Three Common Causes of Differential Foundation Movement

Hello everyone, I hope you guys have been doing well. I’ve been a bit busy lately, but now that I’m caught with my work and various other stuff, I have decided to continue with the theme of foundation movement.  Last time, we talked about cracks in the finishes of the house – I would like to now move onto some of the root causes of the foundation movement.

At its most basic level, most foundation movement is caused by change in the moisture content and resulting expansion/contraction of the soil supporting your house foundation.  Depending on the amount of clay or fill soil on your property, the resulting differential movement can vary by location and magnitude.  In some other cases, it is a failure of the foundation structure; it is far less common and in most cases associated a pier and beam foundation.  Even then, most of those failures I’ve seen were affected in some way by moisture content of the air/soil within the crawlspace.  Having said all that, today I will discuss the effect of soil moisture content as it is the prevalent cause of foundation movement.

Tree Roots within the Vicinity of the Foundation

The most common cause of foundation movement I see is the result trees affecting the moisture content of the surrounding soil.  In times of relative drought, the tree roots will absorb more water in the soil and decrease the relative moisture similar to surrounding areas.  In times of more rainfall, the dry soil will then expand and change the relative soil level again.  In general, tree roots extend an additional 50% further from the trunk than the outer canopy.  If the tree roots extend under your foundation, the soil under your foundation will expand differentially to surrounding areas depending seasonal rains.  The cracks resulting from this foundation movement will typically expand and contract, or reopen when patched.  Differential movement associated with tree roots can be reduced by placing a root barrier around your foundation and maintaining a regular watering program around your house.

Site Drainage

As with the trees, various site drainage conditions can cause water ponding and result in different soil moisture contents around your foundation.  As a result, the soil in areas with increased amounts of water will expand more than the soil in other areas.  Similar to the tree rot conditions, the level of the foundation and resulting cracks will fluctuate depending on the amount of seasonal rains.  Differential foundation movement associated with site drainage can be reduced by maintaining an adequate slope around the perimeter of the foundation so that the site drainage will allow water to flow around and away from your house.

Plumbing Leaks

Water from plumbing leaks can also cause the expansion of soil, typically within an isolated area.  Depending on the size and frequency of the leaks, the leaking water can cause differential foundation movement and result in interior distress associated with that movement.  In most cases, the soil expansion and differential movement does not extend far from the leak location and will not result in wide spread foundation movement.  In addition, the soil will typically contract back to it’s original volume once the leak is repaired.

Given this short outline, I hope that you can get a basic idea of what is causing the differential foundation movement you are having and how to address the issue.

What has been your experience been like in dealing with differential foundation movement?  For the people inspecting foundations, I’d be interested in hearing about your stories as well, since I still definitely have a lot more I could learn on the topic.  If you enjoyed my post, hit the like button, follow my blog for updates and share this post with your friends.  Thanks for reading and have a good week!

Using Cracks in Gypsum Board to Assess Foundation Movement

Hello everyone – I hope you have been doing well. I know I’ve been away awhile but I plan on doing more these blog post again.  The truth is that I got away from it because I wanted to rethink my blog goals, topics, and general post structure and scope. I’ve decided that I would like to refocus my blog on topics I deal with as a forensic engineer, and keep the blog posts simple and focused on a specific topic.  We’ll see how this new blog structure works out in the next month – feel free to leave some comments on how you like it.

With that update out of the way, I would like to jump into our topic for today – gypsum board cracks in a house and how it relates to foundation movement.  A fair number of the house inspections I do involve assessing these conditions and determining if there is a correlation to any possible foundation movement.

In my experience, cracks in the gypsum board finishes of a house fall under two categories – tapered cracks, and expansion/contraction cracks at gypsum board joints.

Expansion/contraction cracks are visible in most houses – most commonly in the garage due to increased outside exposure along with the relatively less insulated and/or finished conditions.  However, these cracks can occur in other areas of the house as well.  These cracks will typically be horizontal or perpendicular in orientation, have an even gap across the length, and be patterned at typical lengths/spaces of gypsum board joints or at wall-to-ceiling and wall-corner joints.  These cracks are not directly correlated to foundation movement in most cases and are instead the result of the expansion and/or contraction of the gypsum board.

