Bentonite vs HDPE?

Log Out | Topics | Search Moderators | Register | Edit Profile

Author Message Margaret G. Chewning FCSI CCS Senior Member Username: presbspec Post Number: 336 Registered: 01-2003 Posted on Friday, October 23, 2020 - 10:25 am:    I have a client who has asked if Voltex (Bentonite panel) is the equivalent to Preprufe 300R/160R (HDPE) membrane. I know they work differently to waterproof foundation walls and slabs, but ask your advice regarding their effectiveness. ken hercenberg Senior Member Username: khercenberg Post Number: 1308 Registered: 12-2006 Posted on Friday, October 23, 2020 - 10:40 am:    Absolutely not. Night and day (and huge cost difference). From my personal point of view and experiences I only advise using Voltex type waterproofing for clients I don't like. There may be other bentonite based products that could be acceptable based on your specific project conditions but I'm usually not a fan. Glad to discuss this offline with you. anon (Unregistered Guest) Unregistered guest Posted on Friday, October 23, 2020 - 12:17 pm:    There are a number of things that you need to know and understand before making a recommendation. First, a bentonite panel is a very old product that has fallen out of favor among architects and waterproofing consultants - this is a product comprised of cardboard with the cells filled with bentonite clay. If this product is being proposed then I would agree with Ken that it is not an equivalent to Preprufe. The next generation of bentonite waterproofing sheets are comprised of a geotextile fabric with bentonite clay "stitched" into the sheet. These are much better products than the panels. Arguable whether or not this type of bentonite is an equivalent to Preprufe, it could be under certain conditions. Improvement on the above is the addition of an HDPE liner to form a composite bentonite sheet, the HDPE offering protection to the WP sheet prior to backfilling/conc pour and improving the performance for WP as well. I would say that this is close to equivalent to Preprufe, and is still widely specified and used throughout North America, with good success. A new range of CETCO products that are NOT bentonite, but commonly referred to as bentonite, are similar to their Voltex sheet products but instead of bentonite use what CETCO calls Advanced Polymer Core (APC). These products from CETCO are called Ultraseal and perform better than bentonite products and are absolutely an equivalent to Preprufe. Finally, CETCO also makes a dual membrane with their APC and a thermoplastic liner, called Coreflex 60. This is a superior WP membrane product and outperforms Preprufe due to its dual membrane construction. Again, not bentonite, but still often called bentonite. All of this information is easily obtained on manufacturer's web sites and I would also encourage you to contact your local GCP and CETCO architectural/technical reps who can explain all of this to you in even greater detail. Hope that this info helps you, and good luck! (Unregistered Guest) Unregistered guest Posted on Sunday, October 25, 2020 - 09:44 pm:    I wish anon had given some sort of description of his occupation. He sounds like a CETCO rep. There's an intermediate generation of bentonite waterproofing that was marketed as Paraseal under a number of manufacturers' names. It's a HDPE bentonite composite. I used it succesfully on a number of projects including the Seattle baseball stadium without problems (for 20 years at least). RH (Hank) Sweers II RA CSI CCS Senior Member Username: rhsweers2 Post Number: 24 Registered: 08-2005 Posted on Monday, October 26, 2020 - 09:41 am:    The some 25-year old rule-of-thumb I used to hear (from way back when I worked at an Engineering/Architectural firm that also did tunnels) was that bentonite was great in "wet" environments, like with a tunnel under a river. But in an environment where it was not always wet (at that time on underground bunker houses, for instance), there would be a period of time necessary for it to expand and then to seal up again before it became waterproof again. So there was a potential of water infiltrating through the cracks before it expanded. Marc Chavez Senior Member Username: mchavez Post Number: 609 Registered: 07-2002 Posted on Monday, October 26, 2020 - 12:45 pm:    I've used it in Seattle for 25 years with no issues at all, I often argue for other products and depending upon the job I use them. But for the vertical walls of a large number of below grade parking garages (with damp soils) it has performed well. anon (Unregistered Guest) Unregistered guest Posted on Tuesday, October 27, 2020 - 01:27 pm:    Nope, not a CETCO rep, spec writer for large design firm. Not sure why it makes any difference, information is information, isn't it? I didn't see any request from OP to weigh in on Paraseal. One might think that Unregistered Guest works for Tremco ;) Nathan Woods, CSI, CCCA, LEED AP Senior Member Username: nwoods Post Number: 830 Registered: 08-2005 Posted on Tuesday, October 27, 2020 - 07:45 pm:    "Not sure why it makes any difference, information is information, isn't it?" Oh my, that was hilarious. Have you been