A repaired reinforced concrete structure is provided which includes one or more reinforcing steel bars of cross-sectional area A.sub.x, the one or more reinforcing steel bars having one or more corroded sections of cross-sectional area A.sub.y, wherein A.sub.y is greater than or equal to approximately 0.6 A.sub.x. A reinforced ordinary Portland cement-based repair mortar is positioned directly on the one or more corroded sections of the one or more reinforcing steel bars without the addition of a lapped reinforcing steel bar. The reinforced repair mortar includes at least approximately 1 percent by volume of reinforcing steel fibers such that the reinforced repair mortar restores a strength of a repaired region to greater than approximately 100% of an original strength of the concrete structure in an uncorroded state. The repaired reinforced concrete structure is highly durable, as the repair mortar exhibits an air permeability resistance of greater than 1000 seconds.

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 method of exhaust gas scrubbing includes providing recycled concrete fines as a waste material rich in carbonatable Ca and/or Mg phases and with d.sub.90≤1000 μm and a Rosin-Rammler slope n from 0.6 to 1.4 , injecting the waste material into an exhaust gas stream containing CO.sub.2 and/or SO.sub.x for reaction with CO.sub.2 and/or SO.sub.x at a relative humidity of 50 to 100 Vol.-% and a temperature from 40 to 130° C. in an amount of dry waste material ranging from 5 to 30 kg/m.sup.3, withdrawing a partly carbonated and/or sulphurized waste material and purified exhaust gas, and recycling a part of the partly carbonated and sulphurized waste material while the remainder is discharged, as well as use of a waste material slurry for exhaust gas cleaning of CO.sub.2 and/or SO.sub.x.

A method of exhaust gas scrubbing includes providing recycled concrete fines as a waste material rich in carbonatable Ca and/or Mg phases and with d.sub.90≤1000 μm and a Rosin-Rammler slope n from 0.6 to 1.4 , injecting the waste material into an exhaust gas stream containing CO.sub.2 and/or SO.sub.x for reaction with CO.sub.2 and/or SO.sub.x at a relative humidity of 50 to 100 Vol.-% and a temperature from 40 to 130° C. in an amount of dry waste material ranging from 5 to 30 kg/m.sup.3, withdrawing a partly carbonated and/or sulphurized waste material and purified exhaust gas, and recycling a part of the partly carbonated and sulphurized waste material while the remainder is discharged, as well as use of a waste material slurry for exhaust gas cleaning of CO.sub.2 and/or SO.sub.x.

Apparatus for converting Spent Pot Lining (SPL) into inert slag, aluminum fluoride and energy includes a plasma arc furnace such that the destruction of SPL occurs therein. The furnace generates an electric arc within the waste, which arc travels from an anode to a cathode and destroys the waste due to the arc's extreme temperature, thereby converting a mineral fraction of SPL into vitrified inert slag lying within a crucible of the furnace. The furnace gasifies the carbon content of the SPL and produces a well-balanced syngas. The gasification takes place due to the controlled intake of air and steam into the furnace. The gasification reaction liberates significant amount of energy. Steam captures this excess energy, to provide part of the oxygen requirement for gasification and to contribute to raise the syngas H2 content. Steam also contributes to converting some SPL fluorides (NaF and Al2F3) into hydrogen fluoride. The plasma SPL processing system is compact (occupying less area than some competitive methods of SPL treatment), can be installed in close proximity to the aluminium plant (minimizing transportation of SPL and AlF3), and requires only electricity as its energy source and thus no fossil fuels.

A method of sequestering gas-phase materials, hempcrete formed using the method, and methods of using hempcrete are disclosed. An exemplary method includes providing a mixture of hempcrete compound material within a chamber and exposing the mixture within the chamber to a gas for a period of time to form hempcrete, wherein the hempcrete exhibits net-negative life cycle carbon emissions. A model to predict net life cycle carbon emission of hempcrete is also disclosed.

The invention is directed towards a process for complete conversion of multiple industrial wastes to sustainable alternatives and usable products resulting in water in-soluble product alike chemical gypsum useful for cement manufacturing used in construction industry. The inventor has utilized industrial wastes from multiple industries together taking into consideration their chemical and physical properties without using any form of energy. The whole process is carried out at ambient temperature under open sky. In described two exemplary processes, the inventor has disclosed process comprising the steps of mechanically mixing metallurgical inert waste of aged dry Jarofix containing crystallized Gypsum with freshly generated Jarosite or dry/wet Red Mud followed by addition of adequate acidic concentration waste water, calcitic wastes, pozzolanic property enhancers & lime treatment. The multiple wastes mix crystallized chemical gypsum mass on drying is used as a whole without any leftover.

Disclosed herein are a lightweight geopolymer foam with low thermal conductivity and a manufacturing method therefor in which coal bottom ash and fly ash are used together as materials for the geopolymer foam and silica fume is added to a mixed solution of an alkali activator and sodium hydroxide. The geopolymer foam can be utilized for improving insulation performance and safety for a structure constructed with eco-friendly cement.

Disclosed is a method of fabricating a construction element, the method comprising the manufacturing of a construction element including a slag, wherein the slag is comprising, on a dry basis and whereby the presence of a metal is expressed as the total of the metal present as elemental metal and the presence of the metal in an oxidized state, a) at least 7% wt and at most 49% wt of iron, Fe, b) at most 1.3% wt of copper, Cu, c) at least 24% wt and at most 44% wt of silicon dioxide, SiO.sub.2, d) at least 1.0% wt and at most 20% wt of calcium oxide, CaO, e) at least 0.10% wt and at most 1.50% wt of zinc, Zn, f) at least 0.10% wt and at most 2.5% wt of magnesium oxide, MgO, and g) at most 0.100% wt of lead, Pb. Further disclosed are improved construction elements comprising the slag.

A method of cementing may include preparing a cement composition comprising: cementitious components comprising: a cement; a supplementary cementitious material; and nanoparticulate boehmite; and water; and introducing the cement composition into a subterranean formation.