The present invention provides a method and admixture composition for making hydratable cementitious compositions, ones believed to have much less stickiness in comparison to prior methods. Decreased stickiness in concrete mixes means that they are easier to pour or to cast into place, as well as easier to finish. Dispersant carboxylate polymers of the invention having this ability are characterized by possessing two different, relatively short chain lengths of polyalkyleneoxide units and low weight-average molecular weights.

The purpose of the present invention is to provide a preceding material for pumping, a feeding of a very small amount thereof being capable of extending the pumping distance. The preceding material for pumping includes an added cellulose nanofiber and having calcium carbonate as a main component. The present invention enables a thin lubricant layer of a uniform thickness to be formed inside a pipe even when the pipe has a slightly roughened inner surface due to, for example, residues of solidified cement paste or the like, allowing the pumping distance to be extended. Thus, the present invention is suitable, for example, for casting ready-mixed concrete at various construction sites.

The present invention provides a method and admixture composition for making hydratable cementitious compositions, ones believed to have much less stickiness in comparison to prior methods. Decreased stickiness in concrete mixes means that they are easier to pour or to cast into place, as well as easier to finish. Dispersant carboxylate polymers of the invention having this ability are characterized by possessing two different, relatively short chain lengths of polyalkyleneoxide units and low weight-average molecular weights.

A method of pressure-pumping a ready-mixed concrete includes pouring a preceding material for pumping into a piping, then, pouring the ready-mixed concrete into the piping, and pressure-pumping the preceding material and the ready-mixed concrete, so that a lubricant layer formed of the preceding material is formed on an inner surface of the piping to thereby pressure-pump the ready-mixed concrete inside the lubricant layer made of the preceding material. The preceding material includes calcium carbonate as a main material, to which cellulose nanofibers and erythorobic acid are added, and an amount of the cellulose nanofibers is 0.005 wt % or more.

Disclosed is a method for producing a carbide derived carbon layer with a dimple pattern. The method includes forming a dimple pattern on the surface of a carbide ceramic material and forming a carbide derived carbon layer thereon. Also disclosed is a carbide derived carbon layer with a dimple pattern produced by the method. The carbide derived carbon layer with dimple pattern has high wear resistance, good adhesion to a machine part, and excellent frictional characteristics. The carbide derived carbon layer can be applied to various fields, such as coating of carbide coated and carbide materials. Particularly, the carbide derived carbon layer is suitable for coating of machine parts (e.g., sliding parts, mechanical seals, piston rings, and compressor vanes) where excellent mechanical properties are needed.

A method of pressure-pumping a ready-mixed concrete includes pouring a preceding material for pumping into a piping, then, pouring the ready-mixed concrete into the piping, and pressure-pumping the preceding material and the ready-mixed concrete, so that a lubricant layer formed of the preceding material is formed on an inner surface of the piping to thereby pressure-pump the ready-mixed concrete inside the lubricant layer made of the preceding material. The preceding material includes calcium carbonate as a main material, to which cellulose nanofibers and erythorobic acid are added, and an amount of the cellulose nanofibers is 0.005 wt % or more.