Precast Prestressed Concrete (Fall 2006) - Full Video


Uploaded by WafeekWahby on 09.04.2012

Transcript:
♪ [music playing-- no dialogue] ♪♪
♪ [music playing-- no dialogue] ♪♪
>> Dr. Wafeek Wahby. And it's my pleasure
to welcome Mart McIntyre, the executive director of...
>> Marty McIntyre. I have a new name!
>> Dr. Wafeek Wahby. Her new name [unclear audio]
they used to be the three [unclear audio]
complete producers for Wisconsin and Illinois.
This is a big name, and she has a big postition but she has
a sweet heart and a sweet spirit; she came all the way
from Chicago to be with us.
She injured her foot.
>> Marty McIntyre. Yes.
>> Dr. Wafeek Wahby. But she is walking well.
>> Marty McIntyre. I am walking.
>> Dr. Wafeek Wahby. Thank you very much for coming.
>> Marty McIntyre. So that's an improvement
for six months ago, so.
[audience applause].
Thank you.
I will, give you all the information I know you need
that, he, Dr. Wahby asks for reports so I'll give you
my name and everything again in a slide.
I came today to talk to you about pre-cast and pre-stressed
concrete, and I'm going to talk a little bit about what
the different products are.
How they all work together, what are some of the construction
issues that you know our members look at and that come in
the erection of a building.
And a little bit about color and texture and how you can make it
look nice and the things that architects probably care about
more than you do.
But just to get started I thought I'd show you
a little eight minute video.
And this just goes through a lot of the history of our industry
and what all of the different products are so it's a nice
video that they did for the 50th anniversary of the association.
And let me start that.
Doing anything.
Okay.
Yeah, there's no...
Oh, okay.
Ah, there we go!
[video audio].
...Images of the past fifty years.
>> Dr. Wafeek Wahby. Sounds good in the back?
[unclear audio].
>> Marty McIntyre. No, they didn't really
miss anything.
>> Dr. Wafeek Wahby. They'd like to see this.
>> Marty McIntyre. You want to see it again?
I...
[video audio].
...ever imagine the changes you've seen in our own industry.
The innovations and architecture.
Construction, and building materials.
When Gustav Maniel designed the Walnut Lane Memorial Bridge in
1950, who could have conceived that an entirely new industry
would take shape based on applications
for pre-cast concrete.
When the pre-cast pre-stressed concrete institute was formed
50 years ago in 1954, we imagined a future.
When pre-cast pre-stressed concrete would be one
of the world's most widely used building materials.
That future, is now.
Today, as always, PCI continues to work closely with producers,
suppliers, and professionals to develop new techniques,
certify pre-cast quality, and educate the industry about
pre-cast's concrete's advantages for today's construction team.
During the recent AIA convention, designers reflected
on pre-cast's past, present and future.
Right now this is, this, you know, pre-cast is back
into the market.
Very strongly with the jump in steel pricing,
everybody's looking to pre-cast.
And speed, speed is what this whole thing is about.
Everybody wants that product fast, and delivered.
Pre-cast's speed of construction is a key benefit
designers appreciate.
I use pre-cast on projects because of cost and a lot of
times because the schedule makes it go quick and pre-cast
is a good way, you know, reducing your schedule.
Pre-cast's quality is widely acknoweldged.
The things we look at: mixture, skim systems we evaluate with
our owners and our architectural partners is one:
the quality of the product.
Two is the cost effective solution
to the overall building.
And what we found most recently is, pre-cast is a great solution
and especially as we're comparing it to other products
such as a granite material or what we call a GFRC,
glass-fiber-reinforced-concrete.
The more that you can do and implant or offsight and bring
onsight, I think the quality is going to be a lot better
and also with material waste, that can be managed as well.
Pre-cast's quality and durability are key benefits
to owner's and architects.
Their benefits are time, constructability, the benefits
in certain climates for certain types of uses.
I believe it is a very flexible material with an inherent fill
and performance and you know with [unclear audio] good
durability and really it's ability to form into the
wonderful three dimensional shapes.
As new ideas take shape, still more are in the imagination's
of designers and producers waiting to be brought to life.
The technology that today is available using 3D modeling
and using more than actually 3D modeling I would like to refer
to it as 4D modeling, is the fact that, that encompasses
the entire building integration modeling.
It refers to the fact that we now have an ability to integrate
all aspects of the trades and the specialties that work
in creating the building in a single cycle.
And the type of technology that allows it to integrate
seamlessly among itself to provide tremendous advantages
for the pre-cast industry.
In the future, more commercial structures will be framed with
complete pre-cast systems, using the various repetitive
components created by pre-casting techniques.
Today's all pre-cast design consists of pre-cast columns,
beams, floor members, exterior finished members, and stair
and elevator shacks.
This approach can create structural components with
architectural finishes, reducing piece counts,
and saving material.
Building height won't be restrained by total pre-cast
systems, as even 50 story builings can be easily designed.
It's a very innovative moment, in all construction, we are
seeing a proliferation of new builind systems and materials.
Things that you really never imagined.
So we are seeing a boom in tall buildings, all over the world.
At the same time there, we're seeing advances in all types of
builing systems and materials.
Buildings now feature precast concrete panels with white
glazing in window openings, and even stud back-ups apply
to the plane.
More complex finishes are being used on architectural panels,
surpassing the traditional finishes that designers expect.
Custom floor glider's, heavier textures, mullti-colored panels,
and intricate desgins are becoming popular.
I love the material.
You can do anything with concrete and give it to span
support, and accept load, in any shape or fashion.
Behavior of the material, [unclear audio] it is a very
easy material to design, very easy material to produce,
and the end results are beautiful.
The advances being made today, in seizmic connections will
continue, producing techniques that create safe, cost effective
desings in every seizmic zone.
Ultra high performance concrete is expanding the durability
of pre-cast concrete to 30,000 PSI and beyond.
New performance characteristics for concrete mixed designs
are creating higher strengths, faster production,
and better aesthetics for all types of projects.
Pre-cast, pre-stressed components are being used for
more bridge pieces including beams, dexslabs, peir caps,
and columns.
Pre-cast can greatly speed bridge replacement
and initial construction.
The fact that today we are able to push the length of the spans
well beyond anything that we had ever considered to do
in the past by using [unclear audio] to design,
it is a tremendous advantage to the pre-casting industry.
We virtually have now an abililty to play in essence
in a market that we have never been able to play in the past.
