A concrete composition that includes (i) a treated palm oil fuel ash, wherein the treated palm oil fuel ash is the only binder present, (ii) a fine aggregate, (iii) a coarse aggregate, and (iv) an alkali activator containing an aqueous solution of sodium hydroxide and sodium silicate. A cured concrete made from the concrete composition is also disclosed with advantageous compressive strength properties.

A concrete composition that includes (i) a treated palm oil fuel ash, wherein the treated palm oil fuel ash is the only binder present, (ii) a fine aggregate, (iii) a coarse aggregate, and (iv) an alkali activator containing an aqueous solution of sodium hydroxide and sodium silicate. A cured concrete made from the concrete composition is also disclosed with advantageous compressive strength properties.

A concrete composition that includes (i) a treated palm oil fuel ash, wherein the treated palm oil fuel ash is the only binder present, (ii) a fine aggregate, (iii) a coarse aggregate, and (iv) an alkali activator containing an aqueous solution of sodium hydroxide and sodium silicate. A cured concrete made from the concrete composition is also disclosed with advantageous compressive strength properties.

The present invention provides a calcium sulphate-based product (e.g. a wall board) comprising gypsum, a pozzolan source such as a clay additive, rice husk ash or diatomaceous earth and a metal salt additive. The product may be produced by drying an aqueous slurry comprising calcined gypsum, the pozzolan source and the metal salt additive. The clay additive may be a kaolinitic clay. The metal salt additive may be a magnesium salt e.g. magnesium nitrate, magnesium chloride or magnesium hydroxide.

The present invention provides a calcium sulphate-based product (e.g. a wall board) comprising gypsum, a pozzolan source such as a clay additive, rice husk ash or diatomaceous earth and a metal salt additive. The product may be produced by drying an aqueous slurry comprising calcined gypsum, the pozzolan source and the metal salt additive. The clay additive may be a kaolinitic clay. The metal salt additive may be a magnesium salt e.g. magnesium nitrate, magnesium chloride or magnesium hydroxide.

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.

Disclosed herein are methods, compositions, and systems for cementing. A method of cementing may comprise: providing a composite cement composition comprising a pozzolan, an accelerator, and water, wherein the accelerator comprises a chloride salt and a sulfate salt, wherein the composite cement composition is free of Portland cement or comprises Portland cement in an amount of about 50% by weight of cementitious components or less; and allowing the composite cement composition to set.

Disclosed herein are methods, compositions, and systems for cementing. A method of cementing may comprise: providing a composite cement composition comprising a pozzolan, an accelerator, and water, wherein the accelerator comprises a chloride salt and a sulfate salt, wherein the composite cement composition is free of Portland cement or comprises Portland cement in an amount of about 50% by weight of cementitious components or less; and allowing the composite cement composition to set.

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.