Thoughts on the Engineering Industry

A blog covering engineering, technology and business topics

Archive for the tag “Technology”

An Innovative Technology for Concrete Roofing in Remote Areas

     Hello everyone! I hope y’all are doing well.  I’m almost done with grad school and looking forward to that.  Other than that, nothing much has happened.  Today, I would like to discuss a recent development in concrete roofing for remote areas.

     Scott Hamel, a faculty member of UAA (University of Alaska Anchorage), has developed a concrete roofing tile that can be used in place of cast in place concrete roofs.   While working with Habitat for Humanity in Port-au-Prince, Haiti, Hamel noticed that the prefered method of roofing is a cast in place concrete slab because it can double as a second floor if needed and was more resistant to the wind and elements.  However, these roofs weren’t adequately designed in regards to seismic issues and this caused a lot of trouble in the Haiti earthquake of 2010.  Additionally, the usual method for constructing these roofs is to carry up the concrete manually to fill the form work for the roof which is highly labor intensive.  These two combined issues lead him to create an innovative new system for creating concrete roofing.  It is concept that was widely used when making clay roofing tiles up until the 1950’s when improved techniques become more common.  He created a “thin shell, latex modified concrete barrel roof unit” – curved concrete roofing tile in which latex from old paint is added to create to increase flexibility.  To build the concrete shell unit, a mold was designed and the modified concrete is poured in to the mold with mesh metal reinforcement located in the center of the cross section.  Testing is being conducted to determine the optimal shape in regards to stresses and construction applications.

     There are several benefits to using this type of roofing system.  The main one is ease of construction in my opinion.  The roof tiles can be made on site on the ground or off site and easily be taken up a ladder to be put together on the roof.  Another benefit is the cost; according the article the tile will cost $2 – $3 per a square foot versus $6 – $10 per a square foot for cast in place concrete.   The other benefit I find very useful that isn’t mentioned in the article is that it is easily repeatable.  Someone with very little experience can build a safe roof and when there is a crisis like a natural disaster a large quantity of these concrete tiles can be built very efficiently on a larger scale as well.

     Do you think this would be a good roofing system for a remote area?  What if any issues do you foresee?  Are there any other applications this could be useful for as well?  Thanks for your time and have a good week!


Kathleen, McCoy, “Hometown U: A Smarter, Stronger Roof Design for Haiti and Beyond”, Hometown U, March 1st, 2014,


Concrete Eating Robots: A More Efficient Method of Breaking Down Concrete?


     Hello everyone.  I hope everything is going well.  I had a good Easter weekend with my family and I’m feeling rested after a busy week.  Today, I would like to talk about an innovation I read about a few weeks ago which is called a “Concrete Eating Robot” as described in a blog post by Peloton Land Solutions.

     The Concrete Eating Robot is a system which uses a high pressure water jet to break down concrete rather than using a wrecking ball or something else to crush concrete.  The water/concrete slurry is then collected to reclaim the reusable materials.  The clean aggregate can be used in other concrete mixes.  The water is reused by the system so that a large of amount of water isn’t wasted in the process.  And the clean and reusable rebar beneath the concrete can be pulled apart for use in other structures.  The only waste that I could find according to the article by Peloton Land Solutions is the cement mixture that can’t be reused.

     This invention has some very good benefits in that the rebar and aggregate can be reused in a very efficient manner.  However, cement is the least sustainable product required for concrete construction.  And in this case, I didn’t see a method for recycling cement which could make this a critical issue.  Depending on the situation, this could negate some of the benefits to the point that this invention might not be worth the investment.  For example, if this is a case where a high amount of cement is required and aggregate can be easily procured locally for any new construction, the cost benefit ratio might tilt back towards a more traditional method.  If this is a low to zero cement usage concrete in an area where the required aggregate isn’t easily obtainable, this would be a better situation for something like this.

   Here is a more detailed article on the device:

   What is your opinion on this invention? Do you see it being used regularly in the future?  Thanks for your time and have a good week!