New strands such as carbon fiber reinforced polymers
are replacing steel and producing more durable,
higher-strength components.
We see advances for instance with new carbon fiber technology
that allows composite products that are twice
as strong as steel.
In concrete we see mixtures, fibers, added to the basic
product that make a lightweight product that is stronger
[unclear audio].
New standards are being promoted by leadership in energy
and environmental design.
An initiative of the US green building council, the result:
a growing interest in sustainable design,
boosting pre-cast's potential even further.
I see green buildings becoming the next way of manufacturing
and using materials that are economically safe and they don't
create harmful, viral, environmental problem
if you wouldn't.
It gives us a lot of flexibilty in terms of the aesthetic
component of our projects and it also let's us move ahead
our agenda to increase the sustainable design content
of all our projects.
In the 21st Century, PCI will continue working closely with
educators to ensure that bright young designers and innovators
continue to join our industry eagler to tackle
tomorrow's challenges.
I've been teaching for 30 years, I've been teaching
a course that deals with architectural pre-cast
and structural pre-cast for the last 30 years.
PCI has been a big part of really getting me the materials,
the books, that our students use in my classes.
These students along with today's designers and producers
will benefit from the market's new technologies.
I think, in the past, of [unclear audio] construction.
Where numerous people were employed and literally hammering
together the thousands of components that make
their buildings.
And think how we can improve that process.
One way is thinking of the assembly of buildings
by component by large panel if you will.
And making those panels smarter, controlling their quality,
and literally being able to bolt together large, affective,
well-designed pieces.
That would take less time to construct, less time
to assemble, and actually we've had I think we're able to get
greater quality by controlling the manufactuing process
of the component essentially.
Computer aided programs offer great potential to promote
interoperative ability and reduce errors throughout the
design and construction process.
There are four major advantages to using 3D modeling.
Number one is reduction of time for adaption.
The second advantage is the abililty to reduce
the engineering and design operations.
The third advantage is to have the ability to reduce the actual
drawing production effort.
And the last advantage but definitely not the least,
is the ability to have a collaborative effort in which
everybody participates in creating a building model.
You are able to present it to your client in a very fast,
and productive way.
And they have an ability to decide that pre-cast
is their choice.
Bridge designs can also benefit.
The dynamics of the bridge industry are very well in tune
for using this type of technology.
On the bridge industry we have many more
standardized cross-sections.
We have much more standardized design
and construction processes.
We have a government agency that ensures in essence that the
development, design production and building of bridges,
it is done to very rigorous specification which are more
uniform across the country.
All those parameters allow 3D modeling to be very well fitted
for this type of design.
The basics of these systems can be adapted to create
new techniques and additional tehnologies
for a more controlled construction experience.
We're starting to evaluate RFID's or technologies that can
be tracked pieces in the yard electronically.
Or using GPS or whether they sit on the buildings.
We're tracking trailers as they come and go out of the yard.
So the industry itself is really becoming proactive in using
technology that are in other industries and really turning
our industry into more of the streamlined flow of
[unclear audio] type of manufacturing.
Which it never had before.
The future promises many surprises
and dramatic improvements.
I really see from the future an ability to have an architect
communicating with a producer, a designer an engineer,
on the web.
Models being posted, multiple people talking and having
conference calls while they're working on the same model
of a building.
An ability that will give us a tremendous potential to increase
the level of production of pre-cast buildings
in this country.
A great future.
It's not surprising given the pioneering work and breathtaking
innovations of the first 50 years.
Fifty years is not such a long time in architecture.
You know, you look at the Roman baths and the Parthenon,
you are lookiong at 2500 years of construction durability
and certainly pre-stressed concrete is right there in line
with all that masonry and concrete construction
from ancient Roman times.
So, what are we going to think about what we are doing today,
2500 years from now is what I'd like to know.
PCI will continue to blend today's solutions
with tomorrow's possibilities.
Always encouraging, nurturing, strengthening, and promoting
our industry, our products, and our people.
The dream continues.
Truly the best is yet to come.
>> Marty McIntyre. Well, the video is a couple
years old but I think it does a nice job of explaining kind of
the history of our industry and a little bit about what we hope
the future's holding.
Most of the pre-cast manufacturers are just that:
they're manufacturers.
And then they're supply and construction products,
and it really is a 'just-in-time' industry.
They truck it to the job site, get it there, you have
the erector ready to put it up on the building and the truck
leaves so they really don't require too much space right
on the job site.
They come right in, get it on the building, and get it out.
Before I get it into my PowerPoint presentation,
I also wanted to show you this, can I back this up?
Let's see if I can figure this out.
Let's see if I can start it.
Here it...woah!
♪ [music playing] ♪♪
Alright.
Okay, we don't need the music quite that loud.
This is a 3D animation that one of the members of the, on the
East Coast did, and this is what we in the industry often call
total pre-cast construction or pre-cast structure and frame.
And it really shows you all the different types of pre-cast
products that are available for buildings.
This doesn't include the bridges.
You see the columns and beams going in.
The spandral panels.
In this case they're putting in double T's.
But in this part of the country we mainly see this kind of
construction for mid-rise buildings, seven to nine stories
condominiums that use hollow-core.
The elevator shafts and stairwells are also pre-cast
and one of the really, the real advantages of this kind of
construction over other typical types of construction
is the speed that you can erect it with.
You see here in a minute and half you have a whole building.
It was a joke, okay you guys got to wake up a little bit.
No it takes, we had one member did an eight story building
and they did 80 days of erection time on it.
So it, it can go up, basically it was a story a week that went
up on it and it was pretty, pretty fast.
Here's the HVAC hanging right off of it.
And then you also have your stairs can be precast as well.
It's very quick to just enclose the whole building and get
the trades inside it and working very quickly.
So this would be a typical office building.
It's a very regional type of construction in Colorado we see
almost all the office buildings being built with
this type of construction.
In Chicago, we're seeing an occasional condominium using it.
Also up in Milwaukee we, we've seen it.
On the East Coast, we're seeing a lot of condominiums and office
buildings both coming in and using that type of construction.
So it's a very regional and there are several things about
the industry that are kind of regional anomalies
as we go on today.
Anybody have any questions about how that went together?
Okay, yeah?
>> male speaker: Just sit on top of
each other or do you hold it together?
>> Marty McIntyre: Yeah usually they have
welded connections and so they're bolted and then
welded together.
Usually the columns can be 20 feet about.
And then they're, they've got welded connections.
