theoretically the strongest concrete

Even more real world.

Have you ever actually seen a cement truck?

They don't measure to the decimal point. Real construction workers throw in a bag of cement, a few shovelfulls of this and that, their lunch bag and soda or beer cans, etc. This is not a precision industry.

Now you've done it! You have opened up a can of worms. "Have you ever actually seen a cement truck?" Probably yes, but you wouldn't know it if you had. A real cement truck is a closed trailer that handles a bulk powder. A "concrete" mixer truck is the one that goes down the road with a rotating drum in back.

Also, we don't throw our beer cans into the concrete any more. We're afraid it might add strength to the concrete.

Pardon me while I take my tongue out of my cheek.

In reality there is a lot of high tech going into concrete these days. Materials science, computer simulation, advanced chemistry and other whiz-bang technologies are advancing concrete to the point that what you see in a modern high-rise building is not the same thing that went into your house slab.

Unfortunately, despite all the high tech efforts, the people who typically control the final placement and quality of the concrete are often minimum wage laborers and barely-trained technicians. Good contractors recognize the problem and have been taking steps to change it, but there is still a long way to go.

Jay Shilstone

how it relates to the quantity

Where one part is tar and the

I'm not certain, but I think that asphalt emulsions usually range about 4-6% by volume. If the numbers were much higher, the asphalt would be prohibitively expensive. I found this web address that gives some general info:

In asphalt they actually want some permeable voids that provide a cushioning effect for the applied load.

Jay Shilstone

how it relates to the quantity

Where one part is tar and the

Hello Jay, it appears that I cannot make a nice easy cross-comparison with concrete portland cement and that of blacktop asphalt.

I suppose the binder of portland cement is 100% of the portland cement and not a small fraction of 4-6%, whereas the binder in asphalt is that tar binder which is a mere 4-6%. I was hoping that there would be a nice and easy comparison but it appears not so.

Jay, has anyone worked out the cost difference because the cost in energy of oil to heat up limestone in order to produce portland cement compared to the cost of getting tar of 4-6%. It seems that the binder of blacktop is so much cheaper because of the quantity needed.

However, there is a constant and that constant is the fact of packing aggregate as per Kepler Packing and as per a 3-d chessboard. And after packing them in a Kepler Packing is to fill the voids with either portlandcement or with asphalt-tar and then compare the strength of each.

So we still have as constants the geometric configuration of the aggregate.

And it may turn out to be the case that concrete is strongest when it has a 3-d chessboard configuration with a 1 :: 1 ratio and that blacktop is the strongest with a Kepler Packing configuration with a 1 :: 4 ratio.

P.S. perhaps the reason tar is not comparable to cement is that tar is a glue whereas cement becomes an integral part of the concrete and not a glue.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

concrete portland cement and that of

a small fraction of 4-6%,

hoping that there would be a nice

The binder for portland cement concrete is the HYDRATED cement (composed of cement plus water). We also call cement + water (and something called "entrained air" - which is microscopic air bubbles) "paste". The paste fraction of concrete typically takes up about 30% of the volume of the concrete. Of that 30%, about 21% of the total concrete is composed of water and entrained air.

The binder in asphalt as I said is about 4-6%, but there is also air between the particles. The voids make up about another 4-5% of the asphaltic concrete.

It is hard to compare asphaltic concrete to portland cement concrete due to the nature of the binder. The asphaltic emulsion has a greater viscosity than the portland cement paste. Also, the cement reacts with the water and rapidly (2-5 hours) forms a spiny product that holds the concrete together. With asphaltic concrete you don't have a reaction, but you do have a greater quantity of very fine particles, primarily to create surface area to hold on to the asphaltic emulsion.

oil to heat up limestone in order

seems that the binder of blacktop is

One of the biggest cost differences between asphalt and concrete is that you can put traffic on the asphalt almost immediately, but the concrete needs to cure and harden, sometimes for as much as a month. I'm not certain, but I think that on a per ton or per cubic yard basis, concrete is usually cheaper than asphalt.

as per Kepler Packing and as

voids with either

Remember that in asphalt not all the voids are filled. This is part of the asphalt design.

Do you mind telling me what your particular interest in this is? Is it an academic question or are you trying to address a specific application? If you are responding to an academic problem, you can probably assume away many of the variables. If you are responding to a real-life problem, I would be happy to refer you to sources that could provide you with a lot better education in asphalt than I can.

Jay Shilstone

whereas cement becomes an

May be concrete technology is still an empirical science, but its not a simple science !!

But ckeep in mind that in the industrial nations there will produce more concrete then steel (more then 2500 kg / person /a)!

