concrete setting time



Most lime mortars cure well wet or dry, but tend to effloresce if kept wet after curing, about like plasters do, but not nearly so badly. Do as block/brick/stone masons do. Put it on as wet as will sustain the load of the stone/brick/block, and just let it cure until cheezy enough to strike the joints -- then leave it be.
Lloyd
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Lloyd E. Sponenburgh wrote:

Well ... I'm bedding the floor stones <graded 2"-2 1/2" thick> in a mix of 5 parts masonry mix , 1 portland , 3 sand , and 1thinset mortar . This gives a mortar that's really sticky when mixed on the dry side and stays very plastic as it sets . Makes it possible to adjust a rock that's been set for a few minutes without breaking the bond . I'm also laying on top of a layer of tarpaper so differential expansion <wood sub , 3/4" Advantech with 1/2" OSB screwed and glued> doesn't tear things up . I'll be covering it with plastic when I finish filling the joints . Then , it'll be the wall ... which is a totally different technique . It'll also be covered with a vapor barrier for a couple of weeks minimum . Actually , I was being sarcastic when I asked that question ... I still remember when my Grandpa poured the floor for his garage , several hours after they finished troweling it he scattered some straw over it and covered it with tarps to control evaporation . I had to be like 10 or 11 , which would put it around 1962 or 63 ...
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wrote:

That's sure nice. I had a fun time with mortar when I did my first cobblestone walkway set in mortar, but it has stood the test of time (7 years) so far. It's harder to get a single stone's surrounding mortar to reliquify for resetting, but it's doable. I used a thick piece of wire made into an L-shaped hook to lift the low stones to level, bouncing them up-and-down to get the mortar back under them.

Good!

How do you like the Advantech over regular ply?

Wow, they had concrete way back then? ;)
I set (actually, reset) my first fake stones yesterday. Four pieces of stone veneer (limestone-like hypertufa) onto the outside of a garage wall. Researching adhesives for it, I could either buy a $45 bag (50#) of thinset or use LiquidNails. I chose a tube of LN for $2.39. It didn't even pretend to hold the stone up to the mortar, so I looked around and asked the lady for a large plastic bag and some old rags or something. She had 4 boxes of winter clothes in the garage so I used some of those. I filled the bag with clothes, tossed loosely into the bag, then squished it up against the stone, using the other boxes of clothing to press against the bag. Worked just great! Steady firm pressure all over the face of the stones, holding them to the wall for the hours until the LN set up. I was applauded for my ingenuity, which is always nice.
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Larry Jaques wrote:

It's great . Very stable , more rigid than plywood , and it doesn't swell up and start shedding if it gets wet . This floor got rained on twice before I got the roof on , no damage at all . Don't even think you can hand-nail it though ... I used my framing nailer .

And even before , if you believe history !

Ingenuity indeed ! I'll have to remember that trick , bet it'd work on reattaching almost any veneer product .
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Italian contractors were pouring concrete in 300 BC, and it still hasn't completely cured.
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On Sat, 23 Aug 2014 12:26:38 -0400, "Jim Wilkins"

That's good reason to be wary of Italian contractors. "We'll be back to finish the job when it's completely cured." d8-)
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On Saturday, August 23, 2014 12:26:38 PM UTC-4, Jim Wilkins wrote:

"Ready mixed concrete was first used in Germany in 1903" -- etd.lib.metu.edu.tr/upload/12609528/index.pdf
I assume that's the type this thread has been referring to. But even the Sumerians described concrete. The Sumerian timeline dates from 3000 BC.
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On Sat, 23 Aug 2014 09:53:11 -0700 (PDT), walter snipped-for-privacy@post.com wrote:

Portland cement is "regular cement" in the US. In Western Europe, they often mix in a large percentage of Pozzolan. Their strengths are similar but Portland cement cures faster.
At least by 1000 BC, the ancients were making Pozzolan cement in much the same way a lot of it is made today: fine-ground, reactive types of volcanic ash, mixed with slaked lime.
Pozzolan has been used for thousands of years, while Portland cement has been around for about 150 years.
--
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On 8/23/2014 12:10 PM, Ed Huntress wrote:

Pozzolan, being made with volcanic ash, has the unique ability to cure in salt water. Piers and mooring points were done by the Romans and the Japanese before and during WWII.
Martin
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On Saturday, August 23, 2014 10:36:26 PM UTC-4, Martin Eastburn wrote:

> Pozzolan, being made with volcanic ash, has the unique ability to cure

>in salt water. Piers and mooring points were done by the Romans and the

> Japanese before and during WWII.
Here: someone said in a: "textbook that saltwater will work, but the total compressive strength will be 10%-15% lower" -- http://www.contractortalk.com/f4/effect-mixing-salt-water-concrete-123800/
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On 8/24/2014 10:43 AM, snipped-for-privacy@hotmail.com wrote:

...

Curing IN salt water is different from mixing WITH salt water
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On 8/24/2014 10:30 AM, Bob Engelhardt wrote:

Exactly.
Plenty of rainwater in the south Pacific but making piers running out into the lagoon requires large dams and pumps .. what a job. Or use ash and the chemical reaction is different from Portland. If the cement were 25% less one would just build better strength versions or just put up with some wear. Once you have an out-of-water pier, a hard top could be added - with or without rails for cargo movement.
Some under water projects for a sub refueling design showed the real magic.
Martin who lived in the south pacific for some time.
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You seem to be a history buff on concrete...
How is it that Henry Flagler could build concrete piers in the ocean 100 years ago in the FL Keys and have the concrete still be in great shape. Meanwhile everything built more than 20 years ago is falling apart in the Keys.
Karl
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On Sun, 24 Aug 2014 15:34:30 -0500, Karl Townsend

concrete is mostly about two things: post-tensioned structures and ferrocement. I've just picked up a few historical tidbits along the way. I have a really great book on ferrorcement (among several others) that took me most of a year of spare time to read.
Back in Flagler's day, we overbuilt all kinds of sructures, because we didn't have the engineering to build them closer to the limits. I'm just guessing, but it could be something like that.
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On 8/24/2014 3:46 PM, Ed Huntress wrote:

He might have researched the subject before he just made concrete.
My furnace isn't Portland - no water is stored. It is a different process and is a chemical reaction that makes the bonds. You cook the water out of it in a long slow ramp up. Water inside of cement can explode.
Simply drop some molten metal on a concrete floor and you might have a hole dished out. Blow cement at you.
His piers might have been high temp cement being very dense as well. One never knows without a core and some tests :-)
Martin
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Karl Townsend wrote:

They were built by the low bidder, and not inspected. Remember all the substandard work uncovered by hurricane Andrew in Miami?
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Karl Townsend wrote:

He used sand and gravel brought in from Georgia and fresh water for the mix. The railroads always built to last forever (except when they were in a hurry )
John
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On 8/24/2014 10:29 PM, John wrote:

Granted.
What was the sand made out of ? What was the gravel made out of ?
Perhaps a chem action and not much if any Portland until later in the cycle.
Martin
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He said "Georgia". He didn't mean the Soviet state of Georgia.
There's really not much in the way of pyrolytic or volcanic stone in Georgia, USA.
He went to Georgia because except for a little limestone, Florida's only mineral commodity is (well, was) phosphates. Our sand is too fine for concrete work.
Lloyd
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Lloyd E. Sponenburgh wrote:

He actually went all over the world to get the materials for the bridges. The below water cement came from Germany, the trap rock came from NY state.
https://friendsofoldseven.org/bridge/
I was wrong about Georgia. it must have been Germany I was thinking of.
John
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