Let me, get into my powerpoint.
Oh it's already open here.
This is who I am.
I know that you, need this information for your report.
And our group now is called PCI of Illinois and Wisconsin.
And we were formerly the pre-cast, pre-stressed producers
of Illinois and Wisconsin but we're the regional affiliate of
the pre-cast, pre-stressed concrete Institute, PCI.
And you'll get more information about PCI, you'll get some books
from them, I think later in the semester and, they are
the national trade group.
Are you guys at all familiar with what trade groups are
and trade industries?
Want to talk a little bit about that?
Basically, our association has member companies and we have
13 member companies who ship their product
into Illinois and Wisconsin.
And they've all banded together and they hired me as their
marketing and executive to run the association to do a lot
of education events, some trade associations, do lobbying,
we do a little bit of that and government relations.
And a lot of industry education as well.
I do education for the pre-casters in our areas as well
and then we all support the National Trade Association.
So if you're familiar with CSI, the Construction Specifications
Institute, The American Institute of Architects,
those are all organizations that are similar to ours,
that are in the construction industry.
So these are who my member companies are.
I thought I would get started today by talking about all
of the different products.
We kind of saw them all fly in together and go together
very quickly in a building.
One of the most common types of products that you're going
to see especially in this area because there's a number
of manufacturer's doing it, is hollow core.
Hollow core, these floor panels, or they can be roof panels,
they come in widths of two-feet, four feet, and eight feet,
and are typically about thirty feet long.
Different manufacturers manufacture them
in different ways.
What you see right down here is called the wet cast process.
And that's, Flexicore is the name of the trade brand of it.
Flexicore is two-feet wide, and they use a wet cast process
where the concrete goes in, is pretty wet as it goes in,
and then it kind of wraps around those pneumatic tubes
that you see in there.
And that's what creates the hollow-cores in there.
There's also a dry-cast method like you see here.
And that's usually either four feet or eight feet wide.
And that is going to be extruded out.
That concrete is so dry that the minute it comes out of the
machine, you can just walk right on it.
It's a very dry method.
They've got, pieces in the extrusion machine that core,
the hollow cores through it.
Anybody have any ideas of why you would have hollow cores
in the floor panels?
Somebody said weight.
Did you say weight?
Yeah, that's it exactly.
Concrete is a very heavy product and you don't need the strength
of that concrete in all of the locations you've got the steel
going in there too and so you want to make it a little bit
lighter weight, shipping, erecting it all in the building.
Just the loads in place.
Yeah?
>> male speaker: What's cheaper the wet or the dry?
>> Marty Mcintyre: It's, as far as manufacturing,
I don't know.
That's a good que-, that's a good question.
No one's ever asked me that, which is cheaper.
You know basically each job is going to be individually bid for
each particular project and so sometimes it works better like
one of our manufacturer's does both types of methods...
Yeah?
>> male speaker: Do you have to have a finisher,
finish all that or no?
>> Marty Mcintyre: No.
Normally they'll just screen off the top of it and then as they
put it in place, you'll usually put about a two-inch layer
of concrete over the top for the floor mix.
And that's not only because of the finish on top,
and you'll have a lot of, you know gaps, not gaps but,
where the pieces meet, so you want to straighten that out.
But also because of the pre-stressing process,
you'll have an arch or a camber and so you want to make sure
that you have a level surface because of that.
Any other questions about hollow core?
Okay.
Oh, here...
Double T's are the other floor product you're going to see.
If you've ever been in pre-cast parking deck before you're sure
to have seen Double-T's.
Anybody know why they might be called double T's?
They look like two T's!
It's not too early in the morning for you guys.
They look like two T's right next to each other.
There's also single T's but we don't really see much
of those used anymore.
Those were used more like 20 years ago.
So parking decks, gymnasiums, industrial buildings, typically
you're going to see about a 60 foot roof span, or excuse
me a 60 foot floor span, with those to sustain a parking deck.
If you have a roof span you might see as much as
a 100 feet with it.
The trick, when you get a 100 foot footspan with
a double T is that how do you get it to the job site?
And the pre-casters have to get special permitting for that
normally, you're usually not going to do that in a really
urban area that's been done in more like suburban areas
and out in ex-urban areas.
So, double-T's are pretty typical.
You know I should have...
Alright, I'll just keep using this.
Insulated wall panels, one of the things you can get
with concrete, is great thermal mass.
But you don't get much in terms of R value.
The R value that you're going to get from the walls is going
to come form whatever insulation you use.
So a lot of times in gymnasiums or prisons or industrial
buildings, they'll add the insulation inside the sandwich
of the wall-panel.
So you'll usually get what's called the 3-2-3 panel,
it'll have three inches of concrete on an interior width,
two inches of insulation, and then another three inches
of concrete on an exterior width.
Then those two widths have to be joined together somehow so that
can be done either by creating gaps in the insulation where
the concrete will go all the way through.
Or there's also some products that Dow and some other
companies manufacture that act as connectors for those
two widths of concrete.
Pretty, pretty typical application for industrial
or schools and things like that.
Modular construction is something that we typically see
only in the prison market; occasionally you'll see it in
the education market or hotels and things like that.
But in Illinois we really have only seen it
in the prison market.
Almost all the prisons being built now use modular jail cells
that are pre-cast.
They're pre-cast, they're usually not pre-stressed
so they just have your typical reinforcing in there
with the wire mesh and rebar cages and things like that.
But you see here, are two jail cells, one right next to
each other it's a five sided piece of pre-cast.
And then at the pre-caster site they can put in the plumbing,
they can put in the electrical boxes, they can put in the doors
and security systems, all off site.
We had the director of prison construction in Illinois come
talk to our group and one of the things that he was saying is all
of the job sites for prisons have to be secure.
So every time a worker comes on at the beginning of the day
and then leaves at the end of the day, that was adding about
45 minutes of time to their job that they're paying
these guys for.
So they liked to have as much work as possible done offsite
and brought onto the job site.
So that's one of the reason's that Illinois is using all this
pre-cast modular construction for their prisons,
although there’s not a whole lot of construction going on
in this area right now.
Then the roof right here is used as the floor of the modular
piece stacked on top of it and you see there's kind of
a lip sticking out, that's going to be a walkway then around it.
So then they just stack back one right on top of the other.
One of the things that you're going to see on Wednesday when
you go down to county materials are the bridge products that
they manufacture.
Most of the time in Illinois, and other parts of the country,
pre-casters are going to specialize in one area
or the other.
