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Hi Rami,
It’s not my area of expertise, but I’m fascinated with “robotic 3D construction” and its ability to use traditional materials (although hybrid-modified) like concrete, metals, plastics, plaster, ceramic, and glass. Although not all of these are ready for “prime time” construction, if properly executed, they would seem to fit into the category of “sustainable development”? Now, would it be considered traditional? Possibly, the materials, to some degree, but maybe not. George 
Rami Kaibni
 Community Champion
George, the example you gave is a good example in the sense that using robotic 3D construction can probably reduce waste, and carbon foot print (using less equipment),
The idea behind this question is basically choosing methods or materials that honor traditional practices but have been upgraded for sustainability. I'll give you a simple example: In construction, many do use timber in joinery techniques such as dovetail joints and mortise-and-tenon connections. Instead, recycled or reclaimed timber can be used in these traditional joinery methods which preserves the traditional craftsmanship and also reduces the environmental impact associated with deforestation and timber processing. 
Keith Novak
Tukwila, Wa, USA
Rami,
From a sustainability standpoint, I would say that structural optimization can reduce a lot of waste. My house was built at a time and place where old growth wood was plentiful and cheap so all the structural beams are center-cut timber. Now many would be steel or wooden I-beams requiring far less material. In commercial construction, wooden framing has been primarily been replaced by steel sheet metal studs using very little metal to get equivalent strength. The carpenters use shears instead of saws and the drywall crew saw little difference. Chip or particleboard made from mill waste is often used when the properties of plywood are not necessary. Recycled glass makes beautiful counter tops and glass has great hardness properties. Part of the trick is meeting codes however. With your structures background, I could explain how all the load in an I-beam is in the flanges, the tension side is the critical one, the web is just for shear, and there is zero load at the neutral axis. I would have a harder time explaining that to an inspector from a regulating agency who knows more about what the rules say, than why they were written that way. Keith ...
1 reply by Rami Kaibni
Aug 01, 2024 10:53 PM
Rami Kaibni
...
Keith, thanks for your feedback. While structural optimization can support sustainability, yet, what maximizes this is the use of sustainable material. Using less timber doesn't fully preserve the environment so I would categorize it as a more temporary solution than a permanent one, in my humble opinion.
Rami Kaibni
Community Champion
Aug 01, 2024 8:20 PM
Replying to Keith Novak
...
Rami,
From a sustainability standpoint, I would say that structural optimization can reduce a lot of waste. My house was built at a time and place where old growth wood was plentiful and cheap so all the structural beams are center-cut timber. Now many would be steel or wooden I-beams requiring far less material. In commercial construction, wooden framing has been primarily been replaced by steel sheet metal studs using very little metal to get equivalent strength. The carpenters use shears instead of saws and the drywall crew saw little difference. Chip or particleboard made from mill waste is often used when the properties of plywood are not necessary. Recycled glass makes beautiful counter tops and glass has great hardness properties. Part of the trick is meeting codes however. With your structures background, I could explain how all the load in an I-beam is in the flanges, the tension side is the critical one, the web is just for shear, and there is zero load at the neutral axis. I would have a harder time explaining that to an inspector from a regulating agency who knows more about what the rules say, than why they were written that way. Keith ...
1 reply by Keith Novak
Aug 02, 2024 11:27 AM
Keith Novak
...
Rami,
I completely agree on the use of sustainable materials, however in my own R&D experience, the development of those materials was still heavily dependent on the structural properties. Foam core rigid panels are a prime example. The face sheets take the structural and abuse loads; the foam maintains the shape and transfers shear. With less traditional materials however, less traditional construction techniques become advantageous. Materials like melamine with uniform properties can use traditional joining methods but heterogeneous materials take more consideration in how they are secured. Foam core suspended ceiling panels? Sure. Dovetailed joints? No. You can add rigid edges to solve that problem, but now you have less flexibility in shape before you have trimmed away the structural material. Tooling also becomes a consideration. If you use less wood, but need a 100 ton hydraulic press and matched metal dies for fabrication, how much did you really save overall? The non-traditional construction methods may also be more sustainable. Tensile fabric stadium roofs require far less material than a metal rigid truss structure, while still managing high loads such as heavy snow by using the natural shape the material takes under strain. Another important consideration was flammability properties. Gypsum wall board is very resistant to fire. PVC melts, drips fire, and releases cyanide gas when burned. When investigating new materials I worked closely with both the stress and flammability labs while partnering with fabrication companies to find materials that were strong enough to be useful, but not fatal in a fire, and natural materials can be quite difficult to beat as nature has had billions of years to find the best solutions. It can be quite the balancing act and why I sometimes joke that I have patents in things I can't even spell. 
