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construction industry

Bad weather proof

A new impermeable material brings together residues of styrene and aluminum scrap

The civil construction industry has gained a new type of impermeable material. The product has been given the name of composite-resin and is formed from two types of industrial waste. The first originates from the production of styrene, a chemical produce used in the plastics industry and already present in resins used in the construction industry. The other is the scrap of aluminum sheets, a material used in the internal walls of telephone cables along with a covering of plastic. The formation of the new product and the tests that approved its impermeable action, were carried out in a project of the Partnership Program for Innovative Technology (PITE, in the Portuguese Acronym) financed by FAPESP. The partnership study was carried out between the School of Engineering of São Carlos (EESC) of the University of São Paulo (USP) and the company Athena Engenharia in the same town.

Coordinated by professor Fazal Hussain Chaudhry, of the Department of Hydraulics of EESC, has reached its end and is waiting for the confirmation of patents carried out in Brazil and the United States through the technical and financial intermediation of the Center of Patents and Licensing of Technology (Nuplitec) of FAPESP.

Too many repairs
The concept of the product was born in the experience of engineer Celso Martinez Junior, the owner of Athena. A graduate in civil engineering from USP in 1980, he concluded his masters in 1986 and went back to work on the applications of new materials in impermeability. He was always worried about the frequent need of repairs on structures. “It always upset me that a great part of the impermeable structures in civil construction suffered from a chronic repair-and -rerepair without ever finding a definite solution.”

With the birth of the Partnership Program for Innovative Technology program, Martinez looked up Chaudhry, his old professor at USP to see if he could turn an idea into a product. “In reality, the idea is old, to discover a way of using industrial leftovers, but I thought of producing a new system for coverings, I wasn’t even thinking about new products.” tells Martinez. Studying processes of impermeability, Martinez knew that the products available in the market needed to be improved. “The results analyzed didn’t correspond to the technical demands and it was necessary to use some other material to make the product more efficient,” recalls the engineer.

One hundred years
Their research produced questions that shaped the project. Putting together the theoretical data on the question, Martinez envisaged bringing together aluminum and the known resins used in impermeability. He looked for a metallic material resistant to corrosion allied to a familiar characteristic for the engineers: viscoplastic adhesion, the capacity for the materials to stay stuck together even in adverse conditions.

The next step was decisive. Martinez spoke with professor José Alexandrino de Sousa, of the area of polymer studies at the Federal University of São Carlos (UFSCar), who indicated the manager of a company that produces aluminum (whose name hasn’t been disclosed). That is how he had access to a special compound, a sheet of aluminium coated with plastic that has durability as its main characteristic. “We are using the scraps of this aluminum as it has a useful life of one hundred years.” he explains.

A coating of resin
The following stage was to test the compound. In a rudimentary form, using a blowtorch, Martinez soldered two halves of a sheet of the compound to mold together an impermeable system plus a coating of styrene resin (available on the market) applied over a small concrete plate. He left this pilot test exposed to bad weather and began to study the results. He verified that, in spite of the rudimentary construction, the piece had its structure preserved. “There was no peeling of the compound and the ultraviolet rays couldn’t ruin the polymer covering on the junction of the two metals, conserving the integrity of the impermeability.”

Exhaustive tests
With the help of professor Chaudhry, a new phase in the work was kicked off. The first major test was the covering of a hall at the Department of Civil Engineering of UFSCar itself. With the resources obtained from FAPESP, Martinez and Chaudhry put into action a thermal blower capable of discharging air at 500o C, sufficient to soften the plastic and to promote the joining of the slices of the compound without damaging the essential, which is the slice of aluminum present in the interior of the sheet.

They also made proof sheets (samples) for testing at the laboratories of Department of Engineering of Materials (DEMa) at UFSCar, under the supervision of professor Elias Hage Junior. In the first tests, simulations were produced for three environmental conditions – light, heat and rain – provided a device equipped with a xenon lamp, to simulate solar radiation, and by water sprinklers. They were able to simulate the aging conditions of a five-year period. Afterwards, Martinez and Chaudhry broke the proof sheets apart and analyzed the changes that had occurred in the material.

“The results were very good. Not one mend, the most critical point in the material, had been broken.” said Martinez. It was still only the beginning. They developed another set of proof sheets, destined for a new series of tests, now to simulate conditions of a day in summer with intense sun followed by rain, which was done with jets of hot air at 75o C for a minute and a half, followed by jets of water at 25o C for six seconds. “We performed tests equivalent to five years of exposure and again, we didn’t find a single problem, all of the previous results were confirmed.”, relates Chaudhry.

To prove the efficiency of the new product in relation to impacts, the proof sheets were submitted, according to conventional standards, to shocks caused by a cylindrical tube of 2.5 kg launched from a height of 1.1 meters. “That’s when we verified that, as well as functioning well in what should be its basic function, sealing out water , the grouping resin-compound proved to be resistant and durable.”, states Martinez.

Success in construction
The new process has already been used on various works in the town of São Carlos. “The results are available. Not one problem occurred in the applications carried out by the technicians of Athena. One of the operations is a roof of 440 m2 that received a covering of expanded clay to provide thermal protection to the setting. “, explained Martinez. For Chaudhry, besides the technical advantages, the new material has the merit of involving environmental control by promoting the recycling of material (scraps of aluminum and the remains of styrene) that normally are burned and end up polluting the air.

While they are waiting for the confirmation of the patents, Martinez and Chaudhry are working to turn the new technology viable. “We are working on two fronts, one commercial, to define strategies for the market, and the other to make the idea operational.” For this, they are going after financing to buy equipment and to build a model factory from where the new impermeable material will come out.

The project
Evaluation of the Recycling of Industrial Derivatives from the Synthesis of  Styrene, from Alumina and of Aluminum Metal with a View to their Application in the Protection of Rooftops In Civil Construction (nº 97/07221-8); Modality Program Partnership for Innovative Technology (PITE); Coordinator Professor Fazal Hussain Chaudhry -Department of Hydraulics of the School of Engineering of São Carlos (EESC) of USP; Investment R$ 16,025.00 and US$ 399.00