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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
Thanks!
I basically know enough that I can make up what I don’t know and it sounds right. lol
As a poet, I deal with terms like synecdoche all the time, but I figured they wouldn’t be commonly used in the concrete business. Of course, on Ricochet, we have some very odd birds who have expertise in multiple areas, the Renaissance Man (or Woman), so one never knows for certain.
Is it true the ancient Romans used wine in their concrete mixtures ? Why, exactly ?
The graph of curing concrete is depicted as strength increasing on the y-axis vs. time on the x-axis. Over time, the strength increases rapidly at first then slower in later time. The curve created approaches a limit but will never reach it on the graph. This is typically how the “forever curing” claim is understood pertaining to curing concrete. Sound, but… there is a finite number of molecules in any concrete mass and an infinite amount of time to eventually reach total hydration of a cementious material. I believe that possiblity of any concrete structure to finish gaining strength is there, eventually. Am I wrong?
Note: They are still removing cores from the the Hoover Dam and measuring an increase in strength.
Concretevol
Thanks for the clarification. In the past I’ve discreetly rolled my eyes when the FIL says c’ment for concrete. I now feel I have your blessing to point and laugh!
How is concrete made waterproof?
As an aside, I hear they are making wine today and storing it in concrete vats.
Also, I’ve tasted some Italian wines that would have benefited from the addition of concrete.
I’ve jumped to the end so am sorry if this has already been covered. Seems like there are a lot of man made disasters in many third world countries due to “bad” concrete. What gives? Don’t know what they’re doing or trying to cut costs – maybe a combination of both?
Cool post by the way. Like.
I believe that is true. From what I remember I think they used animal fat and blood also…..not sure why except maybe experimentation as admixtures. I need to look that up!
This is true….one of the things I love about this site is the wide ranging backgrounds and skill sets of it’s members. Where else for instance would a poet and a contractor be discussing the term synecdoche?
I tend to agree with you. Infinite is a bit of an exaggeration or at least the measurable increase in strength will be insignificant after enough time. The steepness of that curve is impacted by a lot of factors also, both internal and internal to the concrete. As you know, just adding or increasing the percentage of type C fly ash in the mix will slow the initial strength gain but increase the total strength overall.
1. How does weather affect the pouring and setting of concrete? Does the concrete have to be protected from the elements somehow while it sets?
2. Related, is there an optimal time of the year for concrete projects depending on the local climate?
3. Are “curing” and “setting” the same thing?
Thanks!
There are several types of admixture chemicals that are added to the mix when batching the concrete. They are similar in that they have a chemical reaction that causes expansion of the material that fills the capillary system throughout the concrete, plugging the route of moisture migration.
On stainless rebar: My dad looked at it for his new driveway. Would have cost $250,000 (not a huge driveway 2 cars with wings on either side for ease of egress)
On roadways: At our old family cabin there used to be an old Saturday Evening Post with an advertisement from the Asphalt Council or someshuch thing. It showed a long stretch of crasked concrete road and a paving crew covering it with asphalt. The caption said something like: “You know you are going to have to someday anyway. Why not get it right the first time.”
When I see concrete highway being poured they seem to do it under a tent/cover. What is the reason for this?
I would mostly have to guess but have read some accounts that seem to fall under 3 general conditions that you could probably guess.
1. Inadequate materials due to contamination/cost/corruption:
– There are many ways to contaminate concrete to the point of impacting it’s performance in a 3rd world environment. Contaminated water can contain chemicals that drastically impact the hydration process. Using incorrect gradations of stone will also effect the over all strength. As you have pointed out in many of your posts, corruption in a 3rd world country is common not only in government officials but I’m sure builders. Concrete and steel are your two big ticket items in construction. Cutting a few corners on material actually used can mean big money. Leave out some rebar….pour a little less concrete than designed…next thing you know you have a failure.
2. Improper Methods:
– No doubt in some instances the labor force in the field aren’t skilled enough to know the proper installation techniques. In much of Mexico for instance they still pour elevated slabs using wooden ramps and a bucket brigade, so when these same workers are using designed mixes and concrete pumps there may be a disconnect. Keep in mind Mexico is light years ahead of some areas. If there isn’t proper inspections being done on concrete slumps, reinforcement installations etc..it is a recipe for disaster.
3. Inadequate design:
– This is more of a guess but I am thinking the engineering done on building construction in 3rd world countries isn’t quite up to western standards. Probably not an obvious problem until you get into extreme loading situations/high winds or any conditions that push the safety factor of the design.
75 + comments on concrete. This is not possible. I think I will start a paint drying thread. Only a genius could make concrete interesting and I did not write this post. This has shook my very foundations. I feel as if rebar was ripped from my heart.
Luckily this thread will not be the most popular.
It takes comments and fights to be popular. Now if we could get the AsphaltCons and the ConCons supporting different 2020 candidates. (Hey, these people plan for the future.)
When your wife calls you a “blockhead” do you take this as a compliment? Is your wife still “curing” you?
Indeed, especially when his stated goal was to get no response and have it go down as the worst post evah!. To show him how to properly select a topic for worst post, I have demonstrated here. That will probably be the worst post of this year.
Ricochet is a serious site that is why talk about politics. How would it look if the number one post was about C-ment? This is disgusting. Can we talk about pot, SSM, Rinos, etc.? Come on I paid about $40 smackeroos a year for the “smartest, fastest growing place on the web” and we are talking oil stains and aggregates.
Arahant,
How dare you interrupt my rant?
Interrupt your rant? Or help you achieve your goal?
People do not trust the ConCons because they will run Mike Gravel as president. They are only flexible in the beginning but soon harden in their positions. Let’s call concrete for public projects what it really is. They are civil unions and nothing more.
I say we take a jackhammer to this thread.
This is kinda cool. Little twisted pins of metal added to mixes to provide a moderate amount of tensile stength. My thought when first seeing these was that I would not want to walk on these floors with bare feet.
On the other hand, the AsphaltCons tend to melt at the first sign of heat.
It’s nice to see a thread that isn’t theoretical in any way whatsoever.
(Is that joke too subtle?)
Who paves the road to Hell AsphaltCons or ConCons?