How quickly does postcrete finally go off?

[Ferdinand]

Yes .. I know it is solid in 10 minutes,

 

But how long is there value in leaving wedges etc in place for?

 

The context is that it is bracing on a fance that was wobbling in the storm, where I installed a few braces last Saturday, and the wedges to hold it solid are still there. The place is one where the wind howls like a "triggered" member of a student union if some reprobate claps rather than uses Jazz Hands, now that the company I sold it too have removed all the trees which slowed the wind down. It needs every ounce of strength it can get.

 

I would guess it is definitely at 100% by now, but that 24 hours was probably beneficial.

 

Ferdinand

Edited February 27, 2017 by Ferdinand

[Jeremy Harris]

At a guess it won't be "fully"* cured for at least 10 to 12 hours, but it'll be around 80% or more cured within a couple of hours.  After 24 hours it will be around 90% cured, about as cured as it's going to get, anyway, in the short term.

 

*concrete doesn't really fully cure for decades, as chemical changes continue to harden it through life, which is one reason some well-mixed old concrete is so damned hard to break up.

[Ferdinand]

Cheers.

 

I love the idea of concrete curing over the years.

 

Green oak goes off more quickly.

 

[jack]

8 minutes ago, Ferdinand said:

I love the idea of concrete curing over the years.

 

Have read of the "concrete" section of the Hoover Dam Wikipedia article.

[Ferdinand]

7 minutes ago, jack said:

 

Have read of the "concrete" section of the Hoover Dam Wikipedia article.

 

Love this bit:

Quote

" Although there are myths that men were caught in the pour and are entombed in the dam to this day, each bucket only deepened the concrete in a form by an inch, and Six Companies engineers would not have permitted a flaw caused by the presence of a human body."

 

And more soberingly:

Quote

There were 112 deaths associated with the construction of the dam.[70] The first was J. G. Tierney, a surveyor who drowned on December 20, 1922, while looking for an ideal spot for the dam.[70] The last death on the project's official fatality list occurred on December 20, 1935, when an "electrician's helper", Patrick Tierney, the son of J. G. Tierney, fell from an intake tower. Included in the fatality list are three workers, one in 1932 and two in 1933, who committed suicide onsite.[71][72][73] Ninety-six of the deaths occurred during construction at the site.

 

On concrete curing slowly, I have read about that somewhere. It might even have been in the autobiography of Albert Speer.

Edited February 27, 2017 by Ferdinand

[Ferdinand]

Having done it, Postcrete does have a change of tone (as you would expect) when hit with a batten or a mallet when it becomes very solid.

 

This seemed to occur after 2-3 hours for these braces in these cold and miserable conditions. The setup was fence wedged in final position after storm Doris had moved the knocked-in posts (never had that type of fence move before in years in the same location) a little, and 45 degree struts wedged against bricks, with the bottom end and brick postcreted.

 

Edited February 27, 2017 by Ferdinand

[Jeremy Harris]

14 minutes ago, Ferdinand said:

 

Love this bit:

 

And more soberingly:

 

On concrete curing slowly, I have read about that somewhere. It might even have been in the autobiography of Albert Speer.

 

 

One related area to this is the U boat bunkers at Brest.  I remember sailing around from L'Aberach to Brest to visit them in the early 80's, and the tale was that the French had given up trying to demolish them because the 40 year old concrete was now a fair bit stronger than it was when they were built.  Given that we struggled to damage them using Barnes Wallis's Tallboys, when the concrete had only been there for a couple of years or so, I can imagine just what a job it would be to demolish the thing.

 

As an aside, the division at Boscombe Down I occasionally flew with years ago had two Tallboys either side of the entrance door - they are pretty impressive bombs when stood on end!