|
|
You are not authorized to post a reply.
|
 Prev Next
|
| Author |
Messages |
|
eric monkman
Registered Users
Basic Member
Posts:206
 |
| 07/20/2009 6:40 PM |
|
Neilb, I thought I'd better start a new thread, rather than misuse the topic of another thread.
Getting back to consolidation........I think you mis-enterpreted my statement as segregation.
A mix design for a waffle wall with a 2inch web would require a 60/40 sand/rock mix,and
close to 500lbs of powder with slag or fly ash depending on where you are.
Plasticizer would be nice too.
And, as you say 3/8 rock would be suitable, if there is sufficient fines to carry the aggregate,
as noted above.
A good test for your mix would be to pump it thru a small line system...say 2 1/2 inch.
If it will not push thru easily...it will not fill that skinny web you have.
Of this I am sure :-)
How many of these walls have you personally poured ?
|
|
|
|
|
|
|
tdbuilder
Registered Users
New Member
Posts:63
|
| 07/22/2009 7:16 PM |
|
| A few years back I looked at Hobbs. When I talked with a local building official where I had a project going on, and showed him the info. The answer I got was; no waffle grid systems period. They had a local ordinance against them because of so many problems. With that said the waffle grids they had problems with were not Hobbs. I later found out that there are a few place with such ordinances. The more and more I thought about it there is just no way I am comfortable knowing that there were no voids in it. |
|
|
|
|
Hobbsverticalicf
Registered Users
New Member
Posts:5
|
| 07/24/2009 5:33 PM |
|
Neil,
Thanks for your support of our product. Please allow me to respond to this one!
Eric,
Hi, again. I met you while in Brockville, Ontario during a training installlation of our system a while back. I would would like an opportunity to respond to this topic. Our engineers typically will specify a standard 3000#, 3/8" pea gravel or chip mix with a 4-5" slump and NO plasticizers! I DO NOT recommend plasticizer for a couple of reasons. One is that the system doesn't require a plasticizer to consolidate the concrete...not even in the 2" web! Because our design does not have horizontal rebar other than at the top & bottom beam and around windows and doors we DO NOT experience voids in our system. Yes, I do recommend vibrating our system as per ACI 318. However, using the proper mix design will require VERY little vibration. I recommend focusing the vibration around openings and at the top beam, especially at window headers where there is often times a concentration of rebar. Simply put, the concrete doesn't get caught up like some of the typical "waffle grid" systems were the rebar is running is both directions within columns, beams and webs. Our system is a "MODIFIED WAFFLE GRID" design. Please look closely at the design drawings and I think you will understand why this isn't an issue with our system. Another is because we have tested and tested the system without it to stay with the KISS method. Have you heard of this one? Keep it simple stupid. No insult meant by that, it's just a term that I applied to the design of the system. Adding plasticizers only add cost with no realized benefit.
We have yet to experience any issues using our system in ANY state or province that we have done projects in to date. I also know of no where that there is an ordinance against "waffle grid" ICF's. It's really unfortunate that stories like that give a black eye to not only the those products but to the ICF industry as a whole. This is why we DO NOT sell to "do it yourself" type customers. I strongly oppose the mentality that any ICF is a "DIY" product...period! Even as simple as our system is we are focused on construction professionals for the installation of the Hobbs system.
Maybe, to completely convince you of what I am saying isn't to say anything at all! Joe will gladly invite you to the next pour and you can see it for yourself!
Sincerely,
Andrew Hobbs
|
|
|
|
|
eric monkman
Registered Users
Basic Member
Posts:206
|
| 07/24/2009 8:57 PM |
|
Andrew, did Neilb defer responding to you ?
Simply, I do not believe that RM producers are "in tune" with the concrete necessary to achieve proper consolidation within the "shell" area of your form.
Knowing that about our local RM scene would make me hesitant to try your system.
Pumpability thru a 5 inch boom pipe does not translate into a mix that will flow into a 2 inch web.....Right ?
The inability of RM suppliers to understand the differences in concrete requirements between your ICF and a typical parallel face block is the real problem.
RMCAO (Ready Mix Concrete Association of Ontario) concrete specs are perfomance based, and you will find that they apply the Kiss Principle to all ICF mixes by incorporating plasticizers in their mixes.
As much as the RM people smile and nod about your requirements or mine,
...... the majority of them don't get it :-(
They are still using batching plants with 2 bins, sand and rock.... period.
Nobody would think to blend aggregates, or heaven forbid,
bring in a load or two of round rock..which by itself improves flow and consolidation.
