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  • 1.  Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-15-2018 12:42 PM

    I serve, as one of a group of advisers, for a confidential project with a short-term goal of 3D printing, as a demonstration, another concrete house in the U.S.  Based on what I have learned so far (two months), large-scale 3D printing could explode within civil engineering in the next few years, although maybe not in the U.S.

     Elon Musk and his crew of engineers land rockets in reverse and reuse them. In the same spirit of creativity/innovation, maybe the U.S. civil/construction engineering community can 3D print, in concrete and other materials, pre-cast components of buildings and other structures and entire buildings and other structures. By "other structures" I mean essentially everything we now do in formed concrete and beyond.

     Why try to do it?

     *  Reduce construction costs (less manual labor, less material, less wasted material, less energy use, etc.)

     *  Produce structures that are more resistant to natural disasters and terrorism (e.g., use new materials and stronger shapes/configurations)

     *  Slash prototyping time and fail faster

     *  Increase construction site safety

     *  Reduce construction time

     *  Customize each product

     *  Produce a whole new set of tech and other jobs (educators-trainers, structure designers, building code experts, programmers/coders, robot designers-manufacturers-transporters-operators-maintainers, finance experts, site acquisition specialists, government regulations/relations personnel, etc.).

     *Provide greatly improved affordable housing in the U.S. and around the globe.

     

    I am finding, as I suspect you have, that small 3D printers are showing up everywhere -- in K-12 schools and in universities, in public libraries, in homes, etc.  Use of larger 3D printers is taking off in manufacturing. In that sector, it is sometimes referred to as additive manufacturing, in contrast with traditional reductive manufacturing (e.g., milling, turning, boring, etc.).

     My hope is that some of you -- maybe "off the top of your head" -- can answer this question: Who, in mostly U.S. engineering academia or practice is studying/teaching/researching/developing large-scale 3D printing within the civil/construction engineering field?

    In addition, any thoughts you may have would be appreciated.

    Thank you.

     



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    Stuart G. Walesh Ph.D., P.E., D.WRE(Ret.), Dist.M.ASCE, F.NSPE
    S.G. Walesh Consulting
    219-242-1704
    stuwalesh@...
    www.HelpingYouEngineerYourFuture.com
    Author of Introduction to Creativity and Innovation for Engineers, 2017, Pearson
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  • 2.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-16-2018 11:56 AM
    Hi Stuart,

    At Oak Ridge National Lab, a US Department of Energy science and engineering laboratory, we are researching large-scale flexible systems for 3D printing concrete.  A few projects have been completed printing non-load bearing concrete pieces, and we are ramping up research on load bearing segments and on printing large scale molds out of low-cost carbon fiber that can be used to develop pre-cast concrete structures.  I am researching how these techniques could be applied to hydraulic structures.

    For more information you can email me or visit the Manufacturing Demonstration Facility website.

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    Adam Witt, Ph.D., A.M.ASCE
    Hydropower Systems Research Engineer
    Oak Ridge National Laboratory
    865-241-7361
    wittam@...
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  • 3.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-17-2018 04:34 PM
    I am curious how this technology satisfies tensile strength.  Conventional construction of concrete structures uses rebar.  Also, concrete masons etc. might not be too happy if this takes off.

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    Mark Westover P.E., M.ASCE
    Silverdale WA
    (360)373-5677
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  • 4.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-18-2018 10:01 AM
    Edited by Tirza Austin 05-18-2018 10:00 AM
    Hi,

    I was thinking the same thing as Mark regarding the rebar. I think there was an article in ASCE magazine a while back about a machine used to automatically place rebar on a bridge project. I wonder if you could combine the two machines in some way to automate the entire process?  Or is there another material like carbon fiber that could be used to replace the rebar?

    I hear you about the masons. I wonder though if they would be become the O&M and programmers of the machines in the field in the future like the machinists at the auto factories?

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    Ronald Burns P.E., M.ASCE
    Principal Engineer
    Brookline MA
    (617)202-6278
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  • 5.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-21-2018 11:33 AM
    Edited by Tirza Austin 05-21-2018 11:33 AM
    Mark and Ronald mention the possible response of masons and other skilled concrete workers in response to the likely arrival of large-scale 3D printing of what are now precast structural elements and, in some cases, entire structures.

