Provided is an amphoteric composite hydrogel, including: a polymer having a structure of formula I,

##STR00001##

wherein m, n, p and q are each an integer of 0 to 1000, m+n>100, p+q>100, R is

##STR00002##

R.sub.1 is H or an alkali metal element, and R.sub.2 is H or CH.sub.3; and a pozzolanic material incorporated into the structure of formula 1. Also provided are a cement mortar composition and a concrete composition each comprising the amphoteric composite hydrogel and a method of preparing the amphoteric composite hydrogel.

The present invention provides calcium sulphate-based product having reduced shrinkage after exposure to high temperatures, the product comprising gypsum, a pozzolan source (e.g. in an amount between 4-27 wt %) and a metal salt additive (in an amount between 0.5 and 10 wt %). The pozzolan source may be selected from a kaolinitic clay material, fly ash, rice husk ash, diatomaceous earths, volcanic ashes and pumices, micro-silica, silica fume and silicone oil. The metal salt additive may be a metal salt which decomposes between a temperature of 300-500 C. to yield a metal oxide, e.g. magnesium nitrate.

The present invention provides a calcium sulphate-based product (e.g. a wall board) comprising gypsum, a pozzolan source such as a clay additive, rice husk ash or diatomaceous earth and a metal salt additive. The product may be produced by drying an aqueous slurry comprising calcined gypsum, the pozzolan source and the metal salt additive. The clay additive may be a kaolinitic clay. The metal salt additive may be a magnesium salt e.g. magnesium nitrate, magnesium chloride or magnesium hydroxide.

Fresh concrete is treated with carbon dioxide prior to delivery to a product mold for forming concrete products. Carbon dioxide gas is directed through a manifold, which may be coupled to a feedbox or a hopper, upstream from the product mold. Treating the fresh concrete with the carbon dioxide gas while it is in a loose state prior to placement in the product mold may generally promote uniform and enhanced carbon dioxide uptake.

There is provided a gypsum composition for a drying type coating material, the gypsum composition, when made into a gypsum-based coating material by addition of water, capable of forming a coating film in which color unevenness is suppressed even though the coating film is thin and smooth. This gypsum composition for a drying type coating material contains hemihydrate gypsum having a mean particle diameter of 50 m or less, calcium carbonate having a mean particle diameter of 50 m or less, and a setting retarder, wherein the gypsum composition has a content of calcium carbonate of 100 to 400 parts by mass and a content of the setting retarder of 0.1 parts by mass or more each based on 100 parts by mass of the hemihydrate gypsum.

Some embodiments are directed to a new castable cement based material containing a special admixture based internal curing system to reduce the shrinkage and avoid the formation of cracks, and method of producing the same.

The multi-leg fiber reinforced concrete is concrete in which fibers have been embedded to prevent the concrete from being fractured due to cracks developing therein. Each fiber has multiple legs, defining two and three dimensional structures. At least one fiber is embedded in a volume of concrete, where the at least one fiber has at least first and second legs respectively extending along first and second directions. The first and second directions are angularly oriented with respect to one another between 45 and 135, with each of the first and second legs having a free end and a fixed end. Each free end has a substantially Z-shaped contour. The fixed ends of the first and second legs may be joined together to define a two-dimensional fiber structure. The at least one fiber may be partially coated with a polymeric material, such as polypropylene.

The multi-leg fiber reinforced concrete is concrete in which fibers have been embedded to prevent the concrete from being fractured due to cracks developing therein. Each fiber has multiple legs, defining two and three dimensional structures. At least one fiber is embedded in a volume of concrete, where the at least one fiber has at least first and second legs respectively extending along first and second directions. The first and second directions are angularly oriented with respect to one another between 45 and 135, with each of the first and second legs having a free end and a fixed end. Each free end has a substantially Z-shaped contour. The fixed ends of the first and second legs may be joined together to define a two-dimensional fiber structure. The at least one fiber may be partially coated with a polymeric material, such as polypropylene.

The multi-leg fiber reinforced concrete is concrete in which fibers have been embedded to prevent the concrete from being fractured due to cracks developing therein. Each fiber has multiple legs, defining two and three dimensional structures. At least one fiber is embedded in a volume of concrete, where the at least one fiber has at least first and second legs respectively extending along first and second directions. The first and second directions are angularly oriented with respect to one another between 45 and 135, with each of the first and second legs having a free end and a fixed end. Each free end has a substantially Z-shaped contour. The fixed ends of the first and second legs may be joined together to define a two-dimensional fiber structure. The at least one fiber may be partially coated with a polymeric material, such as polypropylene.

In a method of producing nanoconcrete according the bottom-up approach of nano technology with the High-Energy Mixing of composition including cement, water, sand, additives and superplasticizers, the mixing is performed with flow of mixture characterized by Reynolds number and Power number in the range of 20-800 and 0.1-4.0 respectively with installation a disk horizontally into mixing assembly on the top layer of activated mixture coaxially with vertical axis of assembly and with the axis of impeller rotation on the adjustable level to avoid destroying created gel as a result of interruptions of process, to increase laminarity of the mixture flow, energy absorption by the mixture, and shear stress for creation additional quantity of the nanostructured Calcium Silicate Hydrate (CSH) gel necessary for making nanoconcrete.