for the building of houses with PVC walls. The technology was developed as the result of a partnership between Braskem, Dupont, and Global Housing, a Brazilian company based in the State of Santa Catarina.

Referred to as PVC concrete building system, the technology uses fitted PVC profiles or modules filled with concrete. The advantages of this technology lie in the fact that the house is 20% less expensive to build as compared to brick constructions, and quicker – it takes eight days to build a house with this material in comparison to the three months it takes to build a 40 square-meter brick house (m²).

The technology provides 10 kinds of profiles, each with a specific function. The I module is the most widely used one – it is 20 centimeters wide, 8 centimeters thick and the height varies according to the floor to ceiling distance of the house. The multifunctional module measures 8 x 8 centimeters and is used for corners and dividing panels. The finishing profile is the only visible profile after the building is concluded; it covers the other indoor and outdoor profiles and has the same function as that of plaster.

Gilberto Fernandes, the president of Global Housing, says that the idea to develop PVC concrete materialized six years ago, inspired on a similar technology from Canada, where two companies are involved in this line of business. Similar companies exist in Australia, Mexico, and Venezuela. “At first, we developed the technology to then improve it and adapt it to environmental and climate conditions in Brazil”, he explains. “The second step was to create a formula to manufacture the modules”. This is when Braskem and Dupont stepped in. Braskem supplies the PVC resin and Dupont supplies the titanium dioxide, used in the formula that produces the profiles.

According to Marcello Cavalcanti, who is responsible for the development of the PVC business at Braskem, the company supplies the product in powder form. The PVC is then mixed with other components of the formula at Global Housing’s plant. Production output corresponds to approximately 300 tons a month. There is no need for plaster, painting, or covering with this kind of PVC. The white color is provided by the PVC and by the titanium oxide, a substance that acts as a sunblock. The titanium oxide also prevents the formation of tiny cracks and peeling, thus preserving the product’s mechanical performance and increasing its durability. “The owner of the house can paint it another color”, Fernandes says. “In addition, the homeowner can put in floor tiles, wall tiles, or decorative coatings. In fact, he can do everything he would do if he were building a conventional house.”

Other advantages include the fact that PVC is a recyclable polymer. In addition, it is resistant to rain, wind, and salt spray. “This plastic is not affected by fungi, bacteria, insects, rodents, and most chemical reagents”, he adds. It provides excellent thermal, electric and acoustic isolation; it is gas and liquid-proof; it does not spread flames and is totally recyclable. As for the house itself, the president of Global Housing says that the walls are not thick as conventional walls; they measure no more than 8 centimeters, which generates a gain of up to 7% in terms of useful area. In addition, the walls do not crack, swell, become deformed or absorb water.

Finished house at Du Pont, in the city of Barueri (State of São Paulo): demonstration

EDUARDO CESARFinished house at Du Pont, in the city of Barueri (State of São Paulo): demonstrationEDUARDO CESAR

Construction does not require skilled labor – only trained labor. According to Fernandes, this technology is an innovative and quick way of building different kinds of high-quality buildings on an industrial scale. There is not much need for wood or water, and there is hardly any waste in terms of materials. The process to build a house from PVC concrete is similar to the conventional one. The floor can be a concrete sill plate (radier), which supports the PVC walls. The Global Housing company checks the design of the house and provides the assembly kit, which is prepared according to the design, to assemble the house. The profiles, which are in line with the design and the specifications, are assembled at the work site. There are no columns. Each wall contains an iron bar in the corners and in the middle; the iron bar goes all the way up from the floor to the ceiling. In addition, small iron bars, each one 60 centimeters high, are placed along the walls at every 80 centimeters. All of the iron bars are placed inside the walls built in modules, which are later filled with concrete. After drying for 24 hours, the house is ready to get doors, windows and the roof. This technology can be used to build houses with up to two stories – the ground floor plus the top floor – such as single-family, detached houses, for example.

In terms of costs, the price per square meter of a building built from PVC concrete is equivalent to that of a traditional brick building – it ranges from approximately from R$ 800,00 to R$ 850,00, depending on what part of the country the house is being built in. “But in the long run, you can save approximately 20%, especially because fewer construction workers are needed”, says Fernandes. Another cost saver is the fact that the construction process is easy to manage and supervise.

