Thanks to the Elysian thread It' seems as you guys might like some how to's about construction.
In this episode of 'How it's made' we'll talk about precast. Most of the following photo's are of the same project and you will get to see it from beginning to end.
Like all projects we must go through a lengthy drawing process before we may pour a single yard of concrete. I'll spare you the pictures of paper with black lines on them.
Our process begins with setting up the 320' long form in the morning with wood dividers to separate one piece from the next.
Most of you will love this picture. It's a common theme here that precast is bad because it imitates other materials. This picture shows a form liner that will leave the impression of brick. Yeah...as long as they are paying...we are doing.
At least in the next few we get to cast in real brick...
Let the pouring begin!
We work our magic and cook the concrete...DING, the next morning it's ready to come out of the oven.
While the jobsite is hard at work, the product is stored until we get the call to deliver.
GOT TRUCK!!! Yeah that’s an 87' foot long piece of concrete right there.
At the site we hook up to the crane and set the piece in place.
Our version of a structural floor to combat expansive soils.
Here are some general shots of before and after
Where does the precast stop and the other trades begin?
On the left of this photo you are looking at the fake brick with the noticeably white paint grout joints. On the right you'll see our real cast in brick with a more natural joint color.
Another shot of the fake brick area that really doesn't look good but hey we are producers not architects...what cha gonna do?
Thanks for stopping by and if you have any questions just ask.
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Question: in the jobs where you are using the liner to make the brick impression, how do get the usual grey color of the concrete to come out looking red? Also, won't the surface come out too smooth to look like brick, which has a rough surface?
I couldn't find any photos taken real close but the liner does have a texture to it that does not leave it smooth.
I would have loved to see them paint the brick. I can only assume that they actually use a roller to paint the surface of the brick and not the grout joint.
Here is a picture of that it looked like before the paint.
I hope you wont find many of the liner type projects. We have only produced a few in my 15 years, so at least in Denver it would be like finding Waldo.
Precast is really handy though for parking structures and large bay warehouse type buildings. I did a 2 story 125K SF office building with attached 5 story parking garage out of precast in 2000-2001 in Tempe.
We actually did an exposed aggregate finish on the spandrel panels. Looked pretty nice for what it was.
You don't see too much precast over here in coastal California. The welded plate connections don't function so good in seismic zone 4 (though it can and is done).
ColoPrecaster,
78' trailers are allowed in Colorado? In Arizona we were limited in span to 61' due to trailer limitations. It's only 59' in California. I know Nevada will allow a triple-trailer up to like 110'! Just curious.
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Question: in the jobs where you are using the liner to make the brick impression, how do get the usual grey color of the concrete to come out looking red? Also, won't the surface come out too smooth to look like brick, which has a rough surface?
Theres a couple methods to get the color. I've seen a system before that a company I was doing IT work for was experimenting with for doing precast that involved coating the liner with a coloring agent (usually in a powder form) before pouring the concrete into it, and it would absorb in. Didn't always work that well though, it tended to be a bit uneven in coloration.
Using a roller would also make sense, or another that may be possible would be using some sort of grid that sits in the grout and a spray type application.
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To make a panel thick enough to carry the weight of bricks + the thickness of the bricks themselves would make for a very heavy and bulky panel. The additional weight would also require substantial resizing of other structural elements and possibly the use of larger equipment. Placing of bricks and mortar is also more labour intensive and uses additional materials.
The only real alternative I have seen is to use dummy bricks about 1/3 to 1/2 normal thickness and are still placed in panels with mortar. They still require labor to mix & set.
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Yeah but you make it sound like the fakes don't require labor or very little of it but in fact labor is required to paint it, right?
I don't know what you mean by dummy bricks.
A dummy brick is more like a ceramic floor tile in thickness, usually under an inch thick, but has the similar surface texture. Purely for looks, doesn't have any use beyond that. Thats what they were using in some of the photo's that Coloprecaster posted.
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Thanks for this thread Precaster, this is one of the more interesting ones in this section. Its good for people to actually know about something before they criticize it.
Wow, this actually looks pretty good, you could never tell it wasn't a real brick wall if you didn't know that it was actually precast.
ColoPrecaster,
78' trailers are allowed in Colorado? In Arizona we were limited in span to 61' due to trailer limitations. It's only 59' in California. I know Nevada will allow a triple-trailer up to like 110'! Just curious.
We have shipped a double tee that was more then 125' long in the past.
Quote:
Originally Posted by antinimby
But why go through all that trouble to just to get the color when they could just use real bricks in the casts to begin with?
Money...and then there is the Money...and last it would be the Money.
Quote:
Originally Posted by Kelvin
To make a panel thick enough to carry the weight of bricks + the thickness of the bricks themselves would make for a very heavy and bulky panel. The additional weight would also require substantial resizing of other structural elements and possibly the use of larger equipment.
Sorry but that isn't the case. Even if we did use a full size brick it would displace nearly the same weight in concrete effectively not increasing the weight of the panel.
Quote:
The only real alternative I have seen is to use dummy bricks about 1/3 to 1/2 normal thickness and are still placed in panels with mortar. They still require labor to mix & set.
It's a good thing this thread exists because you have alot to learn. We use a brick that is about 5/8" thick with grooves molded in to the back. There is no motar used in the process of casting brick in to a concrete panel. Each brick is set into a plastic 'snap' that is molded in the shape of a motar joint. Our standard concrete mix is poured over the back of the brick, locking it into place because of those grooves.
Quote:
Originally Posted by antinimby
Yeah but you make it sound like the fakes don't require labor or very little of it but in fact labor is required to paint it, right?
Very true...it's labor in the beginning or the end. Many owners can't see the forest through the trees.
Sorry but that isn't the case. Even if we did use a full size brick it would displace nearly the same weight in concrete effectively not increasing the weight of the panel.
Yes, but if you did use a full size brick (3-5/8" deep), wouldn't you have to increase the thickness of the panel in order to make your minimums for concrete thickness over the reinforcing...thus making it more heavy? Maybe that's where Kelvin was going.
Not cost effective I know...but just wondering...
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Yes, but if you did use a full size brick (3-5/8" deep), wouldn't you have to increase the thickness of the panel in order to make your minimums for concrete thickness over the reinforcing...thus making it more heavy? Maybe that's where Kelvin was going.
Not cost effective I know...but just wondering...
Ah...well if that was the point maybe I just misunderstood it. Sure, if you had to go from an 8" thick panel to a 12" thick then you bet it would increase the weight.
In my 15 years of precast we have never used a full size brick, so I can't say what you might need to engineer a panel with those parameters.
That is exactly the case Plinko. A masonry panel would not span the distances used in these cases without a built-in or adjacent lintel unit. The masonry panels would not even come close to take wind load without significant ties to other load transfer mechanisms. That's what makes these types of panels so effective - the RC can take the loads.
The labour required to set and place masonry units is generally much higher than what Colo is showing (highly efficient assembly line production).
The "bricks" (or stone, or anything for that matter) can be either very thin dummies, or could also be "faked" with a reusable formliner.
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