Part of that is because bridge products really require a lot of
cooperation with the state DOT and other county engineers
and the people who are generally building the bridges.
So, most of the time you'll see somebody if they're doing bridge
beams that's all they're doing, although that's not always the
case, one of our members does a little bit of a lot of things.
What you see up on top is a box beam and in the middle
is actually a cardboard piece so there's a large void in the
middle of it so it's not concrete all of the way through.
Down on the bottom, is an I-beam and that's typical for
little bit longer spans than you would see with the box beam.
Also, you're going to see structural products like
the inverted T, the ledger beam, other types of ledger products
that can be used to create that piece that we just saw
flying in together.
So there are a lot of structural products out there as well.
Most of the hollow core producers in this area also
produce these structural products and they are the ones
doing most of the total pre-cast construction.
So that's kind of all of the different products.
Does anybody have any questions about those products?
>> male speaker: How many units can
you put in the prison?
>> Marty McIntyre: Usually they're about three stories.
Yeah?
>> male speaker: Regarding the prison,
do you have to drill holes for the plumbing?
Or are they pre-fabbed already?
>> Marty McIntyre: They can, pre-fabb them,
but depending on the size of them,
if they're more than four inches they'll probably pre-fab them.
If they're smaller than that they'll probably drill them.
Any other questions?
I thought I would kind of take you on a little nickle tour
of a pre-casting plant so you can see what it looks like.
And we're also going to talk a little bit about pre-stressing
and at the same time, and why you pre-stress concrete
and how does it actually happen and the plant.
First of all, it's important to know that there are several
different types of pre-cast.
But most of the pre-casters are members of the PCI,
the Pre-cast Pre-stessed Concrete Institute.
To be a member of PCI, they have to be PCI certified.
That means that it's, an inspector comes to their plant
twice a year, makes an unannounced visit and spends
2 days auditing the plant for about a 175 different items.
Things from how do you store your materials?
What kinds of records do you keep?
Where, what kind of quality control do you do?
Where are you keeping your, your cylindars for the concrete
that you're testing?
Is all of you equipment in working order?
So all of those things are things that the inspector
looks for.
That PCI certification is, I used to say it like
the USDA stamp of approval but then somebody said,
well yeah, you can't trust the government.
So, maybe more like the UL laboratories or the better homes
and gardens so you'll have the seal of approval
on your concrete.
So it is something to look for.
In this part of the country, most of the pre-casters
are PCI certified so it's really not a problem.
Once you know that they're PCI certified you can look up
and see what kinds of products they're certified to do.
Bridge producers have to be separately certified because
there's certain issues with the loads involved in bridges
and the quality of the concrete and the durability of these
standards that you need to meet that bridge producers
are specifically interested in.
Then you have your standard products and those are going
to be things that are cast in what are, in our industry what
we call long-line beds.
And you're going to see that on Wednesday when you see county
materials that change their name so I'm stumbling over the name
of their company.
When you go to county materials, they're casting all of their
bridge products in these long line beds.
And that means that they're made out of steel,
and they're casting multiple pieces at the same time.
So they'll all go on the bed at the same time, come off
the next morning, at the same time.
Then you'll also see your specialty pieces and that when
you go up to Lombard Architectural up in Chicago,
up in Alsip, you're going to see more specialty pieces.
Although he does have the capability in that particular
plant of doing long line casting, most of what Lombard
is doing are these specialty pieces so there's
more color and texture.
And most of the forms are built out of plywood rather than
out of steel.
They'll probably use those forms 25 to 35 times depending
on what they're looking for in that product.
And then they'll recycle them but they will be specially built
for that particular product in more one of a kind more
specialty and therefore usually a little more expensive.
All concrete has to have some kind of reinforcing in it.
In all of the weather it's pre-cast or pre-stressed,
you're always going to see some kind of mild reinforcing.
And that's going to include you're wire mesh, your rebar.
Once in awhile you'll see fibers being used to reinforce
but not too often.
There's some new reinforcement with carbon fiber,
where they're using some carbon fiber grids that are being used
in the panels.
And they're having wall panels that are just as strong as
six or eight inch thick panels but they're only about
two inches thick so carbon fiber is pretty interesting.
Post-tensioning, this one of those regional anomalies
that we were talking about.
We don't see a whole lot of post-tensioning in the Midwest.
You'll occasionally see it for a bridge or a parking deck,
but in general we don't see a whole lot of it.
If you were to see post tensioning, the pre-caster would
create a sleeve within the product, then it woud go out
to the job site, the steel would go into that sleeve at the
job site, it would get tension there, and then grouded
into place.
So you would see it that way.
Most of the time you need extra strength with pre-cast products.
What you're going to see is pre-stressing rather
than post tensioning.
Pre-stressing takes all of the best qualities of a very
durable, high strength concrete, and combines it with
high strength steel.
So you've got concrete that's going to be good
in compression and tension.
So what it's going to create is something with this arch
or a camber.
We're going to kind of go through the manufacturing
process to look at how that happens.
This is a typical wall panel plant, and you see the long line
beds that I was talking about.
There's steel, they're built up a little bit because underneath
they do have heating elements.
They want to always control the temperature.
One of the things that a pre-caster wants to do is
he wants to turn his product over everyday so he's creating
a new product and getting out of the plant everyday.
They do that a couple different ways, one is by controlling
the temperature that they have.
Another is by using a very low water cement ratio concrete.
That means that there's more cement in the concrete that they
use it's so that the hydration happens faster.
You see here, they're putting in some wire mesh, and then they're
also putting in door blocks and windows and then there's pieces
in between each of the pieces of concrete.
So they're casting multiple panels all at the same time
on the same bed.
This is actually Lombard where we're going to be.
You won't see this particular form because this is from a job
about a year and a half ago, but you can see the difference here
in the types of formwork that they have right away.
This looks like a skate park, it's got that radius
construction on it and got a lot of wood, the carpenter's really
work very hard and it's all very individual, very unusual pieces.
So that's more typical of the architectural
type of pre-casting.
Back to the wall-panels where we're looking at it in the
steel plants, you see here that they've got there, they've got
their wire mesh and then right here they've got
their pre-stressing steel.
All the pre-stressing for each of the panels that they're
casting in that long line bed has to be the same because
it's stressed on either end of the, of the bed.
So that's one of the reasons that when you're designing
in pre-cast you want to create a lot of repetition because you
want to create panels that you use all of the same placement
of the reinforcing steel.