Peloton Land Solutions, “Concrete Eating Robots?”, March 3rd, 2014,

CoExist Blog, “This Concrete Eating Robot Can Recycle an Entire Building on the Spot”, April 16th, 2014,

High Performance Energy Saving Design for the Karuna House – Window/Door Design

Passive House Green Home Building Tips: Karuna House Windows & Doors

Hello everyone! Today I would like to go back to my series of posts outlining the design and construction of the Karuna House.  The topic for this post will be the selection and resulting benefits of the improved windows and doors.  Windows and doors are the biggest holes in the building envelope above ground.  These innovations are what allow the HVAC systems to reach their maximum efficiency.  Additionally, windows and doors are also a major aesthetic concern and these aesthetic factors play a big role in the decision process.

The Karuna House uses triple glazed, high solar heat gain, R-8 windows with a very thin frame.  This type of window has an increased level of heat gain, but significantly improves the building envelope by allowing additional insulation to be placed around the frame.  The triple glazed window also has a well documented performance history because it has been in use since the 70’s in Scandinavia.  For the exterior doors, the Karuna House uses Optiwin doors.  These doors are thick with insulation in the middle and airtight with multi-locking mechanisms to ensure a tight seal.  To help with the heat gain issue for the windows, a shading system that can be lowered over the windows was installed.  This has an additional benefit of being modern and aesthetically appealing.  The triple glazing also provides a very clear view through the glass which adds to the modern, aesthetic appeal.  To further improve indoor conditions, these windows and doors increase comfort by reducing the draft found near the window and door openings.  All of the benefits above combine to reduce the impact on the mechanical systems which allows for a simpler, more efficient system to be used.

Overall these systems are simple and nothing too complex.  However, these systems apply the same philosophy that is applied to the building envelope in general – simple and efficient solutions to problems.  Furthermore, the philosophy applied to the building envelope, windows, and doors altogether should reap a lot of benefits for the mechanical systems and the energy usage correlated to that.  The take away here is very similar to the previous post on the Karuna House – a little a effort put into finding cost efficient improvements to small elements of the house can improve the overall efficiency a lot.

What do you think about the window and door improvements on the Karuna House?  Are there any issues that need to be addressed or  improvements that can be made?  Thanks for your time and have a good week!


Hammer & Hand,”Karuna House: Windows and Doors”,

Basic Overview of the Hyperloop

Hello everyone, I hope y’all are doing well.  I’ve taken a bit of a vacation, both literally for a weekend, and then for longer in regards to my blog.  I feel guilty but it just felt like the right time to do something like this.  Nothing else new has really been going on with me – still just looking for work as an engineer and keeping my resume up to date.  I have taken the time to really learn Revit which should help me and my next big to do list in regards to personal learning is getting sharp on AutoCAD again.  One fun thing is that I’m also working harder on getting my Spanish to a conversational level, it would really be nice if I could put that on my resume too although not as important.  I will also start working as a substitute teacher again and I hope that won’t cut into my job hunt and personal job training right now.  We’ll see how that goes.  Anyways, that’s about all as far as updates go – today, I want to talk about the recent Hyperloop Alpha Proposal published by Elon Musk (founder of Paypal, SpaceX and Tesla Motors).  It has created quite the stir in the engineering community and I thought it would be a good topic to come back on. For this blog post, I am going to reference Elon Musk’s Hyperloop Alpha Proposal (  However, this is a complex enough idea with enough attention that I might do some more detailed analysis in another blog post.

The hyperloop is a combination of a maglev and vacuum tube system.  Similar concepts have been proposed by Rand Corporation and ET3.  The main difference is that the previous designs involve using a hard or near hard vacuum in the tube; however, the Hyperloop uses a low pressure system.  The low pressure system is supposed to be much easier to maintain using standard pumps and maintenance than a hard vacuum.  The propulsion system involves a combination of air pumps and magnetic levitation.  An air pump will be put in the front of the train and will pump air below and behind the train.  This will accomplish several things: reduce air pressure in front of the train, create a buffer of air below the train, and reduce drag behind the train.  A pump will also be used directly below the train to reinforce the buffer of air as needed.  The maglev system will propel the train forward and will be powered by a battery similar to the battery found in the Tesla Model S.  There are two options for the size and purpose of the train: one is a smaller passenger train and one that is a larger passenger train that can also carry several vehicles.  The Hyperloop is theoretically designed to travel at 700 mph according to the proposal.  However, the critical part of this design not the propulsion system but the tube system.  The proposal suggests a tube system that is supported above ground using precast reinforced concrete columns that would take up no more room than a power line pole would require.  The track would follow the I-5 Highway and only deviate from the highway when necessary.  Also, due to changes in elevation, it is estimated that the tube would occasionally have to be placed at or below grade.  The track would be stabilized using dampers and minor adjustments would be allowed for to account for foundation settlement.  The different sections track would be connected using expansion and contraction joints that would help account for lateral loads due to earthquakes and other lateral vibrations.  The rest of the report is numbers and calculations used for estimation and comparison in regards to other systems.  The specific numbers and calculations read like a rough estimate and aren’t worth discussing in this post in my opinion; however, I would recommend quickly browsing the numbers and calculations just to get a quick idea about the comparisons to other modes of transportation.  Elon Musk in closing goes on to list the critical issues that need to be considered to implement the idea:

