Cement patent including chromium reduction

Factiva: "A cement admixture of a low environmental load type, capable of reducing hexavalent chromium, having a small slump loss or heat of hydration, hardly neutralized and capable of suppressing autogenous shrinkage to a low level; a cement composition;"

The cement admixture comprises a slowly cooled slag powder which contains melilite as the main component and which has a carbon dioxide absorption of at least 2%, has a carbon dioxide absorption of at least 2 percent, has a loss on ignition of at most 5 percent, contains at least 0.5 percent of sulfur present as non-sulfuric acid form sulfur and/or has a concentration of non-sulfuric acid form sulfur to elute, of at least 100 milligram per litre, and further, preferably, has a degree of vitrification of at most 30%, a melilite lattice constant a of from 7.73 to 7.82 and/or a Blaine specific surface area of at least 4,000 centimeter square per gram."

The inventors were issued U.S. Patent No. 7,459,020 on Dec. 2.