A method of forming a cement composition. The method comprises adding to a hydraulic cementitious material a first strength-enhancing agent and a second strength-enhancing agent, wherein the content of total alkali (Na.sub.2O equivalent) in the hydraulic cementitious material is less than or equal to 0.7% by weight of the cementitious material. The first strength-enhancing agent includes a compound represented by structural formula (I):

##STR00001##

and
the second strength-enhancing agent is sodium sulfate, potassium sulfate, or a mixture thereof. The example values of the variables in structural formula (I) and the example amounts of the first and second strength-enhancing agents being added are defined herein.

A method of forming a cement composition. The method comprises adding to a hydraulic cementitious material a first strength-enhancing agent and a second strength-enhancing agent, wherein the content of total alkali (Na.sub.2O equivalent) in the hydraulic cementitious material is less than or equal to 0.7% by weight of the cementitious material. The first strength-enhancing agent includes a compound represented by structural formula (I):

##STR00001##

and
the second strength-enhancing agent is sodium sulfate, potassium sulfate, or a mixture thereof. The example values of the variables in structural formula (I) and the example amounts of the first and second strength-enhancing agents being added are defined herein.

A modified gypsum set accelerator and a method of preparing the same is provided, which includes dry loose finely ground particles of a mixture of ground dry calcium sulfate dihydrate and a grinding aid selected from one or more of beta-naphthalene sulfonate formaldehyde condensate, trimetaphosphate phosphate salt, tripolyphosphate salt, tetra-pyrophosphate salt, and pregelatinized starch.

The present invention concerns an improved method of grinding or milling fresh feed (i.e. crushed yet not milled clinker (with or without additions)), using two different grinding agent systems added at specific locations of the cement grinding mill, preferably at two different locations of a cement ball mill, depending on the particle size or fineness of the material to be ground, to reduce the energy needed to achieve a targeted cement fineness or increase the fineness of the cement at constant energy consumption.

The present invention concerns an improved method of grinding or milling fresh feed (i.e. crushed yet not milled clinker (with or without additions)), using two different grinding agent systems added at specific locations of the cement grinding mill, preferably at two different locations of a cement ball mill, depending on the particle size or fineness of the material to be ground, to reduce the energy needed to achieve a targeted cement fineness or increase the fineness of the cement at constant energy consumption.

The use of a grinding additive during the dry grinding of clay mineral, wherein the grinding additive is selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, or mixtures thereof. Construction materials also include a ground clay mineral including the additives and the use of the ground clay mineral.

The use of a grinding additive during the dry grinding of clay mineral, wherein the grinding additive is selected from the group consisting of alkanolamines, glycols, glycerol, sugars, sugar acids, carboxylic acids or their salts, superplasticizers, superabsorbent polymers, or mixtures thereof. Construction materials also include a ground clay mineral including the additives and the use of the ground clay mineral.

Disclosed is a method for grinding a hydraulic binder, including: a) introducing:a hydraulic binder, anda composition B including at least one grinding aid B into the first chamber of a horizontal grinder including several chambers, including a first chamber and a last chamber, each chamber being separated from the adjacent chamber by a diaphragm, whereby a composition ? including the hydraulic binder and composition B is obtained in the first chamber; and b) grinding composition ? in the horizontal grinder, whereby composition ? moves from the first chamber to the last chamber and a ground composition C is obtained at the outlet of the last chamber. At the grinding step, the method includes introducing into the last chamber a composition A including at least one grinding aid A including an aminoalcohol. Also disclosed is a corresponding grinding unit.

Disclosed is a method for grinding a hydraulic binder, including: a) introducing:a hydraulic binder, anda composition B including at least one grinding aid B into the first chamber of a horizontal grinder including several chambers, including a first chamber and a last chamber, each chamber being separated from the adjacent chamber by a diaphragm, whereby a composition ? including the hydraulic binder and composition B is obtained in the first chamber; and b) grinding composition ? in the horizontal grinder, whereby composition ? moves from the first chamber to the last chamber and a ground composition C is obtained at the outlet of the last chamber. At the grinding step, the method includes introducing into the last chamber a composition A including at least one grinding aid A including an aminoalcohol. Also disclosed is a corresponding grinding unit.

It is intended to provide an industrially advantageous method for obtaining zirconium tungsten phosphate that is useful as a negative thermal expansion material and exhibits a single phase in X-ray diffraction. The method for producing zirconium tungsten phosphate according to the present invention comprises using a mixture of a tungsten compound and an amorphous compound containing phosphorus and zirconium as a reaction precursor and calcining the reaction precursor. Preferably, the reaction precursor has an infrared absorption peak at least at 950 to 1150 cm.sup.1, and the maximum value of the infrared absorption peak in this range appears at 1030 (20) cm.sup.1.