paying any attention to any media in the past few years? There is a huge credibility issue related to where you hear what and who and why. No one trusts anything anything anymore, nor should they. Denziel Washtington has a great quote recently: "If you don't watch the news, you are uniformed. If you do watch the news, you are missinformed" LOL James Sandoz, AIA, CSI, CCS Senior Member Username: jsandoz Post Number: 309 Registered: 06-2005 Posted on Wednesday, October 28, 2020 - 08:46 am:    Great quote, Nathan. Thanks for sharing it. Full disclosure is important. I've been fortunate in that the great majority of product representatives have dealt with, while extolling the virtues of the products they represent (as they should), have also been forthcoming about shortcomings, when that product is not appropriate for an applications, etc. It seems, in my almost 30 years of experience, they are generally honest about their competition as well. I preface every recommendation, positive or negative, with the caveat that I am an architect who has had either a positive or negative experience with a particular product and I hope I convey the understanding that my experience may be anecdotal, especially in a one-time event. I final word to those who post: Unless you have a real need for anonymity, either register or put your name and particular affiliation at the end of your post. It goes to credibility. ken hercenberg Senior Member Username: khercenberg Post Number: 1309 Registered: 12-2006 Posted on Wednesday, October 28, 2020 - 09:37 am:    Agreed James. Having been threatened with lawsuits by manufacturers for speaking my mind based on project experiences I too would prefer to remain anonymous sometimes. I choose not to. I speak for myself only, not my current or previous firms. When I was writing product guide specs back in the early 80's I was introduced to Paraseal and did a lot of research with them. They explained to me that bentonite, at the time, was primarily used as a soil drilling lubricant to keep the drill bits cool (still is). While working as a waterproofing consultant in the Washington, DC area I was able to notice numerous bentonite failures that were never published but were fixed by drilling through the wall and injecting high-flow urethane grout into the soils, basically a band aid to divert the water. The systems usually work because of exceptional drainage and often dewatering of the site. First law of waterproofing is that if the water isn't there, it can't leak. I highly suggest it. The backstory: Apparently when concrete dries it shrinks and cracks (concrete 101). Putting a lubricant against the crack with a hydrostatic head pushing the lubricant into the wall results in bentonite oozing through cracks. Not a pretty sight or an easy fix. I personally see no reason to use the stuff when there are other products available that don't ooze through cracks. They seem to work better with little to no downside. I get it. The bentonite companies have done a great sales job selling dirt as a waterproofing product, provide really good warranties, are quick to respond to leaks, and should be congratulated. In my personal opinion it's time for them to go away and make room for the next generation of waterproofing options that already exist such as HDPE, TPO, and injectable waterstops like FUKO Hose. One person's opinion. You should continue to do what your conscience dictates. David G. Axt, CCS, CSI ,SCIP Senior Member Username: david_axt Post Number: 1841 Registered: 03-2002 Posted on Wednesday, October 28, 2020 - 03:40 pm:    I don't trust anyone on this forum who is anonymous. I was taught long ago that one should own their communication. David G. Axt, CCS, CSI, SCIP Specifications Consultant Axt Consulting LLC John Bunzick Senior Member Username: bunzick Post Number: 1826 Registered: 03-2002 Posted on Thursday, October 29, 2020 - 05:07 pm:    But Ken, it's a very special sort of dirt! Bentonite is also used in slurry wall foundation construction. Got a sidewalk education on this in the late 70s when the subway was built in the middle of Harvard Square, Cambridge. ken hercenberg Senior Member Username: khercenberg Post Number: 1310 Registered: 12-2006 Posted on Thursday, October 29, 2020 - 09:30 pm:    Very true John. Slurry walls are marvelous feats of engineering. I'm a big fan and love to use FUKO hose in the slurry wall joints to make them watertight. Very big in Europe and the Middle East. Unfortunately US contractors haven't figured out how to use it yet. Shame. Pretty much eliminates the need for membrane waterproofing when done right. It's also big in kitty litter which I don't have much use for but many of my friends do, or at least their cats do. Unfortunately in some instances dirt is dirt. Ever see what happens when below grade water is moving and erodes the waterproofing? I guess that's better than having it enter the concrete cracks. John Bunzick Senior Member Username: bunzick Post Number: 1827 Registered: 03-2002 Posted on Saturday, October 31, 2020 - 03:35 pm:    That's the main reason why I never specified bentonite, though I couldn't say it doesn't have some uses. Dewayne