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>> male speaker: [unclear dialogue.]
>> Mr. Tony Kojundic: No, temperature in
the atmosphere.
Last group.
>> male speaker: [unclear dialogue.]
>> Mr. Kojundic: Chemical contamination.
Okay.
A, what was your worst idea?
>> male speaker: [unclear dialogue.]
>> Mr. Kojundic: Inadequate mixing,
well that's a pretty good idea, not the worst.
No one urinated in your concrete or anything?
[Mr. Kojundic laughing.]
That's a good one, that's a good idea.
>> male speaker: I guess the local aggregate,
not the right material because
you're not taking any local aggregates.
>> Mr. Kojundic: A mix up in materials
that was your least favorite one.
Okay yeah cause the laboratory would have checked that.
What's yours?
>> male speaker: [unclear dialogue.]
>> Mr. Kojundic: Those are all good ones too.
Okay, yeah.
>> male speaker: Sabotage.
>> Mr. Kojundic: That happens.
Where's the light, which light?
Concrete, this concrete that we made was drying up.
We don't really think it was contamination because
we actually saw them make a truck.
They duplicated what they can make in front of your eyes.
They more of less duplicated the same phenomenon
that it was drying up.
Where'd the water go?
We don't think it's a cement water reaction,
we think there's something else that's going on here.
You guys had all talked about temperature and elevation
in the atmosphere and humidity.
You're there your, skirting around the issues.
You probably just don't know the materials well enough
and that's why we are doing this today so
you will know the materials well enough.
But your all touching on the issues right here.
When you make concrete--you guys have probably done this
camping at a fireplace.
You ever get rocks soak them in water then throw them
in the fireplace and watch them explode?
Poof.
Rocks will come flying out of there.
What happens is that rock you threw in a bucket of water
it sucked up water.
When you threw it into the fire, all that water changed into
steam very quickly and exploded that rock like popcorn.
It exploded that rock.
Well, all of these rocks in concrete hold water.
All of these rocks here and all of that sand holds water.
They call it absorbed water.
Most rock will hold in this case probably about 2% of its weight
in water.
In other words if you put, if you dry out rocks in an oven,
you put them in a bucket of water and let them soak over
night, you dry them off so they are surface dry
and you weigh them they are going to be 2% heavier
then they were the day before.
In a case of sand, Wafeek, what, 12% or 14%?
Sand can actually hold up a lot of water not on the surface,
this is inside the material, like a sponge
it's actually sucking up water.
It's the reason why the rock blows up when you
put it in the fire, all that steam is trying to escape
very quickly out of that rock so it pops.
The give away in this particular case was when this guy you can
see the front end loader here picking up his aggregate, he
picked up his aggregate and dumped it into his bucket and a
cloud of dust came off the aggregate and completely covered
the whole back side of his tow motor of his front end loader.
If it's dusty, the aggregate can't be wet, right?
Because if the aggregate is wet, it's not going to be dusty.
You guys had said humidity, temperature,
elevation, atmosphere.
All of these this are conducive in that part of California.
You're all on the issue they are all conducive to drying.
That's why we are capturing the water out there,
there is no water this is California.
That's why we dam up all of the rivers.
They capture all the water so their aggregates were,
they call it saturated surface dry.
If you put those aggregates and let them suck up
their full absorption of water and take them out
and dry the sheen off the aggregate.
Just let it lay out there so the sheen evaporates.
That's considered saturated aggregate surface dry.
The aggregate is fully saturated so the aggregate doesn't know
whether it's getting water from rain or purposely putting water
or whether it's sucking the water out of the concrete.
It's physics this is going to take water.
It needs to absorb so much water.
So when they were making concrete here with this bone-dry
aggregate because it's dusting all over the place.
That was the tip off that they are working with aggregate
that was below SSD.
When they made the concrete, the aggregate literally sucked
the water out of the concrete.
In that 10 to 15 minutes, 25 minutes it took to drive that
100 yards, the aggregate sucked up the water so much
that there was no water left in the concrete.
It was all inside the aggregate or trying to
get inside of the aggregate.
You with me on that?
Does that make sense?
That was actually the root cause.
The coarse aggregate and the fine aggregate,
the coarse aggregate had about 1.8% absorption.
On both we figured the ash was there also, or the sand was
there also, the fine aggregate.
Combined those materials were 2800 pounds worth of material
and 1.8% absorption.
They told us we were roughly lacking 42 pounds of water
which is roughly 8.3 gallons of water.
Which in a yard of concrete rule of thumb,
one gallon equals one inch of slump.
So if we were making a six-inch slump of concrete
at the batch plant and we lost all this absorption,
we went from six inch down to a one-inch slump
and that's why they couldn't get it out of the truck.
The aggregates sucked up the water out of the concrete and
made it so they couldn't do it, so they couldn't place it.
They were able to place it then, pump it into place.
The red fugitive dye on the surface is actually
a curing compound to seal in the water so it fully hydrates.
And that was there corrective action was they batched all the
aggregates first in those trucks and added
the water to those aggregates for 15 minutes,
let them mix inside of the truck and let all of the rock suck up
or at least try to stabilize its initial draw on the moisture,
then made concrete on top of it.
Then they were able to make the 10,000 PSI and pump it
and do all the good stuff they had to do on site.
Questions?
>> male speaker: [unclear audio.]
>> Mr. Kojundic: In most cases, well no.
In most cases that's the first thing on a construction site
that is not allowed is adding water to concrete.
It's what everybody wants to do because it's the easiest
thing to do is to add more water to it.
You add more water to it and you change that water cement ratio
when you do that and that's the number one thing that effects
strength and performance is by adding more water to it.
You're making it weaker the more water you add.
So no, they didn't add water.
They knew it was suppose to work, they had to mix designs
and they knew it worked in the laboratory.
Now they just had to duplicate it in the field.
The whole point here though is even though we are talking about
high performance concrete and real exotic
and in far away places, it's real basic fundamentals.
It's physics.
The rock has to satisfy its water demand.
It all starts there.
You can't make concrete unless the aggregate is at SSD.
I've seen it in Bloomington, I've seen it in Indianapolis,
I've seen it in Troy, Illinois.
I'm thinking of areas around here where people are trying
to make concrete but with aggregates that is below SSD.
They wonder why they can't control the properties
of the concrete.
In the meantime, the concrete is constantly changing
because the aggregate is sucking up the water.
Rule number one, a real fundamental,
the aggregates have to be fully satisfied with
their water demand in order to make concrete.
If they're below SSD, you will see this stuff happening and
when stuff like this happens on a job site, it's real easy
to sit in a classroom and nice peacefully discuss
what's going on, on the job site
there's a little bit more tension that happens when
you are trying to think through these things
and sometimes walk away.
Walk away and go think.
Walk away and go watch them batch the concrete.
Go watch them do it again, and see this cloud of dust
come over top of the front end loader and you know
the light bulb goes off over your head.
It's dry, it's bone dry.
That's the answer.
You go home or go for a hike.
On deck placements something you find with high performance
concretes are that they're very low in bleed water.