VERFAHREN ZUR UNTERDRÜCKUNG DER REAKTION ZWISCHEN ALKALI UND ZUSCHLÄGEN IN BETON UND NACH DEM VERFAHREN HERGESTELLTER ZEMENT.

摘要

PCT No. PCT/FR91/00007 Sec. 371 Date Jul. 29, 1992 Sec. 102(e) Date Jul. 29, 1992 PCT Filed Jan. 8, 1991 PCT Pub. No. WO91/11405 PCT Pub. Date Aug. 8, 1991.Method for eliminating the dangerous alkali-aggregate reaction in concretes which contain hydrated cement obtained by the alkaline activation of Portland cement. The formation in this concrete of a compound which can generate a soluble alkali aluminate is prevented by reacting a mineral composition by alkaline activation, the said compound consisting of a hydrated alumino-silicate whose Nuclear Magnetic Resonance 27Al MAS-NMR spectrum shows a resonance at 66+-5 ppm corresponding to a (Q3)(3Si)-type (AlO4) tetrahedron. The above-mentioned mineral composition contains: a) 100 parts by weight of the said calcium alumino-silicate; b) 10 to 30 parts by weight of powdered synthetic alumino-silicate belonging to the class of silicates whose mineralogical structure is lamellar and whose MAS-NMR for 27Al has at least one main resonance at 20+-5 ppm and/or 50+-5 ppm in relation to AlCl3. c) 0 to 10 parts by weight of a hydrated disilicate Ca(H3SiO4)2 whose (SiO4) tetrahedron polymerization degree is (Q1) as determined by the value of the MAS-NMR spectrum for 29Si. The mineral composition is a rapid-set geopolymeric cement characterized after alkaline activation by its 27Al MAS-NMR spectrum which shows a resonance at 55+-5 ppm in relation to AlCl3, corresponding to a (Q4)(4Si)-type (AlO4) tetrahedron, and a resonance at 0+-5 ppm in relation to AlCl3, corresponding to Al in VI-fold coordination (AlO6) in aluminum hydroxide and/or hydrated calcium sulfo-aluminate (ettringite). The ratio (AlO4)(4Si)/(AlO6) between the intensity of the (Q4)(4Si)-type (AlO4) resonance at 55+-5 ppm and the intensity of the (AlO6) resonance at 0 ppm is equal to or between 0.1 and 1.