Patent ID: 7087110

Claim:
A method for reducing hexavalent chromium in cementitious compositions, comprising: grinding cement clinker to produce Portland cement; introducing to said cement clinker, before or during the grinding thereof, a liquid additive composition comprising stannous chloride present in an amount not less than 20 percent and not greater 95 percent based on total weight of the liquid additive composition, said liquid additive composition further comprising a co-additive selected from the group consisting of an antioxidant and an oxygen scavenger, or mixtures thereof said co-additive being present within said liquid additive composition in a stannous chloride:co-additive ratio of not less than 99.5:0.5 and not greater than 20:80; said stannous chloride being added to said cement clinker at a rate no less than 0.001 and no greater than 5.0 percent based on weight of said cement clinker.