The presentation will start in 30 seconds. Hello, everyone. I am Jim Schneider, the Executive Director of PCI Mountain States. I'll be your moderator for today's webinar titled Ultra High Performance Concrete, a Game Changer in the Precast Concrete Industry. This webinar is sponsored by Georgia Carolina's PCI, an effort by PCI regions across the United States to deliver online learning to design and construction professionals. Be sure to contact your local PCI region to learn more about online learn-at-lunch opportunities for your firms. Direct information for your local chapter is available via a similar map in the webinar handouts and also at pci.org slash regions. This program is an approved program of both AIA and RCEP. You must attend the full webinar and provide complete registration information. The webinar is registered for one hour of continuing education credit and you will earn one PDH or one HSWLU with AIA. If an AIA number is provided at the time of registration, your attendance will be reported to AIA. Within one week of completion of the presentation, you will receive an email from RCEP to download your certificate. If there are any groups in attendance, we do have a group attendance form you can download in the handout section. That can then be emailed to Ruth Lehman, whose email address is on the form. Additionally, a PDF handout of the webinar slides are provided in the GoToWebinar control box. During the presentation, you may ask questions through the questions function on your screen. We will have a question and answer session at the end to try to get through as many of your questions as we possibly can. Today we have two presenters. The first is John Lawler, PhD, PE. Dr. Lawler is a principal with the consulting firm Wisch Jannie Elstner in Northbrook, Illinois, where he's worked for his entire 19-year career. His practice areas include structural evaluation and repair and materials evaluation and research, especially as these topics relate to concrete structures and including UHPC. John is a licensed professional engineer and is a member of PCI's Concrete Materials Technology Committee and TAC, the Technical Activities Council. Our second presenter is Meritat Tadros, PhD, PE. Dr. Tadros is a structural engineer and partner at E-Construct USA LLC. He's an internationally acclaimed researcher, teacher, and designer. He's a principal author of the PCI Bridge Design Manual, over 12 patents, and over 300 journal papers. He has lectured across the globe. In 2004, at the 50th anniversary of PCI, Meritat was named one of the 50 titans of the industry for his innovation, structural expertise, and contributions to the PCI body of knowledge. Meritat invented several precast, pre-stressed concrete products now widely used in practice, including the NUI girder. And he has influenced the design and adoption of numerous other girder configurations to expand girder span ranges, and has patented several other precast and pre-stressed products for both bridge and building construction. This presentation will discuss ultra-high-performance concrete and the potential to replace conventional concrete in large-scale building and infrastructure applications. UHPC has the ability to be cost-competitive on first-cost basis while being far more valuable than conventional concrete on a lifecycle basis. By taking advantage of the key properties of UHPC, building and bridge members will use materials more efficiently while also being able to span farther, improving space utilization, and enhancing the safety of people and vehicles. Lower consumption of construction materials will also be good for the environment because of its potential to reduce carbon dioxide emissions. So with no further ado, Dr. Lawler, over to you. Thank you, Jim. Hello, everybody. We're excited to be here to talk to you about UHPC and the activities within PCI specifically intended to support UHPC implementation for our industry. So today, I'll start this off by providing an introduction to PCI UHPC and discussing the materials aspects of UHPC, and then I'll turn it over to Dr. Tadros to discuss structural design and applications of UHPC. So first of all, what is UHPC? In brief, it's a fiber-reinforced concrete material with a water-to-cementitious ratio typically less than about 0.20. But most of the materials used in UHPC are the same as those used in conventional concrete. First of all, we've got cement and supplemental materials, typically including silica fume, a fine sand, fibers, super plasticizer, and water. You'll notice there's no coarse aggregate here since that can interfere with the function of the fibers. And generally, there's no air entraining admixture. But otherwise, these materials are pretty similar to what you might see in a typical concrete, although proportioned somewhat differently. So how does it behave? Well, there are three properties of UHPC that differentiate it from more conventional concretes. It's got an ultra-high compressive strength. It's got pre- and post-cracking tensile strength. And there's a significantly enhanced durability due to the high density and discontinuous pore structure of UHPC. So of these, the two that really separate UHPC from other more conventional concretes are the tensile performance and great durability. And these two topics are what I'm going to discuss in the next couple slides. So first of all, the tensile strength. UHPC is stronger in tension, and tension can be evaluated by flexural testing, which is the basis for the curve that I'm showing here on this slide. So UHPC is stronger in tension to the point that the tensile capacity can be reliably used in the design of structures. The material actually becomes stronger after it develops its first crack because the high-strength fibers become mobilized and carry tensile forces across the cracks. So the more cracks you've got, the more fibers you actually engage in the process. So after the UHPC cracks, those fibers then hold the material together and absorb energy as it continues to deform. So the area under the curve in a load deflection curve, like I'm showing here, represents the amount of energy required to cause that deformation. So on this plot, there's a blue – Is that conventional concrete reinforced or just plain? There's a blue curve representing the UHPC. Compare that against the red triangle in the bottom left, and you can see how much more ductility there is for UHPC compared to conventional concretes. And again, this tensile performance is really important because it means that we can do different things with the design of UHPC, such as reducing or even eliminating shear reinforcing from the design. Regarding durability, perhaps the best way to describe this is to look at some examples of UHPC subjected