Well foam was developed to allow waterproof adhesion of concrete rings and well shafts. It can also be used when setting shaft rings, drain shafts and domestic sewage plants. This special construction foam is resistant to thinned chemicals and is also resistant to rotting (resistant to bacteria in the earth).
Sealing wells and cisterns with well foam
Wells, cisterns, water pipes, waste water pipes. Well foam was developed to facilitate waterproof adhesion of concrete rings and well shafts. It can also be used when setting shaft rings, drain shafts and domestic sewage plants. But how should it be used properly?
This special polyurethane-based foam meets the usual civil engineering requirements and is watertight. Thanks to its special formula, it is resistant to thinned alkalis and acids. It is even resistant to bacteria and faeces. This either protects the fresh water against contamination or keeps the waste water and its constituents there where they belongs in the waste water pipe.
Preferably under pressure
Well foam adheres to almost all surfaces and is therefore universal. Exceptions are smooth materials like PE or PP where it cannot be used. Modern polyurethane-based well foams often only develop their highest resistance if they are constantly flooded. They are usually watertight up to a water pressure of 0.5 bar.
Protect against light
Also, PU foam is decay and rot-proof. However, like all other PU foams, well foam is not light fast. This means that if it is used above ground, the well foam should be protected against UV light by an extra coating or sealing material. For instance, silicone, polyurethane, acrylic or MS polymer.
The well foam is as easy to use as other PU foams. The same processing steps are required. After screwing on the PU foam gun or the adapter tube, shake the can thoroughly before use (approx. 30 times) with the valve facing downwards, so that the content of the can is well mixed and the quality of the foam is optimised. Then press the trigger to apply the foam as evenly as possible into the joint that needs to be sealed or onto the shaft ring.
After applying the foam, the well foam will continue to swell slightly. This fills out all hollow spaces and leaks. The next shaft ring should be positioned within a few minutes. The product data sheet states the exact time intervals. The general rule here is: the fresher the PU foam, the better!
Ensure a sufficient level of moisture
Depending on the product used, the well foam needs to harden for a period of 6 to 20 hours until it is completely watertight and fully durable. It continues to expand during this time. After this, it retains its form and does not change in volume. To optimise the hardening process, some manufacturers recommend spraying the joint with water before apply the foam because the foam needs moisture to harden. Once the foam has hardened, larger pieces of excess PU foam can be cut off with a sharp knife. If necessary, these cut areas can be coated with silicone again.
Observe processing temperatures
The temperature is important when working with PU foam. To ensure the foam works to the optimum, the temperature of the adhesive surface should be between 5 and 35 °C. The PU foam can itself may have a temperature of between 5 and 25 °C. If the can becomes to warm or too cold, it can be brought to the optimum operating temperature of approx. 15 °C gradually by placing it into cold or warm water.