[Peter Dow (OP)]

Hi.

I am still at the engineering design stage of a new building tile / brick invention project idea and at this point I have a technical drawing produced using my computer graphics skills to show you.

If the tiles or bricks are made of metal then either aluminium or steel are the obvious choices.

Tessellated I in Steel


View larger version of Tessellated I in Steel 1800 x 800

Representing a surface of "I"-shaped steel tiles or bricks. Produced using Paint.NET.

The "I" shape is of square proportions, the column of the I being one third of the width of the square and the top and the base one quarter of the height of the square.

The image has my own watermark added.

I am hopeful that maybe one day this kind of shaped tile or brick could prove useful in engineering where you need to build a strong, maybe temporary, wall, enclosure, barrier, box or other solid structure.

Perhaps the proving ground for my tessellated I / H tile / brick concept would could be first as a building toy?

If as with Lego, the tiles or bricks are made of plastic then maybe multicoloured bricks might be possible ...



if not then single colour bricks like Lego would be OK.

There's nothing new about tessellations in engineering of course. Somebody even used I-shaped paving stones one time.



I still need to work on the design a bit more because I'd want the tiles or bricks to be able to be assembled together then disassembled when necessary without having to be cemented together like a brick wall



and without having to be glued onto a mounting surface like conventional tiles



So I am looking for a design that allows assembly and disassembly such as with Lego, Meccano or other manufactured products.



So still a bit of engineering design work to do and then I'll need to start with models and prototypes first and then see if anyone else might be interested in applying my idea whether as a building toy or for a real world engineering application.

[CliffordK]

Peter,
If you wish to try something glue-free, you might try something like a dovetail joint.

I.E.  Make your individual member segments somewhat like this.

[diagram=677_0]

And, if it is for kids, and doesn't just pop apart, then it has to be made fairly rugged.

[Peter Dow (OP)]

Peter,

Thanks for your reply.

If you wish to try something glue-free,

Absolutely.

you might try something like a dovetail joint.

I.E.  Make your individual member segments somewhat like this.

[diagram=677_0]

Awesome Clifford!  (My smilies don't seem to be displaying properly)

So your dovetailed I would tessellate something like this.



Yes that would usefully prevent the columns of Is moving apart in one direction in which they are otherwise free, so long as the columns stayed in the same plane.

My Is without some further design element constraining them can be separated like this

Code: [Select]

III
III
IIIpull the I's apart with a tensile force in this direction <---------->

Code: [Select]

I  I  I
I  I  I
I  I  I
whereas your Is with the dovetails don't easily separate in that direction, so long as the I's are otherwise constrained to remain in the same plane.

However your dovetail Is are still loose in the direction in and out of the screen / paper / plane in which the image of the Is is drawn.

In other words, faced with a wall of your dovetailed Is, I could still kick your Is in to destroy the structure.

So your dovetails offer a part solution yes but for example if the columns were bolted one column to its neighbouring column together somehow then they'd be constrained in all currently free dimensions which would offer a proper solution to the design problem.

And, if it is for kids, and doesn't just pop apart, then it has to be made fairly rugged.

Well kids toys could be the proving ground but I am aiming to design something that was able to be used for such tricky building requirements as being able stick up a quick temporary house and garage for you and your pick-up truck which has just carried the tiles in the back of the truck or in a trailer - in other words for real world engineering uses. OK, you can do that with a big tent now but tents can be flimsy insecure shelters, not so good at keeping out polar bears etc. So the tiles need to fit together into a cohesive structure that has its own structural strength and can withstand tensile forces in all directions.

And when was the last time you dropped a Lego toy? If I remember correctly, Lego has a tendency to fall apart when dropped. Meccano with nuts and bolts was more robust.

Well thank you once again for your contribution Clifford and I would welcome any more ideas you might have.

[CliffordK]

Whew, freehand, it didn't come out too bad when you stacked them together  []

The angled corners would give you a fair amount of rigidity for the whole wall.  And, you could certainly use the same technology to make 90° corner pieces (or any other angle for that matter, or even hinged.

