By Scott Kelly, Technical Consultant
Recently one of our field representatives sent me a document in which the writer, who happens to be one of our competitors, attempted to discredit several of our products. For the sake of anonymity, we’ll just call him “One Trick Pony”. In an effort to further the education of our customers and our misinformed competition, I felt obliged to present portions of that document here and set the record straight:
(One Trick Pony)
Yes we know about (Prime Resins), they have been around for a little while and have a line of grouts. I went back to research and found they have four products:
(Answer)
Not quite accurate, One Trick Pony. Prime Resins has been formulating and manufacturing chemical grouts and epoxy products for use in all types of concrete structures since 1982. I guess 30 years qualifies as “a little while.” Prime Resins manufactures and catalogs 38 different products, 12 of which are polyurethanes for leak repair, void fill and soil stabilization. I wonder how long ago you did that so-called research.
(One Trick Pony)
Prime Flex 900 XLV - This is a single component like (competitor’s product), the important difference is that the 900XLV is hydrophilic which means it incorporates water into the reaction and the foam it produces. Hydrophilic grouts will shrink when the water source goes away. Hydrophobic grouts expel water as they react therefore it does not shrink no matter what the water availability is.
(Answer)
You’re right on a couple of things, One Trick Pony. Prime Flex 900 XLV is hydrophilic. It does scavenge water as it reacts. That’s precisely why it has better bonding characteristics to wet surfaces than hydrophobic grouts. Hydrophilic grouts chase water into the pores of the concrete. The result is a tenacious bond. So when the structure goes through thermal cycles or any kind of movement, the seal remains intact. Right again O.T.P.! Hydrophobic grouts do expel or repel water during expansion so water trapped in the pores of the concrete actually becomes a bond inhibitor. As far as shrinkage goes, all but 5 % of water absorbed during the reaction phase of 900 XLV is used up during the curing phase. After cure, the resulting high density flexible closed-cell foam is impervious to water and not subject to shrinkage at all.
(One Trick Pony)
Prime Flex - This is a single component hydrophobic like (competitor’s product). However, the Prime Flex requires an expensive (like $30 per pint) catalyst that must be premixed into the grout prior to use. It is extremely difficult to get even dispersion of catalyst through the grout, especially under field conditions. What can happen is you get cold spots, where there is not enough catalyst, where the grout gels and never sets up, or you can get hot spots, where too much catalyst is present, there you end up with open cell foam instead of closed cell foam.
(Answer)
Even though One Trick Pony doesn’t actually identify a specific product in this paragraph of nonsense, I’m going to assume they are talking about Prime Flex 910 or Prime Flex 920 since both are single component hydrophobic grouts that require a catalyst. First, the catalyst is sold in quarts and doesn’t come close to the cost mentioned above. Secondly, one quart of catalyst treats 5 gallons of resin. I dare you to compare cost per gallon against your product, One Trick Pony. Mixing the catalyst in the resin is as simple as mixing a batch of Kool-Aid, something most 6 year olds can handle, but to each his own. I guess stirring can be complicated for some. Actually we suggest you use a paint style jiffy mixer and drill to expedite the mixing process, still not difficult by any means. You see, One Trick, the catalyst gives us the ability to adjust the reaction time in the field for various conditions. So, if we want to slow the reaction for soil permeation grouting, we only add 1 or 2%. If we want a very aggressive reaction, we add 10% for gushing leaks and void fill. All that versatility from the same product is pretty awesome, don’t you think? That nonsense about hot and cold spots can be eliminated simply by having the aptitude to mix a cup of hot chocolate. Following One Trick’s logic, should we all stick to single component drinks like water?
(One Trick Pony)
Prime Flex Hydrogel - This is a gel or foam depending on how much water you mix with it. It is used for curtain grouting and void filling. It is hydrophilic and will shrink.
(Answer)
Hydro Gel is one of the most versatile products Prime Resins manufactures. Just like OTP says, depending on how much water is mixed with the resin, during injection it will produce a dense closed cell foam, great for joints or pipe penetrations subject to movement or a non-cellular gel best suited for curtain grouting brick manholes. Here’s the best thing about Hydro Gel—as the water-to-resin ratio increases, your cost per gallon of chemical grout decreases! The standard water-to-resin ratio is 8 parts water to 1 part resin to produce a gel. Anything below 3:1 will produce a foam. OTP correctly identifies Hydro Gel as a hydrophilic, but shrinkage is only an issue in the absence of water. We don’t recommend using Hydro Gel in applications where there is not a constant source of water or adequate humidity to hydrate the gel. Instead, we recommend use in below grade applications like manholes where there is abundant water inside and usually outside the structure to keep the gel hydrated and prevent shrinkage. You should also never install hydrophilic gels above the frost line. Freeze thaw cycles can damage the gel and lead to leaks.
(Wrap up)
Repairing leaks in concrete structures is very complex. There are all sorts of variables to consider—movement, leak volume, type of structure, above grade or below grade. The fact is all of these variables and field conditions affect the performance of your repair system. Prime Resins has developed a line of polyurethane chemical grouts to deal with these variables and help ensure a successful repair. There is no magic bullet. Rigid hydrophobic structural foams have a place and best suited for void filling and support. They can be formulated to expand rapidly, therefore they seal leaks initially. But given time they will fail due to a lack of flexibility to move with the structure. All structures are subject to movement, whether it’s thermal cycles or vibration. Flexible hydrophilic foams are best-suited for long term repairs to above and below grade structures. These foams cure flexibly and allow cracks, joints or pipe penetrations to move naturally without giving up the seal. They have been in use for many years in the U.S., Europe, and elsewhere with a long-standing successful record.
It was in January at World of Concrete 2011 when Prime Resins was approached by 7 college students from southern California with a material challenge. We love to solve problems—even if it's not our product. 
28 colleges and universities competed for the 24th annual event from 
California Polytechnic State University, San Luis Obispo elected to build a better entry for this year’s competition using Prime Resins Precision Lift™, a 2-component structural polyurethane foam. I can’t give away all their secrets as this year’s competition is just 2 weeks away (June 16-18) at the University of Evansville in Evansville, IN. I will tell you, the team considers Prime Resins their secret sauce.
