Bolt-A-Blok Wall Framing System

Thanks Tigger for bringing this innovative technology to our attention.

After reviewing the literature I do have some questions about the "universal" inclusion of this system in construction, namely in backfilled basement walls where no masonry joints are present to prevent groundwater intrusion. Also, I have my doubts about load carrying capacity of such a system for tall basement walls or even retaining walls. Typically tall reinforced CMU basement and retaining walls rely on vertical reinforcing steel with grout-filled block cells to structurally resist applied lateral loading though composite action. I just don't see enough "meat" in those pencil thin vertical bolts to resist sizable bending moments and shear forces.

Also, there's no load tables or other engineering properties within the Manual that's showcased in the Bolt-A-Blok website in the posted link.

My gut feeling is that this system is suitable for ABOVEGROUND installations and may be suitable for resisting high wind forces only....and until I see and thoroughly review the any manufacturer's supplied load tables and supporting structural calculations/analysis methodology I will remain skeptical.

Just adding my 2 Cents....

Signed,

CaptMoosie, PE

Civil, Structural and Environmental Engineer

You have made some very good points here. I was thinking about using the system for above ground projects. They do show videos of the system being used for some limited below ground applications.

While the posts are thin, depending on the specific alloy used and heat treat condition, they might provide sufficient strength. I don't see that detail (bolt size, alloy) on their site.

Perhaps some information has been withheld for proprietary reasons. I think their website needs a little more work - I had trouble with some links and the addition of more detail technical information would be helpful.

Their product manual indicates that the bolts are 5/16" dia. with a yield of 50 ksi. The last page of the manual indicates they are an Indiana company. Sales reps and staff as well as phone numbers and email addresses are listed.

For basement walls, an exterior membrane is needed to keep water out.

The steel parts are made of Cor-Ten steel to prevent corrosion.

Sound like a very interesting product.

We are presently removing cor-ten from our specs, because it does corrode. We have dug up several sites and found the cor-ten almost completely gone from corrosion.

What is the application where you used cor-ten (I am not familiar with this product).

In the video they show water being directed down rubber sealant down the open blocks, if cor-ten will rust in a wet environment, Bolt A Block should know before they dedicate themselves to it.

Drew

A main use for cor-ten is in making shipping containers. It resists corrosion due to all the alloying material in it. It is really scrap iron with more thrown in - not a new hi-tech material.

Corrosion of the steel would be a serious drawback to using this product. I have not researched Cor-Ten steel but this article indicates some concern about corrosion. See "Disadvantages".

Perhaps Just John would like to respond to this concern.

The article you referred to is a Wiki page.

Unless you want to use stainless or something of that nature there will be rust. Cor-ten or any other 'weathering steel' just slows corrosion down.

I don't know the agenda of the author or the Wiki but from the references noted they were against it. The problem with Wikis is you never know how finished to entry really is.

All rebar in concrete is cheap steel - not even weathering steel - replace it as well? No.

As a general comment on the last set of posts.

Seems to me most steel in air/moisture/dirt is hot dipped gal, or plated, or painted, or powder coated, or plastic dipped or 'oxygen proofed'.

Not difficult - not the end of the world.

And for the record, for the 'stainless' fans; if stainless is subjected to dc current leakage whilst in some sort of 'electrolyte' - it 'de-noble-ises'. Meaning it's no longer 'stainless' but 'active'.

Houses are known to have dc earth leakage from half wave rectification in some appliances - which is why 'earthing' to the water pipes is not smart.

And obviously the following applies to some SS series more than others, but is worth remembering.

"the relative nobility of many materials is highly dependent upon context, as for aluminium and stainless steel in conditions of varying pH."

I would add that corten is used much in construction where exposures to the elements are a concern - bridges, light poles, anywhere the weather may play a major factor to increase oxidation. The alloy does not scale as it oxidizes but rather shuts off the oxygen with the surface as a powder-rust. Hence a fine patina with good results.

I would be interested in the applications you reference and the thicknesses encountered. Light gauge has always been a concern, but the structural thicknesses get high marks. Are you in some special condition where water laps the product or in a high acid condition? Also, are there mixed metals where galvanic reactions can be occurring. I would like to understand more. This alloy has been around since the 1940's but every day finds new information about materials in the real world applications.

