A process is provided for treating raw fly ash used in cementitious material so as to increase the strength of the cementitious material while at the same time providing a near linear strength increase for the material as it cures by processing the raw fly ash, as by milling, and by mixing the processed fly ash with a catalyst such as lithium, with the lithium concentration in the fly ash being between 0.05% and 0.25% by weight. The process applies to Class C fly ash and Class F fly ash when mixed with Class C fly ash. All of the above processes include the use of polycarboxylates.

A process is provided for treating raw fly ash used in cementitious material so as to increase the strength of the cementitious material while at the same time providing a near linear strength increase for the material as it cures by processing the raw fly ash, as by milling, and by mixing the processed fly ash with a catalyst such as lithium, with the lithium concentration in the fly ash being between 0.05% and 0.25% by weight. The process applies to Class C fly ash and Class F fly ash when mixed with Class C fly ash. All of the above processes include the use of polycarboxylates.

A method of separating different constituents of a fine fraction that is produced in a prior method for separating a concrete for deconstruction. The method allows the reuse of these different constituents in the production of a new cement and/or of a new concrete, the fine fraction including sand and at least 30% by mass of hydrated cement paste.

A method of separating different constituents of a fine fraction that is produced in a prior method for separating a concrete for deconstruction. The method allows the reuse of these different constituents in the production of a new cement and/or of a new concrete, the fine fraction including sand and at least 30% by mass of hydrated cement paste.

The present disclosure provides a modified montmorillonite self-repairing agent and a preparation method and use thereof, and belongs to the technical field of cement repairing materials. Montmorillonite is mixed with water, such that water is fully adsorbed between montmorillonite layers. The structure of montmorillonite is modified by supercritical CO.sub.2 treatment at a temperature of 50-60° C. and a pressure of 8-12 MPa, and the self-repairing efficiency of cement is improved by adding the modified montmorillonite into cement. Supercritical CO.sub.2 is adsorbed by montmorillonite, such that the montmorillonite is activated and an interlayer distance is increased to improve the repairing efficiency. When a crack is formed in cement, the adsorbed supercritical CO.sub.2 in montmorillonite is released into the crack and combined with positive ions to generate carbonate deposition, such that the crack is sealed and the self-repairing activity of the cement is improved. Results of examples show that carbonate microcrystals are generated in the modified montmorillonite self-repairing agent provided by the present disclosure. The generated carbonate microcrystals serve as “active sites” that induce additional carbonate precipitation, which is beneficial for crack sealing.

The present disclosure provides a modified montmorillonite self-repairing agent and a preparation method and use thereof, and belongs to the technical field of cement repairing materials. Montmorillonite is mixed with water, such that water is fully adsorbed between montmorillonite layers. The structure of montmorillonite is modified by supercritical CO.sub.2 treatment at a temperature of 50-60° C. and a pressure of 8-12 MPa, and the self-repairing efficiency of cement is improved by adding the modified montmorillonite into cement. Supercritical CO.sub.2 is adsorbed by montmorillonite, such that the montmorillonite is activated and an interlayer distance is increased to improve the repairing efficiency. When a crack is formed in cement, the adsorbed supercritical CO.sub.2 in montmorillonite is released into the crack and combined with positive ions to generate carbonate deposition, such that the crack is sealed and the self-repairing activity of the cement is improved. Results of examples show that carbonate microcrystals are generated in the modified montmorillonite self-repairing agent provided by the present disclosure. The generated carbonate microcrystals serve as “active sites” that induce additional carbonate precipitation, which is beneficial for crack sealing.

The invention generally relates to a method of making a plastic aggregate, and its use to make concrete products. The aggregate is formed by providing a granulated waste plastic material, introducing the granulated waste plastic material into an extruder having a die, the die having a ratio of die nozzle open area to die land area of about 1:10 to about 1:40, and extruding the granulated waste plastic material through the extruder to generate an extruded plastic aggregate. The method can include the presence of controlled cooling, the addition of additives and treatment of the surface of the aggregate to produce a desired aggregate that can be used to make a concrete product with desired properties, such as compressive strength and weight.

The invention generally relates to a method of making a plastic aggregate, and its use to make concrete products. The aggregate is formed by providing a granulated waste plastic material, introducing the granulated waste plastic material into an extruder having a die, the die having a ratio of die nozzle open area to die land area of about 1:10 to about 1:40, and extruding the granulated waste plastic material through the extruder to generate an extruded plastic aggregate. The method can include the presence of controlled cooling, the addition of additives and treatment of the surface of the aggregate to produce a desired aggregate that can be used to make a concrete product with desired properties, such as compressive strength and weight.

Described are cementitious reagent materials produced from globally abundant inorganic feedstocks. Also described are methods for the manufacture of such cementitious reagent materials and forming the reagent materials as microspheroidal glassy particles. Also described are apparatuses, systems and methods for the thermochemical production of glassy cementitious reagents with spheroidal morphology. The apparatuses, systems and methods makes use of an in-flight melting/quenching technology such that solid particles are flown in suspension, melted in suspension, and then quenched in suspension. The cementitious reagents can be used in concrete to substantially reduce the CO.sub.2 emission associated with cement production.

Water-based paint is used as a sacrificial agent to reduce the detrimental effect of carbon-containing fly ash on the entrainment of air in concrete. The invention provides a composition for reducing the effect of carbon contained in fly ash on air entrainment in cementitious mixtures comprising water, cement, fly ash and entrained air. The composition comprises water-based paint and one or more of pulverized or un-pulverized pozzolan, pulverized or un-pulverized cementitious solids, a superplasticizer, a defoamer, an air-entraining admixture, a water-reducing admixture, a retarding admixture, an accelerating admixture, a hydration control admixture and a rheology modifying admixture. The invention also provides a method of reducing the effect of carbon on air entrainment in carbon-containing fly ash, comprising mixing the fly ash with water-based paint.