Abstract: A method is disclosed for rapidly carbonating large cement structures, by forming and hardening cement in a mold under high carbon dioxide density, such as supercritical or near-supercritical conditions. The method is more reliable, efficient, and effective than are post-molding treatments with high-pressure CO2. Cements molded in the presence of high-pressure CO2 are significantly denser than otherwise comparable cements having no CO2 treatment, and are also significantly denser than otherwise comparable cements treated with CO2 after hardening. Bulk carbonation of cementitious materials produces several beneficial effects, including reducing permeability of the cement, increasing its compressive strength, and reducing its pH. These effects are produced rapidly, and extend throughout the bulk of the cement—they are not limited to a surface layer, as are prior methods of post-hardening CO2 treatment.

Abstract: A method is disclosed for rapidly carbonating large cement structures, by forming and hardening cement in a mold under high carbon dioxide density, such as supercritical or near-supercritical conditions. The method is more reliable, efficient, and effective than are post-molding treatments with high-pressure CO2. Cements molded in the presence of high-pressure CO2 are significantly denser than otherwise comparable cements having no CO2 treatment, and are also significantly denser than otherwise comparable cements treated with CO2 after hardening. Bulk carbonation of cementitious materials produces several beneficial effects, including reducing permeability of the cement, increasing its compressive strength, and reducing its pH. These effects are produced rapidly, and extend throughout the bulk of the cement—they are not limited to a surface layer, as are prior methods of post-hardening CO2 treatment.

Abstract: A method is disclosed for rapidly carbonating large cement structures, by forming and hardening cement in a mold under high carbon dioxide density, such as supercritical or near-supercritical conditions. The method is more reliable, efficient, and effective than are post-molding treatments with high-pressure CO2. Cements molded in the presence of high-pressure CO2 are significantly denser than otherwise comparable cements having no CO2 treatment, and are also significantly denser than otherwise comparable cements treated with CO2 after hardening. Bulk carbonation of cementitious materials produces several beneficial effects, including reducing permeability of the cement, increasing its compressive strength, and reducing its pH. These effects are produced rapidly, and extend throughout the bulk of the cement—they are not limited to a surface layer, as are prior methods of post-hardening CO2 treatment.

Abstract: A catalyst useful in the aromatization of light paraffins and other hydrocarbons conversion reactions, formed by preparing an intimate mechanical mixture of a gallium-containing species, such as Ga.sub.2 O.sub.3, with a zeolite having a pore mouth comprising 10 oxygen atoms, such as ZSM-5, preferably followed by treatment with a reducing agent, such as hydrogen.