Thanks for the heads-up.

The bolts are only 5/16-inch diameter w/ a Yield Strength of 50 Ksi? hmmmm, those bolts have a diameter even less than a #3 rebar (3/8" dia.).

Most reinforcement used in masonry walls is much larger (#4's and above) and have a Yield Strength of at least 60 Ksi (ASTM A615, Gr. 60 deformed bars). It's getting very hard to find Gr. 40 now days and falling much out of favor by structural engineers.

Somehow I have my doubts about using this block system below grade, in retaining walls and any masonry wall having an eccentrically loaded uniformly distributed load (live and/or dead load). Probably best used as an "INFILL" wall between structural steel framing components.

That's my take on the system. I just don't think it is strong enough to support lateral earth loads, especially if there's a high groundwater level present.

==CaptMoosie

I agree it is not very heavily reinforced. Perhaps Bolt-A-Block will develop a system using larger bars over time.

It has been quite some time since I worked as a laborer on a block wall, but I don't recall seeing rebar in every block. What would be stronger, one rebar every few blocks or one small rod every block? Plus with stressing the blocks before the load is placed on them the entire wall would have more strength than a rebar wall.

I wonder what living with a wall like this would be like. How would it react when some resident starts hammering into it to put pictures on the wall, or pokes a hole to shove a tv cable through.

Drew

What about the reinforcement from the bars or plates?

In one of their patent applications, they show a much wider, thinner plate being used. However, this could be a result of the illustrator.

It looks like in their original patent, they planned on a system utilizing standard bricks and concrete blocks. They probably realized that it would be far cheaper to have the blocks made to accommodate a thinner strip of metal, centered in the blocks lengthwise. Good thinking.

Just John, thank you for your answers to our questions, and I personally look forward to receiving an engineering & technical manual from your firm eventually.

I do have a couple of questions that have popped into my gray matter overnight:

#1. Did the laboratory testing include eccentric loading at the top of the walls? Many time we structural engineers (and Architects) utilize open web bar joists for roof framing, and typically due to architectural and construction considerations they do not rest squarely atop the topmost CMU bond beam, but rather the joist bearing pads are offset quite a bit from the wall centerline. Ditto for structural steel beams with bearing plates.

Which brings me to my next question....

#2. Is this wall system designed for load bearing conditions? If yes, what have the tests indicated as the maximum unbraced wall height?

#3. Have the tests included lateral wind loading as well as bearing loads?

#4. Are code authorities still insisting that a concrete-filled and steel reinforced CMU bond beam be installed at the top of the wall system?

#5. Is there any provision in the system for anchor ties to wide flange and tube steel columns embedded inside the wall, like the anchors manufactured by H&B as well as others?

#6. Any provision for vertical expansion joints? How treated, and are technical details provided in the manual? A myriad of structural and architectural technical details provided in the manual (as well as AUTOCAD standard details on a disc or downloadable) would be a must have for designers.

Thanks in advance John. I'm sure we'll have many more questions as we get into designing with this new wall system.

===Signed CaptMoosie, LPE/PhD

Civil, Structural & Environmental Engineer

Some of this will be answered by the code compliance report due out before Thanksgiving. I will ddress briefly what we do have:

#1. Did the laboratory testing include eccentric loading at the top of the walls? Many time we structural engineers (and Architects) utilize open web bar joists for roof framing, and typically due to architectural and construction considerations they do not rest squarely atop the topmost CMU bond beam, but rather the joist bearing pads are offset quite a bit from the wall centerline. Ditto for structural steel beams with bearing plates.

ANS: We did te full ASTM E72 tests required by the ICC AC-15. As I recall (and I helped build many and observe) we did 3 each for an 8 feet and 12 feet high wall, 4 foot wide. Transverse, compressive, transverse compressive (all at ATI). Shear (at Kehigh due to size and the variation to the E564 test). Some do require the eccentric set-up to account for the conditions you mentioned. All the block, bars and bolts were also sampled and the lots carefully traced from manufacturing through the tests.

#2. Is this wall system designed for load bearing conditions? If yes, what have the tests indicated as the maximum unbraced wall height?