I'm trying to imagine what it would mean to cross-link the elements, or if one could truly build a 3-D wall of a similar structure, or even why one would want to do it.  One can, of course, make thick and thin elements.

One could probably make a similar, 3-D element which would allow some cross linking, or attaching an internal wall, but probably not for every element.  Consider the element with the middle narrow like a column, but the top or bottom either having a T or + profile.

[syhprum]

I am surprised that traditional bricklaying still goes on I would have thought that bricks could be assembled into say one meter square sections by machine before being incorporated into a wall.

[Peter Dow (OP)]

Whew, freehand, it didn't come out too bad when you stacked them together  []

Awesome for a sketch.

The angled corners would give you a fair amount of rigidity for the whole wall.

Your dovetailed angled corners? Rigid only in one more dimension (giving a new total of 2 rigid dimensions) but not in the 3rd dimension as I have described in my previous post. Please re-read.

And, you could certainly use the same technology to make 90° corner pieces (or any other angle for that matter, or even hinged.

Technology? Making things in metal or plastic? Hey, we've had the technology for decades. What we don't have yet is the full design which shows how to make corners, hinges etc.

I'm trying to imagine what it would mean to cross-link the elements, or if one could truly build a 3-D wall of a similar structure, or even why one would want to do it.

Well perhaps you should review the Three Little Pigs story.

One can, of course, make thick and thin elements.

If one has a design one can.

One could probably make a similar, 3-D element which would allow some cross linking, or attaching an internal wall, but probably not for every element.  Consider the element with the middle narrow like a column, but the top or bottom either having a T or + profile.

Well I have not specified a 3-D tile design though I have suggested that the 3-D design must serve to attach the tiles strongly to each other. Elements which allow cross-linking would need to be designed into the basic shape of the tile for mass production - but there would at construction time, of course, be options to use or not to use a particular cross-linking element of a particular tile.

As with Meccano, just because there are bolt holes that does not mean one must put a bolt in every hole.
 

[Peter Dow (OP)]

I am surprised that traditional bricklaying still goes on I would have thought that bricks could be assembled into say one meter square sections by machine before being incorporated into a wall.

In traditional brick-laying the bricks are small so that they will be light enough to be lifted by one-hand while the other hand uses a tool to spread mortar on the jointing surfaces.

I metre-square of assembled traditional bricks would be too heavy to lift without a crane.

However, this topic is not about traditional bricks or brick-laying but about my proposal for an entirely new kind of brick or tile. Perhaps the new bricks might even approach the size of 1 metre squared for some applications and if made of plastic or aluminium could be fairly easy to lift into place. I have a 5-step step-ladder made of aluminium which I can easily lift with one hand yet it supports my weight to a height of over 1 metre.
 

[Mazurka]

An interesting proposition,

Other than the aesthetics, I am not sure that what advantage the tessellation adds – I cannot see that it is more load bearing than an individual cuboid brick/ block?  It also strikes me that individual blocks having more potential to fail. 

For construction purposes if the blocks were sufficiently large it may be possible to use dowels (through the top/ bottom) of the crossbars of the I ‘s to hold a temporary wall type structure together (without cement) or bolts   This would resist tension (as the dovetails would) and also the deformation of the structure (kicking it in).  It would also allow changes in wall angle.

From a practical point of view temporary (polar bear proof) buildings rather than tents are best achieved using cheap prefabricated panels (such as profiled steel cladding) bolted onto  a structural frame (i.e. a metal tent!). This gives the compromise between strength and weight.  It is possible to get a fairly large barn on the back of a single wagon. 

I guess the key issue is materials.  Clay bricks would not fire consistently (or strongly) enough to tessellate neatly; Cast concrete (such as the pavers pictured) might work to a certain size without reinforcement (although I struggle to see the advantage of a conventional concrete block); Metal would be expensive, potentially heavy and thermally dismal; (engineered) wood might work and plastic might work...

[Peter Dow (OP)]

For construction purposes if the blocks were sufficiently large it may be possible to use dowels (through the top/ bottom) of the crossbars of the I ‘s to hold a temporary wall type structure together (without cement) or bolts   This would resist tension (as the dovetails would) and also the deformation of the structure (kicking it in).