The production of cement itself is about 400kg/person /a in the USA as well as in Germany (steel about 1200 kg)

Some remarks. Very simple said the comprehensive strength of concrete mainly depends on the water cement ratio ore better water / binder ratio and the finess of the material. So take a lot of cement, only a small amount of water, a lot of silica fume and fly ash , coarse aggregate smaller then 8mm and you will get a concrete with more then 100 MPa strength ..seems very simple.. but this is very expensive and the concrete is like a chewing gum so you need souperplastiziser and you will get a lot of shrinkage and so will get cracks...and so on. Not easy but, a real high strength concrete has nearly nothing to do with Mr. Kepler, as well as he is also a German guy like me ;-)

A second point: sand is very cheap, but the transport of sand is very expensive. So you __have__to__use__ the sand you will find near your bulding site. For example here in south Germany we have very smooth natural sand, in the northern part you have only very rough crushed sand.

So google for "high strength concrete" ore "very high strength concrete" ore "self compacting concrete"

for more infos.

Regards

Markus Greim

I'll bet that the ancient Greeks & Romans experimented to find the strongest mixing ratios, so that its been known for 4000 years.

Mitchell Timin

--------------------------------------- "Many are stubborn in pursuit of the path they have chosen, few in pursuit of the goal." - Friedrich Nietzsche

is what I'm into nowadays. Humans may write to me at this address: zenguy at telus dot net

I think that this theory assume uniformity of the sand size/shape and aggrigate size/shape. As such, it is doomed to failure.

concrete portland cement and that of

not a small fraction of 4-6%,

hoping that there would be a nice

Luckly some roadwork nearby of blacktop is going on and was able to observe that the underlayer is a pure tar and then the upper layers seems to be a mix.

Jay, I am doubtful of this 4-6% figure as binder. Because looking at asphalt in that it is black in color indicates that there had to be much more tar constituents than a mere 4-6%. Maybe the binder is a small fraction of the tar-constituents.

So I am wondering if in a cubic centimeter of blacktop that the tar elements comprise much more than 4-6%. Perhaps close to 30% with the 70% of sand and gravel.

Just the appearance of fresh blacktop suggests more than a mere 4-6%.

Perhaps the 4-6% is a tiny fraction of the tar elements.

I suppose if one heats the tar hot enough that the diffusion of the tar throughout the sand and gravel is much easier than the diffusion of portlandcement in the concrete matrix. So I am guessing that it is far easier to insure uniformity of mix with tar than with portland cement.

oil to heat up limestone in order

seems that the binder of blacktop is

Well I was asking more on the lines of theory than on the lines of present day commerce. Something of theory that a cubic meter of portlandcement requires the heat from petroleum of say (I am guessing) 4 barrels of oil. Whereas the oil required to make a cubic meter of tar requires 3 barrels of oil and where the tar of a cubic meter can surface one kilometer of highway yet a cubic meter of portland cement could only pave 1/100 of a kilometer of highway.

aggregate as per Kepler Packing and as

the voids with either

I can accept that but I cannot seem to accept the idea that 4-6% of volume to hold together all that gravel and sand.

I find much satisfaction and enjoyment in tackling theoretical issues. I go from one problem to another and often come back to a problem. Some how I landed on concrete, blacktop and Kepler Packing in the last few days. I am building a concrete block garage and that has focused my attention.

Perhaps the Kepler Packing Problem is entwined in this concrete and blacktop in the idea that KPP is the minimum amount of binder to make a solid mass. If one can imagine a KPP with its 74% touching balls and its 26% holes or gaps in between, and if those 26% holes were filled with tar or portland cement then the entire material is one piece solid and very strong.

But ordinary concrete and ordinary blacktop are never uniform balls that touch at kissing points but at all sorts of angles and flat pieces with air pockets and no binder.

If one could take BBs and pack them Keplerian with a density of 74% and fill the remaining 26% with tar or with portlandcement then they would achieve a solid that is very strong. Such Keplerian Packed concrete or Keplerian Packed blacktop would be a minimum solid because the Kepler Packing is a maximum density.

Experiment: to make a Kepler Packing of BBs and fill the gaps with tar and do the same with a concrete of Kepler Packing. I wonder what the characteristics of the two would be. And of course neither one of these materials have ever been created. And it should be easier to create the KPP of blacktop for I do not see how to infuse a KPP with portland cement.

Anyone know if portland cement can be infused into a Kepler Packing of BBs??

A Checkerboard Packing of concrete and blacktop would be easy in that we get tiny cubes of steel and fill the gaps with tar or with portlandcement.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

... Way out! You would be lucky to get one m^3 of concrete to cover more than a few cm of road!

Suppose you had 1 m^3 of tar and a piece of road 1km long, 10m wide then how thick a layer of tar could you spread on it? Answer: 1/(1000 * 10) m = 0.1 mm - I've seen thicker paint!

If you were laying a concrete foundation for a road, then aim for several tonnes / m^2.