to exposure tests at a test site run by the Army Corps of Engineers on Treat Island, Maine. So this is an island on the very eastern edge of Maine next to New Brunswick, Canada, where a number of different types of concrete materials have been set out and exposed to the elements there. You can see the red arrow in the picture here is kind of pointing to some concrete samples on a dock. And so what we have here are very severe exposures, 20-foot ocean tides, and generally more than 100 freeze-thaw cycles a year. So in the picture on the left, you can see where the samples have been left out, where on the right, the picture in the middle there, is some UHPC samples that have seen that exposure for about 13 years. And what you see is no regression in the material properties due to the freeze-thaw, even for beams that were initially pre-cracked to allow even more moisture to get into the sample. And this is achieved without air entrainment, largely due to the high strength of the matrix and the low porosity of the material. Another important component of durability is the ability of the concrete to resist, or concrete structure to resist corrosion, especially corrosion that initiates as a result of chloride exposure. Well, the Treat Island exposure site gives some information about that topic, too. So the plot I'm showing here is a chloride profile of high-performance concrete, HPC, and some UHPC samples that had been left at that site for up to 13 years. So the profiles show chloride concentration with depth. The blue curves represent what we would ordinarily consider a pretty durable high-performance concrete, with 8% silica fume and a water-cement ratio of 0.33. So that's, in some ways, kind of the state-of-the-art for conventional concrete in terms of durability, while the orange and gray curves in the bottom left show UHPC formulations. So as you can see, for the HPC, there is a measurable chloride concentration down to a depth of about 20 millimeters, while for the UHPC, the chloride concentration is zero beyond a depth of about 7 millimeters. So this means that the concrete was not able to get any further into the UHPC than about that 7 millimeters. And if your chloride can't get through the concrete to the reinforcing steel, you're not going to have corrosion. So you see the difference here between UHPC and high-performance concrete. All right, for the sake of time, I'm not going to say a lot about this particular table, but this slide, which you can access in the handout, puts some hard numbers to some of the properties I just discussed. So where does this performance come from? Well, first of all, we've got a low water-cementitious ratio. So the lower, the less water in the material, the less void space there is that could either lower strength or reduce durability. The materials also include supplemental materials, especially silica fume, and those help support particle packing. That I'll talk about in a second. And then finally, or thirdly, excuse me, the fibers. So these fibers bridge the cracks and provide that ductility that I was talking about a second. But how do these materials all go together? Well, one of the goals in terms of developing a UHPC mix is to achieve an optimized particle packing state. What this means is basically you choose your raw materials to produce your concrete such that you have small materials that fit in the gaps between larger materials that fit between the gaps between even larger materials. So you get a gradation of materials together, pack them very densely, and that gives you strength and it gives you durability, but it also contributes to workability since it reduces the free space within the particles where the water exists. So for a minimum amount of water, you can still coat all your particles. And generally with a UHPC, you're achieving a self-consolidating consistency, and that works because of this particle packing. All right, so far I've talked about UHPC as if it's one thing, but UHPC is really a class of materials that comes in a number of different flavors. One way to group these flavors is kind of thinking about prepackaged materials and then mixes based on local materials. So prepackaged materials are those that have been commercialized. They may come in a super sack and are generally the type of UHPC that has seen most use to date throughout the US. Prepackaged materials are generally more selective regarding the materials that they get, and so they can achieve better batching consistency and perhaps better performance. In addition, since they're pre-blended, the mixing times are reduced. However, one of the big disadvantages of prepackaged materials is the high cost. Now, all UHPC is generally more expensive than typical concrete, but one method to address the high cost of prepackaged materials is to produce a UHPC with local materials. Developing local mixtures gives an opportunity to tailor performance to what's important for a specific application. For example, compressive strength is not always the most important piece of your UHPC, and so you could de-emphasize that for a particular application. However, using local material-based UHPCs does require some local expertise and a little bit more verification testing. But these, frankly, are things that pre-casters can do, skills they can develop, tasks they can execute, and that makes UHPC a particularly good locally-based, excuse me, locally-based UHPC a particularly good fit in a pre-cast setting. So if you're going to develop a UHPC based on local materials, the first step is material selection. The good news is that many of the materials used for ordinary concrete production can be adopted for UHPC. However, there are some materials, particularly the supplemental materials and the super plasticizers, that may need to be tailored a little bit to UHPC. There's a lot to discuss there, but for the sake of time, I'm not going to go into those, but I do want to take a second and talk about fibers, which are likely to be the biggest change in materials for most pre-casters. So for structural UHPC, the most common fibers used are fine, high-strength steel fibers. The fineness allows you to get a lot of them into the material so that they are distributed uniformly within the UHPC, throughout the UHPC, so they are there at whatever location where a crack may want to form due to loading, et cetera. And then the high strength of these fibers allows them to carry the loads across those cracks. Steel fibers can produce a somewhat unsightly pattern where they intersect with the surface. So while it's really only a surficial effect, for architectural applications, it's more common to use non-steel fibers like PVA, glass, or other polymers. The trade-off here is that the structural performance