Presented and described is a method for manufacturing concrete elements having at least one concrete layer, wherein concrete for at least one element is introduced into a mould, the concrete is compacted by vibration and/or by tamping and subsequently cures, wherein to the concrete layer, prior to compaction, at least one portion of a granular material is applied by means of an application device, where the concrete introduced into the mould has a water/binder (w/b) ratio of 0.30 to 0.50 prior to curing and where as granular material a material is used comprising (a) a scatter component having an average particle diameter of 0.1 to 5 mm in an amount of 65 to 95 wt % and (b) binder in an amount of 5 to 35 wt %, based in each case on the overall composition of the granular material.

Well-cementing compositions for use in high-pressure, high-temperature (HPHT) wells are often densified, and contain weighting agents such as hematite, ilmenite, barite and hausmannite. The weighting agents are usually finely divided to help keep them suspended in the cement slurry. At high temperatures, finely divided weighting agents based on metal oxides react with the calcium-silicate-hydrate binder in set Portland cement, leading to cement deterioration. Finely divided weighting agents based on metal sulfates are inert with respect to calcium silicate hydrate; consequently, set-cement stability is preserved.

Well-cementing compositions for use in high-pressure, high-temperature (HPHT) wells are often densified, and contain weighting agents such as hematite, ilmenite, barite and hausmannite. The weighting agents are usually finely divided to help keep them suspended in the cement slurry. At high temperatures, finely divided weighting agents based on metal oxides react with the calcium-silicate-hydrate binder in set Portland cement, leading to cement deterioration. Finely divided weighting agents based on metal sulfates are inert with respect to calcium silicate hydrate; consequently, set-cement stability is preserved.

A downhole treatment composition comprises a rare earth-containing compound comprising one or more of the following: scandium; yttrium; lanthanum; cerium; praseodymium; neodymium; promethium; samarium; lutetium; europium; gadolinium; terbium; dysprosium; holmium; erbium; thulium; or ytterbium, wherein the downhole treatment composition is a cement slurry, a drilling fluid, or a spacer fluid. Also disclosed are methods of cementing a wellbore, methods of displacing a first fluid, and methods of drilling a wellbore in a subterranean formation using the cement slurry, the spacer fluid, or the drilling fluid.

A downhole treatment composition comprises a rare earth-containing compound comprising one or more of the following: scandium; yttrium; lanthanum; cerium; praseodymium; neodymium; promethium; samarium; lutetium; europium; gadolinium; terbium; dysprosium; holmium; erbium; thulium; or ytterbium, wherein the downhole treatment composition is a cement slurry, a drilling fluid, or a spacer fluid. Also disclosed are methods of cementing a wellbore, methods of displacing a first fluid, and methods of drilling a wellbore in a subterranean formation using the cement slurry, the spacer fluid, or the drilling fluid.

Methods including providing a wellbore in a subterranean formation; providing a proposed cement slurry; calculating a fluid migration threshold; manipulating the proposed cement slurry based on the fluid migration threshold so as to produce a fluid migration resistant cement slurry; introducing the fluid migration resistant cement slurry into the wellbore in the subterranean formation; and curing the fluid migration resistant cement slurry in the wellbore in the subterranean formation.

Methods including providing a wellbore in a subterranean formation; providing a proposed cement slurry; calculating a fluid migration threshold; manipulating the proposed cement slurry based on the fluid migration threshold so as to produce a fluid migration resistant cement slurry; introducing the fluid migration resistant cement slurry into the wellbore in the subterranean formation; and curing the fluid migration resistant cement slurry in the wellbore in the subterranean formation.

The present invention describes a hardening accelerating admixture for hydraulic binders, the accelerator being based on transition metal silicate hydrates having the general formula: aMe.sub.xO.sub.y bMO cAl.sub.2O.sub.3 SiO.sub.2 dH.sub.2O 1) whereMe represents a transition metal whose molar coefficient a is in a range between 0.001 and 2, preferably between 0.01 and 1; M represents an alkaline earth metal whose molar coefficient b is in a range between 0 and 2, preferably between 0.3 and 1.6; The molar coefficient c for Al.sub.2O.sub.3 is in a range between 0 and 2, preferably between 0.1 and 1; H.sub.2O represents the hydration water of the silicate hydrate whose molar coefficient d can vary within a wide range between 0.5 and 20; x and y can both be equal to 1 or different, depending on the valence of the transition metal, given that the valence of the oxygen atom in the metal oxide is equal to 2.

The present invention describes a hardening accelerating admixture for hydraulic binders, the accelerator being based on transition metal silicate hydrates having the general formula: aMe.sub.xO.sub.y bMO cAl.sub.2O.sub.3 SiO.sub.2 dH.sub.2O 1) whereMe represents a transition metal whose molar coefficient a is in a range between 0.001 and 2, preferably between 0.01 and 1; M represents an alkaline earth metal whose molar coefficient b is in a range between 0 and 2, preferably between 0.3 and 1.6; The molar coefficient c for Al.sub.2O.sub.3 is in a range between 0 and 2, preferably between 0.1 and 1; H.sub.2O represents the hydration water of the silicate hydrate whose molar coefficient d can vary within a wide range between 0.5 and 20; x and y can both be equal to 1 or different, depending on the valence of the transition metal, given that the valence of the oxygen atom in the metal oxide is equal to 2.

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.