    As with any major change, I expect initial strong negative reactions. And then, gradually, individual skilled workers and unions will begin to see the value in learning how to be part of the new technology. Experts will be needed to design, construct, program, operate, maintain, and transport robots.

    Once robots become operational to the point that they can be used to efficiently construct entire houses (individual houses are being 3D printed now), they will be seen as a way to solve housing problems in developing countries. Teams of experts from, say the U.S., would travel with robots and other equipment to a given country and work with locals to prepare a site and then mass produce hundreds of basic houses. 

    Meanwhile, some members of the U.S. construction industry will ask, why are we still using forms to construct concrete structures?

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    Stuart Walesh PhD, PE
    S.G. Walesh Consulting
    stuwalesh@...
    www.HelpingYouEngineerYourFuture.com
    219-242-1704
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  • 6.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-22-2018 10:32 AM
    Edited by Tirza Austin 05-22-2018 10:31 AM
    In this example from ICON out of Austin, TX, it looks like they are not using any rebar but that they are building the walls with a corrugated internal design sandwiched between 2 straight concrete walls.  Probably fine in this application of a 1-story building.  Notice that they used wood beams for the roof.  I doubt this design would work if you laid it on its side.  I suppose you could also use glass fiber reinforced concrete to add a little bit of bending tensile strength.  I do not see a way that this process could work with a traditional rebar design but I have not put too much thought into it.

    https://singularityhub.com/2018/03/18/this-3d-printed-house-goes-up-in-a-day-for-under-10000/

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    Christopher Casebeer P.E., M.ASCE
    Project Manager
    Houston TX
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  • 7.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-23-2018 09:44 AM

    Chris,

    Thanks that is an interesting example. I would be curious to see the structural data on the walls. I noticed that they used  exterior steel beams for the roof. So  my guess is the concrete walls do not have enough strength to support the roof and  associated wind loads, etc...  But this  is just the beginning and the fact that it got permitted is great.

    Thanks, Ron

    ------------------------------
    Ronald Burns P.E., M.ASCE
    Principal Engineer
    Brookline MA
    (617)202-6278
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  • 8.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-23-2018 09:45 AM
    Christopher:

    Thank you for sharing information about ICON's project. Note that they plan to use large-scale 3D printing to build a 100-home community in El Salvador.

    Regarding rebar. While it is not needed for a one-story building, it could be used to secure the roof against severe weather. Prior to placing the concrete walls, vertical rebar could be installed in the concrete foundation and aligned with the eventual walls. Then concrete walls could be 3D printed around the rebar. When the walls are completed, the roof structure could be attached to the protruding rebar.

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    Stuart Walesh Ph.D., P.E., Dist.M.ASCE
    S.G. Walesh Consulting
    stuwalesh@...

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  • 9.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-24-2018 01:14 PM
    I have a hard time taking 3-D printing of houses seriously. It may have value in some structural applications, but in housing there just isn't much potential cost benefit. Many years ago, when I was discussing packed earth, straw, and other "green and cheap" buildings, it was pointed out to me by an architect friend that the exterior walls of a house only accounted for 10% of the cost. Floors, windows, roofs, mechanical and interior finishes were the main cost drivers. Somebody needs to address the true economics of a given application before we get too excited.

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    Glenn Brown P.E., D.WRE, F.EWRI, M.ASCE
    Granby CO
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  • 10.  RE: Large-scale 3D printing of precast and cast-in-place concrete

    Posted 05-25-2018 11:17 AM
    Edited by Tirza Austin 05-25-2018 11:17 AM
    ​We have been using Cadd/Cam to design homes since the 1990s. This is just a natural continuation of those processes. The outside of the home may only be 10% of the cost and materials, but it is 40-50% of the time. Reducing the amount of effort to 20% would be a significant benefit.

    In low income places where the aUS style mansion is not the standard, premanufacturing or standardization of the shell would have an even greater impact on price/time.

    Think back to the time when people would get together and construct a home for newlyweds during the honeymoon.


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    Dwayne Culp, Ph.D., P.E., P.Eng, M.ASCE
    Culp Engineering, LLC
    Richmond TX
    (713)898-1977
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