| 摘要 |
<p>Provided herein are new uses for red gypsum, a waste material from the production of titanium dioxide which contains between 60-90 % CaSO4.2H2O; 3-35 % iron (II) and iron (III) oxide/hydroxides, expressed as Fe(OH)3; 0.3 to 2 % TiO2; 0.1 to 4% SiO2; 0.1 to 0.8 % Na2O; 0.1 to 5 % CaCO3 0.1 to 0.4 % MgO; 0.1 to 0.2 % potassium, calculated as K2O; and 0.1 to 0.2 % phosphorous, calculated as P2O5. We have found that adding red gypsum to soils stiffens and strengthens the soils. Thus provided herein are stabilized soil mixtures comprising red gypsum. Further disclosed are cementitious compositions which comprise red gypsum; an aluminosilicate source such as a clay, fly ash, or ground blastfurnace slag; and lime. The cementitious compositions of the present invention are not substantially anhydrous as is ordinary Portland cement, but rather contain substantial amounts of water. Yet, strengths comparable to Portland cement are surprisingly exhibited by the disclosed compositions. It seems that the minor components inherently present in the red gypsum contribute to the surprising strengths from the hydrated cements of the invention.</p> |