ANS: We have built up to 20 foot and the tests extrapolate up higher. The empirical data was used by Penn State analysis to extrapolate higher. They also did additional component tests and built other walls with much more stress and strain analysis that required by the E72 tests. This is where my head starts to hurt as I recall my college days. I will defer to our data sine "Just John's memory" will need a boost from the official data and analysis

#3. Have the tests included lateral wind loading as well as bearing loads?

ans: They were bearing loads mostly in the vertical position that can be interpreted as wind loading.

#4. Are code authorities still insisting that a concrete-filled and steel reinforced CMU bond beam be installed at the top of the wall system?

ANS: Where they have asked, our engineers have overcome these successfully.

#5. Is there any provision in the system for anchor ties to wide flange and tube steel columns embedded inside the wall, like the anchors manufactured by H&B as well as others?

ANS: We did some R and D with tubes and other structures inserted into the ducts with the metal bars in a press interference but no mechanical connection. We have had several projects where mechanical fastening and welding has been used for connecting to other contiguous structures.

#6. Any provision for vertical expansion joints? How treated, and are technical details provided in the manual? A myriad of structural and architectural technical details provided in the manual (as well as AUTOCAD standard details on a disc or downloadable) would be a must have for designers.

ANS: We agree and are addressing this as fast as we are able and as resources are available. We fully agree that as we go further, all these details will add to the success of introduction and thaat Cadd details are a must.

Thanks in advance John. I'm sure we'll have many more questions as we get into designing with this new wall system.

This is prestressed concrete construction. The bars apply compressive force in the block system and as a result the system can bear tensile stress. This is not similar to reinforced concrete where the steel is assumed to take tensile stress and concrete compressive stress and the steel bars are placed as close to the tensile surface as possible and a concrete cover is provided to protect re bar against corrosion. The threaded bars in the block system are in the middle of the block(neutral axis) thus to act as a reinforced concrete component has no value because there is no tensile stress at neutral axis. This system could be enhanced if the rods are moved to the outside faces and staggered. The threaded rods need to be interconnected (threaded male and female end) and work as a continuous rod.

I like it. One would think they have done their homework as far as testing and meeting code. Makes me want to build something.

I see one potential problem, and it's a big one!

Those are not standard concrete blocks. They are specially made for that system.

Three big questions:

1) How much do those special blocks cost?

2) Can I get them somewhere close by?

3) If not, how much is the shipping to get them to me?

As I implied before: "where's the allowable load tables"? Also, need the "Design Methodology" spelled out in plain terms along with step by step sample design calcs.....basically I want to see the "homework" completed! LOL

Okkkkayyyy, one poster writes that this system is post-tensioned whilst another writes its pre-tensioned. Okay peeps, which is it? The manufacturer's link just doesn't give us enough technical and engineering information as far as I'm concerned.....where's the beef?

I still believe that this system is strictly limited to "aboveground" applications until such time it can be proven to me that it is otherwise acceptable. Call me cautious and covering my arse from a design standpoint.

I don't buy anything when it's fresh out of the gate. I agree, the proof is in the pudding. Nothing can replace real life hard data.

When is a new design or product safe to use? If we don't take chances on new technology, then I will we make progress. I don't see the harm in applying new method in less critical above ground applications first.

I think they would be fine for above ground, probably below ground too, with a proper membrane seal on the outside. Although, I don't know why they wouldn't just include their test data on the website.

The #1 reason I don't buy anything right out of the gate ties into my last post......it tends to be expensive.

I imagine that if I was a new entrepreneur, that I would find it rather frustrating to hear the same old saw "it ain't proven", or I would anticipate hearing it, and I would find ways to test it in the field, and use the results as part of my marketing.

Subsequently, I find it odd that the engineering data is not readily available on the website. It is after all, and architectural product, and architects are not going to be moved just by simplicity, nor are the structural engineers. (who the architects presumeably do pay attention to.)

Chris

Yeah, the data they have collected should be prominent, as well as updates when they get them. Otherwise, it looks like they're marketing to homeowners.

The people that make the big decisions need the data.

I think I covered most of this in the first reply, but we do load tables and data available for the architects and engineers. We send it out as requested. We are in the process of completing the Code Compliance report which includes the tables we already have in place. This will be posted within a month. We made a clear decision that a more cmplete report was better than just load tables. Call us conservative, we are all engineers and scientists...a few PEs.