just generally isn't as good as that achieved with steel fibers. So what does a UHPC mix look like? Here's an example shown here on the right column. As you'll note here, certainly there's more cementitious materials. So that's the cement, silica, fume, and slag than in a typical concrete. We have higher contents of sand and no coarse aggregate, as I mentioned. The dosages of high-range water reducer, the Creosote Premier 150 is a specific type of high-range, are high to get that self-consolidating consistency I mentioned. And then finally, we've got the fibers at 2% by volume, and then the water is added to give you that water-to-binder. And when I say binder, I'm including all the powders that are included in the material less than or equal to the 0.2. So putting this all together, the cost of the raw materials for these mixes is generally around $600 to $800. And while that does leave out the cost associated with materials handling and production, this is very cost-competitive compared to pre-bagged materials. So in the next couple of slides, I just want to show you some images of production of UHPC. Here are some pictures of a hollow box beam section set up for UHPC on the left. And that solid section, similar beam, to be produced with conventional concrete on the right. Obviously, the amount of reinforcing required for the UHPC is less, where we're trying to rely on the tensile capacity of the fibers in lieu of those bars. So on the next slide here, I've got a video of the production of that UHPC beam. This particular product was about 50 feet long, and it took about 20 minutes to pour, and we were really relying on the self-consolidating nature of the material. So what we did is in the foam blocks that were used to form those voids, we cut some holes so we could look down through the hole and see the UHPC flowing around underneath the void and then along the bottom of the forms. So taking a step back then, I wanted to bring in the PCI UHPC research project. So because of the potential benefits of UHPC, particularly for precast elements, PCI started an R&D project in 2018 with the title, Implementation of UHPC in Long-Span Precast Pre-Tension Elements for Concrete Buildings and Bridges. So the project is currently underway and is being led by my co-presenter, Mayor Tadros, and myself. As the title implies, the goal of the project was to create enough information to allow for the production and structural design of big members, specifically bridge girders that might get up to 250 foot in span and building floors that may cover 60 by 60 foot bays. So there are really two components to the project, the materials and a structural component. So on the material side, the intent was to provide guidance on how to design and produce cost-effective UHPC mixtures based on local materials. As part of this, WJE evaluated mixes for six participating precasters, all of which were produced with those local materials, largely using the existing production facilities. On the structural side, the goal is to provide guidance to designers that is straightforward to use and supported by worked out examples. As part of the development of that guide, some full-scale structural testing has been performed to validate the design approaches. And Mayor will talk more about the structural design side of things in a little bit. But as part of that research project, we developed requirements for what we are calling PCI UHPC, a type of UHPC optimized for precast, pre-stressed concrete. And by optimized, I mean that we have placed the focus on performance attributes that are important for this particular application. So compressive strength is tested on cylinders like normal concrete, but using three by six inch cylinders with the ends ground smooth. And the target properties here at pre-stressed release is 10 KSI and at service is 17.4 KSI, which is equal to 120 megapascals. The flexural performance is evaluated with an ASTM test, specifically C1609. While slightly more difficult than the compressive strength, I want to emphasize that this performance is one of the key properties of UHPC. So this is important. So for PCI UHPC, we've said that the first cracking strength in this test needs to be 1.5 KSI, the peak 2.0 KSI, and then we've got some requirements on ductility to ensure we've got that strain hardening performance that I showed on a previous slide. So here are some examples of flexural test results from the various pre-casters that participated in the PCI project. And a takeaway just from showing this is really to say that, you know, all these mixes were based on local materials and generally showed that with appropriate production and curing procedures, the criteria that we established can be met by PCI member plants. So a few quick comments on environmental impact before I turn this over to Mayor. I expect we're all familiar with the risks of global warming associated with CO2 production and recognize that cement production is a big source of CO2 emissions. Well, UHPC can provide a means for mitigating some of these risks through designs that are made possible through the use of less concrete materials. So the first step there is recognizing that highly efficient structural designs are possible through UHPC. So on the right, we're showing two cross sections for bridge girder and deck. On the top is a conventional concrete structure consisting of a conventional bridge deck girder and the deck itself. On the bottom is an optimized UHPC decked I-beam that combines both of these components into one efficient section. So then the bar charts compare these two options, starting with the green being the conventional concrete and the white being the UHPC. So starting on the left there, we're talking about the mass of materials used. Less than 60% of the material is required for the UHPC. And as a result of this reduction in material, the embodied energy associated CO2 emission and 100-year global warming potentials are all reduced. However, this really is just based on the initial cost of the material, assuming that we have a similar life. But as I've mentioned, what really makes UHPC somewhat different is its durability. So if we make the very conservative assumption that we can actually get twice the life out of UHPC, the relative percentages of these various properties of the UHPC compared to conventional concrete are much lower. So UHPC is not just useful from a structural application perspective, but has environmental ramifications as well. So with that, I hope you've gotten a sense about the materials aspects of UHPC and a recognition that while a bit more complicated than conventional construction, UHPC can indeed be implemented by precast plants here in the U.S. And with that, I'll turn it over to Mayer