
The bane of slab lifting equipment is the iso. It turns your hands black if you get it on them and it is the main culprit that causes pressure imbalances. For some reason, in the past few years the problem has gotten worse. I suspect is has something to do with changes in the chemistry of the raw materials.
Contractors who use their rig on a daily basis have less of a problem. If your rig sits for any length of time, the iso (A side material) can start to setup in the hose. We see this most often at the end of the whip hose right next to the gun. The solution is simple, but you have to be vigilant. Make sure you have greased up the threads on the A side drum, change your desiccant drum cartridge when the desiccant changes color, and follow the instructions below to recirculate the A side material every 10 days that your rig sits unused.
Step 1:
Use the drum pump to shoot some A-side material into a waste bucket. When the material coming out of the hose looks clean, move on to step 2. It shouldn’t take long.
Step 2:
Re-circulate the material through the hose back into the A-side drum. Use a paint filter bag or panty hose to strain the material. This will prevent any cured iso that has formed in the hose from getting back into the drum. Do this step for 5 to 10 minutes (more if you have a lot of hose and less if you only have one or two sections).
Step 3:
Make sure your drum is closed up tight with white lithium grease on the threads. Same with the plug on the end of the hose.
NOTE:
You can pump the A side material using only the drum pump. However, if the pump sits for more than a couple of weeks you will want to also fire up your proportioner for a couple of minutes at low pressure to make sure you have fresh iso in the pump cylinder as well. To do this you will need to recirculate the B material at the same time.








But first you’ve got to understand one thing; you can’t bring a knife to a gunfight. Expert contractors have to know what is going on at all times. In the picture at the top of this post, you can see a slab that I probably would have not attempted to repair. However, with several tools to help monitor the different pieces of this puzzle, this contractor was able to put it back together again. They say information is power and I am a firm believer in that, especially when it comes to taming jacked up concrete slabs. In the picture you can see three different slabs. Our customer Morgan Helms of Helms Polyfoam (Jackson, MS) is using a ZipLevel, a machinist’s dial indicator, and a putty knife to monitor what each of the slabs is doing.
The dial indicator tells him which slab is moving. In the picture, the base of the dial indicator is on the slab that Morgan is injecting under while the dial point is on the slab he doesn’t want to move. It doesn’t really matter how you configure it as long as you understand what the needle movement means. A needle on a machinist dial indicator moves in .001” increments. If the needle on this dial indicator is rising, that would mean the wrong slab is lifting and he knows to stop. If the needle is falling then the slab he is injecting under is lifting, and that’s what he wants.
So what if both slabs are moving equally? In that case the dial indicator would remain stable or fluctuate slightly in both directions. This is where a ZipLevel or a laser transit would come in handy. Morgan has his ZipLevel indicator box (in yellow) on the slab he doesn’t want to move. It will let him know if the slab he doesn’t want to move is lifting so he can stop and re-evaluate what to do next.
One of my favorite tools is the metal putty knife. Slabs often move in increments so small that you can’t detect them visually. If you wedge a putty knife into a crack between two slabs, you will see it wiggle when there’s slight movement. So the putty knife in the picture is on the third section of slab and letting Morgan Helms know what is going on with that piece.


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Hydrophobic polyurethanes naturally repel water (similar to the way oil would repel water and stay separate if you were trying to mix them in a glass). These products push water out of the area in question as they expand. Hydrophobics are used with catalysts which allow you to adjust the set time. They also have zero shrinkage after curing.



Structural Polyurethane Foams For Hurricane Season
A few weeks ago, the start of "hurricane season" was officially recognized. Per usual, meteorologists predicted a higher than average degree of activity for this year. It’s easy to pile on the pressure for accuracy from the weather people, but last year they accurately predicted and tracked two storms that affected our coasts.