After having developed the technology, the company from the State of Santa Catarina began the process to obtain certification for its construction system from government entities. To this end, it relied on the help of Braskem. “We helped Global Housing get all the technical certifications for PVC concrete”, says Cavalcanti. He explains that civil construction laws in Brazil only qualify new building modalities and technologies to obtain funding from the Caixa Econômica Federal (the Federal Government’s Savings Bank) if they are accredited by the National Technical Evaluation System (Sinat), also referred to as the Sinat guideline. This is an initiative of the national civil construction technical community that counsels and evaluates all such products. Sinat answers to the Ministry of Cities. The objective of the guideline is to standardize and evaluate new products and construction systems that are introduced into the market and provide them with the Technical Evaluation Document (DATec), a certificate that ratifies and attests to the quality of the given material or system. The certificate qualifies construction companies to build housing programs funded by the government, such as the Minha Casa Minha Vida lower-income housing project.

Global Housing’s PVC concrete building system has already been qualified under Sinat. It was analyzed by the Technical Building Environment Center (Cetac) of the Institute of Technological Research of São Paulo (IPT), where the assembly system was overseen and accelerated aging tests on the panels were conducted. In addition, resistance to impacts, fire, and acoustic isolation were also tested at the Cetac. “During this phase, our product was considered appropriate for the building of one and two-story detached or semi-detached houses”, said researcher Luciana Oliveira, who is the head of Cetac’s Laboratory of Components and Construction Systems. “This means that the company can request funding from the Caixa Econômica Federal”, explains Braskem’s Cavalcanti. Prior to qualifying under the Sinat guideline, the company had already attracted a piece of the real estate market. Sales of the PVC concrete houses started one year ago; so far, 20 thousand square meters of these houses have already been built in Brazil. “The houses come in different sizes. Besides homes, we have also built day-care centers, schools, detached houses and even beach kiosks”, says Fernandes. “Nowadays we produce approximately 400 houses a month. We plan to increase this number to one thousand”. Global Housing plans to build new plants in 2012 in the states of Rio de Janeiro, Alagoas and Piauí.

078_plasticos_190Wisewood is a company whose main line of business is also plastics, although it is in another market sector. The company was established in 2007, in the city of Itatiba, in the State of São Paulo. Wisewood manufactures wood-plastic composite, used for railroad sleepers, decks, coatings, pallets, modules, benches, trash cans and baseboards. The product’s technical name is wood plastic composition (WPC); it is produced from plastic products collected in trash cans, such as disposable diaper cuttings, fuel oil and dishwater detergent containers, and packaging bags.

Wisewood’s first line of business was the production of polymer sleepers for MRS Logística, a logistics company that had to substitute wood sleepers. “We developed a high-tech engineering product to meet all the specifications and to deal with the enormous mechanical resistance that this market requires”, says Diego Gevaerd, the company’s commercial director. “It was a huge success and nowadays our WPC-based sleepers are being tested by Vale and by All, two huge companies in the railway business.”

Over time, the sleepers led to new technologies and products, such as planks and fence posts. According to Gevaerd, the company currently collects approximately 1,800 tons of plastic – basically polypropylene and polyethylene – every month from landfills and garbage dumps. The company resorts to cooperatives of garbage and scrap pickers and to the plastics manufacturers. Polypropylene and polyethylene are the so-called hard plastics, which, when added to natural fibers, go through an industrial process that, turns them into a material identical to wood. “We transform ‘garbage’ into finished products with industrial applications”, says Gevaerd proudly. “We are currently working in the Brazilian market, but we plan to start looking for new markets abroad.”

He guarantees that the WPC can be handled just like wood. Using the same tools, the material can be cut, glued, drilled, screwed, nailed and machined. It has countless other advantages. “This material is inert, waterproof, and fungi- and termite-proof. It can be washed and does not need fumigation certification”, says Gevaerd. “In addition, it does not need to be treated (which means that maintenance costs are virtually non-existent) and does not produce splinters. Furthermore, it avoids the deforesting of our forests and the use of reforested wood. It is a sustainable solution because it is 100% recycled and recyclable.”