to talk about structural design and applications. Thank you, John. So the issues we will be discussing, we have examined in our PCI project, is a long list. We'll discuss some of the more important ones. Mayer, are you able to grab the screen? Well, I haven't yet. You have not seen it? Okay. Okay, where should I go? Oh, here you go. All right. Perfect. How about now? Yes. We're good. Okay. So this is a list of topics that we are covering in our project. As John mentioned, the report is expected to be in the hands of the PCI by the end of April of this year. We'll go through a serial review process within PCI and will shortly after that be available to the public. And we will have a materials design guide and a structures design guide, as was mentioned to you. We try to keep them as straightforward, as simple as possible, so they are ready for use by owners and designers. So this is a list of items that we've covered. I will touch on the more important ones. We start with flexure. The good news is that when we design a prestressed member, we design it not to be cracked under surface load. The same applies here, except that the stress limits are different. Because we have higher strength concrete in tension and in compression, we have slightly higher limits. When it comes to flexural strength, we do service design and then we do strength design. When it comes to structural design for strength, again, the good news is it can use your favorite software and you will come very, very close to the right answer if you use the right material properties and by very close within 2%. If you want to do fancy nonlinear analysis, that's available too. If the member is not prestressed, so it is reinforced with the fibers and possibly rebar, then it would need to do a moment curvature relationship, which I will discuss here in a minute, and we have a spreadsheet for that. For flexural strength, we are using the curve on the left and the curve in the middle to represent concrete stress-strain relationship in compression. The curve on the right to represent concrete stress-strain relationship in tension. So in tension, normally for conventional concrete, we take it zero, but because we have fibers, we could take advantage of fibers with the tensile stress and strain that is shown. When it comes to transverse direction, this picture, this yellow frame is part of a box, a concrete box similar to the one that John showed you under production, 4 feet wide by about 50 feet long, and you have a wheel load from the truck, and you want to know if the fibers alone can take the load in a transverse direction. So we've done finite element analysis to show how much effective depth we need, and we have done our analysis using an equivalent strip width as now allowed for both bridges and parking structures. And you can see here, we have plenty of capacity and a nice margin of safety. When it comes to shear, we had a choice between the modified compression field theory in AASHTO and the VCW and VCI in ACI, and we chose to go in the direction of AASHTO because that seems to be the international trend, both in Europe and Asia, in Canada, and here, but that would still apply to both buildings and bridges. So the shear capacity is the contributions of the concrete, V sub c, stirrups, if any, fibers, VF, and the vertical component, pre-stress, if you have draped strands or post-tensioning. Most of the time, we're going to only have two turns, VC and VF, because we are recommending that you not use stirrups, and it's unlikely that you drape strands because of the narrow webs. So it's straight strands and only contribution from VC and VF. The new parameter here is VF, and the strength of concrete due to contribution of fibers is shown here, and that's the most important factor, the VF sub rr that we have here, and which is psi times F sub fu, which comes to 0.75 KSI. That alone is capable, most of the time, of resisting the shear that you need for your products. A lot of times, we need to build up a product from two components, the beam and the deck, or the beam and the topping, or a beam and a precast deck in buildings. So for all these situations, we have to marry two pieces together. And we found out that the best solution to prepare the top face of the beam is to corrugate it, or they call it fluted, put flutes in it. And the best way to do it is to use form liners. If you roughen that surface, we call it roughening, but it really is formed that way. If we roughen that surface, we're going to have an awesome interfacial capacity between the two pieces, the lower piece and the upper piece. And you could see that from this chart here. If you have a smooth surface, it's a very low capacity. If you have a fluted surface or roughened surface, the capacity is much higher. But the equation is the same, cohesion coefficient times contact area plus friction coefficient times the strength of the connecting steel. People have wondered how can you have a nine-foot-deep decked I-beam with only a four-inch web? They say, are you sure? Is this thing going to buckle 250 feet? Can you do that? And the answer is yes, you can. We've done enough analysis to prove to ourselves that there's not going to be an issue with buckling. Obviously, we're going to have diaphragms at the ends. But you can have the full section acting for you without any problems. Let's talk about applications. This is the time when we structural engineers shine. This is the time for us. The materials people have been researching this for the last 25, 27 years. We structural engineers need to step up. We just need to step up and challenge structural engineers. Because if we have the lower cost, as John explained, of the raw materials, dropped it by 70 percent, if we can drop the volume of concrete by 50 percent through efficient cross-sections, then we can have a cost-competitive product system immediately on a first-cost basis, without counting the long-term benefits, the durability and the long-term benefits. I'm giving an example here that shows if a conventional concrete sells for $750 a cubic yard, you can sell ultra-high-performance concrete for $1,500, twice as much, and still make money. Because a lot of it doesn't require a whole lot of rebar, detailing is simpler, and production is simpler. For bridge products, we started, and I think that's probably one of my favorite cross-sections, with what we call decked I-beam. And luckily for eConstruct, we have a client in Ontario, Canada, FACA, Inc., Incorporated, that had a bridge that they wanted us to design in UHBC, and we developed this product for them. That was even before the PCI project. And it seems to be one of the most efficient products that you can ever find, whether you have for building or bridges. And we