Concrete news

[Jersey mike]

Some may find it interesting. Hopefully ot does answer some questions as well as can be put into use.

https://www.foxnews.com/science/research-uncover-secret-made-ancient-roman-concrete-durable

[Rams]

An interesting article.   I wouldn't be surprised that the "Professor" isn't right.   Calcium added along with other chemicals will cause a faster drying concrete heated mix but, in my experience, it also produces a more brittle end product.

I've done a huge amount of concrete work in my life, but that doesn't mean I know everything about the product.  Shrug.  As I said, interesting..............

Rams

[Bret SD]

Concrete is a very broad, complicated science, and specificity rules the mix.

[old2soon]

       I have Not perused the article BUT I drove a concrete mixer-10 yarder-in Colorado. We had several different mixes-sacks of cement per yard-for various uses. The different mixes had certain P S I resitances to meet after cure. High summer in Souther Colorado you needed to retard the cure time a bit to have workability at the job site. In winter we sometimes used an accelerator depening on what that Contactor wasnted. Also have seen after a winter pour tarps over the semi set concrete to help retain the heat of the cure. I was also a Cerified concrete tester and weigh master in Colorado. And I did Not then nor now consider myself an expert But I was around that industry near on 5 years. I KNOW concrete finishing was near an art. Working concrete too much drew too much water and sand to the surface and could weaken the cured surface somewhat. RIDE SAFE.

[Jersey mike]

All good responses but I thought I’d get a few humorous replies too like mama mia those Italians will cook anything or I wonder if they tried adding olive oil and garlic too. 

[Rams]

All good responses but I thought I’d get a few humorous replies too like mama mia those Italians will cook anything or I wonder if they tried adding olive oil and garlic too. 

I dated an Italian girl in college, she liked olive oil but that's all I'm gonna say about that.  The topic of concrete never came up between us.   Although olive oil did quite a few times.   Yes, she was an excellent cook.

Rams

[Jess from VA]

Concrete hardens for 80 years (or so).

You can see it (crumbling away when it becomes so hard it turns brittle) visiting old towns that have never been repaved.

[Robert]

Transparent Concrete I would like to use this on a house sometime

https://dreamcivil.com/transparent-concrete/

[Jess from VA]

Ferro Cement boats. (actually float)   

[Rams]

Ferro Cement boats. (actually float)   

If memory serves me correctly, during WWII, there a significant number of concrete barges used.   Not sure how but I'm not interested enough in barges to investigate that. 

Rams

[Jess from VA]

You may be talking about the concrete Mulberry (harbors) used to offload shipping in Normandy after the assault.

They floated concrete caissons (Phoenixes) across the Channel which were then sunk; to drive on.

They weren't harbors, more like raised roadways. 

https://en.wikipedia.org/wiki/Mulberry_harbour







 

[RP#62]

And/or the McCloskey Ships

https://www.concreteships.org/ships/ww2/

-RP

[Rams]

And/or the McCloskey Ships

https://www.concreteships.org/ships/ww2/

-RP

This may be what I was thinking of, not really sure.   The memory muscle seems to think there were concrete barges used on the east coast of the US because of a lack of steel but who knows.

Rams

[98valk]

https://www.roadsideamerica.com/story/6838

The S.S. Atlantus was one of a dozen concrete ships that were built, and it criss-crossed the Atlantic several times, hauling cargo and troops. But when steel again became available, the S.S. Atlantus was mothballed.

Historical Marker and Concrete Ship S.S. Atlantus.

In 1926 she was docked in Cape May N.J. when a storm broke her loose and ran her aground, just off of Sunset Beach. She couldn't be pried off of the bottom because she was made of, well, concrete. For the last 90+ years her slowly crumbling hulk has been a tourist attraction, although not much of her is left above water.

[Rams]

Transparent Concrete I would like to use this on a house sometime

https://dreamcivil.com/transparent-concrete/

I found this an interesting concept and have tried to imagine how I would use it in new construction today.   The best answer I can come up with is using it as a floor or possibly as a concrete roof but, I can't imagine doing that without significant rebar/steel reinforcement.   Which would kind of ruin the effect.   I have no doubt this would be ultra-expensive to construct with.

Thinking I'll have to pass.

Rams

[RP#62]

Reminded me of this (we were living in the Keys when this happened).

Back in the late 70's and early 80's they rebuilt and 4-laned the bridges in the Keys making up the Overseas Highway.  The original bridges were built atop the concrete-arch railroad trestles that Henry Flagler had built back around 1912.  The big labor day hurricane of 1935 wiped out most of the bridges leaving only the concrete arches.  The new highway was built on the old railroad arches about three years later.  When they went to demolish the old arches back in the late 70's to make way for the new bridges, it took three times the amount of explosives that the engineers had calculated based on modern concrete strength.  It seems that Flagler had brought in crews of Italian immigrants to build the arches and they were making concrete using generations old family recipes and methods.