Excellent! You are the first to explain that, Mazurka, and I've posted this in a lot of science and engineering forums. Top of the world!

(If you don't mind, I will call these dowels "Mazurka dowels" - because if I call them the "Dow dowels" there's too many dows in there and anyway, my name can be used to reference this particular shape of I or H tile and brick and structures composed of them, as per "Dow tile" "Dow brick" "Dow I-tile" "Dow H-brick" "Dow I-H-brick" "Dow I-H-brick structure" "Dow I-structure" etc.)

You might think of drawing a diagram so that others can see what you are on about.

It would also allow changes in wall angle.

Well a 90 degree angle is simple enough, other angles less so. I mean other angles can be achieved but it's not possible, that I can see anyway, to leave a flush surface without gaps using all identical I or H tiles or bricks at all angles. For a flush surface finish you really need especially designed corner or edge tiles or bricks, one kind for each angle, whether 45 degrees, 60 degrees or whatever.

[Peter Dow (OP)]

An interesting proposition,

Other than the aesthetics, I am not sure that what advantage the tessellation adds – I cannot see that it is more load bearing than an individual cuboid brick/ block?  It also strikes me that individual blocks having more potential to fail.

Well the problem with traditional brickwork is not that the bricks fail, it is that the mortar fails.

Wikipedia:  Brick - Limitations
Starting in the twentieth century, the use of brickwork declined in many areas due to earthquakes. The San Francisco earthquake of 1906 revealed the weaknesses of brick buildings in earthquake-prone areas. Most buildings in San Francisco collapsed during the earthquake, due to the cement-based mortar used to hold the bricks together. During seismic events, the mortar cracks and crumbles, and the bricks are no longer held together.

Hence the move towards concrete with reinforcement steel bars.

With reinforced concrete so far so good but now here's another way to build without mortar as the weak link - with the tessellated I or H tile and brick design you can even do without setting concrete or grout to hold the rebar in place, allowing for very quick assembly and disassembly. Indeed using Dow I-H bricks with their Mazurka dowels you can build structures without so much as a screw thread and a spanner!

[Peter Dow (OP)]

3-Dimensional model video







Tessellated I or H bricks and tiles for stronger, lighter assembled structures (YouTube)

This video shows my model of the 3-dimensional shape of a simple structure composed of 6 bricks or tiles, each of which, when viewed from one-direction anyway, are a 2-dimensional "I"-shape (equally when rotated by 90 degrees "H"-shaped).

This model has been made from aluminium tubing and in order to distinguish one brick from another they have been coloured using marker pens - so there are two bricks coloured blue, two coloured green and two coloured red. This colouring was necessary for clarity because otherwise the permanent joints within bricks (which are only an artifact of the method to make a brick from square tubing) might be confused with the simple touching surface where two neighbouring bricks abut, abutting securely but without being in any way stuck by glue etc.

This 3-Dimensional model reveals a further design feature of the I or H brick and tile structures, which secures the bricks and tiles together in 2 further dimensions, some such feature being necessary because the 2-D I or H shape in of itself only secures the bricks together in 1 dimension.

This feature is revealed here to be nothing more complicated than dowels or fixing rods which run in the vertical direction of the Is (or the horizontal direction of the Hs) through shafts in the Is' bases and tops and which serve to lock the tops and bases of neighbouring Is together, preventing movement radially from the dowels.

[SeanB]

I would say the I shape with a hole so a rod can be put through will be a good strong structure, able to be locked together quite firmly.

An issue will be tolerancing of the units, bricks are capable of a lot of slack due to the mortar, and with modern bricks having a hole through them where you can stack a reinforcing rod you can build a very sturdy structure,certainly strong enough if you use brickforce and tie rods to withstand an earthquake, up to a certain point. If you are making a prefabricated unit a unit compromising a wall width and a height about the same as a current sheetrock panel will be desirable from a handling and design perspective, most architects design to a multiple of the standard wall panel width and height.

[CliffordK]

While one can potentially put rebar through the holes, I don't think it is commonly done.  The holes, however, allow mortar to seep up (& down) into them, and potentially give better binding than bricks without the holes.

