A carbonation-resistant cementitious blend containing cement, an expandable agent present, a dispersion agent, a fluid loss additive, a defoamer, and an olive waste. Concrete samples made therefrom and methods of producing such concrete samples are also specified. The addition of olive waste provides enhanced durability (carbonation resistance) and maintains mechanical strength (e.g. compressive strength, tensile strength) after exposure to CO.sub.2 and/or brine. The resulting concretes are suitable cementing material for oil and gas wells as well as wellbores for geologic carbon sequestration.

The disclosure relates to a method for controlling carbonation synthesis of silicon and/or aluminium carbonate minerals, wherein the concentration of dissolved silicon and/or aluminium in a mix to be cured is adjusted to at least 1 mmol/1 before curing the mix with gas comprising carbon dioxide (CO.sub.2) having a partial pressure of CO.sub.2 of at least 0.15 bar. In some embodiments of the disclosure an alkaline substance is added to the raw material to provide the mix where the total concentration of dissolved silicon and/or aluminium of at least 1 mmol/1. The disclosure also relates to a product obtainable by the methods of the disclosure as well as to the use of the product as building material, preferably for producing concrete-like products, more preferably for elements, most preferably for pre-casted elements and to the use of the method in construction industry or for production of elements and/or pre-casted elements.