Systems and methods for treating concrete, which includes the steps of wetting a surface of concrete with colloidal silica, allowing time for the colloidal silica to penetrate the concrete surface, and cutting the surface of the concrete with a bladed or segmented tool wherein the longitudinal blade or edge portion is positioned approximately at an angle between 30 degrees and 90 degrees relative to the surface of the concrete.

Systems and methods for treating concrete, which includes the steps of wetting a surface of concrete with colloidal silica, allowing time for the colloidal silica to penetrate the concrete surface, and cutting the surface of the concrete with a bladed or segmented tool wherein the longitudinal blade or edge portion is positioned approximately at an angle between 30 degrees and 90 degrees relative to the surface of the concrete.

Described is an aqueous composition for repairing and/or sealing of hardened concrete structures, the aqueous composition including colloidal silica and polycarboxylate ether. Also described is a method for repairing and/or sealing a hardened concrete structure, including a step of applying an aqueous composition including colloidal silica and polycarboxylate ether to a hardened concrete structure or a part thereof.

Described is an aqueous composition for repairing and/or sealing of hardened concrete structures, the aqueous composition including colloidal silica and polycarboxylate ether. Also described is a method for repairing and/or sealing a hardened concrete structure, including a step of applying an aqueous composition including colloidal silica and polycarboxylate ether to a hardened concrete structure or a part thereof.

A process for treating a substrate made of stone material, preferably in the form of slabs, is provided which process improves the mechanical, thermal and catalytic properties of the substrate. The process includes applying a protective coating to the outer surface of the substrate made of stone material and, to improve adhesion of the protective coating to the outer surface of the substrate, preliminarily subjecting the substrate to one or more pre-treatment steps that eliminate or reduce the presence of pollutants and porosity on the surface of the substrate. The pre-treatment of the substrate made of stone material comprises at least one step of treatment under vacuum conditions inside an autoclave, preferably under pressure conditions lower than 10.sup.2 mbar. Then, after having brought the substrate back to ambient pressure, it is possible to apply and effectively adhere the protective coating to the surface of the stone material.

A process for treating a substrate made of stone material, preferably in the form of slabs, is provided which process improves the mechanical, thermal and catalytic properties of the substrate. The process includes applying a protective coating to the outer surface of the substrate made of stone material and, to improve adhesion of the protective coating to the outer surface of the substrate, preliminarily subjecting the substrate to one or more pre-treatment steps that eliminate or reduce the presence of pollutants and porosity on the surface of the substrate. The pre-treatment of the substrate made of stone material comprises at least one step of treatment under vacuum conditions inside an autoclave, preferably under pressure conditions lower than 10.sup.2 mbar. Then, after having brought the substrate back to ambient pressure, it is possible to apply and effectively adhere the protective coating to the surface of the stone material.

A heat insulating material includes an aerogel that has macro-pores and meso-pores. A method for manufacturing a heat insulating material, including: a sol preparation step of adding a gelling agent into sodium silicate such that a molar ratio of the gelling agent relative to NaO.sub.2 is 0.1 to 0.75, and adjusting a sol into which macro-pores are introduced by leaving unreacted Na and non-cross-linked oxygen in a siloxane skeleton; an impregnating and gelling step of impregnating a nonwoven fabric fiber structure with the sol to form a composite of hydrogel-nonwoven fabric fiber; a hydrophobizating step of mixing the formed composite of hydrogel-nonwoven fabric fiber with a silylating agent to modify a surface thereof; and a drying step of removing a liquid contained in the surface modified composite of hydrogel-nonwoven fabric fiber by drying under a temperature and pressure lower than respective critical values.

Luminescent concrete compositions containing cement, fine aggregates such as sand, and a phosphor such as strontium aluminate. Glow-in-the-dark concrete products made therefrom and methods of producing such concrete products are also specified. The glow-in-the-dark concrete products demonstrate good mechanical strength (e.g. compressive strength) and skid resistance. The addition of phosphorescent strontium aluminate provides luminance that persists for up to 10 hours to the concrete products.

Luminescent concrete compositions containing cement, fine aggregates such as sand, and a phosphor such as strontium aluminate. Glow-in-the-dark concrete products made therefrom and methods of producing such concrete products are also specified. The glow-in-the-dark concrete products demonstrate good mechanical strength (e.g. compressive strength) and skid resistance. The addition of phosphorescent strontium aluminate provides luminance that persists for up to 10 hours to the concrete products.

A coating composition is described, for use in the foundry, in particular comprising particulate, amorphous silicon dioxide (SiO.sub.2) and an aqueous phase having a pH of at most 5, and also coated, waterglass-bound foundry molding elements, especially coated, waterglass-bound foundry molds and foundry cores, which each comprise a coating composition of the invention. Further described is the use of a coating composition of the invention for producing a coating on a waterglass-bound foundry molding element and a method for producing a waterglass-bound foundry molding element (mold or core) coated with a water-containing refractory coating. Likewise specified is a kit whose contents include a coating composition of the invention.