[Swiftwater Gazette] brine-based concretes

Ed kroposki kroposki at att.net
Sat Jul 8 17:18:05 EDT 2017




Secretof how Roman concrete survived tidal battering for 2,000 yearsrevealed. 
http://ammin.geoscienceworld.org/content/102/7/1435
Thelife cycle of Roman harbor concretes structures is about two ordersof magnitude greater than Portland-type cement seawater concretes.Cement-based concretes are designed to hydrate quickly and maintaindurability through a general absence of long-term cementitiousevolution or solubility. In maritime environments, however, theconcrete commonly begins to decay after a few decades... 
Phillipsiteand Al-tobermorite mineral cements produced through low-temperaturewater-rock reactions in Roman marine concrete.
Romanmarine concretes can provide guidelines for the optimal selection ofnatural volcanic pozzolans that have the potential to produce ofregenerative cementitious resilience through long-termcrystallization of zeolite, Al-tobermorite, and strätlingite mineralcements. 
 Thecross-linked structure and Al3+ bonding environments of the RomanAl-tobermorite crystals, recorded by Raman spectra through a range ofcementitious microstructures and crystallization pathways, provideclues to creating new pathways for cation-change in high-performanceconcretes. Furthermore, the chemical and mechanical resilience of themarine concrete provides keys to understanding dynamic mineralcements in young, oceanic pyroclastic deposits, as at Surtsey(Jakobsson and Moore 1986), the seismic response of a volcanicedifice, as in deep Campi Flegrei deposits (Vanorio andKanitpanyacharoen 2015), and carbon mineralization reactions, asoccur in porous basaltic storage reservoirs for anthropogenic CO2(Matter et al. 2016).
Romanprototypes for brine-based concretes could conserve freshwaterresources, generate multiple low temperature pathways to pozzolanicand post-pozzolanic Al-tobermorite sorbents with coupled Al3+ andexchangeable alkali cation sites, and extend applications of naturalvolcanic pozzolans to environmentally friendly, alkali-activatedstructural concretes and cementitious barriers for wasteencapsulations.
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