A lightweight aggregate-based non-steam-cured high-performance pipe culvert and a preparation method thereof. The lightweight aggregate-based non-steam-cured high-performance pipe culvert is prepared from a raw material including the following components by mass per unit volume: 300-450 kg/m.sup.3 of a low-carbon sulfur-aluminum-ferric cementitious material; 800-920 kg/m.sup.3 of a solid waste-based lightweight aggregate; 300-550 kg/m.sup.3 of a solid waste-based artificial sand; 0-100 kg/m.sup.3 of a mineral admixture; 0-50 kg/m.sup.3 of an auxiliary material; and 110-160 kg/m.sup.3 of water; and the lightweight aggregate-based non-steam-cured high-performance pipe culvert further includes a water reducer and a retarder. The lightweight aggregate-based non-steam-cured high-performance pipe culvert of the present invention can be demolded within 4 hours during forming, with short demolding time and no need for steam curing, resulting in a low production cost and high production efficiency. The obtained product has high strength, good impermeability and durability, and can utilize solid waste in a high proportion.

A method of producing magnesium cement. The method may comprise mixing water at a temperature of between approximately 50 C. and 100 C., a magnesium oxygen-containing compound and a magnesium salt. In some embodiments, the water is heated to a temperature of between approximately 70 C. and 90 C. The magnesium oxygen-containing compound may comprise one or more of magnesium oxide and magnesium hydroxide. The magnesium salt may comprise one or more of magnesium acetate, magnesium bromide, magnesium oxalate, magnesium thiosulfate, magnesium phosphate, magnesium nitrate, magnesium silicate, a magnesium chloride in any hydration state, anhydrous magnesium chloride, hexahydrate magnesium chloride, a magnesium sulfate in any hydration state, anhydrous magnesium sulfate, heptahydrate magnesium sulfate and magnesium carbonate.

The present invention relates to a bio-aggregate based building product comprising a macroporous element formed from a mixture of: a calcium carbonate derived binder and a lignocellulosic bio-aggregate. The macroporous element has an air and/or vapour and/or water open matrix with a microcapillary structure formed by the lignocellulosic bio-aggregate. The porosity of the macroporous element is at least 50% of the bulk volume of the building product. Between 40% and 80% by weight of bio-aggregate granulates forming the lignocellulosic bio-aggregate have a maximum particle size falling within the lower 50% of the particle size range. No more than 5% by weight of bio-aggregate granulates forming the lignocellulosic bio-aggregate have a maximum particle size falling within the upper 20% of the particle size range.

Provided are a polyhydroxy aromatic intermediate, preparation thereof and use thereof in a polycondensate water-reducer with branched side chains. The polycondensate water-reducer with branched side chains has a branched side chain structure which provides a stronger steric hindrance. The synergistic effect of the branched side chains and the rigid skeleton of the aromatic ring greatly improves the water-reducing ability. Especially under a condition of low water/cement ratio, the improvement in water-reducing ability is more obvious. The branched polyether side chain is more conducive to the formation of a thicker water film layer, which has an obvious viscosity reduction effect. The conformation of the branched polyether side chain is less affected by different ionic environments in the pore solution in cement, and thus has a stronger adaptability to various raw materials. The water-reducer is suitable for the preparation of high-strength concrete, self-compacting concrete and concrete with low water-to-binder ratio and high volume of mineral admixtures, especially for the preparation of concrete containing machine-made sand.

This invention provides in one aspect compositions that improve the corrosion-resistance of cementitious materials. In certain embodiments, the compositions of the invention inhibit the growth of acidophilic bacteria thriving in/on cementitious material.

A cement-based artificial stone plate includes a cement-based plate body; and a metal mesh being embedded in the cement-based plate body; wherein the metal mesh is arranged with at least one fixing member, the fixing member defines a screw hole along its axis, and the screw hole of the fixing member is exposed on back of the cement-based plate body, and back of the plate body is provided with regular or irregular protrusions, between any two protrusions forms a groove, and bottom of each groove is close to the metal mesh.

A strengthening concrete admixture for the production of high-strength concrete products is provided. The strengthening concrete admixture comprises water; a set retarder comprising a salt of gluconic acid; one or more set accelerators; one or more hardening accelerators; and at least one stabilizing agent. Incorporation of the strengthening admixture in a cement mixture enhances both early and late age strength development and allows for sustainable and more energy efficient construction practices.

A hydraulic binder composition comprising: a hydraulic binder including at least one alumino-silicate compound, for example blast furnace slag, and an alkaline or sulfate activator and a maximum of 10 wt % of clinker, preferably between 0 and 10 wt % of clinker; a guanidine salt and/or a zinc salt; and a polymer.

Cementitious compositions comprising lime, which may be foamed or non-foamed compositions, may increase carbon dioxide uptake of the cementitious compositions. Said cementitious compositions may be used in various cementing methods including pre-casting methods, cast-in-place methods, and primary or secondary cementing operations in a wellbore. The carbon dioxide may be added to the cementitious compositions during mixing, during pre-conditioning, during curing, or any combination thereof. Further, the carbon dioxide may be delivered as a gas (e.g., a gas that includes 1 vol % to 100 vol % carbon dioxide) or as a gas-entrained admixture that includes the gas, water, and a foaming agent.

A method for making a carbonated precast concrete product includes: obtaining a mixture including at least one binder material, an aggregate, and water; molding the mixture into a molded intermediate; demolding the molded intermediate to obtain a demolded intermediate, the demolded intermediate having a first water-to-binder ratio; conditioning the demolded intermediate to provide a conditioned article having a second water-to-binder ratio less than the first water-to-binder ratio of the demolded intermediate; moisturizing at least one surface of the conditioned article with an aqueous medium, thereby causing a weight gain of the conditioned article and providing a moisturized product, a first portion of the moisturized product having a third water-to-binder ratio greater than a fourth water-to-binder ratio of a remainder of the moisturized product; and curing the moisturized product with carbon dioxide to obtain the carbonated precast concrete product.