I brought along a sample of the steel that you're typically
going to see in a pre-cast plant it's called a seven wire strand.
It's a little bit different than what you'd normally see
with re-bar because it actually has the ability to stretch
and give a little bit.
So if any of you can put about 35,000 or 40,000 PSI pressure
on this, you'll actually be able to stretch it.
It functions almost like a steel rubberband.
It's called a seven wire strand because there's one piece of
strand going through the middle and then six pieces of strand
wrapped around it.
And then if anybody's asleep, you can just poke them
with it so.
Yeah you can take off the end of it if you want to see,
what the strand looks like in there.
So, they put that strand in place, and then they're
going to tension it.
This is at, this might even be county material,
so I can't remember which bridge producer I took this at.
This is the end of a box beam form.
You can see there's quite bit more pre-stressing strand here
than if we go back to the wall panel.
Then you'd see here and because that's because there's going to
be far more load placed on this than you'd see on a wall panel.
One of the other things that you see is on the end of each
of these there's what's called a strand chuck.
They're going to come and get the forms all ready and then
they're going to put that 35,000 or 40,000 PSI pressure
on it and they'll use one of these strand chucks,
it's got a little O-ring in here that's got little teeth that
will actually hold that strand with all of that pressure,
while the concrete is curing.
So you can kind of see what that looks like.
And you'll see in the plants that they're all just
as clean as this one is.
So, it does get used quite a bit but they do have to
keep them up and keep them oiled and clean and ready to go.
So then they stress the strand, and that's actually the most
dangerous part of the, of the manufacturing process.
If one of those, occasionally, in a plant one of those strands
will snap, give way, and then it usually will come back.
So as you're touring through the plants, if you see any flashing
lights and people standing behind big wire mesh cages,
you don't want to stand on either side or behind that bed.
You'll always want to stand away from it.
It's not like it always happens it just is one
of the safety precautions.
One of the other things that, keep in mind as you're going
through the plants on Wednesday, you do want
to wear hard-toed shoes.
So you don't want to have any flip-flops or sandals or you
probably, guys, aren't going to wear high-heels but I've seen
architects come in with high heels and, you don't want
to wear those either.
So they've got the pre-stressing in place, and then they're going
to place the concrete in the form.
Most of the pre-casters are now using self-compacting
or self-consolidating concrete.
Are you guys familiar with that at all?
Let's talk a little bit about that so you'll know
what you're seeing.
As you're seeing, these concrete mixes go in the forms,
a lot of times now they just can stop the mixer or stop
the bucket, place the concrete in the form, and then it will
actually level itself through the whole form and not require
any vibration.
A lot of the pre-casters are using an add-mixture that really
does a good job of helping the cement coat all of the different
aggregate in the mix and that means that it's
a little soupier, and that also it flows a lot better.
Yeah?
>> male speaker: We use that for,
a lot for highways.
>> Marty McIntyre: Right.
Yeah, it is being used, it's not like it's only
in pre-cast plants.
>> male speaker: It's more expensive isn't it?
>> Marty McIntyre: It is more expensive
for the product but the pre-casters like it because
they save a lot on labor because they don't have the guys there
with the vibrators going along.
Now your not going to see that in any of the DOT projects that
require pre-stressing because the DOT isn't allowing it
in pre-stress products yet.
But they're, they're finalizing an agreement to start to use
that in the pre-stress products as well.
So that's one of the changes that we're starting to see.
So self-compacting concrete, the architects like it a lot because
it looks pretty, it's smooth, it's got a nice finish without
a lot of big holes or chips or dings.
Pre-casters like it because they don't have to pay as much
in labor costs.
After the concrete is placed in it's going to be cured.
And we have outdoor plants in a lot of parts of the country.
You're going to see county materials as an outdoor plant
for all of their bridge products.
Lombard is an indoor company with all of the
architectural products.
This would be a large bridge beam being cured.
And you can see that they've got a blanket over it,
they're steam curing it.
So even though it's outdoors, and even though they manufacture
it year-round, they still control the temperature
of those beds.
So it still is all quality controlled and keep
the temperature even that also helps speed the process
as they come along.
>> male speaker: How do they reconcile
between 7 days of quick-setting/hardening
and 28 days of strength by having it in 24 hours?
>> Marty McIntytre: Well, the, yeah it's not even 24 hours,
it's overnight so sometimes it's 12 hours strikes.
They're looking at about 3500 PSI and they're usually
looking at 28 days strengths of 7500 PSI and up.
Usually it's even higher than that, usually more like
10,000 PSI and up.
But, they're designing it for strengths of about 7500.
So they come in the next morning, and check and make sure
everything's in place, they look to make sure the concrete is
reached that 3500 PSI and then they're ready to cut the strand.
Now, when we looked at the strand earlier we were talking
about how it's like a steel rubber band.
And the strand in pre-cast is always if you're, if you've got
a beam like this, where, where do you think in the beam
the strand will be placed?
Any, any idea?
It's always going to be placed in the bottom of the strand
and that's what going to help create this arch or chamber.
If you see what's on top that would be a pre- a beam with
no pre-stressing in it.
So the weight of the concrete would actually create a load
that would create this, this is supposed to be
minor stress cracking.
I know it always cracks me up when I see this slide.
If you ever see, minor cracking that looks like this run
for the hills, don't go anywhere near it.
But this is supposed to represent minor stress cracking.
So you would see that on a beam without the pre-stressing in it.
If you do have the pre-stressing, it would look
like this because you've placed your pre-stressing
in the bottom of the form.
The pre-caster comes in and as the concrete cures overnight,
it actually will adhere to that steel that's being stressed
at 35,000 or 40,000 PSI.
So when the pre-caster comes in the next morning, they'll cut
both ends of that strand, while it's being stretched like
a rubber band, and it's cure, the concrete has cured
and snapped around it so it wants to snap back into place.
Well, because the concrete's cured to it, it can't and so
instead it tensions all of that concrete and you get
this arch or a camber.
As you're going through the plants on Wednesday,
you'll actually be able to see this in the bridge beams.
It's actually visible to the naked eye so it's
pretty interesting to see.
Now as you're, when you're engineers or designing
the pre-cast, they can't actually design the camber.
They can approximate what the camber will be but they actually
design it for the loads that are going to be on it
and that is going to create the camber.
That's kind of a nickel tour through
the manufacturing process.
Anybody have any questions about that?
Okay.
