Abstract: The properties of cement matrices are improved by one or more of the three processes, which can be performed individually, sequentially, or in any desired combination. In each instance a supercritical fluid is or includes a solvent for one of two (or more) reactants such as a monomer and a polymer initiator. The resulting mixture is infused into the matrix under supercritical conditions. The other reactant is placed into the matrix; for example, by incorporating it in the wet cement paste prior to curing. When the mixture is infused into the matrix, the reactants react and change the cement matrix in predictable, desired ways. The solvent itself may or may not be supercritical, and if it is not, it is mixed with a supercritical fluid, which might or might not be another solvent. In this manner, the inside of the matrix may be coated and/or sealed with a polymer, for example, or the entire cement matrix may be rendered relatively flexible and ductile.

Abstract: A method of reinforcing cement/concrete mixtures with alkali-intolerant reinforcements and/or aggregate, such as uncoated, common glass filament, plastic filament, fabric and roving made therefrom by reducing the pH of the mixture while in its plastic state, and/or after it has set and cured, to about 7. With a neutral pH, the alkali-intolerant reinforcements need not be coated to protect them from degradation. In the absence of alkalinity, the reinforcement and/or aggregate material bonds with the cement mixture to form a relatively stronger mixture, which can be shaped as desired, made part of permanently poured structures, cement boards and many other small and large products. By selecting appropriate and, if desired, different materials for the reinforcements and/or aggregate, the strength, flexibility, etc. characteristics of the product can be readily changed to adapt the product to the intended use. The pH is reduced by migrating such materials as CO.sub.2 and/or CO and O.sub.

Abstract: Cured cement matrices are exposed to dense-phase or supercritical CO.sub.2 which enters the matrix through passages therein to neutralize the natural alkalinity of the cement so that alkali-intolerant materials can be incorporated in the cement. The CO.sub.2 converts calcium hydroxide in the cement to calcium carbonate and water, and the high pressure of the dense-phase or supercritical CO.sub.2 forms rounded, closely packed and aligned crystals with few or no visible pores or capillaries to enhance the homogeneity and strength of the cured cement and its bonding with, for example, uncoated reinforcing glass fibers. The supercritical CO.sub.2 can be used to transport other organic or inorganic materials, including pulverized metal, in solution or suspension into the interior of the cement matrix to alter its chemical and/or physical characteristics. The supercritical CO.sub.

Abstract: Cured cement matrices are exposed to dense-phase or supercritical CO.sub.2 which enters the matrix through passages therein to neutralize the natural alkalinity of the cement so that alkali-intolerant materials can be incorporated in the cement. The CO.sub.2 converts calcium hydroxide in the cement to calcium carbonate and water, and the high pressure of the dense-phase or supercritical CO.sub.2 forms rounded, closely packed and aligned crystals with few or no visible pores or capillaries to enhance the homogeneity and strength of the cured cement and its bonding with, for example, uncoated reinforcing glass fibers. The supercritical CO.sub.2 can be used to transport other organic or inorganic materials, including pulverized metal, in solution or suspension into the interior of the cement matrix to alter its chemical and/or physical characteristics. The supercritical CO.sub.

Abstract: A simple, environmentally benign building for on-site erection and fabrication is made of monolithic, architectural, structural walls, beams, girders, joists and panels of relatively high physical strength which exhibit great durability and resistance to fire, wind and seismic damage and which have highly desirable acoustic and thermal transfer characteristics. The wall is constructed by casting a core of flowable fibrous, foam-cement mix between two, thin panels of manufactured, exterior-grade fiberglass reinforced cement board. Particles and proteins from the core mix penetrate, migrate into and fill interstitial spaces in the cement board, forming a strong, continuous and homogenous bond between the fill material and the board itself. This imparts additional strength to the cement board by filling the interstitial voids, creating a solid, homogeneous wall. The wall, girder, etc.