“The authors recognize the need for additional work, including but not limited to:

1. More expansion on the control mechanism for Hyperloop capsules, including attitude thruster or control moment gyros.

2. Detailed station designs with loading and unloading of both passenger and passenger plus vehicle versions of the Hyperloop capsules.

3. Trades comparing the costs and benefits of Hyperloop with more conventional magnetic levitation systems.

4. Sub-scale testing based on a further optimized design to demonstrate the physics of Hyperloop.

Engineering News Record wrote an article ( recently sharing some professional critiques.  The first one is a quote from an unnamed source:

“Many media sources offer commentary from professors about the impossibility of the hyperloop. One of those same sources told ENR off the record that “the idea of building a $68-billion rail line that takes 25 to 30 years to complete is just as absurd.””

They go on to say that Elon Musk has addressed the issue that testing and further research is required, but that some blow back has come his way for that.

“Other media critique Musk for being only an idea man who is hiding behind his massive business responsibilities and not moving toward implementation of the hyperloop. Musk admits as much in his proposal and, noting that the hyperloop idea is not complete, asks for help from “all members of the community.””

The article then goes on to share some thoughts Ted Zoli of HNTB, National Chief Bridge Engineer.

““Just the substructure costs alone for elevated structure over the entire length of the alignment is enormous,” says Ted Zoli, national bridge chief engineer at HNTB. The hyperloop’s proposed design requires elevated piers every 100 ft. Zoli says if the structure was built instead at grade, the construction costs could be “sharply reduced.” He adds that it conceivably could be built at grade for much of the route, “particularly if it is in the median of I-5,” which is where Musk envisions much of the transit tube being placed.

Zoli suggested that, given the hyperloop’s 88-in.-dia passenger pipe, any necessary tunneling could be done with horizontal directional drilling (HDD), “an inexpensive pipe installation technique.” Zoli adds that the largest HDD done now is 56 in. in dia, but he thinks custom HDD equipment readily could be developed, given the size of the hyperloop project.””

In closing, a final addition to the list of concerns is added in reference to another comment by Ted Zoli.

“5. A closer look at expansion joints.

“The expansion joints have not been figured in, in any meaningful way, and would be required much more often than at the terminal stations [as the current proposal outlines]. I would expect something on the order of every mile or thereabouts, even with a telescoping connection. Bearings would also have to accommodate relatively large relative movements for this distance between expansion joints,” says Zoli.”

In my opinion, there will be several critical issues if this is pursued.  The main one is the tube system in regards to column supports or on grade and expansion and contraction joints.  Given the high portion of the budget it involves, the high maintenance cost, even if it is designed well, could make it infeasible.  That combined with the earthquake and dynamics issues make that the most critical issue.  Another possible issue is testing – this is a system that has never been used on this scale before and would need significantly more testing and research to make a final decision, both of which cost money and won’t magically happen overnight.  And the final issue I see that has not been mentioned in the article at all is the reticence of the government to use unproven systems.  Take a look at how long it has taken to get high speed rail going in California and that is a system that has been proven to work for a couple decades in other countries.

Well this post got longer than I expected for my first post back in a while but thanks for reading if you got to this point.  What are your thoughts on the Hyperloop?  Do you have any concerns about the hyperloop?  Do you think this system can realistically be designed and implemented?  Thanks for your time and have a good week.

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