developed for them a series of these beams to cover spans all the way to 60 meters or 200 feet. And the first bridge that we designed for them is called the Hitch House in Ontario, and that's how the cross-section looks like. It's not only efficient in terms of cross-section, it's also efficient in terms of speed of construction. So this is considered accelerated bridge construction, because you don't have to form or pour a deck in the field. And this is a series of sections going to two meters, or about six foot seven inches, and spanning up to 60 meters or 190 feet. Now if you could please pay attention to this picture. On the left is our conventional construction, with a whole lot of stirrups, a ton of stirrups. On the right, we expect almost nothing, if we do UHBC. Now we explored other bridge cross-sections. This U-shape happens to be very popular in Malaysia, which is one of the leading countries in the whole world. They've already built over 150 bridges with UHPC. And it's good here also because we use it in parts of the country, and particularly Florida, and California, and Washington, Texas. But we could skinny it down to make it work for UHPC. This is one of my favorites, not because it uses the least amount of materials, but because it is the easiest to form, and it requires the lowest capital. You're not going to have any fancy forms for it. It's a voided box, and it can go from 1 foot 6 inches to 8 feet, 8 foot 6 inches. And we have a bridge that's under design at this time in the state of Florida using it. We already showed this, but in the form of pictures. This is value engineering of a product from a solid slab on the left to UHPC voided box on the right. We saved 50% of the weight, and we saved about 85% of the steel. Again, as structural engineers, and obviously I'm biased for structural engineers, we can use our creativity. We can help the pre-caster convert a 24 inch by 24 inch square pile into an octagonal pile by blocking out the corners and putting a sauna tube in the middle. With this design, this pile has only 50% of the weight of the square pile. And only very little of the spiral is only put at the ends. And we put it because we just wanted to be sure. It's possible that in the future, people will eliminate it. So this was made at Standard Concrete Products in Tampa and was tested at the structures lab at Florida DOT in Tallahassee. And we thank both the Standard Concrete Product and the DOT for helping us out with this design. Thank you, Steve, for helping us out. And we've come up with outstanding results. Opportunity. Save the cost of steel forms. I think that's what a lot of the pre-casters like. And I'd like to convince them to get off of that and start investing in steel forms because in the long term, that's going to be very helpful to them. Take, for example, the popular NextBeam that is used a lot in the Northeast region, the New England region. Very popular, has the limit on the span because of the heavy weight. If you take that same form, and I'm not suggesting that this is what you do permanently, but if you want to convince yourself of the value of UHBC, take that form and fill it with expanded polystyrene in the areas that I'm showing. You save 50% of the concrete. You save most of the steel. And you have, actually, because of the lower weight, you can have longer spans. Now, we'll talk a little bit here about residential construction. We developed a voided slab system because we felt there was a need for podiums in the Midwest. This is used quite a bit. You would have wood structure above a concrete floor where parking takes place underneath. And sometimes, you have the 18-parking space plus 24-foot aisle space plus 18-foot parking space. But you have the columns at the edge of the parking space so that you can reduce the spans. Of course, that's not as efficient as using a 60-foot clear span without columns. I think architects would love that. Owners and drivers would appreciate it. So eliminate all of the columns, all of the footings, all of the inside framing, and just have it go wall-to-wall 60 feet. So we have done that as a value engineering for Gage Brothers in Foothill Falls, South Dakota. And we are doing, also, a very, very exciting product for Kendall and MetroMod. And we call it Voided Slab System. Each of these two companies have their own product that they like. But we started with what you see here. You can think of it as a hollow core, but a huge hollow core, 60-foot span. The beauty of this is that you can do all of this with 100 pounds per square foot live load with an equivalent thickness of about 4 inches. There's nothing else that could match that. Again, the same theme, pre-stressing only, no rebar. And you can also have significant and generous blockhouse in the webs, so you can house your utilities. This is one of the panels we had Kendall produce and test it at North Carolina State University. And it performed extremely well. We tested in flexure at two points, two load locations. And we got a lot more than 100 pounds per square foot we designed for. These are pictures of the specimen. This is the shear test, again, 200%, 230% of the design factor load, no shortage of capacity. And you need to keep in mind that the top slab of this is only one inch thick, and it has no rebar. So people will say, OK, well, how about punching shear? If I put the piano on it, the leg of the piano will punch through. That's not true. You could look at the results that we have come up with through analysis, finite element analysis, and actual testing. So for parking structures, we only designed for three kips. This one had 10.5 kip capacity before the four inch by four inch bed punched through. So I'm going to walk you through some applications in the US initially, and then outside the US. By far, the state of Iowa has been the most progressive state in the whole country. They started off back in the early 2000s. They had the Wapello County Bridge in Iowa. For that bridge, my recollection is that they had to have the girders made in Canada. And it performed very well. Then the next one, again, Iowa, is called Pie Shape. And that was done with the help from the Koreans. Korea is one of the advanced countries in UHBC. And they helped out with the mix and with the construction of this bridge in Buchanan County, Iowa. Again in Iowa, with help from FHWA, they had a system in which they used ultra high performance concrete waffle deck, what they call waffle deck. And that was produced by Coors Lab in Omaha. Of course, a lot of you have already seen this. This was the very first bridge built in Sherbrooke, Canada. A footbridge was built in 1997. Now, you will ask a valid question. We started in 1997. Why in the world are we still slow in implementing