I thought I would take you through some of the,
I thought I got rid of this.
Okay, let's go back.
I thought I would take you through some of the different
details that you can get with, with pre-cast and some
of the trends that we're seeing.
One is the sculptural shapes, we're really starting to see
pre-casters being pushed more to do 3D sculptural shapes
and actually one of my members just did a project called
Varsity Village, it's at the University of Cincinnati.
And they had 3D modeling used for all of the pre-cast
components on the exterior section.
He did not have any right angles on the entire pre-cast portion
of the project.
So it was pretty challenging to do that.
We're starting to see more architects and designers look
for unusual shapes and sculptural pieces
out of the pre-cast.
We're also seeing a lot of details being used.
This is a hospital up in the Chicago area called
Condell Medical Center.
And this attention to detail with all of the different motifs
is something that we're starting to see quite a bit
on the products.
We're also seeing a lot of color being used more so than
it was ten years ago.
In this case this is stained.
Concrete producers who do wall panels generally don't include
the stain as part of their contract.
The stains are usually part of the, done at the job site
and are part of the contractor's subs but not part
of the pre-cast contract.
Security is an issue, there's a new FBI building in Chicago that
was built using pre-cast concrete and the US Air Force is
doing some blast resistant design testing with pre-cast.
So we are seeing more and more people looking for ways
of building secure buildings whether it be for floods
or hurricanes or attack.
Early consultation is a trend that my members really like
to see there.
They're starting to get involved in projects usually
in the schematic design phases when they like to get involved
when they can talk to the architect and say, "Yes this'll
make a good pre-cast project," or "no it's, it's not an ideal
project for pre-cast."
This is Soldier Field and it really represents the speed
of design and construction in a lot of ways in the teamwork
that people are looking for on some of these bigger projects.
It was pretty interesting to erect because you could only
erect it from inside the bowl of the field.
You couldn't do anything from around there was a roadside
on one area and there were parking decks on either side so
they really were limited so the cranes were quite challenging
on this project.
The pre-caster worked with the team and came up with some
solutions for some lightweight concrete on some of the larger
pieces of the pre-cast on the top of the bowl because
the crane just wasn't able to have that reach with some of
the heavier pieces of concrete.
They also had to do some finagling
with the steel erectors.
The steel erectors actually came in and used the cranes during
the daylight hours so from 6 AM to 6 PM the steel erectors
came in and then the pre-cast erectors came in and I don't
know how they drew the short end of the stick.
But they do erect pre-cast all night.
so they actually had 24 hour erection going on,
in the project.
So, you know typically this would have been a 24 month
schedule, with the parking decks and the stadium.
But because of the Bears playing schedule they had to finish it
in 18 months and they did it.
The contractor would have been fined I guessed
five million dollars for any games that the Bears were going
to miss at the stadium so.
They had real incentive to get it done on time.
The other portions of this that were pre-cast were
the parking decks and they're pretty interesting parking decks
as well because they've got large planters on the top
of it that actually have trees inside the planters.
And then part of the parking deck is underground
so the loads, and oh Soldier Field rests on top of one
of the parking decks too.
So the loads that they were taking were not typical parking
deck loads and it was a pretty interesting projects
So they were originally designed as cast in place,
but cast in place couldn't meet the design schedule
or the construction schedule.
So it was a pretty interesting project as far as the speed
of construction in the way that the group had to really function
as a team to get it done in time.
Just a little bit about finishes and colors, there are a lot of
possibilities out there when you're talking about
architectural pre-cast and how are you going to finish
a building and what is it going to look like?
One of the things that you'll see at the architectural plant
is that you can finish it, finish the surface of pre-cast
product in different ways and get very different looks.
This is actually an example of just a 12 inch by 12 inch
sample of concrete.
And it's been finished in three different ways.
On the far side is an acid-etch finish, and that uses muratic
acid and a hot water wash and it just removes the finest
particles of the concrete to give you a kind of a smooth
limestone like finish.
In the center, they've sand-blasted it so you get that
kind of white halo-effect.
And they've also gone a little bit deeper so you can see more
of the aggregate.
In the section here you've got a chemical retarder,
that's actually a sugar-based retarder that stops the concrete
from curing on the surface.
So you stop the concrete from curing, you then use a high
pressure water wash and you can expose a lot
of the aggregate that way.
So you really can get very different looks that's all
the exact same mix of concrete.
What's, what they've changed is the way they finish it.
>> male speaker: [unclear audio].
>> Marty McIntyre: Yes, and it's all going to vary
on the project and how many pieces you're finishing that way
and the sizes of the panels and how many panels you have
to move in the yard and things like that.
But also you know some of the pre-casters do more acid-etching
than sand-blasting and those really cost about the same.
Chemcial retarders cost a little bit more than those.
>> male speaker: Do you wait until it dries
all of the way before you do that?
>> Marty McIntyre: Typically, yeah, you'll do it,
you'll cue it overnight, cure it out it might sit
in the yard for a day or two and then they'll go ahead
and finish it that way.
So it's not like they're waiting weeks and weeks.
But sometimes they'll let it cure a couple days.
Any other questions?
One of the things that we've seen a lot of lately are these
insulated wall panels where they're adding insulation
and you can see this a DOW system where they've got these
connectors that are done out of a composite material.
Sometimes you'll also see connectors done out of steel.
But those will carry the cold temperature through.
So a lot of the people who were really concerned about
the thermal mass and not having cold spots in a wall panel
will use something more like this.
It is possible now to have insulation from top to bottom
and side to side in a project.
Pre-cast connections just talk about that when you’re
connecting wall panels you really are going to have
two basic types of connections.
One is your gravity connector, and that's going to be what
defies gravity and holds it up on the wall.
Gravity connectors are, you're going to have at least one,
you might have two but you'll never have more than two
because you can't predict the loads.
If you have more than two so those are going to be on the
wall panel where they need to connect to the structure so
it's going to change in every wall panel.
The gravity connectors will be in a different place.
Then the wall panels will also have tie-back connections.
And the tie-back connections, you're always going to have
a minimum of four connections and then sometimes you'll also
have six connections.
I need a brighter location but you've got them located
on the corners here and then if you have a long panel
you'll also have them located mid-span.
So the structure of the building needs to have a place where
those tie-back connections can actually connect or tie-back
to the building.
This just shows you again in a building where are all
the connections going to be for it.
You've got your cast in place slab on grade on the bottom.
