Webinar 2: Concrete Overlay Technology, Jan 2022

Webinar 2: Concrete Overlay Technology, Jan 2022

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♫ music ♫ [Federal Highway Administration logo] Shree Rao: "We will review all the questions  from participants and that will be answered during   the Q&A session towards the end of the webinar.  So I will do the presentations first and then   get to the Q&A parts, but you can ask the  question at any point during the webinar. To see a list of the participants, you can click  on the participants button again in the bottom   panel and if you want to raise a  hand or if you have any reactions,   there is a button on the bottom  panel as well for those reactions.

If you have any technical issues with  Zoom again please use the chat function   and send a direct message to the two hosts. The  two hosts are Monica Doebel and Eric Schulman.   So if you send a message to Monica, she'll try to  resolve the any technical issues that you might.   Just a brief overview of today's webinar, I will  introduce the speakers as I mentioned. Sam Tyson   with Federal Highway Administration will give you  a briefing. We'll provide a brief introduction  

and give you some background regarding Everyday  Count Six Targeted Overlay Pavement Solutions   program and followed by that we'll have two  speakers from CP. I couldn't have asked for   two better speakers for this program most of  you know them very well. Peter Taylor from the   National Concrete Pavement Technology Center and  Gary Fick from Transtec, and I will introduce them   later on in the program and we'll follow that by  the Q&A. So I'm gonna introduce Sam Tyson. Most  

of you don't need any introduction to Sam Tyson  but Sam is the Concrete Pavement Engineer with   the Federal Highway Administration with the Office  of Reconstruction Construction and Pavements out   of Washington D.C. He actually runs the Federal  Highways program to advance best practices for   construction rapid repair and rehabilitation  of concrete pavements and is leading Federal   Highways' effort to increase the use of concrete  overlays to extend performance of both existing   asphalt and existing concrete pavements. So Sam  is a registered professional engineer in D.C.,   District of Columbia and a graduate of the  University of Virginia. Sam, please take it away." Sam Taylor: "Okay thanks a lot, Shree.  As you can see on this slide  

Tim Aschenbrenner from FHWA headquarters and Derek  Nener-Plante from FHWA Resource Center are on the   asphalt team. On the concrete side of course as  Shree mentioned, I am at the headquarters along   with help from Bob Conway and the FHWA Resource  Center, so that's extremely helpful to me. I was probably surprised a bit myself and  some of you may be that over 25 percent of all   state DOT infrastructure funds go to pavement  overlays. Now this is both asphalt and   concrete given the fact that state DOTs  manage 2.8 million miles of pavements,   maybe this is not particularly surprising,  but states do have to prioritize their funds   and look at the most important use  of each dollar that they receive. And this leads us into how is the TOPS  management of pavements different from   typical overlays and really they're  not in terms of the technical process   in which they're applied. They're different in  the process of determining what the priority is  

for the use of the overlays. High priority  pavements pavements that simply cannot be   taken out of service for  an extended period of time,   so the difference is really in the process of  selecting which pavements get the overlays first. Our mission with the TOPS program of  course is to extend pavement life,   to take existing pavements-- both asphalt and  concrete in the case of concrete overlays--   and overlay them to preserve the  existing investment in the pavement that   is in place with as little maintenance  as possible on that pavement, which gives   the DOTs the ability to both save money  and to deliver the targeted pavement in   the most economical and the most  environmentally sound manner.

Our goals for the EDC-6 program really are  to reinforce the use of concrete pavements   for the DOTs that use them already, perhaps not  to the extent that they might use them in total,   and introduce other states to the use of  concrete overlays if they're not using   them currently because they can actually save  a lot of money save a lot of time and preserve   a lot of existing pavements for extended  use through the use of concrete overlays. When we look at what's in the toolbox  for concrete overlay products,   it's really pretty straightforward for  both asphalt and concrete, there's a bonded   and an unbonded process of  applying concrete overlay. Both   Peter and Gary will get into some detail and  how this is accomplished. I would just say   that from the standpoint of concrete overlays,  the unbonded overlay is probably the greatest   percentage maybe 60 or 70 percent of concrete  overlays are unbonded for performance issues   but again I'll let Peter and Gary get  into the details of those applications. Since the TOPS program includes asphalt as well,  we should look at what's in the asphalt toolbox.  

Tim Aschenbrenner is going to, in a future  webinar, talk about this in detail but if you look   down the list of asphalt overlay products there  are what two, four, six, eight, listed that Tim   will talk about in some detail. So we've got both  concrete and asphalt overlays that are available   for your use and we're looking to increase the  use of those products through the TOPS program. The ultimate goal is to improve safety,  improve performance, long-term performance,  retain the investment in the existing asphalt  and concrete pavements by overlaying, them   saving money of course, and doing it all in  an environmentally sound manner. So with that,   I'll get back to Shree and Shree  will introduce the next speakers."