Tapered cracks, usually at doors, windows, and ceiling and wall joints, are visible in most houses as well.  These cracks typically extend diagonally at susceptible areas when not at wall or ceiling joints and are indicative of some form of foundation movement.  It is more common to see these tapered cracks in houses with a concrete slab foundation due to the foundation resting directly on ground which makes them susceptible to seasonal fluctuations of supporting soil.  However, these cracks can be present in any house depending on their construction and conditions of the surrounding lot.

When discerning the cause of the gypsum board cracks, these inspections also require the correlation of the location and relative age of the cracks to measured low spots or high spots.  When my company performs these foundation inspections, we use a compulevel to determine relative differential movement of the foundation.  If a crack is located away from a high spot or low spot, it typically indicates that it is either expanson/contraction related or the result of foundation movement that has occurred previously and has since leveled again.  In addition, if paint or significant amounts of dust/debris are present in the cracks, it usually indicates that the crack has been present for a relatively longer period of time (depending on when the interior finishes were last painted).   Using the above information, we can determine which cracks are the result of relative foundation movement and how long the possible foundation movement has been occurring.

While most of you probably don’t have access to the equipment to find a relative floor elevations and measure differential movement, this information should help when initially assessing the cause of gypsum board cracks, and also help in understanding the foundation inspection process.  I will probably write a few more blog posts covering the basics of foundation inspection, so feel free to ask me any questions you have and I will answer them if I can.  I would also like to hear from people in the inspection business as well.  For those with inspection experience, how do you assess gypsum board cracks in relation to foundation movement?  If you enjoyed my post, hit the like button, follow my blog for updates and share this post with your friends.  Thanks for reading and have a good week!

Four Basic Steps to Determine if your Shingle Roof Has Been Damaged by a Hail Storm

Hello everyone, I hope your weekend went well.  I went to see the new Bond movie with my brother Friday and last night I went to a west coast swing dancing class and social event.  Other than that, I’ve been doing my usual stuff like working out and my job inspecting buildings.  Today, I’ve decided to write a blog post explaining four basic steps to determine whether a composition shingle roof has been damaged by a hail storm and quantify the extent of damages.  I’ve avoided this topic for two reasons: one is that there is a lot of information out there about this already, and the second is that it takes some prior experience to make an accurate assessment.  However, it is one major component of my job and I feel like I can provide some practical information that will help you should you need it.

1) Look for spatter marks on surrounding surfaces (http://goo.gl/COQH3i)

Spatter marks serve as a indicator of the size and direction of the recent hail.  The size of the spatter can be compared to the impact marks elsewhere to determine the extent of recent damage.  The directionality can be determined as well by figuring out which directional faces have or do not have spatter.  In addition, spatter will fade over time – this can differentiate between different ages of spatter marks within a recent time period in most cases.

2) Look for impact marks at susceptible surfaces (http://goo.gl/m15Wmc)

Impact marks can also be observed on some metal and wood surfaces.  Air-conditioning units are a good indicator due to the fact that they have 4 sides and metal/coil fins that are either soft or oxidized.  Spatter can be observed as mentioned before, as well as indentations.  Furthermore, the indentations can be examined to check for soiling, oxidation, or other forms of staining to determine the relative age of the older indentations.

3) Look at the general condition of the roof (http://goo.gl/7p5Yul)

The general condition of the roof will also affect the extent of hail damage.  Examples of other things that damage shingles aside from hail are general weathering, mechanical scrapes, blistered asphalt, and raised nails.  A roof with a worse general condition will be more susceptible to damage and could reduce the compensation should you involve the insurance company, similar in practice to automobile insurance compensation.

4) Look for hail impact marks and examine their condition/quantity (http://goo.gl/2nguV8)

The last step is to look for hail impact marks on the shingles.  Sometimes a relative age can be determined by checking for weathering of the reinforcement or asphalt within the exposed asphalt/shingle reinforcement.  To quantify the extent of damage, you can count the number of recent and/or old hail impact marks, as well as other general conditions if desired, withing a 10′ x 10′ square.  This is referred to as a test square by engineers and inspectors in the roofing business and is helpful information when estimating the cost of various types of repairs.

