A building product is made from granular material and a binder that includes steel slag. A process for making the building product includes combining the granular material and the binder and then curing the combined granular material and binder with carbon dioxide. A building material includes a mixture of steel slag and a silica-rich material. The steel slag and silica-rich material is treated by heating. The silica-rich material may be waste glass and/or fly ash. A process for making the building material includes mixing the steel slag and silica-rich material and further heating the mixture.