Shree Rao: "Thank you very much, Sam, for the introduction  to the TOPS program. So we'll start with the   main part of today's agenda and our first  speaker is Peter Taylor from the National   Concrete Pavement Technology  Center at Iowa State University.   I couldn't have asked for two better  speakers to talk about concrete overlays.   Gary Fick and Peter Taylor literally wrote the  book on concrete overlays and that's not just an   expression, it it is actually true. So peter is  the Director of the National Concrete Pavement   Technology Center at Iowa State University. He's  been involved in conducting projects and programs  

in regarding concrete pavements and spends a  lot of time helping agencies and contractors   implement best practices in concrete pavement  design, construction, and maintenance. He also   conducts a lot of research that's focused  on developing mixtures that are engineered   to meet requirements of the environment that  will be used in. He's a professional engineer   registered in Illinois and is an active  member of many professional societies.   We're really glad to have you, Peter and  present in today's webinar. Peter, take it away." Peter Taylor: "Great, thanks very much, Shree. I  appreciate the opportunity to be able to  

join you on the session and talk about a  topic that we're pretty passionate about   and it's also great to be teaming up with Gary  is that I bring the theory and Gary brings   "how do I actually do it in the real life." So  I've got about 30 slides to go through so let's   get started. What I'm going to be providing is  basically a motivation. The value proposition of   why we should be thinking about overlays.  A lot of the material actually comes from   a publication that Tom Cackler developed for us  and has been published on the CP tech website. The topics I'm going to be covering include, you  know, what's the issue, why do we bother talking   about it, Sam has already alluded to some of  the questions that we're trying to address,   the value proposition, the barriers we need to  get past, why people don't do it all the time   everywhere, how to get started, and then Gary  will pick up on some some successful projects   that we've run in the past and some resources  that are available to you as potential users. Okay so for those of you that work for agencies,   departments of transportation, cities,  counties, I've yet to hear anybody   representing those organizations say to me  that they've got more money than they can use.  

Everybody is running on extremely tight  budgets. They're trying to do more with less and   working very hard to maintain and upgrade the  pavement systems that they have under their   jurisdiction. The bad news is that it's always  deteriorating. Any time that you put something   that lives outdoors, the weather is going to  beat it up, the traffic is going to beat it up,   and it will start to decay at different rates  over a period of time. At the same time,   the traffic's getting bigger, the traveling  public is getting more fussy about ride quality   and they're also getting far more  fussy about continuous access   to their roadways, particularly I live  in Iowa predominantly a farming community   and if you close down a road so that the farmer  can't get his plant from his farm to the point of   delivery, he's going to come out and get very ugly  with you as you're trying to work on the system.   And so continuous access is a pretty  big demand. And so in many ways we're   effectively burning the candles at  the both ends. We're asking more  

of far with far less resources  in at our availability. So we have an existing pavement system it's  a lot of it is actually getting pretty old   and the Eisenhower system was built in the 60s  and 70s, that's 40, 50, 60 years old and some   of it's starting to get a little tired and  it's not so surprising and that deserves to   to tired it's survived very well and remarkably  well over the period of time it's been exposed.   So when you as an agency start to look at it  and say okay we've got to do something about it,   let's review some of the choices that you have.  One a bit like we do in a lot of with our other   activities, if you know my cell phone gets  more than a couple years old I throw it away   or at least recycle it so we can get the lithium  out of the battery and go and get a new one. Now   it's kind of tough to pick up 30 miles of  pavement and take it into a store and say   give me another one. And it's it's an effective  approach to say we'll let's beat it up take it  

out and remove it and replace it from the point of  view that it's a long-term solution. You can buy   another 40, 50 years with the product that you're  putting down, but the negatives are not trivial.   You have a disposal headache. There's a lot of  material on every mile of existing pavement.   You lose a lot of equity in the existing  system that's not economically sound   nor is it sustainably sound is that if  you've got a good system in place that needs   some minor treatment, it's an awful waste and  an awful carbon load to simply throw it away.  

It also takes time and energy and money to  do this removal and replacement and at the   same time the other one we're starting to pay  more attention to is this whole idea of safety   is that if you shut down a road for the several  months that it takes to beat it out and replace   it, traffic on the other roads, or if you're  building under traffic safety becomes a real   issue. And I've been encouraging my safety  colleagues to start looking at this idea of   a life cycle safety, as well as life cycle  cost and life cycle environmental impacts. So all of those things in red may be  considered negatives for this solution.   So then we can also go to the other  extreme and say well let's just patch it   it's very limited in the amount of materials  that you use in this photograph we've got   the joints hav e started to fall apart  but the rest of the slabs are actually in   really good shape and so let's just do something  with the joints. And this is not a bad solution  

if you want a a reasonably short-term  answer. Generally patches don't last,   particularly partial depth patches, don't last  as long as the original pavement. So they might   buy you five years while you raise the money  to do a repair. There's also the aesthetic. In   this town the chief city engineer was pretty  excited about the fact that his roads look so   ugly in the condition that they were in having  been patched the way they were. Limited usage,   limited energy, limited traffic impact, but it's  not a long-term solution. What else have we got?

And that's where we turn to this concept of using  overlays. We do make use of the existing equity is   that the system that's in place, we don't remove.  We build on top of it. It makes a very good   foundation for the new layer that we're going to  be putting on top of it, and it means that we may   be able to reduce the amount of material  in this new layer because it is sitting on   a pretty good system. It minimizes the  sustainability impacts, again because we're   reducing the amount of materials that we're  having to put into place and replace, that   a good that's a good benefit. Can be a long-term  solution or if you're only looking for a few years  

we can also tune it to be a short-term. So  again it's very flexible you tell us how   long you want to last we can design a system  that will last for that length or maybe more. The biggest challenge with this is that in you  know midwestern corn belt farm roads, you don't   really care if you add another few inches onto  the top of an existing system. But if you're  

working in urban or city-based environments, the  elevations, the connections to the side drains,   the manholes getting under the multiple bridges  that we drive under every day in our commute,   those can be interesting and we do  have to stop and think about that.   There are solutions for all of these  issues and we have published about those,   but it's not just a slam dunk and we  do have to think about it. So in this   slide we've got more green than red that  sounds pretty promising let's keep going.