Rami -
While cost might be prohibitive, I wonder about the opportunity to use composite materials such as Trex as are used on decks for more general purpose building in place of lumber. If there is sufficient demand, more suppliers will emerge and prices will come down. While these composites tend to be made of things like old car tires, if there was a way to do the same using microplastics or shredded plastic it might be a way to deal with the vast amounts of those pollutants. Kiron ...
1 reply by Rami Kaibni
Aug 02, 2024 12:18 PM
Rami Kaibni
...
Kiron, good point. Trex can also be used to Exterior Cladding, Fencing and Railing due to their durability and low maintenance cost.
Keith Novak
Tukwila, Wa, USA
Aug 01, 2024 10:53 PM
Replying to Rami Kaibni
...
Keith, thanks for your feedback. While structural optimization can support sustainability, yet, what maximizes this is the use of sustainable material. Using less timber doesn't fully preserve the environment so I would categorize it as a more temporary solution than a permanent one, in my humble opinion.
I completely agree on the use of sustainable materials, however in my own R&D experience, the development of those materials was still heavily dependent on the structural properties. Foam core rigid panels are a prime example. The face sheets take the structural and abuse loads; the foam maintains the shape and transfers shear. With less traditional materials however, less traditional construction techniques become advantageous. Materials like melamine with uniform properties can use traditional joining methods but heterogeneous materials take more consideration in how they are secured. Foam core suspended ceiling panels? Sure. Dovetailed joints? No. You can add rigid edges to solve that problem, but now you have less flexibility in shape before you have trimmed away the structural material. Tooling also becomes a consideration. If you use less wood, but need a 100 ton hydraulic press and matched metal dies for fabrication, how much did you really save overall? The non-traditional construction methods may also be more sustainable. Tensile fabric stadium roofs require far less material than a metal rigid truss structure, while still managing high loads such as heavy snow by using the natural shape the material takes under strain. Another important consideration was flammability properties. Gypsum wall board is very resistant to fire. PVC melts, drips fire, and releases cyanide gas when burned. When investigating new materials I worked closely with both the stress and flammability labs while partnering with fabrication companies to find materials that were strong enough to be useful, but not fatal in a fire, and natural materials can be quite difficult to beat as nature has had billions of years to find the best solutions. It can be quite the balancing act and why I sometimes joke that I have patents in things I can't even spell. ...
1 reply by Rami Kaibni
Aug 02, 2024 12:21 PM
Rami Kaibni
...
Keith, you bring some very good points. I agree with you. We should have a holistic view on the whole process. Thanks for bringing this up!
Rami Kaibni
Community Champion
Aug 02, 2024 7:22 AM
Replying to Kiron Bondale
...
Rami -
While cost might be prohibitive, I wonder about the opportunity to use composite materials such as Trex as are used on decks for more general purpose building in place of lumber. If there is sufficient demand, more suppliers will emerge and prices will come down. While these composites tend to be made of things like old car tires, if there was a way to do the same using microplastics or shredded plastic it might be a way to deal with the vast amounts of those pollutants. Kiron
Rami Kaibni
Community Champion
Aug 02, 2024 11:27 AM
Replying to Keith Novak
...
Rami,
I completely agree on the use of sustainable materials, however in my own R&D experience, the development of those materials was still heavily dependent on the structural properties. Foam core rigid panels are a prime example. The face sheets take the structural and abuse loads; the foam maintains the shape and transfers shear. With less traditional materials however, less traditional construction techniques become advantageous. Materials like melamine with uniform properties can use traditional joining methods but heterogeneous materials take more consideration in how they are secured. Foam core suspended ceiling panels? Sure. Dovetailed joints? No. You can add rigid edges to solve that problem, but now you have less flexibility in shape before you have trimmed away the structural material. Tooling also becomes a consideration. If you use less wood, but need a 100 ton hydraulic press and matched metal dies for fabrication, how much did you really save overall? The non-traditional construction methods may also be more sustainable. Tensile fabric stadium roofs require far less material than a metal rigid truss structure, while still managing high loads such as heavy snow by using the natural shape the material takes under strain. Another important consideration was flammability properties. Gypsum wall board is very resistant to fire. PVC melts, drips fire, and releases cyanide gas when burned. When investigating new materials I worked closely with both the stress and flammability labs while partnering with fabrication companies to find materials that were strong enough to be useful, but not fatal in a fire, and natural materials can be quite difficult to beat as nature has had billions of years to find the best solutions. It can be quite the balancing act and why I sometimes joke that I have patents in things I can't even spell.