////

Some people are *so* critical..... Any street that is not more than 1 meter wide could be paved for 1/100 km with a cubic meter of concrete, couldn't it? A good four inch thickness even.... :-)

But....if a cu meter of concrete weighs 2 or 3 tonnes, and you suggest several (=3?) tonnes per sq meter, you are proposing to pour a meter depth? Naaa! You meant per linear meter of road that's say 7 meters wide, giving a road bed 14 cm deep = 5 in plus....

(Remember what they say about arguing with fools?)

Brian W

that the underlayer is a pure tar and

that it is black in color indicates

binder is a small fraction of the

comprise much more than 4-6%. Perhaps

The 4-6% value I gave you was based on actual data from an asphalt extraction of asphaltic concrete. I just had the data on 1 mix, however. You might want to go to

for information straight from the horse's mouth.

throughout the sand and gravel is much

guessing that it is far easier to

Personally I would think it would be the other way around, since the asphaltic emulsion has a higher viscosity than portland cement paste.

oil to heat up limestone in order

seems that the binder of blacktop is

commerce. Something of theory that a

oil required to make a cubic meter of

portland cement could only pave 1/100 of

I think people have done that, but I don't know who.

aggregate as per Kepler Packing and as

the voids with either

the idea that KPP is the minimum

touching balls and its 26% holes or

then the entire material is one

at kissing points but at all sorts

the remaining 26% with tar or with

Keplerian Packed concrete or Keplerian

the same with a concrete of Kepler

neither one of these materials have

do not see how to infuse a KPP with

It wouldn't do to infuse the Keplerian Packing with just portland cement. You need to infuse it with cement and water paste. That should be very easy to do, depending on the ratio of water to cement. More water means lower viscosities, but also lower strength of the paste.

Jay Shilstone

compressing concrete is quite common, and done with a vibrator, before it sets.

also, there are additives that help reduce viscosity or increase fluidity, while keeping initial water content low (but still enough water to react), similar to what is used in potter / ceramics.

E.V

steel balls of the size of

foot of concrete that has marbles

used and the ratio is close to

and 10 liters of BBs.

which diminish strength and cause

only BBs and portland cement.

there is a Kepler Packing and where

infuse the crevasses between the

the interstatials with

the strongest such block over

serves me (mathematician would

that the underlayer is a pure tar and

in that it is black in color indicates

binder is a small fraction of the

comprise much more than 4-6%. Perhaps

throughout the sand and gravel is much

guessing that it is far easier to

of oil to heat up limestone in order

seems that the binder of blacktop is

day commerce. Something of theory that a

oil required to make a cubic meter of

portland cement could only pave 1/100 of

aggregate as per Kepler Packing and as

fill the voids with either

in the idea that KPP is the minimum

touching balls and its 26% holes or

cement then the entire material is one

touch at kissing points but at all sorts

the remaining 26% with tar or with

Keplerian Packed concrete or Keplerian

the same with a concrete of Kepler

neither one of these materials have

I do not see how to infuse a KPP with

Hi Jay, I am having a hard time of believing this 4-6% tar binding in typical road asphalt. Hard believing because it is so black that it must have more than 6% tar. And due to the theoretical notion that the densest of packing whether they be oranges in a grocery store or baseballs or sand grains that are somewhat round that the densest packing is a Kepler Packing and so the percentage of volume of gaps to glue together those sand grains would be 26%. Now I realize that a concrete mix of portlandcement and sand that many of those gaps in the sand will have no portlandcement.

What I am saying is the the Minimum Strongest Perfect concrete of sand that is round would be of a 74% sand and 26% portland cement filling each of those gaps of the Kepler Packing.

So I am having a difficult time of envisioning highway asphalt as being only a mere 6% by volume of a tar binder. Granted that the gravel used in asphalt and concrete is not round shaped but having many flat surfaces where one flat surface rests upon another relatively flat face surface and so you would need less tar than the Kepler Packing amount of 26%. But I cannot envision that the flat surfaces would reduce the 26% down to a mere 6%.

Perhaps there is something about the term "binder" of a 6% binder that I am missing in that the tar consists of a binder plus some other tar ingredients.