Okay so let's look at this idea  that Sam has already alluded to,   a toolbox. And that's what we're trying to  present to you particularly for those of you   who haven't thought about this before. Concrete  overlays may not be applicable everywhere   but they should be something that you think  about in a lot of cases. They extend life,   they restore ride, they increase capacity and  they can be applied onto a fairly wide range of   existing systems. This photograph was a site that  I went to that was undergoing an overlay treatment  

and you can see the condition of it and not a  lot of pre-treatment was being applied to this.   So yeah we think it has benefits of  being cost effective, sustainable,   and providing what agencies need to  keep their systems up and running. Alright, what do they cost, how do they perform,   what are the environmental impacts. We'll  touch on each of these in the next few slides.   Basically there's b een a fairly significant  growth in the amount of overlays being placed   particularly since 2005 since we started talking  about this. It was a bit of a dip in 2020   and I think that's more related to COVID and budgets than popularity of the system.

How much does it cost? People often ask us this  and we gener ally try and avoid that question.   It's politically incorrect, but here is  some data that we did collect is that   you're looking at about four to five dollars  per square yard per inch thickness of concrete,   but it's very dependent on where you are, what  sort of industry, what sort of construction   community that are familiar with the game in  place, what are the costs and materials for   you locally. But the message that we're  trying to portray here is that it can be   very competitive and it's well worth  looking at this from a cost point of view. The other one is this is just an  image that I stole from MIT is that   one of the messages that's out there is  that if you have an asphalt community   and a concrete community that competition  between the two different systems   actually helps you as the user. We found  that the single material communities   tend to be paying more because there is less  competition. Therefore if you're paying less   because of better competition you're you're  spending less dollars to maintain your network   condition, and again there's a bunch of material  available from MIT to support the this contention.

Environmental impacts, we think are pretty  pretty strong. A long life meaning, you don't   have to replace it every few years. If you can  go in every 40 years instead of every 10 years,   that's a quarter of the  amount of material that you   you're fooling with. It's also the amount a  quarter of the amount of traffic delays, so you   know those together have a fairly substantial  impact on reducing environmental impact.  

There is work out there indicating that a concrete  pavement particularly under track traffic does   cause the vehicles to burn less fuel  and that's a benefit. That the high   albedo particularly early on in the age of the  pavement reduces the heat element effect and   light reflect lighting that needs to be provided.  The other sustainable part of it that we like to   talk about is the concrete is fully recyclable,  there are many sites around here where all of the   if an old pavement has been recycled or replaced,  all of that material doesn't move far. In fact   there's machines that walk up and down our street  our our roadways that dig out the old concrete,   recycle it back into the base, and it  doesn't move more than 20 or 30 feet.   So recycling is a big part of our conversation.  There's also some discussion about the idea that   concrete will absorb CO2, so it actually  may reduce its overall carbon footprint   and that one is still under  investigation by the research community.

Resiliency is the other fashionable term that's  starting to get our attention as engineers. This   concept that if we have a disaster how long does  it take us to get back and functioning. And this   is not a trivial question. Here in Iowa, we have  a Missouri River on one border and the Mississippi   River on the other border. And it wasn't long  ago, both of those rivers were under significant  

flood and a large amount of our farming community  and many roads were inundated for several months.   Whole towns had to be evacuated and stay evacuated  because they were flooded by these two rivers.   And in fact you know just watching the news right  at the moment, disasters happening on the island   of Tonga, sort of wonder if they're ever gonna be  able to recover, because of both the volcano ash   that's been dumped on him and the tidal wave that  came and swept over them that place is in trouble   and so it's not trivial for us to think a little  bit about, okay a disaster happens how long is it   going to take us to get back up and running? And  the the conversation is being focused around the   fact that concrete being stiffer imposes  lower stresses onto the foundation system   that means -- and is far less sensitive to the  stiffness of the foundation system -- that means   you can put rescue vehicles back onto the pavement  a whole lot earlier without causing damage, and   again that's not a trivial issue. We're actually  working on a tech brief and hope to have that  

published in the next month or two so sensitivity  subgrade softening is markedly reduced. So is this the newfangled  thing that we're talking about?   Nope, we've been building overlays since 1901  there's about 2,000 miles of overlays in service   in Iowa and again a large amount large number  of them have been built in more recent years,   but there's more than 100 years of experience on  how to do this so let's look at some of these. How well do they perform? Well that's a bit  like the economics question and I'll give you   an economics answ er: it all depends. It depends  on the thickness of the pavement of the overlay  

that you put down it depends on the condition  of the existing pavement that you're placing   it on top. It also depends like anything  else that we do in our engineering world,   the devil is in the details. Are you getting the  right details in place for the environment that   you have, for the conditions and traffic that you  have, and for the to to address the condition of   the existing pavement. And Sam alluded a little  earlier to this idea of bonded and unbonded.  

The real difference between  these two approaches and why we   talk about them both is that unbonded if we put  down an unbounded system it's typically placed   on a pave an existing pavement that's in a fair  amount of trouble. We separate the two layers   because we don't want any cracking or other damage  to reflect through the new layer so we allow the   two different systems to move independently  which means then that the upper layer has to be   thicker to be able to be structurally competent  to carry the loads. If we go with a bonded layer,   then we're getting the structural benefit of   that lower system because they move together. But  

moving together means that the risk of reflective  cracking is fairly high and it also means that we   have to be pretty sure of that bond. Because the  bond is less than we assumed at the design stage   then we've got one layer that's thinner than  it should be and the potential for failure goes   up a little bit. And Sam alluded to the fact  that most overlays that we're putting down at   the moment are unbonded and that's partially  because they're a little easi er to work with   and they are known to be very reliable.  The data and the plot that I have up on   the screen there is from some data we collected  here in Iowa. I think these were 12-foot panels,   seven to eight-inch-thick sections, and you  can see that if we draw a straight line graph   through these things we're getting 30, 40  years out of them without any trouble at all.   Now what we do find at the bottom of that plot,  there is some systems which have not performed   as well. We actually went back in and had a look  at those pavements and it turned out that there  

