Decorative panel, in particular a floor panel, ceiling panel or wall panel, including a core layer having an upper side and a lower side, a decorative top layer connected to said upper side of the core layer, a first panel side edge including a first coupling profile, and a second panel side edge including a second coupling profile designed to interconnect with a first coupling profile of a second, identical panel, both in horizontal direction and in vertical direction. The core layer includes a layer of foam concrete which is constituted by a matrix of concrete material in which air pockets in the form of cells are present.

In some aspects, the present disclosure pertains to methods for the electrochemical production of calcium silicate compounds in an electrochemical cell that comprises (a) a Ca-based electrode that comprises calcium metal or an inorganic calcium material, (b) an SiO.sub.x-based electrode that comprises a SiO.sub.x material, where x ranges from 1 to 2, and (c) a liquid electrolyte disposed between the Ca-based electrode and the SiO.sub.x-based electrode. In these methods, the electrochemical cell is operated under conditions such that calcium cations are produced at the Ca-based electrode and one or more calcium silicate (Ca—Si-oxide) compounds are produced at the SiO.sub.x-based electrode. In other aspects, the present disclosure pertains to systems for the electrochemical production of calcium silicate compounds.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

A method of curing a low Ca/Mg cement composition is described that includes providing a predetermined quantity of the low Ca/Mg cement composition in uncured form; and reacting the uncured low Ca/Mg cement composition with a reagent chemical for a time sufficient to cure said cementitious material, wherein said reagent chemical is a compound synthesized from CO.sub.2 and comprises dicarboxylic acids, tricarboxylic acids, or alpha-hydroxycarboxylic acids.

A method for producing a carbonate-containing species-rich, nitrogen-containing species-free solution from a urea-rich solution is proposed. The method comprising the steps of: providing a first reservoir comprising a first mixture including urea and a catalyser comprising an enzymatic catalyser and/or a microorganism; allowing an enzymatic reaction catalysed by the catalyser to decompose urea, thereby obtaining a second mixture comprising nitrogen-containing species and carbonate-containing species; converting at least some of the nitrogen-containing species into gaseous nitrogen-containing species to obtain a third mixture comprising the gaseous nitrogen-containing species and the carbonate-containing species; filtering the third mixture by a gas- permeable filter, thereby separating at least some of the gaseous nitrogen-containing species from the carbonate-containing species while keeping the catalyser away from the gas-permeable filter; and collecting the so-obtained carbonate-containing species-rich, nitrogen-containing species-free solution.

Disclosed is a CO.sub.2 solidified fiber cement board and its preparation method. The matrix composition of the fiber cement board prepared in this disclosure is calcium carbonate, which has high compactness, and the crystal form of calcium carbonate is adjusted by adding shell powder to improve the toughness of the matrix, so that the fiber cement board has excellent mechanics and durability performance. In addition, the preparation process does not require high temperature maintenance, and has the characteristics of normal temperature preparation, which creates conditions for the introduction of organic synthetic fibers, so that the organic synthetic fibers can further improve the brittleness of cement fiberboard. While reducing energy consumption, the preparation process can also effectively solve the problem that excessive pressure is easily generated in the fiberboard under high temperature conditions in the existing high-temperature and high-pressure curing process.

A method of curing a low Ca/Mg cement composition is described that includes providing a predetermined quantity of the low Ca/Mg cement composition in uncured form; and reacting the uncured low Ca/Mg cement composition with a reagent chemical for a time sufficient to cure said cementitious material, wherein said reagent chemical is a compound synthesized from CO.sub.2 and comprises dicarboxylic acids, tricarboxylic acids, or alpha-hydroxycarboxylic acids.

Decorative panel, in particular a floor panel, ceiling panel or wall panel, including a core layer having an upper side and a lower side, a decorative top layer connected to said upper side of the core layer, a first panel side edge including a first coupling profile, and a second panel side edge including a second coupling profile designed to interconnect with a first coupling profile of a second, identical panel, both in horizontal direction and in vertical direction. The core layer includes a layer of foam concrete which is constituted by a matrix of concrete material in which air pockets in the form of cells are present.