My parents house has a 12" brick wall in it. 
2 facings of brick.
Some kind of a wire mesh occasionally put in between the layers to join the two sides and give crosswise support, perhaps every half dozen rows of bricks.
Lots of rebar in the middle.
And filled with concrete.
Most of the doorways & openings also have arches with every brick cut to a taper.

There may be cold joints in the concrete.  I'm not sure why.  Perhaps it was decided that construction of the wall would be better to do in phases, rather than building a hollow wall, and pouring a 30 foot vertical slab in a single step.

[David Cooper]

I see an opportunity with this to use expanded polystyrene instead of metal and to make extremely inexpensive bungalows with good insulation. 90 degree corners would be easy to build, and it would be easy to leave gaps for windows and doors. The roof would be the next challenge (perhaps a dome - the design of "I-bricks" could be shaped to make the walls circular), but again it could be extremely light. The whole structure could then be coated in something to keep the water out and to make it more robust (both inside and out), as well as stopping it catching fire. Ideal for earthquake zones, not only as temporary housing but also capable of housing people safely and comfortably for decades.

[Peter Dow (OP)]

I see an opportunity with this to use expanded polystyrene instead of metal and to make extremely inexpensive bungalows with good insulation. 90 degree corners would be easy to build, and it would be easy to leave gaps for windows and doors. The roof would be the next challenge (perhaps a dome - the design of "I-bricks" could be shaped to make the walls circular), but again it could be extremely light. The whole structure could then be coated in something to keep the water out and to make it more robust (both inside and out), as well as stopping it catching fire. Ideal for earthquake zones, not only as temporary housing but also capable of housing people safely and comfortably for decades.

Well the fire risk is a big issue with expanded polystyrene.

Wikipedia: Polystyrene - Fire hazards
Like other organic compounds, polystyrene is flammable. Polystyrene is classified according to DIN4102 as a "B3" product, meaning highly flammable or "Easily Ignited." As a consequence, although it is an efficient insulator at low temperatures, its use is prohibited in any exposed installations in building construction if the material is not flame-retardant. It must be concealed behind drywall, sheet metal, or concrete. Foamed polystyrene plastic materials have been accidentally ignited and caused huge fires and losses, for example at the Düsseldorf International Airport, the Channel tunnel (where polystyrene was inside a railcar that caught fire), and the Browns Ferry Nuclear Power Plant (where fire breached a fire retardant and reached the foamed plastic underneath, inside a firestop that had not been tested and certified in accordance with the final installation).

Nevertheless David you may have given me an idea for temporary shelters in flood-hit disaster areas, likes of Bangladesh, where it would useful to have raft shelters that, OK you would anchor but, are free to float as the water rises. Expanded polystyrene is about the best there is for building floating things - that's what they give you to hold on to when you are learning to swim. Also, it doesn't puncture like an inflatable raft.


BBC, 2007 - In pictures: Bangladesh floods

[David Cooper]

How well does expanded polystyrene burn if it's nitrogen filled instead of using air? I suspect the main reason it burns so badly normally is that it contains its own oxygen supply.

[SeanB]

Polystyrene burns because it is a hydrocarbon, and the large surface area of the bubbles along with the low melting point makes it burn easily. No way other than covering with an insulation like thick concrete to make it fireproof. however if you build a frame of polystyrene and coat it with chicken wire or steel mesh you can gunite it to make a very strong lightweight concrete structure. Do both sides with gunite and it will be strong, quick to make and well insulated. You do need to mask for doors and windows though unless you are willing to cut them afterwards and compromise the structure.

You do get a polystyrene filled concrete that is used where you want a lighter mass and are willing to lose a little strength in exchange for a much lighter floor panel.

[Peter Dow (OP)]

How well does expanded polystyrene burn if it's nitrogen filled instead of using air?

Firstly, don't assume that the gas in expanded polystyrene is air. Many dictionary definitions will say "air" but what they really mean is "gas", or they never thought about it and just assumed it was air.

Secondly, you can't just order up your preferred gas in the bubbles. It's more difficult and therefore more expensive with certain gases as "blowing agents" than with others.