was always some sort of issue with inappropriate  design, that the construction wasn't the quality   that we wanted, or that the materials were not as  specified so you know the premature failures are   substandard but if we manage to build everything  accordingly to the way that it should be done,   we can really get a good long life  out of these systems if we want them. Versatility, they can be applied  on all sorts of surface types.   We can accommodate all sorts of distress and  again that becomes part of the thought process   is the first question is am I building on top  of asphalt or am I building on top of concrete?   Well that's easy to answer. You go outside  and kick it. Then you do the question of is  

my existing pavement in good shape or is it in  trouble? If it's in trouble, we will probably   consider an unbounded layer. If it's in pretty  good shape and what we're trying to do is to   increase capacity or do a widening or to deal with  joint issues then we can consider a bonded layer   and so again we can cope with all sorts  of trouble it just takes a little bit of   thinking to make the wise decisions. They've  been used roads, intersections, parking lots,   airfields. It's not just limited to farm fields.  Yes we can do use these systems almost anywhere. Can be really relatively quick. If you're  putting down a six-inch section or even thinner,   you move pretty fast, you can put a  fairly big machine on top of it the 35,   40 foot paving machine you can be in and  out of a neighborhood relatively quickly. You're also not really affected by the weather   and we're starting to figure out how we can get  traffic back onto this pavement within a weekend,   particularly for residential traffic. I live in  a cul-de-sac all of my neighbors are grumpy old  

professors and when the city started talking about  refurbishing the street, that was the message that   the city engineer got. We want to be able to  go home tonight and we managed to compromise   it that yeah we'll get home in a couple days.  And so I was pushing hard for concrete. I didn't   succeed but even so we do believe this can be done  without much disruption to the local residents. Traffic, there is always any time we have  traffic and we have construction there is   an impact and it's something we have to pay  attention to. We always joke about two seasons:   snow and construction. Either one of those  is slowing us down, but we can build under   traffic. The photograph is from a test section  that we built here in northern Iowa, where  

we deliberately built it with traffic  still flowing through the construction   section. It meant a lot of management in terms  of how we were only allowed to close down a   couple miles of the road at a time. Traffic  control with traffic lights and pilot cars   was fairly involved, but we did it and  there were no accidents and it can be done. Early opening is also possible. I've alluded  to that is that if we need to get particularly   residential grade traffic on back onto the the new  roadway pretty quickly that can be negotiating. I've put the heading in here of effectiveness  and just was a casual title for some of the   things that we're doing a little bit different  we are using AASHTO, ME is able to address   design of overlays now that bottoms out at about  six inches, so if you've got very little traffic   you may want to look at other design tools  and there are other tools out there and   Gary and I can talk to those and Shree has  a lot of expertise in that world as well.  

We can optimize the mixtures. Again that's work  that I've been doing, looking at can we make a   mixture that delivers what you want using far  less cement far less cementitious materials   that we can reduce our environmental footprint  without using a recipe-based mixture.   The other innovation is this idea of stringless  control. You can see there's a lidar or a total   station parked behind the gator in the photograph  and two poles sticking out the top of the paving   machine, so that machine there's no string line  on this construction site that machine is being   controlled entirely by the total station and that  actually means that you can be remarkably precise   with the control, so that again, instead of adding  an inch onto the pavement because you're worried   about getting the thickness bonus, we can narrow  that error down and make our systems far more   efficient. We have large, very efficient very  adaptable paving machines. Machines that can  

do multiple cross falls. If we want to do the  shoulders at the same time as the main cross fall   as the main line and we can do full width if  we have to. We can mount real-time smoothness   measurement systems on the back so that we've got  a far better control of knowing almost immediately   what's coming out of back of that paver in  terms of the smoothness at the end of the day.  

And again the world's expert on that topic is  the next speaker in this webinar. We can also   use tools like maturity to be able to keep an  eye on what is the performance of this mixture,   when can we open it back up to traffic, and we can  shave that down from a rule of thumb 24 48 hours   if we've got the strength measured using maturity  and the traffic can get back on in 8, 9, 10 hours.   That's a huge benefit for both the  contractor and the local community. We also talked, I alluded to safety a little bit  earlier, but again, the less that we have to shut   systems down, the better the safety is for the for  the workers, and safety for the traveling public.   And also you know somebody who  hates getting trapped in traffic,   it's really better for our blood pressure and  our health all around, so again getting in   fixing it getting out is a real  benefit to the community as a whole. Alright, so how do we do this it's actually not  very different from conventional concrete paving.  

