Presentation by Dr. Marcus Leberfinger - Polyurethan Elastomeres, BASF Polyurethanes GmbH, Lemförde
The main function of a roof is to keep out the wet. All the same, leaks and penetrating moisture are by no means uncommon especially on flat roofs. The plastic- and bitumen-based membranes conventionally used are susceptible at the joints, particularly where complicated roof geometries are involved. Such membranes can additionally become brittle at low temperatures and no longer bridge concrete cracks sufficiently. For such applications BASF has its Elastocoat® coating system that gives roofs jointless waterproofing and has been attracting increasing interest. The polyurea-based protective coating is sprayed on and reacts to form a continuous membrane devoid of seams and joints.
Sticks to almost any substrate and is easy to process
Elastocoat from BASF has been on the market for several years. Its first classic application was for the sealing of the cargo beds of pick-up trucks in the USA. The surfaces were sprayed with the plastic and were then watertight and dirt-repellent. All the same, Elastocoat has a good deal more to offer and is therefore constantly conquering new fields of application. It can be used on different substrate materials such as concrete, metal, wood and plastic. With spray application, its processing could not be more straightforward. The 1 to 1 mixing ratio of the two reactive components is simple and ideal for construction site conditions.
Furthermore, the material has a variety of properties. It features high processing tolerance at low outdoor temperatures and high humidity and the ability to bridge concrete cracks up to ten millimeters across. On top of this, it shows exceptional mechanical strength, chemical resistance, ageing resistance and high adhesion.
For industrial surfaces and imposing structures
In the meantime, the coating system has found a whole series of new applications. In the construction sector, the BASF material is used for coating concrete surfaces. Damaged seals allow moisture to penetrate into the roof, which can have disastrous consequences. These can include concrete degradation, long-term weakening of the building’s structural strength and downstream damage in interiors through to the proliferation of mold. Elastocoat is the reliable antidote to such scenarios. As a liquid film, the coating system wraps itself around even the most complex geometries such as roof edges, skylights and air conditioning shafts and also seals vertical surfaces without seams or joints. Thanks to its rapid hardening, even at temperatures close to zero, sealed surfaces are load-bearing after only an hour. Large industrial surfaces of new or modernized buildings can be quickly, efficiently and lastingly waterproofed by spraying.
Two imposing examples of applications can be found in Astana, the newly built capital of the Republic of Kazakhstan. This is where the biggest mosque in Central Asia has been built. The prestigious building, whose main hall alone can accommodate 5,000 people, has a central dome 40 meters high and four minarets. The domes and roofs have been given an Elastocoat coating that will withstand extreme temperatures of as low as minus 50 °C. A very similar solution has been chosen for the openable roof of the stadium in Astana. The new arena with a ground area of 10,000 square meters provides space for 30,000 spectators. These two unusual construction projects demonstrate that Elastocoat coatings remain stable even in extreme weather conditions and are therefore constantly opening up new applications.
Protection for car park floors and secondary containments
This applies particularly to multi-storey car parks, which are usually concrete and steel structures. It is important that the uppermost, usually uncovered floor is given protection from penetrating moisture so that it remains serviceable for decades. Otherwise, concrete degradation could dangerously weaken the building and shorten its service life. This is where Elastocoat provides a long-term remedy, as the coat also effortlessly withstands the high stressing from car traffic. BASF itself as one of the biggest fabricators of chemical plants is the beneficiary of another application. Tanks for a variety of liquid products are themselves placed in storage basins known as secondary containments. Usually made of concrete, their purpose is to prevent leaking liquid from contaminating the soil and groundwater. Since these surfaces are themselves at risk from escaping chemicals, they have to be rendered impervious. This is where the BASF system provides an effective solution.
At petrol stations, full-scale protection of the environment also calls for special measures. It is very important here that fuels and lubricants do not seep into the ground. Experience has shown that the main causes of contaminants penetrating into the soil are damage to the elastic joint sealant and cracks in the concrete slabs. For such cases, BASF has developed a multi-layer system. On the carefully prepared ground, a two-millimeter thick film of Elastocoat is sprayed. This is in turn sealed by an aliphatic Elastocoat top coat that is highly resistant to fuels.
Secures loads and stops concrete degradation
Elastocoat has yet another positive feature, in that it displays anti-slip properties on the load beds of trucks. Additional transport securing, which would otherwise be necessary by law, is therefore unnecessary. The reason for this is Elastocoat’s high static friction that prevents piece goods from slipping during transport. The higher this static friction, the less necessary it is to secure pallets or drums to prevent them from slipping. This saves time and money. Truck and semitrailer manufacturers are already successfully using this system. Bio gas installations and waste water shafts pose special difficulties. This is where biogenic sulfuric acid formed by special bacteria (thiobacillus) can very quickly cause considerable concrete degradation. The surface develops cracks and becomes permeable. Elastocoat puts an end to acid aggression with a seamlessly sprayed barrier layer.
Stronger than steel
In ore, gold and diamond mines and in quarries, steel surfaces are exposed to impacts and abrasion from bulk materials. Elastocoat coatings cushion the impact of the materials on the surface and protect it from destruction thanks also to its high resistance to tear propagation and good abrasion values. In this way, a plastic coating is capable of even protecting steel, prolonging its useful life, boosting productivity and reducing maintenance costs. The BASF system is already used in mines in South Africa.
The polyurea system (polyurethanes.basf.de) has been awarded important approvals and certifications, and more are on the way. BASF (basf.com) offers its customers comprehensive advice on correct processing so that the wide range of customer sectors can readily exploit the advantages of this versatile material for sealing joints and cracks.
Contact: Dr. Marcus Leberfinger
P: +49 5443 12-4210 - E: marcus.leberfinger[.]basf.com.