At the International Warsaw Invention Show (IWIS 2007), a group of pioneering Cracowresearchers won the gold medal in the environmental protection category for their Aqua Stopper package designed to restrain flood waters, and the silver medal for their domestic rainwater tank. And they even took the bronze for their PTP PK intelligent fertilizers and plant protection chemicals. The Cracow researchers have previously been awarded medals at exhibitions of innovative technology in Brussels, Geneva, Nuremberg and Moscow for their ideas on how to utilize used plastic bottles.

Dr. Jerzy Polaczek from the Department of Chemistry and Technology of Polymers at the Cracow University of Technology receives phone calls from Poland and abroad from people inquiring about slabs better than those made of concrete. Some callers even want to purchase a license. Polaczek is pleased to inform them that the slabs have already been patented. A few of them are leaning against the wall of the university lab. I inspect them carefully and even test them for weight. Neither the gray-green pieces nor the solid panels of indescribable color are particularly heavy. All the rough-surfaced slabs are made of recycled polyethylene terephthalate (PET) bottles, commonly used as containers for mineral water and other drinks.

According to their inventors, the slabs will revolutionize construction and save humankind from the mountains of PET waste piling up at dumping sites.

I can see a light cube made of bottles next to the slabs. Here, however, the bottles have not been squashed but arranged so as to allow water to flow freely into their open necks. "This is a domestic rainwater tank with a capacity of five cubic meters, constructed from some 3,000 PET bottles," explains Polaczek, one of the inventors.

"It can be fitted under a lawn to collect and store rainwater flowing down the gutters of the building. Once a pump is connected to the tank, the collected rainwater can be distributed throughout an orchard or garden."

Engulfing the planet
The slabs produced at the Cracow University of Technology might be lightweight but the problems associated with those plastic materials steadily engulfing the planet are anything but.

More than 5,000 different kinds of plastic materials are currently produced and used, and demand, particularly for polyolefins, is increasing. PET occupies pride of place within this group, having been used to make wrapping foil in the 1950s and '60s, and bottles for non-alcoholic beverages and packaging for cosmetics and dairy products since the mid-1980s.

In Poland, where the plastic bottle market developed from scratch less than 16 years ago, there are more than 150,000 tonnes of PET bottles being produced annually. Moreover, output is increasing by several percent every year and is expected to reach 200,000 tonnes by 2010. This would not be a problem were it not for the fact that some 80-85 percent of these disposable containers end up on dumping sites, disturbing the ecological balance. Polyethylene terephthalate, the material from which these bottles are made, does not degrade naturally.

In Poland, only around 10-15 percent of the annual output of PET bottles is recycled and the method used in this process is quite complex. It differs from the one described in this article in that it requires separating PET from other plastic waste, removing labels and caps, grinding and washing, and then homogenizing and regranulating.

No downside
The recycling method proposed by the researchers of the Cracow University of Technology is both simple and straightforward. This is partly because it does not involve the time-consuming and costly processes of sorting bottles from other plastics, removing their labels and caps, and washing them. "Once the bottles have been ground into small flakes, we can bind them precisely using a special binding agent. The mix obtained is then pressed into steel or wooden molds to produce rectangular slabs. That's a brief description of how the process works," explains Polaczek.

The final product has the properties of B-20 grade concrete and can be used in construction as panels, blocks or confinement materials. It can even substitute for polystyrene foam. The openwork and solid slabs have attractive physical and mechanical properties in that they have higher compressive and bending strength. Another advantage is that they "breathe" well.

Wawel and beyond
At the behest of the Cracow Board for the Restoration of Historical Complexes, porous PET slabs have been used to protect the remains of Queen Bona's Gardens on Wawel Hill. Placed on plastic sheeting and covered with a layer of soil, they constitute a drainage and insulation system.

The slabs, which are sold under the trade name of Izopet-R 350, are used to insulate and drain basement walls, terraces and industrial floors. For more information, go to http://www.izopet.promos.com.pl. Apart from Queen Bona's Garden, they have recently been used in the renovation of Cracow's Old Market Square on account of their high mechanical strength, their resistance to biological corrosion, and their insulation and sound-absorbing properties.

"Our products are also frost-proof and water-permeable, which is highly desirable, particularly for foundations and floors in industrial plants," says Piotr Przybek of the Promos research and development company. Promos works with the inventors and produces the slabs, albeit on a small scale. "The openwork slabs, which resemble those concrete slabs used to build 'green' car parks, can be used to reinforce escarpments along roads or municipal landfills," Przybek adds.

Flood defenses
A team of inventors comprising Prof. Jan Pielichowski, Dr. Jolanta Polaczek, Dr. Jerzy Polaczek and Bogdan Przybek, was recently awarded a gold medal at the IWIS 2007 exhibition for the Aqua Stopper flood package. What did the judges find so special about this invention?

"At the IWIS 2007 exhibition, we unveiled our flood packages-an environment-friendly replacement for sandbags. The packages weigh 0.2 kilograms and contain a special polymer mix," says Prof. Pielichowski. "The packages can absorb 15 liters of water in five minutes, which means they can be used to build walls and reinforce embankments during floods."

Simple and convenient. Not only do they obviate the need to transport sand, which is heavy, but thanks to their innovative polymer mix, they can be dried and reused. Additionally, the contents of the packages can be used in forestry and horticulture as a biodegradable soil enhancer, making the soil hold more water. The material can also be used to increase the water content of treeless strips designed to stop fire spreading in forests.

Aqua Stopper has also received an award from the International Federation of Inventors' Associations.
Teresa Bętkowska