Use the same machines. We use the same mixtures.  All we're doing is putting a slightly thinner   layer now if we're using an unbonded system, we  do have to think a little bit about how do we make   sure that we get the unbonding that we want. The  plan sets are simple, there's lots of materials   and training and troubleshooting available both  from us, from Gary Fick, from the TOPS team,   and so a lot of information is available to  help you get on top of this sort of question. Okay so what are some of the  challenges? Why don't we do more of this   and what we hear from the community is  that we haven't thought about it before,   it's not part of a conventional  project management system.   Innovation is hard. As engineers, we are  risk averse and particularly from an agency  

point of view risk adverse, because there's  no upside to taking a risk in it going wrong.   But we believe that we can provide you with  the resources to help you understand that risk   and make decisions that may have fairly  significant benefits in terms of cost, time,   reliability, all of the things that I've been ran  rambling on about for the last 30 minutes or so. Many agencies focus on the surface condition  only, and they're under political pressure,   as many square feet or square yards or square  miles as possible. The catch being with this   is that a quick and dirty repair may also fall  apart a little faster and so you may end up with   a never-ending cycle of just playing catch-up on  repairing a system. So we would encourage you to   consider the full life cycle benefit. If I'm  getting a 40-year system at a small increment   of cost, are you not better off at the end of  the day. And the other thing we can consider  

with overlays, is that if the surface is the part  that's deteriorating, we can put an overlay on   with a couple of inches extra material which you  can then go through and grind every 10 years so   keep that friction resist up and still have plenty  of structural capacity at the end of the day. Difficulty is identifying candidate  projects and again that's true. And   for people who haven't played before we have   teams of experts who are able to come out talk  to you to walk the pavement with you and to   say this is a good candidate or this is not.  Now this photograph is a candidate. Yeah no,  

it's a little too far gone. But anything better  than that, we can probably make it work somehow.   As I said some of the other challenges include  connections, dealing with getting under bridges,   the extra work you have to do in service access,  and again we have a lot of solutions available   there on our website, the tools are there if  you need help, feel free to give us a call. What about traffic do we detour do we shut it  down and get in and out that's entirely up to you   and again we can help you with that  conversation. We can build an overlay   pretty quickly as I've already said, but  it's also possible to build under traffic.  

In some ways that's an economic decision  and it's also a conversation you have with   whoever's living or working on that street how  long are they prepared to let you shut it down.   Either option is available and can be talked  about it. A key part of all of this what we found   is that life gets a whole lot better when you  spend effort on communicating and planning. I   think one of the war stories that was really  interesting is that when we were planning   an overlay in a rural community, one of the  farmers was really hot about not being able   to get home at night. The solution at the end  of the day, the contractor paid for him to stay  

in a hotel for the three days so he didn't  have to go to his farm at all it was during   the fallow season and so just providing a simple  solution like that was more than enough to keep   an impacted homeowner from being totally mad. So  again work with your contractors. They often have   really good ideas on how some  of this stuff can be addressed. How do I get started? I've never paved  before. Well like anything that we do in life,   start simple, pick a fairly short section,  something that's not very complicated,   get help and there's abundant help available both  from FHWA, from TOPS, from the CP Tech Center,   call us. We can be there. Then once you've built  it, keep an eye on it, how did it work out for   you, was it cost effective, is it giving  you the performance that you like? If so   then yes, let's build some competency. Let's get  your construction community used to doing this   kind of work. Let's get your consulting community  used to doing the designs. Then you can build this  

process into your mix of fixes that you have  for your system and we've done this on more   than one occasion, on a number of agencies both  city, county and state throughout the country. So what do we do, as I already alluded to a little  earlier, the first thing is identify what type of   pavement you've got to work with. Well that's  not a hard decision. Assess the condition of   the pavement and then based on that you can  make a choice on how much effort do I have   to put into restoring some functionality out of  that existing pavement or am I just going to put   a debonding layer and an unbonded concrete  pavement on top. The debonding is in the form of  

a thin asphalt layer typically about an inch or  we're getting more and more familiar with the   idea of using geotextile cloth sections that go  between the concrete and the existing pavement   and provide that layer of separation,  the debonding, the sheer separation   and both of them work pretty well and  again there's just environmental and   cost implications and time on doing both. So the  four different systems that we talk about at the   moment, we changed the tournament terminology  about a year ago is concrete on asphalt,   bonded or unbonded, concrete on concrete, bonded  or unbonded, and you know basically the top layer,   the differences are what have you got there and  what is the condition of the existing system. And with that I'm done so I will hand the  control back to Shree and let him introduce Gary."

Shree Rao: "Alright, thank you very much, Peter. That  was excellent background on concrete overlays   and really sets the stage up well for Gary's  presentation. If anybody has any questions for   Peter, as I mentioned before in the beginning of  the program please use the chat function and send   a message to me or to everyone and we'll get to  the questions in the Q&A portion of the program. I'd like to introduce our next speaker. Our next  speaker is Gary Fick. When I asked Gary for a  

short bio, he literally gave me the shortest  bio ever a couple of sentences. But Gary's   name and experience really spans well past those  two sentences. He's been really doing concrete   construction for over 30 years and many many  projects and has also done a ton of concrete   overlays across the country. He's currently  a project manager at the Transtec group and   as a project manager at Transtec group, he has  worked with multiple contractors and he didn't   say it in his bio but I'm going to plug it in.  He's the lead author for the concrete overlay  

guide um that is produced by the CP Tech Center.  So without any further ado, please welcome Gary." Gary Fick: "Thank you, Shree. I'm gonna leave my video off.  I've had some bandwidth challenges here lately   at the office and so I'll spare everybody having  to look at my face just to be on the safe side   with regard to bandwidth, but appreciate the  introduction, humbled by that. So Peter's   done an excellent job of outlining a framework  for agencies to move forward with implementing   concrete overlays. Now peter and I, I mean for  over 15 years, he and I, along with the help of so   many others and and those so many others basically  taught me everything I know about overlays   and they've forgotten more than they taught me,  so a huge shout out to all the other folks that   have been with us over the last 15 years on the CP  Tech Center's efforts towards implementation and   concrete overlay. So part of those projects and  Peter mentioned this -- I mean we've got teams of  

experts that go out and you know boots on the  ground and walk you through scoping a project   and I guess it's maybe we've had different mission  statements all along or objectives -- but from my   perspective, I mean the whole objective  of of us doing this and I think TOPS is   is the the perfect continuation of what's been  happening, is to assist agencies with finding the   appropriate application of concrete overlays  for their payment preservation strategies.   And I'll be the first one to show up to scope a  job and say well just this is just not appropriate   for concrete overlay, I mean it's it's too far  gone or perhaps there's a better solution a better   preservation solution and we still have an overlay  down the road 10 years from now, let's squeeze   everything we can out of this pavement before  we have to overlay or remove or reconstruct. So   I get the privilege of presenting some examples of  concrete overlay projects from across the country.