And then you've got wall panels and then if you look kind of
behind it you can see where all of the connections are with your
gravity connectors, your mid-span connectors,
your floor connectors, and that's on a steel piece.
And there it is again you can see all of the framing.
This is with steel framing.
Then if you've got like a wall panel, you're also going to have
it connect back a lot of times you'll have some kind of shim
or some kind of composite material that the connections
are actually going to rest on.
So you don 't have steel resting on steel.
The weld plates are going to be cast right into the pre-cast
panels and so the precaster was going to have working drawings
in the plant that really shows the guys where are all
of the steel needs to go, where all the connection panels go.
And then you can connect it to a steel building, a casting place
building or a pre-cast building.
And those other, the partners to those steel plates
or the connection plates have to be ready on the building
where you need them.
Just another panel-to-beam connection system where you've
got the panels or the sorry the pieces embedded right into
the pre-cast and then bolted on.
Then sometimes you'll also have a pane-to-panel connection
to keep there from being too much movement in between
the panels.
And those are usually done with a threaded insert.
Typically you are going to have a joint-in-between the panels.
It'll be caulked on those wall panel projets with either
a single line or double line of caulk.
That is something that a precaster can give you
advice on but it's not always part of the precaster's contract
to caulk those joints.
That is going to be a maintenance issue so 20 years
down the line, 15 years down the line they will have to be
recaulked to keep the seal.
Usually you're looking at about a half-inch to three quarters
inch of space in between those panels.
I don't spend a whole lot of time on the connection issues
because the precaster is the one who is going to create
all of the connection details.
He's going to actually engineer his own product; he's not going
to engineer the whole building.
He'll need to know the loads, he'll need to know the codes
from the local area and he'll create all of the connections
for his own product.
Some things to keep in mind with fabrication delivery
and installation, just a little bit on that.
First of all, how do you make precast affordable?
How, what's going to happen?
There's two things that I talk about that really make
the biggest difference.
There's other little things that you can do as well but there's
only two things that really, really matter when you're
talking about the costs of pre-cast.
Whether it be panels or bridge beams or anything.
First of all, you want to have as much repetition as possible.
And that's because of the manufacturing process.
You want to be able to have multiple pieces all on that
same long line bed.
You want to have the same crane be able to pick them up.
You want to be able to use the same drawings and engineer
each piece so you're not re-engineering
each piece separately.
So a lot of repetition really is going to help keep
the cost down.
The second thing is the piece size.
Do you think pre-cast pieces should be bigger, or smaller?
Bigger.
Exactly.
You, you want to have them be bigger because bigger
will be less expensive.
You want to have fewer time with the crane, you want to have
the crane pick up fewer pieces of pre-cast.
That being said, you still need to be able to get the pre-cast
to the job and as we've talked about before, concrete is heavy,
so there are going to be some limitations on the size.
You'll also have limitations with just trucking it
to the job site.
In general, a wall panel is going to be limited by about
twelve and a half feet in one direction.
In the other direction, you'll typically see about
20 to 30 feet long.
And that's going to be something that they don't need any special
permitting, it's pretty easy to get it to the job site that way.
If you start getting bigger pieces than that, you have
issues with the precaster having to have cranes in his yard that
are big enough to pick up the pieces.
You'll have to have special permitting to get it on the
highway, so there will be issues that will come around with that.
Just as we are talking about the repetition, especially when
you're talking about architectural pre-casts,
they're building all of the formwork.
So you want to be able to use those forms as many times
as possible.
You can build repetition in a lot of different ways,
sometimes you have funny looking pieces because of that.
But in general, also, rectangular pieces of precast
are going to be a lot easier to hang on a building than
pieces like, like this.
Panel, size, in general, like we said, bigger is going to be
better, or less expensive.
One of the things you do need to keep in mind with
the panel size, is the pick price.
And that's one of the reasons that you want it to be larger.
Everytime a crane picks up a piece of precast on the job site
and puts it on the building, the contractor is going to pay
a pick price.
And in downtown Chicago right now, that range is in about
the fifteen hundred dollars per piece range.
So if you have a one-by ten-foot column covers that's still going
to cost you fifteen hundred dollars.
It'll cost you the same fifteen hundred dollars if you have
a twelve-foot by thirty-foot piece of wall panel.
So if you start looking at the square footage cost of putting
it on the building, bigger will be less expensive.
There you are, getting to the job site.
It's kind of unsual to have two pieces of pre-cast but because
they have those big punched out windows in this case,
they could do it with the weight of the concrete.
Sometimes too you're going to see some larger pieces.
It is possible to do one of a kind or larger pieces onto
a jobsite but then there will be special issues that you need
to take into consideration.
In this case they, they're tilting it on it's side.
One of the things that we've seen in this part of the country
is a fifteen foot-wide double T, which is new.
Most of the double T's that you see around the country
are twelve-feet wide.
So fifteen feet wide, that's a little bit wider, and they are
shipping those also on an angle as well.
In an ideal world, this is what a precast job site would look
like, except that it would be a pre-cast structure in the back
instead of a steel structure.
It's got this nice flat surface, it's got the crane right up next
to the buidling, you can see the truck with the pre-cast on it
can pull up right next to the crane.
And you pick up the crane and have this nice plumb line
between the crane and the building and it
goes on pretty simply.
So in an ideal world, that's what it would look like.
In the real world, a lot of times, they look more like this.
You know you might have issues with, you've got water
right next to the site or electrical wires, or it's muddy
and the crane is sinking into the mud.
And so there's all sorts of issues that have to be taken
care of before you get that nice crane picking up the pre-cast
off the truck and putting it on the site.
So, real world versus your ideal world.
Hoisting early a lot of times when you're hoisting concrete,
you do want to either think about starting at the back
of the site and moving forward.
Sometimes you can move around or move from the inside
of the building out.
What, the things that you want to avoid are double handling.
You don't want to have to use two cranes to pick up a piece
or pick it up twice.
You want to avoid coming underneath something else with
the pre-cast becuase you're asking to just ding or chip it.
Pre-cast is actually pretty fragile you wouldn't expect
concrete to be fragile but with the pre-stressing you have to be
very careful about how you're going to pick it up.
You're never going to pick up a long beam from the center of it.
It would just snap right in half.
So you're always going to pick up the beam
from the four corners.
This is a, we talked earlier about Soldier Field,
just to give you an idea of what the erection issues were
at Soldier Field building that bowl.
There they are erecting from the inside.
And you can really see that it was really tight sight.