Dean Senior Member Username: ddean Post Number: 218 Registered: 02-2016 Posted on Saturday, October 31, 2020 - 05:55 pm:    Bentonite is a well drillers best friend. When drilling through porous layers, adding bentonite chips to the drilling mud seals the bore hole walls and keeps the drilling mud circulating back to the top of hole. Chips also work well to plug unwanted artesian flow. I just felt like someone needed to say something nice about bentonite William C. Pegues Senior Member Username: wpegues Post Number: 990 Registered: 10-2002 Posted on Saturday, October 31, 2020 - 06:53 pm:    I will chime in with good word and history with Bentonte. Used it since the mid-70s when with SOM in DC. It was their preferred system. And in DC with the underground streams where it could be pretty dry at one time where a building goes in down the block and the ‘stream’ diverts! Anyway, maybe 50% of projects over 40+ years had bentonite on it. There was never a problem with it. And we only used CETCO products. So, yes, I went through the evolution of the corrugated cardboard, the woven mats and the hybrid mat/membrane systems with it. The only time you end up with problems of some kind is when you get a manufacturer using an inferior source of clay, or really bad installers. The 40 plus years breaks down to 6 with SOM in DC and 37 with WDG for a total of something like 400+ projects ranging from NY to FL and MI to TX. Hmmm... looks like I have to post about 10 more messages to get into the 1000+ post club! William C. Pegues, FCSI, CCS, SCIP David G. Axt, CCS, CSI ,SCIP Senior Member Username: david_axt Post Number: 1842 Registered: 03-2002 Posted on Monday, November 02, 2020 - 12:07 pm:    Here in the Pacific Northwest bentonite is probably the most commonly specified type of waterproofing. This is probably due to our damp soils. I prefer HPDE waterproofing but nowadays envelope consultants are writing the roofing/waterproofing specifications. They almost always specifying bentonite products. Years ago I saw a demonstration where a product representative took a paper cup and put a hole in the bottom. He added in bentonite granules about a quarter of the way. He filled the cup up with water. The cup dripped for a very short time but became watertight and did not leak. After a few days the water evaporated and the bentonite dried up and cracked. One of the specifiers poured water into the cup and the cup leaked all the water out. What I learned from this experiment is that bentonite must remain damp and restrained. David G. Axt, CCS, CSI, SCIP Specifications Consultant Axt Consulting LLC ken hercenberg Senior Member Username: khercenberg Post Number: 1311 Registered: 12-2006 Posted on Monday, November 02, 2020 - 12:34 pm:    See, now this is where I'm going to get into real trouble especially since I currently work for a waterproofing consultant who occasionally advocates using bentonite. I suggest that you ask your consultant how often they get paid by bentonite manufacturers to field-inspect bentonite installations. I don't know of any large, reputable firms that don't and that includes many structural engineering firms. To be fair they may inspect other waterproofing system installations. Speaking off the record with a few waterproofing consultants on projects several years ago, the attitude was essentially that yes, it could leak but it almost never causes big issues. Occasionally concrete has spalled, requiring removal and replacement, but it is rare. Sometimes the building owner has to pay to repaint some cars that get damaged but again the cost savings and risks of using bentonite seems to be justified in their minds. Be aware that there is some question as to whether bentonite products are able to create a suitable vapor barrier under slab so if that is needed consider adding a separate membrane. It's probably not an issue for parking garages without traffic coatings. To be fair, when I was an independent consultant I used to chase jobs in the Washington, DC and mid-Atlantic region that used certain products that had a history of failure, not just bentonite, in hopes to getting work as a result. It was a pretty good work plan. I just wasn't a very good business person. Michael Chusid, RA FCSI CCS Senior Member Username: michael_chusid Post Number: 571 Registered: 10-2003 Posted on Tuesday, November 03, 2020 - 08:06 pm:    Is the paper cup experiment David described representative of the conditions where bentonite is at least somewhat restrained by backfill? If some bentonite particles penetrate cracks and voids in concrete, might residual moisture in the concrete keep the bentonite moist? And, if it dries within the cracks and voids, will the concrete hold the material in place so it swells again when exposed to moisture? I do not have a position pro or con about bentonite. But I do think alot about how to create meaningful tests for materials. Michael Chusid, RA FCSI CCS 1-818-219-4937 www.chusid.com www.buildingproduct.guru Phil Babinec Senior Member Username: pbabinec Post Number: 33 Registered: 09-2004 Posted on Tuesday, November 24, 2020 - 10:49 am:    Any experience with crystalline waterproofing?