[Swiftwater Gazette] brine-based concretes
sanderico1 at gmail.com
Sun Jul 9 07:13:05 EDT 2017
I thought everybody knew that.....
On Sat, Jul 8, 2017 at 4:18 PM, Ed kroposki <kroposki at att.net> wrote:
> Secret of how Roman concrete survived tidal battering for 2,000 years
> The life cycle of Roman harbor concretes structures is about two orders of
> magnitude greater than Portland-type cement seawater concretes.
> Cement-based concretes are designed to hydrate quickly and maintain
> durability through a general absence of long-term cementitious evolution or
> solubility. In maritime environments, however, the concrete commonly begins
> to decay after a few decades...
> Phillipsite and Al-tobermorite mineral cements produced through
> low-temperature water-rock reactions in Roman marine concrete.
> Roman marine concretes can provide guidelines for the optimal selection of
> natural volcanic pozzolans that have the potential to produce of
> regenerative cementitious resilience through long-term crystallization of
> zeolite, Al-tobermorite, and strätlingite mineral cements.
> The cross-linked structure and Al3+ bonding environments of the Roman
> Al-tobermorite crystals, recorded by Raman spectra through a range of
> cementitious microstructures and crystallization pathways, provide clues to
> creating new pathways for cation-change in high-performance concretes.
> Furthermore, the chemical and mechanical resilience of the marine concrete
> provides keys to understanding dynamic mineral cements in young, oceanic
> pyroclastic deposits, as at Surtsey (Jakobsson and Moore 1986), the seismic
> response of a volcanic edifice, as in deep Campi Flegrei deposits (Vanorio
> and Kanitpanyacharoen 2015), and carbon mineralization reactions, as occur
> in porous basaltic storage reservoirs for anthropogenic CO2 (Matter et al.
> Roman prototypes for brine-based concretes could conserve freshwater
> resources, generate multiple low temperature pathways to pozzolanic and
> post-pozzolanic Al-tobermorite sorbents with coupled Al3+ and exchangeable
> alkali cation sites, and extend applications of natural volcanic pozzolans
> to environmentally friendly, alkali-activated structural concretes and
> cementitious barriers for waste encapsulations.
> ---- // ----
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