These 4 steps are the basic process I use to determine the extent of damage to a shingle roof.  Does anyone else have experience in roof inspections?  If so, what would you add to this list as a basic procedure?  For homeowners, have you had to deal with an issue like this before and how was the experience?  If you enjoyed my post, hit the like button, follow my blog for updates and share this post with your friends.  Thanks for reading and have a good week!

Image source

http://goo.gl/1MbnTT

Incorporating Engineering into Government to Improve National Programs

Hello everyone, I hope y’all have been doing well.  Today I would like discuss ways to improve our country by involving engineers and engineering concepts in the management of our national systems.  I have narrowed it down what I believe to be the 5 basic ideas.  As a reference, I have used data and assertions made by Evan Twarog in an article describing the role technocracy in China.

1) Become more technocratic in regards to politics

Data shows that the government is mostly run by engineers in China and in the government in the US is mostly run by lawyers.  In addition, Chinese people believe that knowledgeable elite should run the government which led to a technocracy being a part of the political system.  Based on the way government seems to operate in the US, I could see a shift towards the concept technocracy being beneficial for the U.S. as well.  Especially considering some of the issues that confront us, such the deterioration of the infrastructure, climate change, drought in various areas through out the country, and the production of energy in regards oil, wind, solar, etc.  A technocracy provides the critical knowledge and skill sets to properly deal with these issues.

2) Any problem can be solved with an engineering mindset

Engineers have a unique skill set that allows them to solve problems through a standard process.  On a personal level, I apply this mindset to difficult decisions in my life.  I bet you a lot of engineers say the same thing.  I don’t know about them but it works well for me.  And when considering the successes and failures of both China and the U.S., a correlation between the application of technology and the engineering mindset can be observed.  A good example of that in the U.S. is the space program and national arms race in general.  It is this correlation that leads to believe that the engineering problem solving mindset would be a good framework to apply to struggling government processes and programs.

3) An education in a technological field is more respected by society

For years, the culture in China has valued being technologically informed.  This means that changes in the direction of the country are more easily understood and communicated to the masses.  This is not to say there aren’t people capable of doing that here in the U.S., but there still seems to be a large portion of the political system that caters to the lowest common denominator instead of embracing the intelligence of the U.S. population.

4) Some projects need support from the government to succeed

A lot of the great engineering accomplishments require a large amount resources to back them up.  There are very few people and companies that can fully implement these systems.  This means that if there is some technology or engineering program that would improve our country and it is sufficiently large enough that it would be difficult for private organizations, government should not be afraid to step in and help.  If applied with an engineering problem solving mindset and backed by an informed public, these projects should benefit the country overall.

5) Export your technology for economic profit

This is where the practicality of investing money in solving these problems is realized.  In a perfect world, providing infrastructure and services to improve the lives of people is enough.  But government cannot be expected keeping doing so if it cannot be maintained as far as resources are concerned.  This means that sharing the technology nets the government money which can be used to further improve in other areas.  Business concepts like public-private partnerships were designed to improve profits and gains for the country through the development of these infrastructure and service ideas.  If we can keep this end goal in mind, it can ensure that all government systems improve the country socially and economically.

What is your opinion on these 5 concepts?  Is there anything you would add or take away and why?  If you enjoyed reading the blog post, be sure to like the post and share it with your friends.  Thanks for your time and have a good week!

Source

“The Three Gorges Dam, Why China is Run by Engineers”, Twarog, Evan, Atomic Insights, April 13, 2015, http://goo.gl/sZf3Zn

3-D Printed Buildings Elements Created from Building Construction Waste

     Hello everyone, I hope y’all have been doing well.  Today I would like to talk about an improved application of 3D in building construction.  For a while now, 3-D printing has been applied to building construction on a smaller scale.  However, the large portion of the structure has still been constructed using conventional methods.  Experts in various fields of building design and construction have been researching applications that expand the usage of 3-D printing in building construction.  This is an area of building construction expertise in which China has recently lead the global market according to Brittney Stevenson.

In April 2014, WinSun Decoration Design Engineering Co. revealed that 10 homes were constructed entirely out of a 3-D printed, recycled concrete material – an advancement that surprised the engineering and construction community.  In January 2015, it was revealed that WinSun had made further advancements in the applications of this 3-D printed material.  A 6-story apartment building and home has been constructed and the apartment building itself has an approximately 1,100 square meter floor plan.

