Self Healing Concrete

Self Healing Concrete

As the years go by, people in every industry are always finding ways to improve different aspects of their respective fields whether it be by coming up with a better process for something or making a better final product. The construction industry is no different. One of the most common materials used throughout the construction industry is concrete. It is the most commonly used man-made material on earth and is used in a wide range of applications from buildings, bridges, roads, pipes, and more.

One of the biggest problems with concrete is that it will eventually crack. Water then gets into these cracks which then can freeze and thaw and make larger cracks or get to rebar within the concrete causing corrosion and eventual failure. Scientists have found bacteria that allows concrete to “self-heal.” It took years of research to find one that wouldn’t compromise the integrity of the concrete, but that could also live dormant in a dry environment for years until needed. The way this works is that the bacteria are put into biodegradable plastic capsules along with a food source and added to the wet concrete mix. When cracks in the concrete occur, water finds its way through and causes the capsules to open. The bacteria then germinate and multiply, and in doing so, they produce limestone which is what closes the cracks. There are some disadvantages to using this self-healing concrete: it can be almost double the price of conventional concrete, and since it makes up around 20% of the volume it can create a shear zone or a fault line.

The ultimate goal is to develop concrete materials that will monitor, regulate, adapt and repair themselves. Self-healing concrete will be able to save lives and resources and significantly reduce life cycle carbon emissions. There is ongoing research to try to improve upon this idea of “self-healing” concrete and one solution being looked at is using a fungus that would act similarly to the bacteria. Other solutions include continuing to try different additives of nano-scale minerals and chemical additives. One other solution may be right in front of our faces though. The ancient Romans built structures such as the Pantheon that still stand today. The secret seems to be a pozzolanic reaction of the material with intrusive water that takes place after construction and produces calcium/aluminum silicate crystals that fill voids and cracks, which strengthens the structure long after the work has been finished.

hand of builder worker use trowel plastering a newly poured concrete floor

Every day scientists and researchers are looking into better solutions for anything that will make our lives better. Phones, cars, and computers are things we use every day, and we notice when a new and improved model comes out. We also use concrete every day whether it be the sidewalk outside, the bridge you drove over, or the building your sitting in right now and we don’t notice them until something is wrong. Self-healing concrete will help to prevent any issues from arising. There will always be research and advancements in all different technologies that will usually go without notice.

3D Printed Homes

3D Printed Homes

In recent years, you likely have started hearing more and more about 3D printing. Currently, 3D printing is being used in medical and industrial fields and even to make art and jewelry. Another area that they are starting to use 3D printing is civil engineering. There has been a lot of research done and it is still in its early stages but different applications in this field are already starting to pop up.

A major reason why people are looking into the use of 3D printing for civil engineering applications is that it can reduce the amount of money invested on tools for manufacturing and the associated labor. The initial investment cost tends to be high but is usually a one-time cost. Right now, 3D printing is being used in a construction process called contour crafting which is used to make 3D homes. This process tends to be fast, uses less energy, and produces little to no waste and therefore this will continue to grow and become used more widespread.

Figure 1: Creating a wall with a 3D printer

Construction technology concept with 3d rendering robot welder build house

Figure 2: House in Russia built in one day

3D printing of concrete can save a lot of time, reducing a 2-week job to just 3-4 days. It also removes laborers from common construction-related injuries. Companies in countries like Brazil, Italy, and Russia to name a few, have been using this technology to build homes that are able to withstand their respective climates. This process may run into some problems trying to be implemented in the U.S. by the many codes and standards. Townships and other governing bodies don’t currently recognize this process as a construction method and the associated plans and calculations are different than ones that these governing bodies are used to. This can cause some reluctance to accept such a process but if they are allowed on a case to case basis and studied then, this process may eventually be more common.

An Engineering Collapse

Have you ever experienced a situation where just because you work in a specific field that people think you know everything about it? After the pedestrian bridge in Florida collapsed back in March, I have received the question of what happened to it numerous times. Family, friends, and people I’m just meeting for the first time have asked why it collapsed and act like I should know what happened to it since I work in the Civil Engineering field but in reality, I don’t work with bridges at all and have no idea what happened to it, so I decided to do some digging.

One of the first issues was that the project was behind schedule and over budget (wait, aren’t all projects?). In addition, the engineers were asked to move the signature pylon of the bridge to accommodate for possible future road expansion, changing their design (below image shows a rendering of the final design). Videos that captured the incident show that part of a prefabricated segment of the bridge started crumbling on the same end where the pylon redesign was to be located. The pylon was to be installed later into the project with each prefabricated section being able to withstand all the forces they would experience before completion of the project. An engineer had reported cracks in the same location where the bridge failed two days prior and stress testing was being conducted the day of the collapse. There was even a meeting the same day in which engineers and state officials discussed whether the cracks in the structure presented a safety risk.

Some engineers involved in trying to find the reason behind this collapse have said that any slight modification to a bridge design is inviting possibilities for failures. The same care and attention that the original design had does not always continue once a change is proposed and designed for. The proposed design change put the engineering team further behind schedule and over budget. This project was being federally funded and the engineering team was worried that funding might run out before they could complete it causing them to further try to speed up their designs.
Engineers and other officials are still looking into the exact cause of the bridge’s collapse while FDOT and the engineering team responsible have been hush-hush for the most part. Although all projects are different, a valuable lesson can be learned from this. Time and money are always key driving factors for projects, but they should never be able to dictate the final design. It may take some more time and money, which leads to unhappy clients, but sometimes that is what is needed for a successful project.

Geosynthetic Engineering Alternatives

Geosynthetic Engineering Alternatives

Engineers are constantly being challenged with the task of trying to find cheaper alternatives for projects to save money for their clients. This presents a challenge because it is not always easy to find an alternative while maintaining the same characteristics that accommodate the standards and regulations that the project’s design must meet. Engineers are turning more and more to geosynthetics to help them accomplish these goals.

Geosynthetics are synthetic materials that are used in contact with soil, rock, or other geotechnical materials and have a wide range of forms and applications. The main categories that these geosynthetics fall into are geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells, and geocomposites. Each of these has different applications and products that can be tailored to most jobs. They can be used to replace different raw materials such as cement, steel, rocks, and soil and can provide the same characteristics at a fraction of the price.

Filtration, drainage, separation, reinforcement, and protection are just a few areas where geosynthetics are becoming more prevalent. Some examples of uses include soil reinforcement structure, the separation between in-situ and imported soil to avoid mixing, filtration behind hydraulic structures, and erosion control blanket to protect the top of the slope and avoid erosion. Companies continue to test and research their geosynthetics to find more uses and to find ways to improve their characteristics to make them more favorable for designers.

The use of geosynthetics continue to grow as engineers become more familiar with them and as they become more viable options then what is normally commonplace. The cost benefits continue to make geosynthetics more popular and something that engineers will be turning more and more too. So, the next time you think there is no solution to your problem, remember that the solution may already be right under your feet.