Set retarded cement compositions for cementing across a zone or zones in a well having enhanced compressive strength and rapid gel strength development after placement. The cement compositions are comprised of hydraulic cement, sufficient fresh water to form a pumpable slurry, a set retarder comprising a copolymer of 2-acrylamido, 2-methylpropane sulfonic acid and acrylic acid having an average molecular weight below about 5000 and any other desired additives. Methods of cementing utilizing the cement composition also are provided.

Set retarded cement compositions and methods for well cementing

The invention generally provides gypsum-containing slurries including stucco, naphthalenesulfonate dispersant, and pregelatinized starch. The naphthalenesulfonate dispersant is present in an amount of about 0.1% - 3.0% by weight based on the weight of dry stucco. The pregelatinized starch is present in an amount of at least about 0.5% by weight up to about 10% by weight of pregelatinized starch by weight based on the weight of dry stucco in the formulation. Other slurry additives can include trimetaphosphate salts, accelerators, binders, paper fiber, glass fiber, and other known ingredients. The invention also comprises the gypsum-containing products made with such slurries, for example, gypsum wallboard, and a method of making gypsum wallboard.

High starch light weight gypsum wallboard

The invention provides a lightweight composite gypsum board including a foamed low density set gypsum core, a top non-foamed (or reduced foamed) bonding high density layer and a bottom non-foamed (or reduced-foamed) bonding high density layer, a top cover sheet bonded to the foamed low density set gypsum core by the top non-foamed (or reduced-foamed) bonding high density layer, and a bottom cover sheet bonded to the foamed low density set gypsum core by the bottom non-foamed (or reduced-foamed) bonding high density layer. The foamed gypsum core and the non-foamed (or reduced-foamed) bonding layers are made from a gypsum slurry including stucco, pregelatinized starch, and preferably a naphthalenesulfonate dispersant and sodium trimetaphosphate. The foamed gypsum core has a density of less than about 30 pcf using soap foam in the gypsum-containing slurry. The gypsum board is lightweight with high strength. A method of making the gypsum board is also provided.

Composite light weight gypsum wallboard

An additive for cementitious compositions is provided comprised of a cellulose ether, a starch ether and a polyacrylamide. This additive, when added to cementitious compositions, improves the workability of the resulting cementitious composition when used as a tile grout or mortar.

Additive for cementitious compositions

Additive combination for improving the processing properties of water-containing mixtures of building materials. The invention relates to an additive combination for water-containing mixtures of building materials, comprising a) at least 65% by weight, preferably 65 to 98% by weight, of a water-soluble cellulose ether or a derivative thereof, b) from 1 to 15% by weight of polyacrylamide, c) from 1 to 20% by weight of an alkali metal salt or ammonium salt of a crosslinked, ungrafted or starch-grafted polyacrylate, d) from 0 to 20% by weight of a starch ether and e) from 0 to 15% by weight of a water-soluble alkali metal salt, alkaline earth metal salt or ammonium salt of an arylsulfonic acid-formaldehyde condensation product or of a sulfonic acid-modified product of the polycondensation of melamine and formaldehyde, and to building material mixtures which contain these additive combinations. The additive combinations according to the invention are suitable for all water-containing mixtures of building materials, in particular for plasters, mortars, adhesive cements and fillers.

Additive combination for improving the processing properties of water-containing mixtures of building materials

A method for the production of a water-permeable porous concrete comprising the steps of mixing a concrete mixture containing A. GRANULAR MINERAL AGGREGATES OF A UNIFORM GRAIN FRACTION IN THE RANGE OF 3 TO 30 MM WITH A TOLERANCE RANGE OF 4 TO 15 MM, B. HYDRAULIC CEMENT IN THE PRESCRIBED AMOUNT ACCORDING TO THE JOB SPECIFICATIONS, C. A MACROMOLECULAR WATER-SOLUBLE COMPOUND IN AN AMOUNT OF FROM 0.05 TO 2 PERCENT BY WEIGHT BASED ON THE CEMENT, SAID COMPOUND BEING SELECTED FROM THE GROUP CONSISTING OF PLANT GUMS, STARCH PRODUCTS, CELLULOSE ETHERS, AND SYNTHETIC POLYMERS. D. WATER IN SUCH AN AMOUNT THAT THE WATER-CEMENT RATIO IS BETWEEN 0.32 AND 0.48 WHEREBY SAID CONCRETE MIXTURE IS SPRAYABLE, AND PLACING SAID CONCRETE MIXTURE BY SPRAYING, AS WELL AS THE HARDENED CONCRETE MIXTURE.

E Grunberger

Papers

Method for the production of water-permeable porous concrete