The 3-D printed elements were created by inputing a CAD file into a 20′ tall, 33′ ft wide, and 132′ foot long machine printed using a concrete mixture.  The concrete mixture includes concrete, fiberglass, sand and a hardening agent.  The usage of this material allows for improved reusage of general construction waste while also being flexible, self-insulating and resistant to earthquakes.  Reinforcement was used where further strength was required and some of the larger pieces were built off site and transported there.  Details of the of building construction process are listed in the article.  According to WinSun, they are able to save 60% of the materials required for home construction, construct the building in 30% less time than traditional construction and reduce the required labor by 80%.

These are impressive results if true.  I still wonder about the expense of owning and maintaining the machine might be a hindrance at first. And I would hope the cost of collecting the construction waste and creating the concrete mixture is included in those statistics.  I think this is a good innovation, especially for low rise buildings since the loads and stresses are lower (although I believe a 6 story building is pushing the limits of standard low rise construction).  I would be interested to see how the material ages in regards to long term durability as well.  Overall, there are several applications that this would be useful for in the building construction industry.

What your thoughts on 3-D printed building elements? What about the concrete mixture used?  Have you heard of any other building materials being used in relation to 3-D printing?  If you enjoyed the article, please like it and share it with your friends.  Thanks for reading and have a good week!

Source

Brittney Stevenson, “Shanghai-Based WinSun 3D Prints 6-Story Apartment Building and an Incredible Home”, 3D Printer & 3D Printing News, January 18, 2015, http://goo.gl/TwVSKC

What does it truly mean to be an expert?

Hello everyone! I hope y’all had a good week.  Today I just wanted to share a quote I read online that describes what it means to be an expert in a field of study.  The quote is from Pablo Picasso: “Learn the rules like a pro, so you can break them like an artist.”

Pablo Picasso is well known for his abstract art that was definitely considering breaking the rules at the time.  Yet he was a legitimately good artist, which means he was technically a professional painter.  It initially seems like a a quote anecdotally reference to his views as an artist. However, if you dig a bit deeper into what is really beings said, it can be applied to a lot of different fields of study.  Think about a business man.  He might have some issues in selling a product.  There is probably a standard process that is followed to resolve the standard issues, but in this case it might not apply.  Therefore, by knowing the rules, he knows when is the right time to break them to achieve the results he desires.  It can be applied to engineering or science type stuff as well.  Every new break through in science and engineering occurred because some who would be considered a pro and studied in their field made a connection that hadn’t been made before.  They succeeded because they went against the norm (“broke the rules”) at the right time and discovered a way to improve a product, project or application.  So with this greater concept in mind, it becomes clear that an expert in any field of study knows not only when to follow the standard rules in a given situation, but also when those rules don’t apply and another solution needs to be found.

With that being said, I am going to leave you guys with this thought and hopefully you can implement it well in your career or life general – never get so caught up in the rules that you forget to break them when it comes time to do so.  As I have told many people before about my job, I have a lot of boring days where people wonder why I need my degree and other technical skill sets to do my job.  However, that knowledge informs me when a serious situation could come up that needs to be addressed, and I used that knowledge to prevent any further issues.  How do you guys interpret the quote?  Is there a particular story and event that describes your opinion?  If you enjoyed reading, like the post and share it with your friends.  Thanks for your time and have a good week!

Image Source

“Problem-solving is the Problem”, Florian Totu, blog.opteemum.net, August 10, 2012, http://goo.gl/YNzbI4

Applications of Shape Memory Alloys in Concrete Infrastructure Rehabilation

Hello, I hope everyone is doing well.  I’ve been busy with the holidays but I’m finally going to get back to my blogging and will hopefully maintain my weekly posting schedule this time around.  Today, I would like to talk about some research on applications of shape memory alloy (SMA) in concrete infrastructure rehabilitation being done at University of Houston and Qatar University.