Our extensive empirical data has been analyzed and we continue to do additional testing for specific applications and the individual components reaction within the wall as it is stressed. ICC requires the AC 15 tests which report on the whole wall as a system. We have gone beyond that. I would be happy to discuss other questions or concerns. You can contact me direct off the web site through the sales or tech link.

The Bolt-A-Block manual claims that the blocks are post-tensioned. I don't know how highly the rods are stressed, but it would appear from looking at the video that the stress level is very low.

So far as allowable load tables, I couldn't find any. I suspect that strength calculations would be the responsibility of the engineer of record, although the company likely would have some helpful information to share.

Great insight Bruce. Most of the structural engineers we work with and many architects want our full test books. The buiding contractors and the inspectors want the code compliance reports, a PE stamp or the table. But I do understand the desire to have the tables posted on the web. We all use the websites much more than the books.

All our commercial builds to date - to my best recollection - have an engineer of record. The residentials are a mix.

Good morning Tigger,

That is a very interesting system. The main thing I was wondering about is how does one get the gravel level and compacted around the entire footing before laying the first layer of block?

I know it says it is self-compacting, but it seems as more layers of block and thus more weight is added, the self-compacting will mean maybe more settleing in one area than another. Of course, being bolted together as a single monolithic unit, the wall loads will merely be transferred to the most supportive, compacted gravel.

The last thing is that I would've liked to see a short bar connecting any two horizontal bars, including at the corners. Perhaps slight overkill.

I assume you would have someone good at flat work pour a flat level pad or footer first. The advantage of not needing water are lost with this approach.

I think I saw special footer blocks on their site, so perhaps these could be used after gravel is filled in and leveled.

Bolt-A-Blok was named the 2010 Technology Innovation Award Winner Runner Up by the Wall Street Journal.

According to the article, they are licensing the technology to various concrete companies: "In the U.S., current licensing and multi-state distribution agreements are in place with County Materials Corporation (more than 25 locations throughout the Midwestern U.S.) and ABC Concrete (nine locations serving part of the Southern U.S.), with many more expected in the coming weeks."

Welcome Just John

what is the r value?

could you address Drew's comments?

are special methods used to attach firring strips?

R value the same as regular CMU once you have any sealer on the system and stop any infiltration. Our Betas had good acceptance on this. However, we have several new coatings that tout higher value but we haven't yet tested them.

The block are 3 core so all ducts line up which facilitates easy fill of any materials, unlike their two core counterpart on standard CMUs.

I will relook for Drew's questions later.

As to firring strips, you caan use sandard methods or we have a notch block that acceptas a ssimple plastic anchor...then you use an inexpensive drywaall screw or equal.

Sorry

I should have recapped

similar to the firring strip question

how many intrusions for utilities & such before the integrity of the structure is compromised?

are there plans for other corner angles?

Thanks for responding John. Good answer to the thread and to my question on availability.

Kevin

"Moose's comments perplex me a little."

Luckily your blocks are "placed" not "poured".

_{(don't worry, it's a standing joke. someone had to say it)}

great! good work.

Welcome to CR4!

best wishes.

is there a solution for compressed earth blocks? (CEB) especially helpful for places like Haiti after the quake, and I believe and presume that this has a higher quake resistance than normal block walls in a quake?

Nice one Guest...hardy har har

Regardless if its a joke or not you, some of you guys still don't know diddly between placing and pouring....of concrete.

We have analyzed several structures for Haiti with very good ratings. We have travelled over ten thousand miles with our show trailer aand had very little concerns. We did loose a door at an overpass in Florida. The blocking came loose and tore it off the hinges. The block system survived intact.

We have contacted Purdue for potential shaker table tests. What are your capabilities or who should I contact at your location for seismic info?

I didn't answer the CEB portion...I will have to do a little homework first.

Just John, I'm getting more intrigued about the system after reading up on it more, and after reviewing your statements herein.

Could you please inform those of us in this forum when the engineering and technical data becomes finally publish? Likewise with the posting on your website of the test data that's been performed to date?

Thank you.

Within the month it should be posted. Dr. Memari just included a chapter on his work in a recent Civil Engineering book. If you need it ahead of that contact me through the website tech contact.

I am very open to other questions and ideas how to get other information to you beyond the load tables.

Thanks to all for your interest and comments.

