An additive formulation for reduction or prevention of microbially induced corrosion in concrete, cementitious material (such as mortar or grout), or a combination thereof. The additive formulation comprises a Quat Silane and a fungicide, wherein the ratio of the Quat Silane to the fungicide in the formulation is in a range of about 10:1 to about 1:10, preferably in a range of about 5:1 to about 1:5.

A method of treating the surface of a metal casing used in a wellbore by conditioning the metal casing in a conditioning fluid to form a conditioned metal casing, contacting the conditioned metal casing with a treatment fluid to form a treated metal casing, and drying the treated metal casing. A method of increasing the bond strength between cement and a metal casing surface treated with a reactive organic compound by curing the treated metal casing with a cement slurry.

It has been unexpectedly discovered that the addition of a natural or other pozzolan to non-spec coal ash significantly improves the properties of the non-spec coal ash to the extent it can be certified under ASTM C618 and AASHTO 295, as either a Class F or Class C coal ash. The natural pozzolan may be a volcanic ejecta, such as pumice or perlite. Other pozzolans may also be used for this beneficiation process. Many pozzolans are experimentally tested and may be used to beneficiate non-spec coal ash into certifiable Class F coal ash. Additionally, this disclosure provides a method of converting a Class C coal ash to a more valuable Class F coal ash. This discovery will extend diminishing Class F coal ash supplies and turn non-spec coal ash waste streams into valuable, certified coal ash pozzolan which will protect and enhance concrete, mortars and grouts.

[A] curable mixture configured to set in the presence of water, wherein the mixture comprises magnesium oxide, a primary cementitious component and at least one accelerant and at least one second accelerant, the at least one second accelerant is different than the at least one first accelerant, wherein a proportion by weight of the at least one second accelerant is equal to or less than 2% of a proportion of magnesium oxide by weight of the mixture. A proportion by weight of the primary cementitious component is 80% to 120% of a proportion of magnesium oxide by weight.