And we are literally just going to hit the  highlights. I don't want to get into the weeds on   these. I think the intent here is for the audience  to be able to look at at these projects and say   hey that's similar to something we've got on our  three-year program. Maybe we need to consider   a concrete overlay solution on that. Maybe it's  a potential strategy so that that's kind of  

the idea it's not to get into the weeds and go  through every single detail of these projects.   So hopefully they're representative. I mean  there's some geographic and climatic distribution   to these. They vary from six years old to 14 years  old, there are other case studies out there at the   CP Tech Center's website where you'll find  case studies of concrete overlays that are   30 years old. So these just happen to be let's  find something that's that's fairly recent,  

spans a wide variety, we've got different  facility types, we've got different overlays. So   Peter just kind of went through those.  We've got concrete on concrete unbonded,   we've got concrete on asphalt bonded, and  we've got concrete on asphalt unbonded,   varying levels of traffic volume and  loading and then different approaches   to maintaining traffic during construction. So  let's take a look at these projects one by one.

First one is North Carolina and Yadkin  County on I-77, so constructed 2007, 2008.   It is concrete on concrete unbonded.  The existing pavement a 43- year old   continuous reinforced pavement. It was  experiencing punch outs, ruptured steel,  

faulting at cracks, it obviously was needing some  attention. North Carolina DOT chose design build   delivery method on this, that that fits, I've seen  plenty of overlay jobs in our design bid build.   There's nothing you know special that it has to  be designed build this one just happened to be. So when we talk about the maintenance of  traffic on this job obviously pretty heavy   used facility, lots of trucks, lots of  vehicles. So the approach was a median detour  

with limited duration of one lane operation. So  most of the project main to maintain two lanes   in each direction. The contractor was allowed some  windows where they were allowed to reduce down to   one lane in a direction. The ramps also had some  time frames they had a maximum 11-day closure.   Now what's interesting about that is is the design  build RFP had those ramps constructed in asphalt.   The contractor proposed unbonded concrete on  concrete unbounded overlay for the ramps to save   time, so they saw this as rapid construction. In  fact taking less time on the schedule with those   11-day closure limits than an asphalt alternative  would have. Typical section is 11-inch JPCP,  

jointed plane concrete pavement, on an inch and  a half thick asphalt separation layer. Now really   elegant solution to, and and Peter mentioned this  a couple times in his section of the presentation,   of how you do transitions, how do you match  existing features so the bridges on this project   actually were able to be jacked to the overlay  elevation. So they raised the bridges by 12 and   a half inches to match the 12 and a half inch  raisin profile grade from the existing pavement,   and then by specification, the entire surface  of the concrete overlay was 100 percent ground.   That was just a decision that was made in the  design build RFP that they wanted in ground   surface for smoothness for noise whatever  it was but that's that's the way that went.

So our second project is Colorado State Highway  13, kind of north, well maybe central west,   I guess you'd call it western slope. Kind  of dry country out in Western Colorado,   existing pavement was asp halt so we have a  concrete on asphalt bonded overlay, the COAB.   This asphalt was profile milled, so we're trying  to optimize the volume of concrete and optimize   the potential for pavements smoothness, so it's  important to recognize that profile milling   process so that involves collecting roadway  profile data and then developing a proposed   profile of the overlay which, given those two  things, we're trying to find the best compromise   between the potential for smoothness and volume  of concrete that it's going to take to get there.  

And we've got to maintain a minimum thickness of  our overlay. We've designed for a certain number   of ESALs traffic loading, whatever it is. So  we're looking to find that that best compromise of   concrete thickness volume of concrete which  all boils down to cost and then also being   able to produce and construct a smooth pavement  in the end. So the typical section on this job is   six inches thick, again, jointed plain concrete  pavement with six foot by six foot slabs   commonly referred to as a six by six by  six. Colorado was kind of an innovator with  

the six by six by six design. This project  again was 2016. It was also an alternate bid   so alternate bid concrete versus asphalt and in  this case concrete was lowest cost alternative. Maintenance of traffic on this one, a little  different than what you see sometimes. We've got   a six-mile-long pilot car operation, so we're  maintaining traffic in both directions using   a pilot car constructing the overlay one lane  at a time. The picture on the right if you can   see it kind of shows that we've got pilot car and  then and paver and on one side. Final smoothness   for this project, average I RI was less than 45  inches a mile so really complete success there.