P.S. I am having trouble in getting posts to the Internet in that they appear on my ISP but not on any other ISP. Suggesting that someone wrote a virus program that censors my posts and perhaps other posts.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

Subject: censorship of Internet posts Re: blacktop ratio tied to concrete ratio?? Re: Kepler Packing on concrete mixes Re: theoretically the strongest concrete Date: Sun, 21 Sep 2003 11:27:53 -0500 From: Archimedes Plutonium Reply-To: NOdtgEMAIL Organization: whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies Newsgroups: sci.materials, sci.engr, sci.math References: 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13

James Shilst> >

that the underlayer is a pure tar and

in that it is black in color indicates

binder is a small fraction of the

comprise much more than 4-6%. Perhaps

throughout the sand and gravel is much

guessing that it is far easier to

of oil to heat up limestone in order

seems that the binder of blacktop is

day commerce. Something of theory that a

oil required to make a cubic meter of

portland cement could only pave 1/100 of

aggregate as per Kepler Packing and as

fill the voids with either

in the idea that KPP is the minimum

touching balls and its 26% holes or

cement then the entire material is one

touch at kissing points but at all sorts

the remaining 26% with tar or with

Keplerian Packed concrete or Keplerian

the same with a concrete of Kepler

neither one of these materials have

I do not see how to infuse a KPP with

Hi Jay, I am having a hard time of believing this 4-6% tar binding in typical road asphalt. Hard believing because it is so black that it must have more than 6% tar. And due to the theoretical notion that the densest of packing whether they be oranges in a grocery store or baseballs or sand grains that are somewhat round that the densest packing is a Kepler Packing and so the percentage of volume of gaps to glue together those sand grains would be 26%. Now I realize that a concrete mix of portlandcement and sand that many of those gaps in the sand will have no portlandcement.

What I am saying is the the Minimum Strongest Perfect concrete of sand that is round would be of a 74% sand and 26% portland cement filling each of those gaps of the Kepler Packing.

So I am having a difficult time of envisioning highway asphalt as being only a mere 6% by volume of a tar binder. Granted that the gravel used in asphalt and concrete is not round shaped but having many flat surfaces where one flat surface rests upon another relatively flat face surface and so you would need less tar than the Kepler Packing amount of 26%. But I cannot envision that the flat surfaces would reduce the

26% down to a mere 6%.

Perhaps there is something about the term "binder" of a 6% binder that I am missing in that the tar consists of a binder plus some other tar ingredients.

P.S. I am having trouble in getting posts to the Internet in that they appear on my ISP but not on any other ISP. Suggesting that someone wrote a virus program that censors my posts and perhaps other posts.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

I wonder if sand grains are mostly flat faced and not roundish? The Kepler Packing deals with spheres and it is the densest packing with 26% void gaps.

Does anyone know what the usual or average sand roundness or flatness is?

I suppose one can get gravel that is mostly roundish. I know the gravel of quartzite to make a concrete mix is mostly angular with alot of flatlike surfaces. Perhaps sand is much like this quartzite in having many flat surfaces. So that when one mixes a concrete mix of sand and aggregate gravel that many of the flat surfaces touch and leaving little if any room for portland cement to glue together those flat surfaces. And that the Kepler Packing of spheres with its density of 74% and 26% gaps for a glue. That in a sand and or gravel mix of concrete or asphalt that the 26% gaps need not have a glue because they are mostly flat surfaces touching one another. So I suppose the 26% can be drastically reduced in these mixes because of "flatness"

E.V. , I am having trouble posting in that I suspect someone wrote a virus to prevent these posts of mine from appearing on all outside ISP, except for my own ISP of dtgnet. So am double posting.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

Subject: Re: Kepler Packing on concrete mixes Re: theoretically the strongest concrete Date: Sun, 21 Sep 2003 11:43:20 -0500 From: Archimedes Plutonium Reply-To: NOdtgEMAIL Organization: whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies Newsgroups: sci.materials, sci.engr, sci.math References: 1 , 2 , 3 , 4 , 5 , 6 , 7

Erez Volach wrote:

I wonder if sand grains are mostly flat faced and not roundish? The Kepler Packing deals with spheres and it is the densest packing with 26% void gaps.

Does anyone know what the usual or average sand roundness or flatness is?

I suppose one can get gravel that is mostly roundish. I know the gravel of quartzite to make a concrete mix is mostly angular with alot of flatlike surfaces. Perhaps sand is much like this quartzite in having many flat surfaces. So that when one mixes a concrete mix of sand and aggregate gravel that many of the flat surfaces touch and leaving little if any room for portland cement to glue together those flat surfaces. And that the Kepler Packing of spheres with its density of 74% and 26% gaps for a glue. That in a sand and or gravel mix of concrete or asphalt that the 26% gaps need not have a glue because they are mostly flat surfaces touching one another. So I suppose the 26% can be drastically reduced in these mixes because of "flatness"

E.V. , I am having trouble posting in that I suspect someone wrote a virus to prevent these posts of mine from appearing on all outside ISP, except for my own ISP of dtgnet. So am double posting.

Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies

If you use round sand the concrete will be weak. Sand like

makes lousy concrete.

really. I hadn't realized taht AP used the same presentation as JSH, continually restarting the item as a new group. it's a good question, though, just like the realtion to Avagadro's #.

--les ducs d'Enron!