this? Again, I go back to the very high cost initial introduction of this material. Created a very specialty item that had a high cost. Now, we're down to $600 to $800 a cubic yard. And we structure engineers would sharpen our pencils and come up with efficient structural systems. I go to Malaysia. Dr. Vu, our friend here in the middle of this picture, between Bob Risser and the former chairman of the board, the PCI, was honored in 2016 with an ultra high performance concrete bridge that spanned 100 meters. And a group of us went to Malaysia and saw that and a bunch of other projects he had. Czech Republic, this main span is 156 meters. About 500 feet or a little more. It's a really awesome bridge. And to prove to the public and to the authorities that it is strong, they put a bunch of trucks to represent the live load on it. And it passed. Again, the Czech have come up with a really creative pedestrian bridge, all made in one piece. It's just like a piece of art. I think this was just a study. I don't think they have built it. Maybe they have. I'm not sure. Of course, the French are the pioneers in the whole world. They were the ones that introduced UHPC to America. And again, they started in 2002, about eight years after the introduction of the material itself. And their system is they use what we could call here a double T, but it has bulbs at the bottom. Again, accelerated bridge construction. The bridge is still standing and in great shape. As I said, the Koreans are one of the most advanced country in the world. They tend to, they and the Europeans tend to use post-tensioning. We tend to use pretensioning here. So this is one of their bridges, which was transversely post-tensioned. Now we go to an apartment building, just to give an example. That joist, that voided slab that I showed you, could be used in a 10, 15 story building in all floors. But if you have wood construction, just like this one shows, and you try to frame the podium, I hope you can appreciate that we have hollow core in the middle. We have rectangular beams between hollow cores to catch the weight of load bearing walls above. We have inverted T beams that support the rectangular beams and the hollow core. And finally, we have columns. When you add all of this up, it adds to about 105 pieces on that floor. And you can see that at the bottom of this section of the building. And these are cross sections of the conventional system. So we managed to come up with a UHPC solution, which is what you see here. Only one piece, decked I-beam or decked Q-beam, that is about 10 to 12 feet wide by 60 to 70 feet long, with no columns, no supports other than the outside walls. So we were able, together with Gage, we were able, together with Gage, to prove to ourselves that the conventional system would cost $173,000, the UHPC system $125,000. I'm not dreaming this up, folks. This is stuff that we have consulted with pre-casters and have done our due diligence on. So this is real life stuff. Now I go to architectural applications, which a lot of people in the audience would love to hear. This picture is courtesy of E-Construct in Dubai, our Dubai office. And I was personally involved in it. These fins here used to be stainless steel, and they changed them to ultra-high performance concrete. They were made in a shop in Dubai, full-scale tested. For all cases, of course, it doesn't carry external load, but it has to carry its own weight. So it's kind of tricky. You have to support it right. You have to ship it right. So this was all studied. Another villa building, just like the first one, again using fins. Low sail facade, again by E-Construct. And these are external that we felt would be very interesting to you, but they are not our work. And you could see the elegance of UHPC cladding. Also, some work was done here in the US. And now the University of Toronto in Canada and the US, there is a company called TAKTL in Pennsylvania that produces ultra-high performance concrete. I'm sure they would welcome your inquiries and business. This is another one from their projects. Very elegant. And some of you may have heard of the famous architect, the British architect Zaha Hadid, who was originally from Iraq. And she designed, for example, the One Southern Museum building in Miami, Florida, an awesome building. And she came up with this floating stair option using ultra-high performance concrete. So the sky is the limit as far as your imagination is concerned. The Louvre Museum that opened in Abu Dhabi was also made with ultra-high performance concrete with help from Lafarge. And you can even do furniture or some decoration on walls using UHPC. So in summary, UHPC can be produced with local materials at a fraction of pre-bagged material cost. That's one key ingredient of success. The second one is structural. You need to come up with a system. You don't want to sacrifice the stiffness, but you will want to reduce the volume. So you cannot tell me that you want to have a much shallower ultra-high performance concrete floor, because that doesn't work. You need to have the stiffness. But you can reduce the thicknesses. So it becomes like a shell, still deep, but has not as much material as conventional concrete. We're able to make it work for, as was mentioned earlier, for buildings, office buildings, 100 PSF, 60 foot by 60 foot bays. And we have fully worked out example showing a joist and a beam for that, for a typical floor. And that will be part of the report. And the weight is lighter. Because the weight is lighter, you can have a longer span. You can reduce the number of shoring towers. And you can, of course, save on shipping. And obviously, durability is a big factor. So it is attractive structurally. You can make it out of white cement, white silica fume, pigments. You can do a lot with it. Our project, our PCI-HPC project is structural concrete with steel fibers, as John explained. But obviously, one can extract from it the possibilities of architectural precast. The last bullet is the most important one. We do the heavy lifting in the project. We do the legwork. We explore what everybody else in the whole world has done, including the US and Canada, and put it in a simple enough form for you to apply it. We're very near the end. And hopefully, you will get results coming out very soon. Thank you very much. Thank you very much, gentlemen. That was a fantastic presentation. We really appreciate your taking the time to share all that with you. I will say we've got a bunch of questions. So we're going to make our way through a few of them. I'll also just note, while being sensitive to the fact that, of course, we're going to come up at time in a few minutes, we might just go 5 or 10 minutes over today for anyone who wants to stick around