Third project is Blaine County Oklahoma  State Highway 51. Again constructed in 2016.   this was an existing asphalt pavement and again  a concrete on asphalt bonded overlay application.   This one was not bid alternate but  went through a couple rounds of bid   as an asphalt project and were rejected twice  and then redesigned as a concrete overlay and   finally awarded to that. Typical section is five  inch thick fiber-reinforced concrete so again   jointed plain concrete pavement six foot  slabs by seven and a half foot long. Again this was profile milled so the idea is  and you can see part of the roadway milled. The   gentlemen Neyland in the the foreground here  is actually the pavement was widened as well   I think a couple feet on each side so those  millings part of them were utilized to widen   as a sub base under the concrete overlay. So just  out of coincidence the guy in the foreground,  

one of those people that have taught me so much  over the years, he and I worked together for 15   years but he has been doing concrete overlays  since 1984. And still doing it every day,   wealth of knowledge and certainly appreciate  all that he's taught me through the years. So maintenance of traffic on this one. Up to now  we've kind of looked at different approaches for  

how do we get traffic through a job. This  one was actually closed to through traffic   so let's get in here and and  get out as fast as we can,   close the roadway to projects five and  a half miles long to through traffic,   obviously local traffic maintained so property  owners can get into and out of their property. So to do that, they you know kind of segmented  the project to where they could get people   in one way out the other way, but still  have the road closed to through traffic.   If you think about 90 days you know this the  second bullet project completed less than 90 days,   so you go bid opening, project award, pre-work  meeting, mobilization, construction of the   overlay, and then reopen the traffic all in less  than 90 days. Whatever the terminology you want to   use, whether it's you know rapid construction,  accelerated construction, it fits the bill. So  

my experience, first 15 years of my career was  with a contractor and built a bunch of overlays,   and I can tell you that when you get to go to  an overlay job it 's like vacation. You are not   fighting the weather. I mean literally unless  it's snowing or raining you're paving. You're   basically weatherproof and it just shows up and  in the production you can make, in the in the time   savings that are available when we look at overlay  solutions like this. Another thing you know,   I mentioned that the roadway was widened by a  couple feet on on each side so you can kind of   see on the left there all the drainage structures  were extended to accommodate that widened roadway.

Fourth project is County Road in Iowa  so Worth County, very north Iowa,   23 miles long. I mean this, you know,  county is only 36 miles square so   most of a county right 23 miles long. It was an  alternate bid, it was awarded the concrete based   on initial cost, a combination of initial cost and  estimated life cycle cost. The typical section is   four inches thick again JPCP, six foot by six foot  slabs. The plan set was ten pages, so yeah maybe  

it's a new technology to certain agencies but once  an agency gets comfortable with concrete overlays,   the project development and engineering is  pretty straightforward. I mean we do not need   hundreds of sheets of plans to go build a 23-mile  long county road. It's doable with with only the   information you need. I mean here's an outline,  here's station to station, here's the typical   section, make sure you get people in and out of  their house that's tha t's about all it takes. So zero pre-overlay repairs on this old roadway.  And no milling so whatever was there got overlaid   with four inches of concrete. Now obviously  it's not you know not high volumes of traffic,  

but I will tell you the the loads from the  agriculture equipment up here are not light   so again it just did not require any  pre-overlay repairs. Closed it to through   traffic kept it open to property owners  and then again 23 miles, 110 calendar days,   and that roadways gone from old asphalt pavement  to new concrete overlay open for the full length. Alright, the last job and I see quite a few  of these now, not always an unbonded like it's   presented here but this is an urban intersection  in Salina, Kansas filled in 2012. So for Salina,   this is the busiest intersection in town. What was  interesting, they actually had in their their kind  

of infrastructure plan another intersection that  was going to be reconstructed in the following   year and they knew they needed to do something  with this one before that next project. So   what do we do? What can we do? Kind of short  time frame what can we do without disrupting   forever what's going on with with the  businesses around here and a concrete on asphalt   unbonded design was a solution. Now it does  happen to be an existing composite pavement   so with the new terminology, the fact that it's  composite, we just call it concrete on asphalt   and this one happens to be unbonded. They did  some partial depth milling so if you've ever   done any work on on an urban intersection you know  we've got a jillion things that we have to come   back and match: elevation, whether it's curb and  gutter, whether it's utilities, whatever it is.  

We're pretty much locked into whatever elevation  we were at so the approach was partial depth   mill what was there, place an eight inch  thick JPCP with 12 foot by 12 foot slabs. Maintenance of traffic on this one is really  just like you build any other intersection.   I mean you're staging it by quadrant and  maintaining traffic all times during construction.   You might limit the turning movement now and then  but you know same as you'd stage any intersection   construction. The entire thing completed  in 45 days kind of see a before and after. Those are the project highlights and I really  hope again that they just kind of remind you of   projects you've ever had in the past and say  hey we might have been able to do a concrete   overlay there or you're looking at something in  the future and possibly a concrete overlay is a   potential solution for that upcoming project.  That's the idea here, we don't want to get   into the weeds about you know, what are the  design details, how thick does it need to be,   what's the fiber dosage, a lot of that  information. In fact there's there's just  

a ton of resources available at the CP  Tech Center, at FHWA DOT. You'll just find   tons and tons of resources related to concrete  overlays. I encourage you to check them all out. Shree, it's back to you." Shree Rao: "Alright, thank you very much, Gary.  That was an excellent presentation  

and it really shows the different ways you can  do concrete overlays in different situations. It   really covered many different types of concrete  overlays and it was exciting to see all those   different projects. Again,  if anybody has any questions   please type it in the chat board and I'll  have Peter and Gary answer those questions.

