Overview of the ATC
If you’ve heard me talk recently, you have probably heard me mention the ATC, or the Autonomous Truck Corridor. This is an idea that I came up with by working with an awesome team at Oklahoma State, Penn State, and University North Carolina Charlotte. This is an idea that has infected my brain. I can’t get it out, and so I thought I would write a blog post about it. I also have some videos I have made about the concept at the end of the post.
The US National Highway System (NHS) is critical for the efficient transport of goods and the safety and freedom of the traveling public. A special vehicle on the NHS is heavy freight trucks. Here are a few of the issues related to heavy freight trucks on the NHS:
Vehicle manufacturers are developing autonomous and electric trucks to address these needs but their limited haul distances and challenges interfacing with passenger vehicles have not allowed them to enter the market yet. If these needs are addressed it would create a monumental improvement in the US economy while improving the lives of the traveling public, and reducing the impact on the environment.
I am part of a team of engineers who have a vision for a heavy freight truck corridor with a long life that uses autonomous, continuously powered, and electric heavy freight trucks. This corridor will be separated from passenger cars, specially designed for autonomous heavy freight trucks, and have an overhead electric power line to provide constant power. We call it the Autonomous Truck Corridor or ATC for short. Pretty cool name right?
The ATC is a game-changer because the freight trucks can travel continuously without stopping, the vehicles can travel at higher speeds and at closer spacing, and the vehicles will be separated from passenger vehicles and so they can be autonomous. Batteries on the trucks will be charged so that they can remain powered once they leave the ATC to make local deliveries. This corridor will be largely built using existing right of way or it can be added as major highways are expanded. This will reduce land acquisition cost, allow freight to follow existing delivery lines, and leverage existing infrastructure. This will create unbelievable economic opportunities for the US.
The ATC will reduce delivery times up to 50% while reducing traffic on existing highways. This reduction in traffic will improve diver safety and extend the life of existing roadways. The proposed electric motors are more energy-efficient and will reduce costs and emissions by > 25% per mile. A portion of these savings could be used to pay for the cost and maintenance of the ATC.
Watch these videos if you would like to learn more about the ATC.
By Kristin Karleskint, Chad Staffileno, Michael Dickey, Zac Wilson, Alla Acheli, & Jon Choat
This entry is part of our student collaboration series.
What is porosity and how does it pertain to concrete? If you were told that a household sponge and a slab of concrete had anything in common, would you be surprised? At first glance, concrete appears to be an impenetrable solid, but in reality it’s porous much like a sponge! Porosity is a term commonly used in the concrete world and for good reason. This property refers to the amount and distribution of pores in the material. This description may present porosity as unimportant, but it actually controls many other significant concrete properties that determine the concrete’s durability! Properties including compression strength, tensile strength, flexural strength, modulus, resistivity, and permeability are all heavily influenced by the porosity. In general,when porosity increases, the strength decreases and the relative penetration increases. Both of these relationships are bad, meaning that these unseen pores could actually be detrimental to our concrete. Who would have thought that some holes in our concrete would play such a vital role in the lifespan of our infrastructure? In order to minimize our pores we must first understand how they develop and how to determine how many there are. There are three critical rules to determine the amount of pores in our cementand if used, secondary cementitious materials. These are the initial proximity of cement grains, the final proximity of cement grains, and the degree of hydration. All three of these rules are critical factors that determine the porosity of concrete and each will be discussed, coming up!
Rule number one: the initial proximity of cement grains.
It’s important to note that idealized situationsare expressed in drawings to better demonstrate theseprinciples in the real world.These schematics are extremely helpful for you if you want to understand the big picture! However,you must keep in mind that they are based on THEORY. The drawing shown here represents how initial proximity contributes to strength of concrete, but it is idealized in the sense that cement grains are not always equally distributed and that the hydration products are not always the same length. Despite this, the drawing makes it obvious that the different water to cement ratios create very different load pathsand pore systems. Loads become easier to distribute when the path can spread out within the concrete. These load paths also act as barriers for fluid penetration, whichwill increase the durability of the concrete!What is even scarier is that cracks make this concept even worse. To learn more about cracks, Dr. Ley has several videos on his YouTube page. If you love concrete and you want it to last a long time, then this information should be exciting! This concept can be defined as tortuosity, and when a system is more torturous it becomes more durable.
By Erin McArtor
This article is part of our student collaboration series.
