Cement composition for alkali-reactive aggregate and for sulphate resistance

A cementitious composition for use with alkali-silica reactive aggregate to produce a concrete exhibiting acceptable low expansion or for increasing sulphate resistance of a concrete comprising:

• a) a cement composition comprising in weight %, to a total of 100%
• i) 45 to 87 of a hydraulic cement,
• ii) 10 to 45% of a Class C fly ash having a calcium oxide analytical content greater than 15%, by weight of said fly ash, and
• iii) 3 to 10% of silica fume, and
• b) water.

A solidifiable concrete formulation comprising:

• A) alkali-silica reactive aggregate, and
• B) a cement binder in an amount to bind said aggregate in a solidifiable mass, said cement binder comprising:
• a) a cement composition comprising in weight % to a total of 100%:
• i) 45 to 87 of hydraulic cement;
• ii) 10 to 45% of a Class C fly ash having a calcium oxide analytical content greater than 15%, by weight, of said fly ash, and
• iii) 3 to 7% of silica fume, and
• b) water;
• said concrete formulation in a solidified state, exhibiting low expansion.

A solidified concrete comprising:

• an alkali-silica reactive aggregate bound in a solid mass with a solidified binder derived from a cement binder comprising:
• a) a cement composition comprising in weight % to a total of 100%;
• i) 45 to 87 of hydraulic cement;
• ii) 10 to 45% of a Class C fly ash having a calcium oxide content greater than 15%, by weight, of said fly ash, and
• iii) 3 to 10% of silica fume, and
• b) water.

A method of inhibiting expansion of a concrete derived from alkali-silica reactive aggregate comprising:

• binding said alkali-silica reactive aggregate in a solidifiable mass with a binder comprising:
• a) a cement composition comprising in weight % to a total of 100%;
• i) 45 to 87 of hydraulic cement;
• ii) 10 to 45% of a Class C fly ash having a calcium oxide content greater than 15%, by weight, of said fly ash, and
• iii) 3 to 10% of silica fume, and
• b) water.

In a concrete formation comprising a mineral aggregate bound in a solid mass with a solidified binder, said concrete formation being disposed in an environment in which it is exposed to attack by sulphates, the improvement wherein said binder is derived from a cement binder comprising

• a) a cement composition comprising in weight % to a total of 100%
• i) 45 to 87 of hydraulic cement;
• ii) 10 to 45% of a Class C fly ash having a calcium oxide content greater than 15%, by weight, of said fly ash, and
• iii) 3 to 10% of silica fume, and
• b) water.

A method of rendering a concrete resistant to sulphate attack comprising:

• forming a solidifiable concrete formulation comprising:
• A) mineral aggregate, and
• B) a cement binder in an amount to bind said aggregate in a solidifiable mass, said cement binder comprising:
• a) a cement composition comprising in weight % to a total of 100%;
• i) 45 to 87 of hydraulic cement;
• ii) 10 to 45% of a Class C fly ash having a calcium oxide analytical content greater than 15%, by weight, of said fly ash, and
• iii) 3 to 10% of silica fume, and
• b) water;
• solidifying said concrete formulation to a solidified state having a resistance to sulphate by ASTM C 1012, of less than 0.1% at 1 year.