and listen for additional questions if the presenters are open to that. But I will throw out sort of a general question to begin with that I'm sure is on the minds of many listening. When can folks start specifying and designing with UHPC? What's the timeline on that? Is this a now thing or a future thing? Can you guys speak to that a little bit? John, do you want to take this, or do you want me to take it? Well, why don't you go ahead, Mayor. I mean, obviously, our goal with the PCI project is to make that happen sooner rather than later. But I'll let you speak to it. Yeah. Thank you, John. I think if you want to start designing with UHPC, you can do it now. My analogy is this. We have very extensive research and development program in all kinds of conventional concrete and conventional reinforcement. Research and development will never end. But based on our experience in the past almost 30 years, we have enough information to design with UHPC. If people want to wait until the materials guide and the structures design guide come out, that's going to come out later this year, about the middle of the year. But we have designed with UHPC before the PCI project. We'll continue to design. The purpose of the project is to make things simpler for people. OK. Then I'm going to start making our way through some questions here. So with such low water to cement ratios, does the mix have enough water to hydrate the cement fully? Generally, the answer to that is no. You do not fully hydrate all the cement in your UHPC. But that's not necessarily a bad thing. The cement particles remain within the material and act as small little aggregate particles you could think of. Unreacted, but still present, helping to contribute to that at high density of the UHPC. OK. The chloride ingress data refers to Thomas in 2012. Does this mean there are nine more years of data available? I'm not sure whether Mike Thomas has gone back and done a follow-up examination. I know periodically more work is done at Treat Island and that exposure site. And I expect sooner rather than later we'll get more data as to how much chloride has been able to get into those particular beams. But that's not the only data that indicates the very, very high resistance to chloride ingress of UHPC in general. Other people have seen similar kinds of things where you get chloride that moves in about a quarter inch, and then it just kind of stops moving into your concrete. So from the durability perspective, that's obviously a huge finding of UHPC, a huge advantage of UHPC. What role does colloidal silica or liquid fly ash play with UHPC? Well, as I perhaps explained a little bit, there's no one formula for UHPC materials. It's really all about selecting the combination of materials that fit together well. And so if you're trying to develop a mix with the specific objective of producing the structural performance at the lowest cost, which is really what our focus was with the PCI UHPC project, then you're going to choose your materials to fit together in a certain way. And that may start with saying, OK, well, I just want to use the cement I've already got and not introduce something, a new cement. And then I'm going to find other things that would fit together with that cement. So perhaps on a given application, colloidal silica or certain types of fly ash might fit and kind of be part of that puzzle that works well with UHPC. Certainly, those materials could be used, but lots of other materials have been used as well. Ground silicas, ground limestones, slag and fly ash like I talked about. So the sky's kind of the limit there. OK. Let's see. How would you compare crack development in ordinary and UHPC concrete? Well, one of the things special about UHPC, and Mayor, you can chime in a little bit too if you'd like after. But one of the things about UHPC is the way the cracks develop is heavily influenced by the presence of those fibers. So you typically get a multiple cracking pattern rather than with conventional concrete, you might just get one big crack and that crack opens up. But with UHPC, where you get one crack and the concrete tries to separate there, well, the fibers that cross that crack catch that load and transferred back into the surrounding material. What you often have is then a secondary crack that happens adjacent to that first crack and then the fibers bridge across that one and transfer the load around. So instead of getting one big wide crack, you generally get lots of little cracks. And that's part of that strain hardening process that I alluded to in one of the early slides talking about the great ductility of UHPC. I would just add to this the fact that, yeah, as John said, you have a lot of very tiny cracks as opposed to fewer bigger cracks when you load the member up to failure. But I want people to remember that when you do a pre-stressed concrete design, we design it to be uncracked under service load. So our focus is to under service load, no cracking. Ultimate strength, of course, there would be cracking to failure. OK. Is there or has there been any fire rating testing done with UHPC, for example, on floor decks to get floor-to-floor fire ratings? Well, the resisted, oh, go ahead. Go ahead, Meir, if you want to. I can take that, John. When you use steel fibers in the mix, the fire rating is not very good. So if you want to have a fire rated underside of a floor, you would want to mix steel fibers with PVA fibers in the ratios of 3 to 1. That's what we were told. Our project did not involve fire rating, but PCI has sponsored other projects as well that are ongoing. The way to resist fire to the point that it's acceptable is to use fire rated gypsum board underneath the product, unless you use lightweight concrete or fibers that are non-metallic. So there are solutions, but steel fiber alone, if you have a requirement for fire rating, would probably not be adequate. Yeah, and if I can just add a little explanation, the idea behind the polymer fibers, the PVA or polypropylene fibers in UHPC, is they can actually melt when you have high temperatures. And so they form voids within the UHPC that relieve some of the pressures that are the problem associated with fire and concrete. OK, does UHPC have benefits for both precast and prestressed concrete? Yes. Yeah, I think that's an easy yes as well from my perspective. All right, that's a way up. I thought I'd give you guys that one, sure. When testing 3 by 6 cylinders, does the load rate increase to about 150 PSI per second instead of the normal 35 PSI per sec loading rate? Yes, according to the standard, and there was an ASDM standard, and there was an ASDM standard adopted in 2017 C1856. Basically, that ASDM document references other existing concrete testing procedures. That