Have you ever wanted to know what cement does after water has been added to it? Well, this is the video for you! In this video, Dr. Tyler Ley delves deep into the cement hydration process, with a step-by-step break down of what goes on inside the concrete.Concrete is made of rock, sand, cement, and water. All aspects of concrete are important; however, the cement and the water are what make the magic happen. In Portland Cement, there are compounds present before hydration, and other compounds that are formed after hydration. As you may already know, un-hydrated Portland Cement contains C3S (Alite), C2S (Belite), C3A (Aluminate), C4AF(iron), Gypsum, and Limestone. This video introduces the more unknown compounds that are found in hydrated Portland Cement,what each of them provide to the cement, and how each of them are related to the Avengers. Crazy, right? The first compound Dr. Ley introduces is Calcium Silicate Hydrate, also known as C-S-H (C-S-H! C-S-H!). It is formed from the reaction of C3S and water, and it gives hydrated Portland Cement its strength.C-S-H can also be developed in other ways. Pozzolans, such as Class F Fly Ash consume CH (another hydration compound) and convertit to C-S-H. The relationship between concrete and C-S-H. It is very similar to the relationship between Thor and his hammer; without his hammer, Thor has none of his “God of Thunder” powers and is basically just a normal Asgardian. You might ask yourself, “hey, what about in Thor Ragnarok where he basically becomes lightning, right?” Well we are not considering that for this example. However, great action films aside, without C-S-H, the concretewill lackstrength.It also keeps the “outside nasties” out of the concrete. C-S-H is also known for its shape-shifting abilitiesalso very hard to characterize because its structure and chemical composition changes depending on when, how, and under which situation it is formed and looked at. It does not have an ordered structure, so it is always changing its structure and chemical composition depending on when and how it is looked at. Shown below is an image of magnified C-S-H.
By Chad Staffileno, Kristin Karleskint, Michael Dickey, Zac Wilson, Alla Acheli, Jon Choate
This entry is part of our student collaboration series.
Have you ever seen concrete that is cracking, shrinking, or even falling apart? A large part of why this happens is due to the pore structure in our concrete. A pore is basically a void inside concrete. Think about a sponge, you will see all the gaps and holes. That is pore. If we can control the pore structure to help reduce cracks and permeability of our concrete, we will create durable long lasting structures that will last generations. In order to understand why the pore structure of our concrete is so important, we first must take a look at the types of pores that actually form in concrete. In a typical mixture there will four different types of voids. From smallest to largest, there is CSH interlayer space, Capillary pores, entrained air, and entrapped air. The CSH interlayer pore is the space between the CSH particles. This space really cannot be avoided because there are formed during the creation of CSH and do not affect the concrete as much. These voids are really small, about .5-2.5nm and really do not affect the permeability or strength of the concrete. Next is what we call capillary voids, these pores are the space between the cement grains themselves, usually about 2.5nm -5μm in diameter. To compare these to the CSH voids imagine that you are at a crowded bar. The space between your fingers, arms, and legs would be the CSH interlayer space and the Space between another person and you would be capillary voids. The volume of these voids is largely dependent on the water-to-cement ratio(w/c), and the degree of hydrationand other factors talked about in other videos.If you know how to control these pores you can have better control of the creep, shrinkage, andpermeability and other properties of your concrete. The next pore is an air entrained void which is actually formed by putting a soap like material called a surfactant (air entrainer) into your concrete mixture. These voids are generally 10μm –to 1mm in diameterand actually have a distinct spherical shape. The construction industry refers to this add mixture as adding “air” into your concrete. The reason we add air into the concrete is to get good freeze-thaw durability. Finally, we have entrapped air which is air that naturally gets trapped in your concrete while mixing. These entrapped pores are usually larger the 1mm. All of thesevoids can contain water, air, or both depending on the conditions your concrete is in. Having pores in your concrete can both help and hurt your durability which no one wants. If you have too many poresthat are interconnected, this allows outside chemicals to penetrate your concrete which can over time decrease the structural integrity of your concrete
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Dr. Tyler Ley, Ph.D, P.E., is a professor of structural engineering at Oklahoma State University. He was named a Most Influential People in the Concrete Industry by Concrete Construction Magazine in 2019, and was named the outstanding professor at a research university by the Oklahoma Foundation of Excellence in 2018. He has a passion for researching and educating people about what he considers to be the greatest material in the world.