Method of preventing the deterioration of a hardened cement-based mass

In a method of preventing the deterioration of a hardened cement-based mass having a corresive metallic material embedded therein, or containing an aggregate which is reactive with an alkaline substance, the improvement which comprises:

• impregnating said mass with a solution prepared by using an aliphatic alcohol having 1 to 3 carbon atoms, and containing 1 to 50% by weight of a dissolved nitrite of an alkali metal or alkaline earth metal, and 0.01 to 20% by weight of a dissolved organic silicon compound represented by geneal formula II, or a dissolved polymer of said compound:
• R.sup.1 - Si(OR.sup.2).sub.3 (III)
• wherein R.sup.1 represents a monovalent hydrocarbon group having 1 to 12 carbon atoms, and R.sup.2 represents a monovalent hydrocarbon group having 1 to 8 carbon atoms;
• and
• allowing said mass to dry in the air.

In a method of preventing the deterioration of a hardened cement-based mass having a corrosive metallic matrial embedded therein, or containing an aggregate which is reactive with an alkaline substance, the improvement which comprises:

• coating the surface of said mass with an unsolidified cement paste, mortar or concrete containing 1 to 25% by weight of a nitrite of an alkali metal or alkaline earth metal and 0.01 to 20% by weight of an organic silicon compound represented by general formula I, or a polymer of said compound, based on the weight of the cement which said cement paste, mortar or concrete contains:
• ##STR3## wherein M represents a sodium or potassium atom, and R represents a monovalent hydrocarbon group having 1 to 12 carbon atoms;
• and
• allowing said cement paste, mortar or concrete to harden in the air.