-RP

[98valk]

Transparent Concrete I would like to use this on a house sometime

https://dreamcivil.com/transparent-concrete/

I found this an interesting concept and have tried to imagine how I would use it in new construction today.   The best answer I can come up with is using it as a floor or possibly as a concrete roof but, I can't imagine doing that without significant rebar/steel reinforcement.   Which would kind of ruin the effect.   I have no doubt this would be ultra-expensive to construct with.

Thinking I'll have to pass.

Rams

like transparent aluminum. so time travel is real.

[Jersey mike]

Reminded me of this (we were living in the Keys when this happened).

Back in the late 70's and early 80's they rebuilt and 4-laned the bridges in the Keys making up the Overseas Highway.  The original bridges were built atop the concrete-arch railroad trestles that Henry Flagler had built back around 1912.  The big labor day hurricane of 1935 wiped out most of the bridges leaving only the concrete arches.  The new highway was built on the old railroad arches about three years later.  When they went to demolish the old arches back in the late 70's to make way for the new bridges, it took three times the amount of explosives that the engineers had calculated based on modern concrete strength.  It seems that Flagler had brought in crews of Italian immigrants to build the arches and they were making concrete using generations old family recipes and methods.


-RP

I believe many of those originals are still in place today and still do not weather as the new ones do.

[Robert]

Ferro Cement boats. (actually float)   

I actually helped to build a ferro cement boat with a friend. It was 45 feet long and stood about 25 feet high from keel to top of the deck. IF you looked at it, you could not tell it from fiberglass at first look. It looked much sleeker than than the one in this pic. Took years to make from scratch. The frame was rebar tied together that made the mold essentially. Once everything was in place the concrete pour started. There were about 5 vibrators that when the concrete was put in the wire the vibrators would push it in and smooth it out. It was me and one other guy that actually shoveled the concrete into wheel barrows. My freind made a building that helped support the structure even though a flat section of the keel was on a slab but when the pour was happening and the cement needed to cure the temp inside the building needed to be brought up. So with 2 big steam jenneys running and keeping the moisture up it was cured in a few days. 

[Moonshot_1]

Was speaking with a guy the other day who has been doing concrete for years.

Said whether you are a seasoned pro or a novice, concrete is hard.

[Crackerborn]

All the early 20 to 40 era houses along the eastern seaboard used salt water to batch the concrete (at site). You could drive a common nail into the walls but a sledge would just bounce off. Steel rebar?  Nope, only sand and seashells. D-9 dozer, minimum, required for demo. Some of the railroad magnate era homes are still standing from Palm Beach all the way to the Grove.
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I will not contest concrete curing time but I was under the impression it was over 150 years to full strength if properly mixed.

[Skinhead]

A few years back me, my brother, and BILs poured a sidewalk and some steps for my mother.  When I was paying the driver that delivered the concrete, he gave me the total and said, "And that price includes the fire and theft insurance on the concrete."  I found that amusing.

[Rams]

I will not contest concrete curing time but I was under the impression it was over 150 years to full strength if properly mixed.

That must be a special mix, generally the accepted curing time is 28 days in 50 to 90 F degree temps.



How Long Does Concrete Take to Cure?
https://www.hunker.com/13401156/how-long-does-concrete-take-to-cure

To allow concrete to cure correctly, keep it wet and warm at temperatures between 50-90 degrees Fahrenheit for the first week at least. Concrete that does not cure properly can shrink, crack or even develop a dusty, weak and crumbly surface. The longer you allow concrete to cure, the harder it becomes. While you may only need to keep the concrete protected for the first week while it cures, it actually takes it about 28 days to reach its full strength and hardness.

Rams

[Jess from VA]

Curing is not the same as hardening. 

Concrete gets harder for decades, but there comes a time it becomes so hard, it's brittle. 

[Rams]

Curing is not the same as hardening. 

Concrete gets harder for decades, but there comes a time it becomes so hard, it's brittle. 

Of course it isn't but, both hardness and strength are results of the curing process.   The curing process can be slowed with the addition of certain chemicals.   The slower the curing process (generally speaking) the stronger and harder concrete will be.   But, concrete that dries too quickly will become brittle.   Concrete will develop it's own heat during the curing process, it's important to control that heat.

In that I never intend to do any more concrete work, I hereby wash my hands of the subject, I know from experience that it's hard.

Rams