identifies some specific modifications for compressor strength, including the specimen size. But yes, the load rate for compressor strength testing is greater to make the completion of the test practical, right? You've got to get all the way up to that 18,000, 20,000 PSI. OK, and I will just quickly note, I know that we're at 2 o'clock Eastern right now. If the speakers are OK with that, are you guys all right hanging around for another five minutes or a few more just to get through a few more of these questions? Whoever wants to stick around, Ken, is that all right with you guys? Sure, sure. All right, so here's a 1,900 total pounds of cementitious material, cement, slag, and silica fume. What is the shrinkage of a mix like that? We spec shrinkage requirements for mix designs to be less than or equal to 0.04% ASTM C157 modified. A mix with that much cementitious material will never meet our shrinkage requirements. Long-term durability is sacrificed in the concrete cracks. This is also an unfriendly mix for sustainability and lowering total embodied carbon in concrete, which the region and country is moving toward. John, let me take this one first, and then you can continue. We just need to remember that we are doing structural pre-stressed concrete members. That's the focus of the project, structural pre-stressed concrete members. Ultra-high performance concrete, because of the high cement content, there are some schools of thought that says that the shrinkage is up to 900 microstrengths. But a lot of it happens in the first couple of days. For pre-stressed concrete, that's not an issue, because he designed for initial pre-stress, and he designed for final pre-stress. Geometric concern, width of bearing, stuff like that, but that shrinkage is not going to be any harmful, because it's taken up by the pre-stress and the pre-stress losses, and he designed for that. If you're doing a non-reinforced product, by non-reinforced only fibers, no rebar, no pre-stress, then it may be a different situation. But in that case, you will have only very, very wide, very small width of box, like four feet box width, or two foot I-beam top flange width. Shrinkage in that direction is not a factor. But as far as the material property, you need to be aware of it, and you need to take into account in your structural design. Yeah, and if I can build on that a little bit, I mean, most of the shrinkage that happens is autogenous shrinkage, meaning it's the water getting consumed by the hydration reaction, as opposed to what we think about with conventional concrete, which is more about drying, evaporation of the water from the concrete. So that autogenous shrinkage does happen early. And as Mayer said, if you know it's coming, you can address it before the beam, or whatever it is you're building, actually gets installed in the structure. One thing I didn't get into with my presentation here, but what is sometimes used with UHPC mixtures is a post-cure thermal treatment. So this is something that still happens in the plant, and involves applying steam for 48 hours to get the UHPC up to 195 degrees or so Fahrenheit. And what that does is it kind of locks in all of the dimensional stability of the UHPC. So subsequent to that treatment, there is actually very little shrinkage that occurs, and much reduced creep. So from a dimensional stability, that's one additional way to address that. I guess back to the point, the environmental concerns. I tried to cover that. I know I went pretty fast, but had a couple of slides where we talked about, ultimately, if you can reduce the amount of concrete required with UHPC, and based on some of the designs Mayer showed, we anticipate your cross-section might be 50% of what a conventional mix would be. When you factor that in, and especially if you include the durability of UHPC from an environmental perspective, there are actually benefits to UHPC. It compares very well, very favorably to conventional concrete. Great, thank you. I think we'll probably just, we've got a bunch of questions. We'll maybe just get through two more. And I'll say to those folks who have asked questions and weren't able to get them all hit on here, there is an opportunity to send questions in after the presentation with the survey and everything as well. So just a couple more. What are the typical concrete unit weights per cubic foot for UHPC? Is there a lightweight version? And if so, what are the typical unit weights? So it's typically a little heavier than conventional concretes. Might be 155, 160, but not that much heavier. I personally am- We assume 155 in our design. Yeah. And I'm not aware of any lightweight. I don't know if you are, Mayor? No. Okay. Let's just give this maybe one more here. Will or have you encountered vibration issues? And if so, how do you minimize vibration loads within sections? We design for vibration. If it's the floor that is sensitive to vibration, there are rules in the PCI handbook and we design according to these rules. That's why I mentioned a couple of times that the goal is not to reduce the depths. The goal is to create a shell that is equal depth but uses thinner thicknesses, well thicknesses, to give the efficient design. But vibration could be a problem. It's probably not as much of a problem as steel and aluminum and other materials. It's more sensitive than conventional concrete because of the heavy weight of conventional concrete. And you just have to design for it. All right. Well, thank you very much, gentlemen. Thank you very much to everyone for attending our webinar today. Big thanks to Dr. Tadros and Dr. Lawler for taking your time to share your expertise with us today. Just a reminder to attendees that you will be receiving an email from RCEP to download your certificate. Be sure to complete the one minute survey at the conclusion of this webinar. This also provides an opportunity for you to ask additional questions or request follow-up. Also be on the lookout for an email announcing our next webinar, which will be held on Thursday, February 18th at one o'clock Eastern time, titled Design Assists and Architectural Precast Case Studies. This will be presented by Mo Wright, Marketing Director with Gate Precast Company. Big, big thanks to everybody for joining us today. This is a really fascinating topic. Dr. Tadros, Dr. Lawler, thanks again. Appreciate it, guys, for hanging around a little bit afterwards. Great questions, and I hope everybody has a really good day. Stay safe out there. Thanks very much for the opportunity. Thank you. Thank you.

Ultra High Performance Concrete

Precast Concrete Industry

UHPC

Large-scale Building

Infrastructure Applications

Compressive Strength

Tensile Strength

Durability

Cost-competitive

Environmentally Friendly