This geopolymer molding production method comprises: a mixing step (S1) for mixing a first material containing aluminum and silicon with a hydrate of an alkali stimulant containing a hydrate of an alkaline hydroxide and/or a hydrate of an alkaline silicate; a compaction step (S2) for compacting the mixture obtained in the mixing step (S1) into a compacted mixture; and a curing step (S3) for curing the compacted mixture.

Described herein are cementitious composite materials incorporating carbon nanostructures (e.g., nanotubes, nanoplatelets, nanoribbons) that are employed as amendments (i.e., admixtures or additives) to cementitious waste forms as a means to enhance radionuclide and hazardous waste (e.g., heavy metals, toxic organics) retention wherein the incorporation of well-dispersed carbon nanostructures yields more effective waste forms through the resulting modification of the cementitious composite nano-, micro-, and meso-structure (e.g., hindering the infiltration of oxygen and the leaching of waste), and the chemical interactions between chemically-affine waste molecules and the amended cementitious composite.

Novel composites having improved performance such as compressive and/or tensile strengths are formed from carbon-based nanomaterials and a binder. Sheared carbon-based nanomaterial in solution is typically mixed with a binder and then cured. The composites may have several improved properties such as higher compressive strength, tensile strength, lower shrinkage, and modified viscosity which are greater than the binder alone.

The present invention relates to a method of solidifying radioactive waste containing boron, The method includes (a) mixing the radioactive waste, metakaolin, fumed silica, potassium hydroxide, and water to generate a second mixture, in which the radioactive waste contains boron.

The method includes forming an inner monolithic layer from crystals of beta phase stoichiometric silicon carbide on a carbon substrate in the form of a rod by chemical methylsilane vapor deposition in a sealed tubular hot-wall CVD reactor. The method further includes forming a central composite layer over the inner monolithic layer by twisting continuous beta phase stoichiometric silicon carbide fibers into tows, transporting the tows to a braiding machine, and forming a reinforcing thread framework. A pyrocarbon interface coating is built up by chemical methane vapor deposition in a sealed tubular hot-wall CVD reactor. Then, a matrix is formed by chemical methylsilane vapor deposition in the reactor. A protective outer monolithic layer is formed from crystals of beta phase stoichiometric silicon carbide over the central composite layer by chemical methylsilane vapor deposition in a CVD reactor. And then the carbon substrate is removed from the fabricated semi-finished product.

The invention relates to a composition which contains modified chromate-deficient red mud, comprising a mineral composition of10 to 50 wt. % of iron compounds,12 to 35 wt. % of aluminum compounds,5 to 17 wt. % of silicon compounds,2 to 10 wt. % of titanium dioxide,0.5 to 6 wt. % of calcium compounds,0 to 1 ppm of chromium (VI) compounds, andoptionally additional unavoidable impurities. The composition, in particular the modified chromate-deficient red mud, contains a poorly soluble reducing agent for Cr(VI). In this manner, an inexpensive chemical composition is provided in particular as an iteratively functioning long-term adsorbent for pollutants in liquid, gaseous, and solid milieu. The invention further relates to a method for producing same and to uses thereof.

Ceramic composite materials that are reinforced with carbide fibers can exhibit ultra-high temperature resistance. For example, such materials may exhibit very low creep at temperatures of up to 2700 F. (1480 C.). The present composites are specifically engineered to exhibit matched thermodynamically stable crystalline phases between the materials included within the composite. In other words, the reinforcing fibers, a debonding interface layer disposed over the reinforcing fibers, and the matrix material of the composite may all be of the same crystalline structural phase (all hexagonal), for increased compatibility and improved properties. Such composite materials may be used in numerous applications.

A method for preparing low-background cement includes: uniformly mixing a seed crystal of cement, C.sub.4AF whiskers, and high-magnesium raw material to yield a first mixture, calcining the first mixture at 1400-1500? C., to yield a low-background clinker, the first mixture including 1.0-5.0 wt. % of the seed crystal of cement, 1.0-5.0 wt. % of the C.sub.4AF whiskers, and the balance is the high-magnesium raw material; and grinding a second mixture of the low-background clinker and gypsum, to yield low-background cement. The seed crystal of cement is a high-magnesium and low hydration heat clinker, has a specific activity of Ra-226 radioactive nuclides within 50 Bq/kg, and the MgO content of the clinker is between 4.0 wt. % and 5.0 wt. %, with 50 wt. %?C.sub.3S?55.0 wt. %; and the high-magnesium raw material has a MgO content between 2.5 wt. % and 3.0 wt. %.

The present invention provides a bidirectional energy-transfer system comprising: a thermally and/or electrically conductive concrete, disposed in a structural object; a location of energy supply or demand that is physically isolated from, but in thermodynamic and/or electromagnetic communication with, the thermally and/or electrically conductive concrete; and a means of transferring energy between the structural object and the location of energy supply or demand. The system can be a single node in a neural network. The thermally and/or electrically conductive concrete includes a conductive, shock-absorbing material, such as graphite. Preferred compositions are disclosed for the thermally and/or electrically conductive concrete. The bidirectional energy-transfer system may be present in a solar-energy collection system, a grade beam, an indoor radiant flooring system, a structural wall or ceiling, a bridge, a roadway, a driveway, a parking lot, a commercial aviation runway, a military runway, a grain silo, or pavers, for example.

The present invention provides a bidirectional energy-transfer system comprising: a thermally and/or electrically conductive concrete, disposed in a structural object; a location of energy supply or demand that is physically isolated from, but in thermodynamic and/or electromagnetic communication with, the thermally and/or electrically conductive concrete; and a means of transferring energy between the structural object and the location of energy supply or demand. The system can be a single node in a neural network. The thermally and/or electrically conductive concrete includes a conductive, shock-absorbing material, such as graphite. Preferred compositions are disclosed for the thermally and/or electrically conductive concrete. The bidirectional energy-transfer system may be present in a solar-energy collection system, a grade beam, an indoor radiant flooring system, a structural wall or ceiling, a bridge, a roadway, a driveway, a parking lot, a commercial aviation runway, a military runway, a grain silo, or pavers, for example.