| 摘要 |
<p>Method for eliminating the dangerous alkali-aggregate reaction in concrete which contains hydrated cement obtained by the alkaline activation of Portland cement. The formation in this concrete of a compound which can generate a soluble alkaline aluminate is prevented by reacting a mineral composition by alkaline activation, said compound being composed of a hydrated alkaline alumino-silicate identifiable by its analysis spectrum in Nuclear Magnetic Resonance (MAS-NMR) for 27Al of which the resonance at 66±5ppm corresponds to a Q¿3?(3Si)-type (Al04) tetrahedron. The above-mentioned mineral composition contains: a) 100 parts by weight of said calcium alumino-silicate; b) 10-30 parts by weight of powdered synthetic alumino-silicates belonging to the class of silicates whose mineralogical structure is lamellar and whose MAS-NMR for ?27¿Al has at least one main resonance at 20±5ppm and/or 50±5ppm in relation to AlCl¿3?; c) 0-10 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 ?29¿Si. The mineral composition is a geopolymetric quick setting cement characterized after alkaline activation by its MAS-NMR spectrum for 27Al which has a resonance equal to 55±5ppm in relation to AlCl¿3?, corresponding to a Q4(4Si)-type (AlO4)tetrahedron, and a resonance of 0±5ppm in relation to AlCl3, corresponding to the VI(AlO6) coordinated Al cation in alumina hydroxide and/or hydrated calcium thioaluminate (ettringit). The ratio between the intensity of the 55±5ppm resonance of Q4(4Si)-type (AlO4) and the intensity of the 0±5ppm resonance of (AlO6), (AlO4)/(AlO6) is equal to or between 0.1 and 1.</p> |
