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.

It has been unexpectedly discovered that the addition of a natural or other pozzolan to non-spec fly ash significantly improves the properties of the non-spec fly ash to the extent it can be certified under ASTM C618 and AASHTO 295, as either a Class F or Class C fly 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 fly ash into certifiable Class F fly ash. Additionally, this disclosure provides a method of converting a Class C fly ash to a more valuable Class F fly ash. This discovery will extend diminishing Class F fly ash supplies and turn non-spec fly ash waste streams into valuable, certified fly ash pozzolan which will protect and enhance concrete, mortars and grouts.

The invention has as object a cementitious composition for forming mortars or concretes having reduced tendency to react with alkali, characterized in that it comprises as additive at least a compound of general formula:
[RN(CH.sub.2COOH).sub.n].sub.x(I)
R being an aliphatic or aromatic hydrocarbon chain, n=2 or 3 and x=1 or 2.

Chemical test methods for evaluating the alkali-silica reactivity (ASR) of an aggregate or an aggregate within a particular concrete job mix design by exposing the aggregate to a simplified system with the same or simulated long-term pore solution conditions is provided. ASR is a chemical reaction occurring between alkaline hydroxides within cement paste and certain types of amorphous silica found in mineral aggregates. Causing an accumulation of internal pressure within concrete structures due to the formation of a hygroscopic gel through the absorption of water, ASR leads to expansion and cracking of concrete. The present test method determines the reactivity index (RI) of a given aggregate, or an aggregate as it is to be used in a proposed concrete job mix design by determining the average concentrations of calcium, aluminum, and silicon across multiple tested samples, wherein the RI is the ratio of the concentrations of silicon to that of aluminum and calcium combined.

It has been unexpectedly discovered that the addition of a natural or other pozzolan to non-spec fly ash significantly improves the properties of the non-spec fly ash to the extent it can be certified under ASTM C618 and AASHTO 295, as either a Class F or Class C fly 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 fly ash into certifiable Class F fly ash. Additionally, this disclosure provides a method of converting a Class C fly ash to a more valuable Class F fly ash. This discovery will extend diminishing Class F fly ash supplies and turn non-spec fly ash waste streams into valuable, certified fly ash pozzolan which will protect and enhance concrete, mortars and grouts.

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.

Method and composition for mitigating alkali-silica reaction in concrete. According to one embodiment, the composition may comprise a lithium-stabilized colloidal silica or a powder that is obtained from a lithium-stabilized colloidal silica. The composition may be used as an admixture for a concrete mix that also comprises cement, one or more aggregates, water and, optionally, one or more supplementary cementitious materials.