Thirdly, anything burning near the polystyrene will draw in a fresh air supply by convection so it doesn't really matter what gas is contained inside the bubbles because on the burning surface there is air, with oxygen, so it is going to burn.

I suspect the main reason it burns so badly normally is that it contains its own oxygen supply.

No Sean is closer to the mark.

Polystyrene burns because it is a hydrocarbon, and the large surface area of the bubbles along with the low melting point makes it burn easily.

No way other than covering with an insulation like thick concrete to make it fireproof.

OK but for my floating raft shelter, the expanded polystyrene needs to be under water to provide buoyancy and there it is covered with water to prevent it catching fire. How and where you store your E.P. raft when it is not in use to protect it from fire is another matter. If you were using E.P. I / H bricks and dowels above water to make a light-weight shelter from wind and rain instead of an open raft then obviously you would need an insulating layer.

however if you build a frame of polystyrene and coat it with chicken wire or steel mesh you can gunite it to make a very strong lightweight concrete structure. Do both sides with gunite and it will be strong, quick to make and well insulated. You do need to mask for doors and windows though unless you are willing to cut them afterwards and compromise the structure.

You do get a polystyrene filled concrete that is used where you want a lighter mass and are willing to lose a little strength in exchange for a much lighter floor panel.

Yes. That's a relatively quick and cheap and a tried and tested method, used since the 1960s. Wikipedia: Insulating concrete form.

A strong outer layer to the bricks is needed if the brick is going to be supporting heavy loads, such as floors for people's feet or walls which can support shelves.

Lightweight aluminium sheet is also an option for the outer layer.

I am thinking though that a fireproof fiber-reinforced plastic would be the ultimate high strength-to-weight material for the outer, strong insulating layer - which would also be tough and resist pressure and hold its shape.

Fiberglass, used to make fire blankets, is the fiber of choice I think, to make Glass Fiber Reinforced Plastic - GRP.

If you were very lucky you might find a supplier for GRP square and circular tubing of the right size to make bricks and dowels out of. Otherwise you can make GRP from the fiberglass cloth and resin, which is slow, not so good for mass-production but possible.

GRP commonly uses a plastic flammable resin, burns more easily than concrete certainly, but less easily than bare polystyrene I think.

I would speculate without having researched this at great length and without being able to provide any links to available kits from suppliers that perhaps fiberglass set in a silicone plastic resin would be ideal because then both the fiber and the resin are fire-proof? If that's even possible it must be a lot more expensive and probably too expensive but I don't really know.

[cherrysun]

Wow,so excellent!

[CliffordK]

You can buy spray foam for use as a fire-stop, but I wasn't impressed that it seems to burn quite readily.

Your normal fiberglass as used in roofing, or bathtubs will also burn, releasing a nasty black smoke...  don't ask how I know!  The resin burns out, leaving the glass fibers behind.

A while ago I looked for fireproof cushions to put in front of the fireplace, but pretty much everything I found was "fire resistant", but little was documented as "fire proof".

I think you are right that silicone based products do, in fact, have low flammability.

I don't think I'd be too keen on a "floating house" in most flood prone areas.  It would need a lot of excess buoyancy to hold up the appliances and etc, and not flood the floor.  Like building a house boat on land.

Many floods like tsunamis, and some river associated floods have a strong current associated with them, so a floating house would tend to float away, or if tethered, it would be subjected to extreme stress.

There may be some places, such as in the Amazon where it floods annually, and one might choose to build a type of house designed like a houseboat that could raise and lower with the water level.

Now, I'm not saying that there would not be some need for temporary shelter.  Foam blocks might be unwieldy to ship. 

However, I could imagine a house in a 50 gallon drum (or two).
One drum might contain a double walled tent.  The second drum might contain a spray foam. 

Unpack and inflate your tent.  Then, spray in the foam.  Let it dry overnight, and you would have a good "temporary" structure the next day.  Add a durable outer layer (metal sheeting, or concrete/stucco), and it might actually last fairly well.  Could you reinforce it with fiberglass?

There are also a number of manufactures of foam concrete forms (or insulated concrete forms) which can provide the insulation properties of foam, and mass and durability of concrete and rebar.