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Everything You Ever Wanted To Know About Concrete* (But Were Afraid To Ask)
In the comments on another post, I mentioned it would be nice if someone talked about concrete — that noble material of the Pax Romana — so I might sound at least slightly knowledgeable on a topic here for once. Sure, it’s not as fun a topic as Same-Sex Marriage or drug legalization, but it may also help me in Dime’s contest this year for worst poster!
A little background: I am one of the owners of a commercial and industrial concrete construction company that does work all across the southeast and as far west as Oklahoma. Yes, it’s exactly as glamorous as it sounds! Concrete is a basically a mixture of cement, aggregate, and water. Yes, cement is an ingredient of concrete, so now you know if someone refers to concrete as “cement” it is appropriate to point and laugh.
Fellow member Captainpower was gracious enough to ask a few questions that I will try to answer adequately here:
Q: Are there different types of concrete?
A: Absolutely! It varies in both compressive and flexural strength, abrasiveness, color, reflectiveness, weight, etc.
Q: What’s the difference between good and bad (or proper and sloppy) concrete mixes and application?
A: I think this question is about the “slump” or “wetness” of concrete when it is first placed. The key measurement in a mix design that many times the “slump” indicates is the water/cement ratio. The concrete is weaker, both chemically and because of material segregation, when that ratio is too high.
Q: Are there any craftsmen left, or is everyone in it for a quick buck?
A: Yes there are some very talented craftsmen out there! It’s actually a pretty tough business to make a quick buck in, though I know residential contracting can attract some unsavory types that will try to take advantage of the unwary homeowner.
Q: Is concrete technology still progressing, or do we pretty much have it mastered since forever?
A: Concrete technology is constantly evolving and advancing, and the Romans would recognize very little about modern concrete, other than that it hardens. There are many chemical admixtures that can make concrete behave in various ways, which means it can be applied in all kinds of different ways. It can have its set time delayed indefinitely, or can be made to set almost immediately. It can be made to flow horizontally like water without losing strength, made waterproof… the list is endless.
Q: What’s better than concrete? What’s worse?
A: It depends on the application. People use concrete in all types of construction. Roadways, precast, structural building elements, kitchen counter tops, even concrete canoes. Does it make good carpet? Not especially, but a polished concrete floor that is colored or stained can look pretty darn good!
Anyone else have questions? The floor is open.
Published in General
I am just piling it on. I hear to make pilings there needs to be a lot of boring. ;-)
Concretevol,
This is a wonderful post because it has been substantive with some fun. I love to see people laughing and learning.
I thought about you publishing a book called “Concrete: All that you wanted to know but were afraid to ask?” The sad part about Ricochet is that you would write the book and it would be a runaway bestseller. Oh the sad part that is my slab of the action.
Serious question.
What is the lightest concrete? I have heard of Styrofoam mixed into it I think.
Steel fiber reinforcement…very cool. Sometimes referred to as “hairpins” when they are bent at the ends. They are actually very effective although a pain the the finisher’s “CoC” when dosage rates approach 50lbs per cuyd. The advantage over welded wire reinforcement in slabs is the fibers are evenly distributed while wire must be pulled up into place and then is tramped back down while screeding the concrete.
I remember back when the fixed a tunnel here in Oregon that was made with giant timbers. They used concrete impregnated with lots of those small metal hooks. The blew the concrete up onto the wall and the hooks dug into the old timbers helping to strengthen the tunnel wall.
At this point it is definitely a Movement!!!
I would have to research the actual lightest. The rule of thumb for standard concrete weight is 150 lbs per cuft. Typical lightweight concrete is in the 90-115 lb per cuft range. There is something called EPS concrete (expanded polystyrene?) that basically replaces some or all of the large aggregate with styrofoam. I’m not sure on this one but I think it easily gets down to below 50 lbs per cuft and has better insulating properties but much lower strength. One of my partner’s sons was in UT’s engineering program and was in charge of their concrete canoe competition team. I know he got into some seriously light mixes designs with that but I’m not sure how light.
I thought that now everyone had moved on from this topic I would go back and post a nice glossy photo of a building we recently completed. Better late than never!
the original prompt: http://ricochet.com/the-kurdish-question/comment-page-3/#comment-2739258
I’m glad you posted a conversation about it.
Just goes to show that someone who knows that they are talking about and is passionate about it can carry a conversation quite a ways almost regardless of topic.
I’ve heard it said that when people tune out such knowledgeable/passionate people, it says a lot more about themselves than the speaker.