Yeah.
[unclear audio].
>> Marty McIntyre: They had, where is it,
I think it's right here, they had a piece that everything
came in through this one piece of the, one piece
of the stadium.
I think it was there, and they might have dissassembled them
before they brought them out.
It's been about three years since I sat through
a presentation on this.
Yeah?
[unclear audio].
>> Marty McIntyre: Usually, in this part
of the country, the pre-cast is usually part of the precaster's
contract and so they don't usually use helicopters
or anything like that.
Now I did have a precaster up in Milwuakee, have you ever been up
there and seen the river walk that they've built up there that
kind of comes out on the river?
That uses all double T's.
And that was actually an FOB.
They just took the pre-cast to the site and dropped it at
the riverbank and then they had barge that came in
and they barged it out to the site and placed it in.
But the precaster didn't want anything to do with it but
he just didn't feel like he knew enough about barges and water
to get that erection so that was a specialty erector.
But I've never heard of anybody using helicopters for it.
So.
We talked about this earlier but I always liked to just mention
it again that PCI certification is your good housekeeping seal
of approval on your precast.
And it is something that you know it's always looked for when
you're talking about who's going to actually going to do
the pre-cast on a job.
Just to finish up, I thought I'd talk a little bit about
what kinds of pre-cast products are out there?
What kinds of projects are our members working on?
We really are going to be in just about every market
that's out there.
So the commercial, specialized in industrial transportation
and housing are the ones that we see a lot of.
Commercial, everything from retail stores to
office buildings.
A lot of mixed use.
A lot of parking decks are being done in that area.
We're seeing quite a number of stadiums now that are using
pre-cast concrete, whether it be for the decorative uses
or for the actual structure.
All of the risers, the vomitories, things like that.
Industrial manufacturing, you, if you've got anything that
requires USDA finishes on it which are very smooth, you can't
have a lot of bug holes or places for food particles
or bacteria to get in.
We see a lot of pre-cast used in those areas because
of the quality control that you can get up front.
Transportation, sound walls are an area that we haven't talked
much about but...
And you don't see too much of them down here but up closer
to the city where there's more housing near the highways
you will see a lot of pre-cast sound walls being used as well
as all the bridges that we've talked about.
This is an unusual part of the country that we actually have
some single family homes being built out of pre-cast.
There is one of our members does these, these homes in the city
of Chicago that are scattered site, low income housing.
And it basically is using eight pieces of precast and it goes up
in a day, so pretty, pretty fast.
Why would an owner want to use pre-cast?
Well one of the biggest things is the speed of construction.
You can put a Wal-Mart up in a week, you can part an apartment
up in 80 days of construction.
Basically, if you're using wall panels for instance, a precast
director can put up in one day what a mason would take about
two weeks to put up.
So you can really, really move pretty quickly with pre-cast.
The long clear spans, the 60 feet, for parking decks
and hollow core can get 30 to 50 feet long so you can get
some nice spans.
Fire resistance is a big issue, eveything that goes into
concrete is resistant to fire except the steel so what you
want to do is have good coverage of your steel.
You want to usually have about two inches of coverage
and that's going to give you fire ratings very easily.
Two hours of fire ratings and you can go up from there.
Acoustical control, we're seeing a lot of requests for this
especially where there's an airport nearby or train tracks
or something else.
Concrete has a nice ability to bounce sound away from the,
from the building.
We are seeing a lot of our members getting involved in lead
certified projects where sustainability is an issue.
They want to have energy conservation.
Sometimes the precast or one of the precasters was telling me
this week, they're doing a project for food processing
plant near Beloit, Wisconsin.
And they're having to bring all of their waste from the
hollow core to the job sites so they can measure
how much construction waste is on the project
for the lead certification.
So, you know precasters are willing to work with you if you
have energy conservation or sustainability issues.
Low maintenance, you're not going to have to tuck-point it,
you're not going to have to paint architectural pre-cast
and so you can really get something that's
pretty simple maintenance.
Things that are going to add maintenance, I was just talking
to an architect last week who added a graffiti coding to,
to a university project that they were doing.
So you know if you've got special codings like that,
that will be a maintenance issue.
You will have to come back and caulk it and that's usually
a maintenance issue every 15 to 20 years depending
on the weather and exposure to the weather that you're in.
And I think the best, the best benefit to member or to your
customers is the attractive appearance that you can really
create something that speaks to them.
That you are giving them what they want as far as
the color and texture.
Some resources for you, you can go to our website which is
PCI-IW.org and I've got some projects on there that
you can look at.
I've got a list of our member companies.
I've also given you all a list of our member companies
in the newsletter and the map that I had.
Yeah?
[unclear audio].
>> Marty McIntyre: It was dash "I-W."
"P-C-I" dash "I-W" dot "O-R-G."
And then the national group is PCI.org which
you've got up here.
So, on the PCI website, they've got something called
the designers knowledge bank and it's got a lot of
full text articles.
If you want the hollow core manual you can find it online.
If you want an article on sustainability using pre-cast
you can find it online and they've got that right there
so you can do it without going to the library,
without ever leaving your desk.
You can find all of that information right
at our website.
And that's who I am again.
And I'd be happy to stick around and answer any questions
that you might have.
[audience applause].
Thank you.
>> Wafeek Wahby: Any questions?
>> Marty McIntyre: Yeah?
>> male speaker: What do you think
are the biggest advantages of pre-cast since the big boom
of the 1960's pre-cast?
>> Marty McIntyre: Well, there's a couple things.
One is just the spans that they're able to get
with the product.
The double T's now that they can you know use more durable
concrete and highstrength concrete.
They're spanning parking deck 60 feet, that's typical.
But they're even going longer to you know getting that hundred
foot span with it and with the larger pieces of you know
fifteen-foot wide so they can use even fewer pieces of it
so it can go up even faster.
They're also using that self-compacting concrete
and that's really for some of our members revolutionized
the way that they're manufacturing.
That's been really a big benefit to them.
Hollow core also has much longer spans than it used to,
it's got deeper sections and longer spans.
So, I think too for the architects would probably tell
you the sculptural abilities of the product and how pre-casters
have kind of stepped up to the plate and been able to you know
make it look like limestone if they want it to
look like limestone.
You know make it look like concrete if they want it to look
like you know they have that organic look of concrete to it
so I think that's, that's really come a long way too.
[unclear audio].
Thank you.
[audience applause].
♪ [music playing-- no dialogue ♪♪.