On Saturday, August 23, 2014 10:36:26 PM UTC-4, Martin Eastburn wrote:
On 8/23/2014 12:10 PM, Ed Huntress wrote:

On Sat, 23 Aug 2014 09:53:11 -0700 (PDT),

wrote:

On Saturday, August 23, 2014 12:26:38 PM UTC-4, Jim Wilkins wrote:

"Terry Coombs" wrote in message



...

Larry Jaques wrote:

On Fri, 22 Aug 2014 23:01:21 -0500, "Terry Coombs"



wrote:

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 ...

Wow, they had concrete way back then?

And even before , if you believe history !

Italian contractors were pouring concrete in 300 BC, and it still

hasn't completely cured.

"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.

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.

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.

He someone said in a: "textbook that sal****er will work, but the total compressive strength will be 10%-15% lower"
-- http://www.contractortalk.com/f4/eff...ncrete-123800/