Without doing "test pours" (Kiss Principle) before you enlist an RM plant, you will have nothing but grief.
As Ron White says "you can't fix stupid"
|
|
|
|
|
Rio
Registered Users
New Member
Posts:75
|
| 07/25/2009 10:45 AM |
|
Hi. I've been reading the previous post and this one with great interest and have also perused the hobbs building systems website. I have a question on the R-30 insulation rating. Are the furring assembly flanges (studs) cold formed steel or are they plastic? Are these furring assemblies providing a thermal bridge? Does the R-30 rating take this into account? Also, by having these continuous furring assemblies will this allow a path for water?
Also, I have a question regarding lateral load resistance. With all of the elements being vertical, with the exception of the top of bottom having a horizontal piece of rebar how is the lateral load resistance acheived? I work in California in a #4 seismic zone.
I'm also curious why there is no ICC report. Is this a question of cost? I work in San Diego County and it's difficult to get the plan checkers to okay anything without one.
The product itself looks very innovative and easy to use and really strong! Thanks for any answers.
|
|
|
|
|
Hobbsverticalicf
Registered Users
New Member
Posts:5
|
| 07/27/2009 12:00 PM |
|
| Eric,
I haven't spoken to Neil about this. But, I intend to. I just came across the thread and thought I would comment.
Let's approach the issue of the 2" web from another angle. The web is 12" in width so the concrete needs to flow 6" in each direction from each of the columns. We specify a 3/8" aggregate so I haven't experienced problems with consolidation. I prefer round rock vs. chip, however, I have poured both and it's not a problem and the engineers support either.
Also, I agree generally with your assessment of Ready Mix plants. However, I have also found that a slump of between 4-5" is ideal when pouring our system and you will find that the system pours very nicely. I recommend that you order a 4" slump and go from there. It's when the RM plants try and anticipate flow being an issue and add way too much plastizer and now we end up with an 8" slump that it becomes a problem.
Your concerns about the RM plants really apply to ALL ICF's, right? Concrete spec's matter and we all have found challenges when it isn't right. I respect your concern about the RM plants, but I really recommend that you contact Joe in Ontario and schedule a time to visit a pour and see for your self. I am confident that you will see that our 2" web isn't as much of a challenge because we are a "modified waffle" design.
"Think of how stupid the average person is, and realize half of them are stupider than that"
George Carlin
Take care......Andrew Hobbs |
|
|
|
|
Hobbsverticalicf
Registered Users
New Member
Posts:5
|
| 07/27/2009 8:05 PM |
|
| Rio,
Thank you for your inquiry and interest. Our furring assemblies (studs) are made of rigid PVC. This material is ideal for reducing thermal conductivity. Also, we have a stucco ready version that has 1/2" of EPS that covers the furring assembly which also reduces thermal conductivity (like typical "block" ICF's).
"R" value is factored based on the "R" values of each of the components. EPS foam has specific "R" value per inch, as well as, concrete, drywall, siding ect.. So, it's a simple calculation. The EPS foam at the thickest point is a total of 7 7/8" on our stucco ready version. Our design flexibility allows for the panels to be even thicker if you would like.
The furring assemblies are punched out to allow for the flow of concrete through the assemblies. The furring assemblies are not continuous at the web. Also, with the inherent design gravity channels moisture down the face towards the drainage system. As far as, I know all ICF's and even poured foundations have webs. To my knowledge a path for water isn't a problem with either of those type systems either.
Every project we do is engineered "by project". The horizontal rebar is not doing the work of the vertical rebar with regard to lateral loads. That's why our system works the way it does. Under flexure the vertical rebar is what gives the wall strength. Check out our physical testing that was done at Iowa State University on our website (www.hobbsbuildingsystems.com). The results were fantastic. We gained 50% more strength as a composite system than just the rebar and concrete alone.
In high seismic zones, you would need to go to our "modified flat wall" design which allow for horizontal rebar between the top and bottom beams. The reason that we have not opted to get an ICC listing is because we are not "prescriptive" by design. So, we provide engineering per project for our components. Yes, the cost of an ICC listing is expensive but that is not the reason have chosen this path. We have yet to be rejected when using and engineer that provides a "stamp". I believe in providing engineering by project for liability and credibility sake.
Sincerely,
Andrew Hobbs
Hobbs Building Systems
|
|
|
|
|
|
| You are not authorized to post a reply. |
|
|
|
ActiveForums 3.6
|
Professionals Serving
Your Location:
|