There have been studies done on the effects of temperature on reaction time and the results are conclusive and unsurprising. Whether it is the human body and mind, a golf ball, or a chemical reaction, when the temperature is cold the reaction times drastically slow down. If you inject polyurethane for a living, you know there are times when the weather is cold but that leak still has to get stopped or that slab has to get lifted. Cold conditions are not that hard to overcome if you plan ahead.
Condition the Materials
Our AP Lift series of slab lifting resins like to be kept above 60° F (16° C) in the drums. Warmer is certainly better. Most slab lifting rigs have insulated walls, etc. And often a heater installed as well. A good slab lifting rig will have a 110 V shore power outlet so you can plug it in and keep the heater running overnight. By keeping the material warm, you will be able to efficiently pump the material from the drums to the proportioner / reactor. If you allow the material in the drums to become cold, the resin side (B side) will not transfer fast enough and you will have pressure imbalance issues. Keep the inside of your rig warm at night and avoid the headaches the next day.
For single component injection it is the same situation. Single component resins are water reactive and in the winter you are most likely going to be fighting cold water. Cold water will slow a reaction down so much that the resin will wash away from the leak before it has a chance to react. This could be in a seawall or in a dam. In fact a lot of polyurethane injection on dams is done in cold weather because the cracks open up and it's easier to inject.
So how do you fight the cold?
- Keep the material warm - we consulted with one of our customers on a job in Canada last year and there was a giant void full of approx 45° F (7° C) water right behind a vault we were injecting. We kept the AP Fill 700 in a hot van and pumped through insulated hoses.
- Adjust the Catalyst - on the above project we used the fastest catalyst we have for our AP Fill 700. With a 10% AP Cat 107 to resin ratio, the material reacted almost immediately and our customer was able to fill the void and push out the water.
- Inject further away from the leak - sometimes in a buried vault or pit, you may have to grout behind the structure to create a curtain wall effect. If a joint, crack, or pipe penetration is leaking, and you have slow-reacting resin pushing through, you need to inject further away from the leaking area to give the material more time to react. These polyurethane foams will find the leak. Move further away and let the material do the work.
- Twin streaming - we have twin streamed polyurethane and warm water in some cold weather applications. This gets the polyurethane reacting as it's being injected, rather than hitting cold water and having a shock to the temperature of the polyurethane. Click here to read an entire blog article on twin streaming.
As always we welcome your questions or feedback. I am from Atlanta so my idea of cold is much different than someone like Bill McGloin (Special Breaks) up in Connecticut. Those contractors have many more tips for working in the cold. Hit up our NE Regional Manager Anthony Sandone as well. He can teach you how to inject in cold weather. All that being said, I think I'll head to Florida.