It has been discovered that divalent metal oxides other than zinc oxide (ZnO) perform equivalently as activators in preparing asphalt polymer compositions. Typically, the crosslinker in these compositions is sulfur. Divalent metal oxides such as cupric oxide (CuO), magnesium oxide (MgO), and calcium oxide (CaO) provide alternative activators to give versatility to designing asphalt polymer compositions. In addition, some of these alternative divalent metal oxides are less expensive than the traditionally used ZnO.