[FoRK] KK: the art of endless upgrades

Eugen Leitl eugen at leitl.org
Tue May 17 23:39:30 PDT 2011


On Tue, May 17, 2011 at 04:58:11PM -0400, Gary Stock wrote:
> On 5/17/11 10:04 AM, Eugen Leitl wrote:
>> I can see very permanent
>> things decay in my own lifetime. Surprising, asphalt doesn't last forever,
>> nor do iron and even stone.
> I recall a class in Segovia, touching on design features of the  
> aqueducts built there ~2,000 years ago.  The professor noted that they  
> may remain standing (and essentially functional) that long again --  
> perhaps longer.  He then commented on the pomposity of our use of steel  
> rebar to "improve" concrete construction.  In half that time,  
> archaeologists will be either confused or amused by the little round red  
> holes -- hollow tubes where those steel bars once were -- presuming any  
> of the concrete remains intact.

Actually the rusting iron expands, and breaks up the concrete
matrix from within. The Roman concrete was not reinforced, and
remarkably sophisticated:
http://www.geopolymer.org/archaeology/roman-cement/high-performance-roman-cement-and-concrete-high-durable-buildings

Arguably today we could use mineral fiber reinforced concrete
or geopolymer, and achieve much better durability.

-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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