There's a few questions already  on the chat board and I''m gonna   ask those questions until we see more questions. The first one is from Bob Hackman who says  won't IIJ, I guess that's the infrastructure   investment and jobs act, provides some funds  for use in looking at concrete overlays? This is probably not a question for  Peter or Gary. I don't know if Sam,   you want to take this question? Peter, do you know anything about the IIJA?" Peter: "I was kind of hoping Sam was gonna pick that one.   I don't know a lot about it. I was actually  looking to see if Leif was on but he's not   here either. I'm not sure that I fully understand  the question. I'm pretty sure that there will be  

concrete overlays built using IJA funds depending  on how the states tackle it. I'm not sure that any   of that money would be available for investigation  or promotion but you know that's the activity that   you're doing under the TOPS program and that  we're doing under our cooperative agreement,   is providing the resources to help the  agencies. So two answers to one question, Gary?" Gary: "Yeah, no. I really can't provide anything that  

of a meaningful help regarding that." Shree: "It's probably more a comment than a question. The next question is from Thomas Tate. He  asked how is widening accomplished? Gary   do you want to talk about widening of a  roadway when you do concrete overlays?" Gary: "Yeah, I can briefly and and I will say it's one  of the most challenging parts of overlays when we   try to tackle kind of integral widening with  an overlay, things can get complicated pretty   quickly. There's some some good guidance in a  couple of the resources. First being guide to   overlays the other being, I forgot the title, the  plan details one Peter that Jared and I worked   on. But anyway it goes through some pretty good  details on on how you would approach widening  

integral with a concrete overlay. But again, it  is sometimes one of the more complicated things   we do. So if it's your first overlay maybe  you look for one that's a little easier, but   it's been done a lot so it can be designed  around and, again the devil is in the details."   Peter: "Is it worth going back slide seven we actually  had a photograph of a widening happening?" Gary: "Yeah we did. I'm not sure that matches up  with the current kind of guidelines for  

you know reinforcement of a integral widening and  are some drainage considerations as well. In fact   I think that that photo Peter came  from one we learned a couple lessons." [Laughter] [Crosstalk] Shree: "Okay. Thank you, Gary and Peter. Bob Hackman  has a comment about the American Concrete   Pavement Association has a national map of  overlay, so if anybody wants to check that out   again go to ACPA's website. There's a question  here from Z. Lootens working on project that is   adding a third lane to existing two-lane each  direction interstate. Considering using PCC   pavement section for third lane and PCC overlay  of two existing HMA lanes. What is your advice,  

example tied untied wedge mill to match PCC  thickness for longitudinal joint between   new PCC auxiliary lane and PCC overlay? So, Gary.  I'm not sure you got that but essentially how do   you tie a new PCC lane to an overlay PCC?" Gary: "Yeah, so it's similar to a project I did back in '98   I think. '96 maybe where we had existing four  lane facility we did an unbonded overlay on the   existing lanes and then widened both to the inside  and outside with additional lane and shoulder.   I would say tie them just as you would if all of  them were from ground up new concrete pavement,   because what you're looking at that concrete  on the existing asphalt that's an overlay.   That asphalt is is simply a a sub-base course  it's their support you want to be a little bit   aware of what movement might take place between  placement, of unless you're placing it all at   the same time 36 foot wide say, what movement  might take place between the the construction of   the separate lanes. But I would say tie it  just as you would any other concrete pavement."

Shree: "Peter, is there anything you wanted to  add to that in terms of the movement   and the friction, different friction you have  between the different support conditions?"  Peter: "Yeah, I'm semi wondering how much, yeah  they are going to move differently and   so you may want to consider how you can allow  them to move without causing faulting. I'd be   reluctant to tie them together too tight because  I suspect you'd get some cracking coming through." Shree: "Okay, thank you both Peter and Gary. John Sudela   asked Eric can you just move back one slide  so people can look at the resources page? Here's another question, is there a maximum  traffic or ESAL limit where you should no   longer consider bonded overlay and use unbounded  instead? And the question further says ACPA guide   to concrete overlay reference suggests  only up to 15 million ESALS for bonded. Peter, you want to take that?" Peter: "I'll defer to Gary." Gary: "Yeah, so I think rather than theory, and  

I'm gonna get way out of my area of expertise with  design. But what's gonna happen is if you have a   a facility with with millions and millions and  millions of ESALs, you're going to end up with   a thickness of overlay which, it doesn't matter  if you bond or unbond, so you might as well call   it an unbonded. If that makes sense. I mean  once you get above six inches of thickness,   any any contribution you're getting by bonding  to the layer below is is negligible. That upper  

slab the overlay slab is carrying all the load,  so I think it's just going to be driven by the   ESALs and the thickness of the pavement you end up  with. And if you don't have to bond, don't bond." Peter: "I would agree with that." Shree: "Alright, thank you very much. Greg Dean asked was this   presentation recorded and will it be available  for others to see? I can answer that question.   Yes, it is recorded and it will be  posted on Federal Highways website.

[Indistinct muttering] Greg Dean asks on the thinner  asphalt overlays the six by six   sections should the joints  be sealed or left unsealed? Opinion?" Gary: "Peter take a stab at that? Peter: "I'll start. I think they should be filled. The reason being   that if you leave the joint unsealed and water is  able to transport through the joint, you increase   the risk of stripping of the asphalt below the  concrete and then you've got a support issue.   And you may have a failure because the concrete's  got nothing to sit on. So you know seal or fill,  

you know it's another debate altogether, but I  would like to keep the water out of the system." Gary: "I agree and and I guess I'd add just a little bit.  I mean so if you go back to the very pre-history   of of thin concrete overlays, where we ended up  with these small slab sizes, the approach was   not to seal. And we've learned plenty of lessons,  especially in wet freestyle environments, that the   benefit of filling those joints is worth the cost  of filling those joints if you're not in a wet   freeze thaw environment, I think we've also seen  some lessons learned with just simply filling of   incompressibles in those joints and some premature  distress. So I would agree, fill the joints." Shree: "Okay thank you both Peter and Gary. I did want to  mention to the participants that

2022-03-28 03:50

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