Keith Novak
Tukwila, Wa, USA
I do apologize if I geek out on this subject a bit. Studying it professionally for a few years left me with definite opinions. :-)
Trex is the perfect example of picking the right application for the material and the engineering tradeoffs. It can be manufactured from some of the worst waste plastics, and it is maintenance free but it is also more flexible than wood and requires twice the floor joists. That is one of the things that haunts you in business cases because you eliminated the wood in the decking, but need more larger center cut timber from older trees to support it. When you have thermoplastics that you can melt down and reuse, you can tailor the chemistry a lot, but fundamentally the molecules have weak bonds between each other so they tend to lack in strength. You can help that a few ways like adding glass fibers, but you're still fighting the chemistry. Engineering becomes more important to find the right applications. By contrast, thermosets (think spray foam and epoxy) are created by a chemical reaction where the molecules are cross-linked. You can't melt it back down because the reaction created a new material, but the properties are very customizable and it eliminates a lot of expensive manufacturing processing as a different angle at sustainability. Almost everything you see in your car interior from the headliner to the door panels with all the wires and switches embedded came out of a low temp and pressure mold for that reason. It produces more landfill waste but eliminates a lot of parts and processing steps that require energy to make and assemble. The Trex type of materials make great trim, cladding, fence posts and panels where things are not loaded in bending. If you tried to build a fence the traditional way though where horizontal wooden beams span between posts to support the vertical slats, those would quickly sag so instead the loads are are carried by the flat panels themselves, not with 2x4 beams (or 47x100mm for your metric countries) between the posts. As they say, the devil is in the details, or to mix metaphors, there's no such thing as a free lunch. The materials have some very desirable properties, but still require creative engineering to get past the non-desirable properties. That's where the problems come in for the PM trying to optimize for sustainability. As one variable improves, like use of recycled materials, another gets worse, such as engineering costs and manufacturing processing. ...
1 reply by Rami Kaibni
Aug 03, 2024 4:56 PM
Rami Kaibni
...
Keith, you don't need to apologize. I actually want to thank you for this great feedback as I learned something new from it. Very interesting!
Rami Kaibni
Community Champion
Aug 03, 2024 1:24 PM
Replying to Keith Novak
...
I do apologize if I geek out on this subject a bit. Studying it professionally for a few years left me with definite opinions. :-)Trex is the perfect example of picking the right application for the material and the engineering tradeoffs. It can be manufactured from some of the worst waste plastics, and it is maintenance free but it is also more flexible than wood and requires twice the floor joists. That is one of the things that haunts you in business cases because you eliminated the wood in the decking, but need more larger center cut timber from older trees to support it. When you have thermoplastics that you can melt down and reuse, you can tailor the chemistry a lot, but fundamentally the molecules have weak bonds between each other so they tend to lack in strength. You can help that a few ways like adding glass fibers, but you're still fighting the chemistry. Engineering becomes more important to find the right applications. By contrast, thermosets (think spray foam and epoxy) are created by a chemical reaction where the molecules are cross-linked. You can't melt it back down because the reaction created a new material, but the properties are very customizable and it eliminates a lot of expensive manufacturing processing as a different angle at sustainability. Almost everything you see in your car interior from the headliner to the door panels with all the wires and switches embedded came out of a low temp and pressure mold for that reason. It produces more landfill waste but eliminates a lot of parts and processing steps that require energy to make and assemble. The Trex type of materials make great trim, cladding, fence posts and panels where things are not loaded in bending. If you tried to build a fence the traditional way though where horizontal wooden beams span between posts to support the vertical slats, those would quickly sag so instead the loads are are carried by the flat panels themselves, not with 2x4 beams (or 47x100mm for your metric countries) between the posts. As they say, the devil is in the details, or to mix metaphors, there's no such thing as a free lunch. The materials have some very desirable properties, but still require creative engineering to get past the non-desirable properties. That's where the problems come in for the PM trying to optimize for sustainability. As one variable improves, like use of recycled materials, another gets worse, such as engineering costs and manufacturing processing. |
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