Corrosion mitigating cement compositions and methods for their preparation are provided. The cement compositions are derived from self-cementing pozzolans and chemical accelerators, retarders, mechanical strength modifiers and corrosion inhibitors. The corrosion inhibitors include boron compounds such as boric acid. Concretes prepared using the cement compositions possess low conductivity and a conductivity which further decreases with aging.

An accelerator powder for cement and also rapid-setting binder compositions which contain the accelerator powder and the use in mortar or concrete. The accelerator powder includes from 10 to 99.7% by weight of a water-insoluble mineral powder P and from 0.3 to 90% by weight of at least one compound V selected from the group consisting of alkali metal halides and alkaline earth metal halides, alkali metal nitrates and alkaline earth metal nitrates, alkali metal nitrites and alkaline earth metal nitrites, alkali metal thiocyanates and alkaline earth metal thiocyanates and hydroxyalkylamines or salts thereof, and mixtures thereof.

The present invention belongs to the technical field of oil well cement preparation, discloses a long-term high-temperature resistant and toughened well cementing and silica-cement composite material and a preparation method. A solid component comprises cement, alumina, superfine, high-purity silica sand, a suspending agent and a toughening material according to weight fractions; the toughening material comprises a latex fiber toughening agent and a nano graphene sheet; and a liquid component is composed of water, nano iron oxide and an oil well cement admixture according to weight fractions. Cement slurry with a ratio of the present invention can achieve compressive strength reaching up to 31 MPa after being cured under a high-temperature and high-pressure environment of 200° C. and 150 MPa for one year; and the gas permeability is controlled below 0.02 mD.

A geopolymer cementing fluid with controllable thickening time includes the following components in parts by weight: 100 parts of a cementitious material, 10 parts-30 parts of an activator, 0.2 parts-5 parts of a retarder, 0.4 parts-4 parts of an anti-settling agent, and 30 parts-70 parts of water. The geopolymer cementing fluid of the present invention has the advantages of controllable thickening time, excellent compressive strength, good settlement stability, good rheological properties, green and eco-friendly, and the like. The geopolymer cementing fluid can be better suited for the operations of oil and gas well cementing and ensure cementing safety.

Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries have, among other attributes, an extended thickening time, leading to improved retardation, flowability, and pumpability and may be used, for instance, in the oil and gas drilling industry. The cement slurry includes water, microfine cement material, and bisphenol-F diglycidyl ether resin.

A concrete composition for use in construction that is free of cement includes calcium sulfate hemihydrate (CSH), polypropylene (PP) fiber, sand, retarders, and superplasticizers. The retarders include poly condensed amino acid and calcium (Ca) salt. The superplasticizers include specially formulated polycarboxylate powder. Further, a method of using the concrete composition in one or more construction related activities (e.g., architectural applications) includes adding the concrete composition to water in a mixer, the concrete composition including CSH, PP fiber, sand, a retarder, and a superplasticizer; and blending the concrete composition with water in the mixer for a first predetermined amount of time. The method further includes mixing the concrete composition with water at a predetermined sheer in the mixer for a second predetermined amount of time. The method excludes the steps of steam curing, accelerated curing, and water curing that are used in conventional solutions.

Methods of cementing, cementing compositions made from the methods, and articles manufacturable by the cementing compositions are disclosed. The method can include mixing a cement composition and water to make a cement slurry and applying to the cement slurry an alternating magnetic field of from 25 mT to 60 mT at a frequency from 50 kHz to 200 kHz in order to set the cement slurry. The cement composition can have a cement and an amount of magnetic nanoparticles from 0.01 wt % to 10 wt % relative to the amount of cement (0.01% to 10% BWOC). The magnetic nanoparticles can have a mean particle size determined by Transmission Electron Microscopy (TEM) from 10 nm to 50 nm and a crystallite size determined by the Scherrer equation which is at least an 80% the mean particle size.

Disclosed are surface retarder composition and method for etching cementitious materials which achieve a desirable light acid etch look without using muriatic (hydrochloric) acid or sand blasting, removing the human health and environmental concerns. Formulations in accordance with embodiments disclosed herein are easier to remove from formwork or molds after demolding than conventional retarder paints. Surface retarders prevent the hydration of cement particles, which allows the uncured layer of paste next to the form to be removed such as by washing with water or other fluids, or by brushing, revealing aggregates. Also disclosed are molded cement and concrete materials or articles exhibiting such light etch.

The invention involves an exposed aggregate architectural coating to be applied to existing concrete structures. The invention includes a method of preparing and roughening an existing concrete structure surface, mixing the components of the exposed aggregate architectural coating, applying the coating to the existing concrete structure, spreading the coating to a thickness of one-fourth of an inch or thinner, using a trowel, gauge rake, or other method to smoothen the coating, allowing the coating to cure, applying a surface retarder once the exposed aggregate architectural coating has stiffened, allowing the surface retarder to cure for twenty-four hours, and washing the surface with a pressure-washer to remove the surface retarder, then acid-washing the surface to remove residue and create a desired texture. The resulting applied exposed aggregate architectural coating will have an exposed aggregate finish that is durable and suitable for high vehicular and pedestrian traffic areas.

A self-healing cement structure may be used for repairing defects. An example method of using such a cement structure includes: providing a cement structure in a wellbore, wherein the cement structure includes: a cement and elastomer particles at 1% by weight of the cement (bwoc) to 25% bwoc; applying heat to the cement structure to heat at least a portion of the elastomer particles above a melting point of an elastomer of the elastomer particles to cause at least a portion of the elastomer to melt and infiltrate into a defect in the cement structure; and allowing the elastomer to cool below the melting point of the elastomer to yield a repaired cement structure.