Followup question:
FYI, the proper/sloppy question was poorly worded.
Was wondering – what differentiates a well done project from a lazy/mickey mouse/half-assed project? What sets the experts apart from the amateurs (and teh charlatans) when it comes to concrete?
Nice work. Both here and in the photo.
Thanks much
i haven’t read the comments, but I read the post. I like it. Interesting to learn about cement, and concrete, and aggregate.
:)
this does not qualify as a bad post, I’m sorry.
I would have liked to have posted a pic of the recently completed O’Callaghan-Tillman Memorial Bridge as one of my favourite concrete structures. I was beaten by the complexity of the system to upload images.
Imagine instead, the graceful span between Nevada and Arizona over the Colorado River. A 4 lane road, and footpath, a sweeping single arch, affording a spectacular view overlooking the Hoover Dam below, the bridge stands over 400 feet high. A great project and one of Las Vegas’ free attractions.
Hello Captain, I was hoping you would notice the post you inspired so you could share the blame! :)
Ok my bad, I get what you are saying now. I guess the final outcome is what sets them apart. When properly done the project should be dimensionally correct, have the proper finishes and elevations, and done in the agreed upon timeframe. Now to tell them apart BEFORE the project is the key isn’t it…. Of course everyone is an expert when you talk to them so checking previous work is key as well as getting recommendations from the local ready mix companies.
For the homeowner in general, let’s say you have a concrete contractor prepping and pouring a slab for you. They should always build on a hard/compacted subgrade and always use stone base under the concrete. They should be familiar with the different mix designs for interior and exterior slabs. (non-air mix and air entrained). If they add excessive water to the truck before discharge, ESPECIALLY if they haven’t even looked at the concrete, then you could have a serious problem. Basically I would say the main difference between a quality contractor and the charlatan is pride in their work. One cares about quality, the other about getting paid and gone.
That isn’t typical, is this in a very hot environment?
RACIST!!!!
Concretevol,
Recently in Japan parking lots are not completely paved. Some of the parking spots have plastic squares with holes in them. There is dirt and some grass like vegetation. Is this to save cost only or is there another reason?
“Concretevol
thebeekeeperkissedme:When I see concrete highway being poured they seem to do it under a tent/cover. What is the reason for this?
That isn’t typical, is this in a very hot environment?”
I have seen this in Africa and Germany (during summertime).
Is it turfstone, perchance?
Designed to reduce runoff problems, I believe.
If this is in an urban center I would venture to guess it is to increase the pervious surface area in the area. Lots of cities have come to realize there is virtually no water going directly into the ground and leaching to the water table. Almost all water is collected in storm drains and rerouted to containment ponds or into the main storm water system. Many metropolitan areas now tax commercial property based on how much of it is covered by impervious surfaces. This of course includes the building footprint, sidewalks, and traditional parking lots. They are trying to encourage the use of Pervious Concrete among other things that allows water to pass through and resupply ground water.
If this isn’t it maybe its for decoration…. :)
That is what I imagined…that the unpaved portions were a way for water to get off of the parking lot, into the ground, without having to build drainage cisterns and ponds.
Quit making jokes this is a serious thread. It was a joke, right?
This more of a plastic or rubber round hole thingie. It is probably as the Big ConCon says and for ground water.
Ricochet!!! (In a shouting DJ voice.)
Where Concrete Roooooooocks!
Concretevol,
I have often thought that we can learn a lot from pilots and checklists. I think people who work in concrete are similar. Like the pilots when you guys have a bad day it is hard for the rest of us. (No pun intended.) Do things in the right order and not forgetting is key. The weather is also a big factor.
Out of curiosity, what is the biggest mistake that a “friend” of yours has made?
I enjoy learning about “mundane” topics that are not nearly as mundane as they initially seem.
Q: Why are concrete guys always stoned?
A: You would be too if you tried to smoke a joint*.
*Concrete joint
Editors? Can someone be banned for bad puns?
In the awl bidness we call it SEEment and pump it downhole to SEEment the iron wall-cake.
And FWIW, any ground water contamination from an awl or gas well is more than likely due to a poor SEEment job that didn’t isolate the aquifer (as opposed to mythical contamination from hydraulic fracturing).
As they say in Nigeria: you are welcome.
Concretevol,
I would like to buy some swimwear for Arahant. What do you recommend? Do you give a lifetime guarantee? (wink, wink, nod, nod)