SMA’s are metal alloys that can be deformed and then return back to their original shape when re-heated.  In this case, researchers are testing the usage of SMA’s in a rod that would be wrapped around concrete beams or columns.  Their ability to deform, then return to their original shape, would apply an active confinement pressure.  The design/usage of SMA’s would perform the function of current fiber-reinforced polymers (FRP’s); however, FRP’s only apply a reactive confinement pressure.  The confinement pressure provided by the SMA’s would, in theory, further reduce long-term deterioration and degradation.

The researchers will focus on determining the best available material for concrete columns and beams.  There are three types of metal alloys being tested.  The alloys that are most commonly available are the nickel/titanium alloys, referred to as binary alloys.  Ternary alloys include a third metal in addition to the binary alloy metals.  A third option are the iron- and copper-based alloys, which are generally less expensive.  Since binary alloys require constant heating to have continuous active confinement pressure, the scientist are focusing their studies on a Ternary alloy using Niobium and Iron/Copper alloys.

I believe the application of SMA’s in this application could improve infrastructure rehabilitation.  However, there are some concerns I have.  I think we need to see definitive proof with testing that, by adding the active confinement pressure, we effectively improve the serviceablity life of the infrastructure. The other concern is that we don’t know how much the rods will expand due to creep – especially since the rods will be continuously loaded with an outward force and have already been deformed to a previously outward deformed shape.

What is your opinion on this application for shape memory alloys?  Do you think it will be effective and practical for concrete infrastructure rehabilitation?  If you enjoyed reading, like the post and share it with your friends.  Thanks for your time and have a good week!

Source 

“Shape Memory Alloys Could Bring Stabilizing Force To Concrete Infrastructure”, David Hill, Civil Engineering Magazine, June 2014

Image Source

“Shape Memory and Palladium Iron Alloys”, taboodada.wordpress.com/2011/03/31/41/, March 31, 2011

Application of 3-D Printing and Modular Design to Construction

Hello everyone, I hope you guys had a good weekend.  Today I would like to discuss a couple innovations which apply 3-D printing and modular design innovations to construction practice.  These are applications that were more common in manufacturing and prototyping initially but can be applied to construction as well according to the article by Business Review Weekly.

The first innovation is the application of 3-D printing to the creation of moulds for precast concrete.  Traditionally, other materials such as wood, foam or rubber have been use, and constructing these moulds could take months to construct.  The Laing O’Rourke Company has developed a method that 3-D prints a large scale wax substrate mould at a rate of 150 kg/hr using a robots.  They have applied this to common projects such as stormwater pipes and have achieved cost savings of 50% to 90%.  Additionally, this solves the waste problem because the wax mould is lifted off or melted away in a water bath after the concrete is cured.  The wax can then be filtered and recycled.

The second innovation is the use of modular components in hospital construction.  Hospitals are one of the most expensive areas of infrastructure because they are individually designed.  Hickory Group has developed a modular panel for use in reception and administrative areas.  These areas use what is referred to as “accommodation components” which constitutes up to 40% of the construction cost of a hospital.  By using the modular panel, construction time can be cut by 40%.  Furthermore, the panels are easily replaceable.  If a panel is damaged, the hospital  can simply order a replacement and have their maintenance worker install the new panel.

Both of these are very good innovations in my opinion.  They are taking methods that have been proven effective in several previously tested applications and expanded their usage.  Furthermore, a reduction in time of construction and cost of maintenance/construction has been achieved.  I would be interested in seeing a more detailed account of the numbers and statistics.   However, based on the information provided, these are great examples of low risk/high reward solutions that can greatly improve construction practices.

What is your opinion on these innovations?  Do you think they’ll be effective?  If you enjoyed reading, like the post and share it with your friends.  Thanks for your time and have a good week!

Sources

Michael Bleby, “BRW Most Innovative Companies 2014: Why Construction Companies Are Thinking Like Manufacturers”, Business Review Weekly, October 9, 2014, http://goo.gl/O0oD6E

Image Source

Anne-Mette Manelius, “Concrete After Dark – Is There An Afterlife for Concrete?”, Concretely, October 17, 2014, http://goo.gl/IYI6q2

Development of Transparent Concrete

Hello everyone! I hope the last couple of weeks has gone well.  I was preoccupied with a small vacation, school stuff, and having to get a new vehicle since my car was totaled.  However, I hope to get back on schedule after this.  Today, I would like to talk about a new development in concrete technology: concrete designed to be transparent.