John,

Will you be adding a T-block to your product line ? and similarly a 4-way block ? Will they improve the structural integrity any better than what your system already offers ?

Thanks,

Sorry for the delay. I have been off the grid a couple days...my laptop gave it up. Just as I was getting good at Vista, I now shift to Windows 7. Plus the opportunity to reload all my geekware.

We are considering various configurations as we have a request or the need arises. Currently, since our block system cubes - or interconnects perpendicularly - we do not see the immediate benefit to the structural integrity. Cubing refers to the fact that the length is twice the width so one cn place a course perpendicularl. thw website shows this structure for piers and columns and it also works for walls. Two or more wythes may be placed contiguously, yet the courses can interlace as block. In addition, the bars can extend and provide structural ties to corners and walls and wherever added tensile strength is desired.

Is there any reason that a dual system of Bolt-A-Blok and mortar can't be used? For example, where block is filling a space up to an upper metal header, the top course would be difficult to bolt... and mortar is the traditional solution, and is allows bonding of the to course. Or do you have an alternative bolting solution for such a situation?

just curious...

Chris

You can bolt to a fairly tight clearance with other drivers (wrenches and rachets, etc.).

As to mixing technologies, we have done this...especially at the top of sloped walls. It works fine but may impact the roof structure's connection to the Bolt-A-Blok wall mass. Like all projects - there are textbook and design answers and then there is some field fits and modifications required.

I was watching a guy laying block, asked him about the adhesive qualities of the mortar. "The mortar doesn't hold the blocks together, it holds them apart" he said. It took me a while to get that. Blocks are brittle, will crack and shatter if load is placed on one small spot. The mortar spreads out the load. That's why mortar is soft, not hard like concrete.

Also, how are you going to keep the wall level? Mortar allows for corrections in footing fluctuations, many block walls are set right on poured footings. Then the blocks are set to a level string.

Filled walls are popular here, rebar will be cast into footings, and pieces as long as possible will be dropped down the holes, then concrete poured in. Most contractors here don't have vibrators, so the block filling is pretty hit-or-miss in my opinion. They will jiggle the rebars to help the concrete settle, but I prefer vibrators.

It's lots of fun drilling a block wall and hitting the rebar. I have a wall downtown where a contractor was mounting large conduit to the building. It looks like the backdrop to the St. Valentine's Day Massacre. Now I have to have all the holes filled in to keep rain out, just noticed it the other day.

You prefer vibrators ? You do ??

Hi Tigger - I agree: a very nice / useful product. The extra-strong resulting wall structure is particularly appropriate for seismic or hurricane prone areas around the planet, IMhO. - Larry

I'm guessing a bit here, but it may be that Cor-ten weathers well in air, but is not as ideally suited to underground burial. Then again, being intimately surrounded by cured concrete or grout might be okay if it keeps moisture out.

This is an intriguing technology. I imagine that one key to its success will be to stay on top of various concerns that may arise, and address them proactively. If any problems are taken care of by suitable modifications, this could mature into an effective and popular system.

If decent QC can be built into easily achieved instructions, this could become a good DIY or remote-area technique.

Thanks for the comments. We do have a good quality system in place for the components.

As to the DIY manuals, we see a need but have not tried to enetrate that market yet. With the internet, we can share much via the website...but we need more focus on the DIY materials.

IMO, apart from the lifetime of the steel, since no filling material is used between the blocks, the tolerance between the block dimensions must be kept almost impossible minimal in order to avoid cracks on the long run.

This in particular to bearing walls.

Comparing with the quality, available in standard concrete blocks, this will be a challenge towards QC and QA for production.

The corners also seem fragile to me without a "through" steel connection

I also don't like the "foundation" as shown in the video.

Some binder in the gravel composition would be welcome.

According to our building code, roof and foundation need to be connected to form one unit.

As demonstrated, I doubt it will pass without strong guarantees.

Pre- hurricane rains soften up the soil (the foundations when saturated become spongy in the rock cut-outs) and the winds do their part afterwards. A building is just as stable as the foundation it sits on/in. I think these points, however, can be considered and adapted or adopted.

Bolt-A-Blok systems are available through Hudson Knorr at www.hudsonknorr.com. The website clearly outlines the available products and how they can be incorporated into new and existing structures.