A hydratable cement composition which will bond to both asphalt and cementitious substrates is supplied for the repair of various surfaces. The composition comprises of a combination of Portland cement, calcium sulfoaluminate cement or calcium aluminosilicate, and an alkali metal salt activated pozzolonic powder, wherein the Portland cement content of the hydratable portion of the composition is greater than 20%. The composition is free from latex bonding agents and calcium aluminate. The composition is mixed with water to form a typical cement, mortar, or concrete consistency, placed and allowed to cure. The result is a self-adhering patch to damaged surfaces. The hydratable cement composition may also be used to fabricate items of original construction by casting into molds or forms.

A method of diffusing CO.sub.2 within a concrete mixture that includes mixing a non-recycled aggregate material with a CO.sub.2 gas in a pretreatment chamber of a concrete preparation system to form a CO.sub.2 adsorbed aggregate material, transferring the CO.sub.2 adsorbed aggregate material from the pretreatment chamber into a cement mixing chamber of the concrete preparation system, and mixing the CO.sub.2 adsorbed aggregate material with cement and water to form the concrete mixture, where mixing the CO.sub.2 adsorbed aggregate material with cement and water releases CO.sub.2 from the CO.sub.2 adsorbed aggregate material and diffuses CO.sub.2 into the concrete mixture to form a carbonated concrete mixture.

A method of diffusing CO.sub.2 within a concrete mixture that includes mixing a non-recycled aggregate material with a CO.sub.2 gas in a pretreatment chamber of a concrete preparation system to form a CO.sub.2 adsorbed aggregate material, transferring the CO.sub.2 adsorbed aggregate material from the pretreatment chamber into a cement mixing chamber of the concrete preparation system, and mixing the CO.sub.2 adsorbed aggregate material with cement and water to form the concrete mixture, where mixing the CO.sub.2 adsorbed aggregate material with cement and water releases CO.sub.2 from the CO.sub.2 adsorbed aggregate material and diffuses CO.sub.2 into the concrete mixture to form a carbonated concrete mixture.

A low strength backfill material having a 28 days compressive strength less than approximately 2.0 MPa is provided. The backfill is suitable for use in areas with dense underground utilities due to its high excavatability and good thermal conductivity. The backfill includes a cementitious binder of approximately 1 weight percent to approximately 10 weight percent and fine aggregates in an amount of approximately 40 to approximately 75 weight percent. Filler is provided at 20 microns to approximately 100 microns for high flowability. A density-controlling agent of 0.0001-5 weight percent is used such that the density of a cured backfill material is approximately 1600 kg/m.sup.3 to 2000 kg/m.sup.3. Thermally conductive particles having a size range of approximately 0.01 microns to 500 microns in an amount of approximately 0.1 to 10 weight percent are evenly dispersed throughout the backfill.

A low strength backfill material having a 28 days compressive strength less than approximately 2.0 MPa is provided. The backfill is suitable for use in areas with dense underground utilities due to its high excavatability and good thermal conductivity. The backfill includes a cementitious binder of approximately 1 weight percent to approximately 10 weight percent and fine aggregates in an amount of approximately 40 to approximately 75 weight percent. Filler is provided at 20 microns to approximately 100 microns for high flowability. A density-controlling agent of 0.0001-5 weight percent is used such that the density of a cured backfill material is approximately 1600 kg/m.sup.3 to 2000 kg/m.sup.3. Thermally conductive particles having a size range of approximately 0.01 microns to 500 microns in an amount of approximately 0.1 to 10 weight percent are evenly dispersed throughout the backfill.

An improved process for the preparation of aggregates for use with mixtures of various carbonatable substances, in particular mixtures comprising pulverised fuel ash and/or steel slag. The mixtures also comprise a carbonatable binder. The process comprises the steps of a. blending a combination of two carbonatable wastes, b. mixing the blended carbonatable waste with a carbonatable binder, c. mixing the blended carbonatable waste and binder with water, and d. carbonating the damp blended carbonatable waste in the presence of carbon dioxide.

An improved process for the preparation of aggregates for use with mixtures of various carbonatable substances, in particular mixtures comprising pulverised fuel ash and/or steel slag. The mixtures also comprise a carbonatable binder. The process comprises the steps of a. blending a combination of two carbonatable wastes, b. mixing the blended carbonatable waste with a carbonatable binder, c. mixing the blended carbonatable waste and binder with water, and d. carbonating the damp blended carbonatable waste in the presence of carbon dioxide.

The invention provides a whole-granulation steel slag pavement base course material for a heavy-load pavement, which is prepared by uniformly mixing dry materials with water. The dry materials include a binder and a steel slag aggregate. The percentages in total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%. The binder is prepared by mixing cement with steel slag micropowder according to a certain proportion, wherein the mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%. The water accounts for 5% to 6% of the total mass of the dry materials.

The invention provides a whole-granulation steel slag pavement base course material for a heavy-load pavement, which is prepared by uniformly mixing dry materials with water. The dry materials include a binder and a steel slag aggregate. The percentages in total mass of the binder and the steel slag aggregate are as follows: the binder is 3.4% to 5.0%, and the steel slag aggregate is 95.0% to 96.6%. The binder is prepared by mixing cement with steel slag micropowder according to a certain proportion, wherein the mass percentages of the cement and the steel slag micropowder are as follows: the cement is 70% to 90%, and the steel slag micropowder is 10% to 30%. The water accounts for 5% to 6% of the total mass of the dry materials.

The present invention relates to a novel cementitious product produced from steelworks slag additivation to obtain material having properties suitable for use in the partial or total clinker replacement for the production of different types of cement. The process, which is also object of this invention, aims to adapt the properties of steelworks slag, by means of thermochemical treatment, including and preferably, but not only, still in the liquid steelworks slag pot, taking advantage of the thermal input of steel processing, to form a greater amount of alite (essential compound to increase pozzolanicity), under controlled conditions. After additivation, preferably, but not exclusively, the additivated steelworks slag is subjected to quenching, comminution and concentration to stabilize the alite fraction, to release the present phases and to remove any excess contaminants, such as metallic iron.