According to the article by Giatec Scientific, the concrete mixture is modified such that 4 to 15 percent of the mix is fiber optics materials.  Ideas for transparent concrete since 1935; however, serious development had not been pursued until 2001 by Áron Losonczi for use in his architectural designs.  In 2004, production was started for other commercial usage as a type of concrete called “Litracon.”  Since then, other competitors have developed similar designs.  These products have been used with back-lighting or natural light.

I think the concept is very interesting.  It’s something I would probably enjoy working with or using in a design.  The aesthetics would be amazing to see and I like the idea that it could be used in circumstances where you need more stiffness than a big window could provide.  The situation would be similar to structures that use the glass masonry units.  There are however some issues I can see. One is when and where can it be used safely.  The article mentioned examples where it’s used in floors and floors can see a lot of loading in certain types of situations, i.e. stadiums or concert halls.  The other issue I see is behavior of over time.  Will the bonding of the cement hold up in a mixture with that much of a potential void ratio?  Even if it holds up in regards to it’s initial bonding, will the mechanical strength related properties such as creep and general durability such as cracking be reduced?  Along with that, I would imagine the aesthetics have to hold up as well.

What are your thoughts on the idea of transparent concrete?  Is it something that is practical to use in building design?  If you enjoyed the blog post, feel free to like it and share it with your friends.  Thanks for your time and have a good week!

References

Giatec Scientific, “Concrete Innovation Part 3: Design”, http://goo.gl/Ee7VBo

Benefits and Constraints of “Self Repairing” Asphalt

Hello everyone, I hope your week went well.  Today I would like to talk about current research in designing “self repairing” asphalt.  Erik Schlangen, a civil engineer from Deft University in the Netherlands, is doing research with the goal of creating asphalt that can repair itself.  Schlangen has started testing an asphalt mixture made of basic asphalt with strands of steel wool mixed in.  His research shows that the asphalt when heated with microwave radiation will melt the asphalt so that the cracks will be smoothed out.  Schlangen has invented a vehicle which uses induction coils to heat the road and melt the asphalt/smooth out the cracks.  To properly maintain the asphalt roads, repairs would need to be performed every 4 years.

There are a some benefits I see with this:

Maintenance Cost

Currently, one of the biggest costs in the infrastructure industry is maintanence and repair.  If this is truly as effective as it seems, it could save a lot of money and free up some room in the budget for other projects.

Maintenance Schedule Requirements

The other big issue when considering maintenance and repair of infrastructure is time.  Living in Dallas, I am currently experiencing this issue right now.  If repair or maintenance takes a long time, it can make traffic conditions worse long before it improves them.  With this technology, repairs can be done quicker and will reduce the poor traffic conditions as a result.

That being said, there are some potential issues that aren’t addressed in the article:

Durability

The obvious issue in durability is the asphalt.  Since the asphalt can melt when heated theoretically, will it also be stiff enough to withstand the loads.  There are a lot of heavy trucks that travel over a highway on a daily basis and this adds to maintenance issues as it is.  Furthermore, at what point does the damage become too much to repair?  If this asphalt system is not durable enough, the technology becomes ineffective.

Scaleability

When and where can this be used? On most the of the highways in D/FW, traditional concrete topping is used.  If this asphalt system cannot be applied on a larger scale, the increased equipment and training cost for the maintenance itself will be greater than the cost savings of the technology.

I look forward to seeing research on this product.  If this is effective, this could improve the maintenance of our infrastructure a lot.  What are your opinions on this research?  Do you see any other potential benefits and/or issues?  If you enjoyed the article, feel free to like it and share it with your friends.  Thanks for your time and have a good week!

Source

Jason Fell, “Self Healing Phones? Try Roads That Fix Themselves”, Enterpreneur, September 16, 2014, http://goo.gl/a6uk5z

US Depart of Transportation, Federal Highway Administration, “What Can Be Done to Enhance HVUT Revenues?”, 2006, http://goo.gl/sG9VlF

Image Source

Karissa Rosenfield, “Erik Schlangen Demonstrates the Potential of ‘Self Healing Asphalt'”, archdaily, July 12, 2013, http://goo.gl/794P6