A method of reducing lost circulation in a wellbore includes introducing an activation solution including an aqueous solution, Na.sub.2SiO.sub.3, NaOH, and one or both of CaCO.sub.3 or Mn.sub.3O.sub.4 into the wellbore. The method further includes introducing Saudi Arabian volcanic ash into the wellbore. The Saudi Arabian volcanic ash comprises SO.sub.3, CaO, SiO.sub.2, Al.sub.2O.sub.3, Fe.sub.2O.sub.3, MgO, and K.sub.2O. The method further includes allowing the Saudi Arabian volcanic ash to contact the activation solution in the wellbore, thereby forming a geopolymer barrier between the wellbore and a subsurface formation to reduce lost circulation in the wellbore.

The invention provides novel aerated composite materials made from a carbonatable calcium silicate composition, and formulations and methods of manufacture and use thereof, in particular, the use of novel additive mineral compositions in the form of magnesium, magnesium salts or magnesium oxides, to improve physical chemical properties of low density concrete materials. The low density, aerated material is comprised of calcium carbonate (CaCO.sub.3) and silica (SiO.sub.2), as cured products of carbonatable calcium silicate compositions.

The invention provides novel aerated composite materials made from a carbonatable calcium silicate composition, and formulations and methods of manufacture and use thereof, in particular, the use of novel additive mineral compositions in the form of magnesium, magnesium salts or magnesium oxides, to improve physical chemical properties of low density concrete materials. The low density, aerated material is comprised of calcium carbonate (CaCO.sub.3) and silica (SiO.sub.2), as cured products of carbonatable calcium silicate compositions.

The invention provides a process for producing a cement clinker comprising: (i) mixing one or more starting materials providing each at least one or more of CaO, SiO.sub.2, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3; and, optionally, SO.sub.3, to form a raw meal comprising CaO, SiO.sub.2, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3; and, optionally, SO.sub.3, wherein the molar ratios among the aforementioned oxides is given by Formula I: (CaO).sub.1(SiO.sub.2).sub.a(Al.sub.2O.sub.3).sub.b(Fe.sub.2O.sub.3).sub.c(SO.sub.3).sub.d, wherein: a is comprised from 0.05 to 1, b is comprised from 0.01 to 0.6, c is comprised from 0.001 to 0.25, and d is comprised from 0 to 0.3 and wherein at least 35% (p/p) of the starting materials of the raw meal have a critical microwaves absorbance temperature (Tc) comprised from 15 to 650 C. and a critical microwaves absorbance time (tc) comprised from 1 min to 1 h; (ii) heating the raw meal by irradiating with microwaves during 15 min to 3 h to reach a sintering temperature comprised from 300 to 950 C.; (iii) maintaining the microwave sintering temperature of step (ii) during 1 min to 3 h by further irradiating with microwaves; and (iv) cooling the clinker obtained in step (iii).

The invention provides a process for producing a cement clinker comprising: (i) mixing one or more starting materials providing each at least one or more of CaO, SiO.sub.2, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3; and, optionally, SO.sub.3, to form a raw meal comprising CaO, SiO.sub.2, Al.sub.2O.sub.3, and Fe.sub.2O.sub.3; and, optionally, SO.sub.3, wherein the molar ratios among the aforementioned oxides is given by Formula I: (CaO).sub.1(SiO.sub.2).sub.a(Al.sub.2O.sub.3).sub.b(Fe.sub.2O.sub.3).sub.c(SO.sub.3).sub.d, wherein: a is comprised from 0.05 to 1, b is comprised from 0.01 to 0.6, c is comprised from 0.001 to 0.25, and d is comprised from 0 to 0.3 and wherein at least 35% (p/p) of the starting materials of the raw meal have a critical microwaves absorbance temperature (Tc) comprised from 15 to 650 C. and a critical microwaves absorbance time (tc) comprised from 1 min to 1 h; (ii) heating the raw meal by irradiating with microwaves during 15 min to 3 h to reach a sintering temperature comprised from 300 to 950 C.; (iii) maintaining the microwave sintering temperature of step (ii) during 1 min to 3 h by further irradiating with microwaves; and (iv) cooling the clinker obtained in step (iii).

A method for manufacturing a binder of a hydratable material includes providing a starting material from one or more raw materials convertible by tempering at 600 to 1200 C. into the hydratable material, tempering the starting material to provide the hydratable material containing not more than 10% by weight monocalcium silicate and at least 15% by weight hydratable phases in the form of lime and dicalcium silicate, wherein the residence time and the tempering temperature are adapted to obtain the hydratable material by converting not more than 80% by weight of the starting material, and cooling the hydratable material to provide the binder comprising the hydratable material. The binder can be mixed with water and optionally one or more of aggregate, additives, admixtures to obtain a binder paste that is placed, hydrated and carbonated to produce a building product.

A method of manufacturing building elements has the steps: providing a binder comprising at least 8% by weight ternesite, at least 15% by weight dicalcium silicate and at least 5% by weight ye'elimite, each with respect to the total binder, as hydraulically reactive phases; mixing the binder with water to form a paste; casting the paste into a desired shape for the building element; reacting the paste hydraulically to form calcium-silicate-hydrates, calcium-aluminium-silicate-hydrates, portlandite, brucite, stratlingite, hydrotalcite-like phases and ettringite/AFm and capillary pores, and carbonation hardening to provide the building element and to building elements obtainable by the method.

A method for inerting polluted soil, comprising adding to a polluted soil a composition comprising: from 40% to 99% of a sulfoaluminous clinker comprising as a phase composition, to the overall weight of the clinker: from 5% to 80% of a calcium sulfoaluminate phase possibly iron-doped corresponding to the formula C4AxFy$z in which x varies from 2 to 3; y varies from 0 to 0.5; and z varies from 0.8 to 1.2; from 0 to 25% of a calcium aluminoferrite phase of a composition corresponding to the general formula C.sub.6A.sub.xF.sub.y; x varies from 0 to 1.5; and y varies from 0.5 to 3; and from 10% to 70% of a belite phase C.sub.2S; and from 1% to 60% of a lime.

A method for inerting polluted soil, comprising adding to a polluted soil a composition comprising: from 40% to 99% of a sulfoaluminous clinker comprising as a phase composition, to the overall weight of the clinker: from 5% to 80% of a calcium sulfoaluminate phase possibly iron-doped corresponding to the formula C4AxFy$z in which x varies from 2 to 3; y varies from 0 to 0.5; and z varies from 0.8 to 1.2; from 0 to 25% of a calcium aluminoferrite phase of a composition corresponding to the general formula C.sub.6A.sub.xF.sub.y; x varies from 0 to 1.5; and y varies from 0.5 to 3; and from 10% to 70% of a belite phase C.sub.2S; and from 1% to 60% of a lime.

The present invention relates to a method for manufacturing a binder with high belite content comprising the steps: a) providing a starting material by selecting one raw material having a Ca/Si molar ratio of 1.5 to 2.5 or by mixing two or more raw materials to obtain a starting material with the Ca/Si molar ratio of 1.5 to 2.5; b) hydrothermal treatment of the starting material produced in step a) in an autoclave at a temperature of 100 to 300 C. and a retention time of 0.1 to 24h, wherein the water/solids ratio is from 0.1 to 100 to provide an intermediate product; c) annealing the intermediate product obtained in step b) in a flash calciner at 620 to 630 C., wherein the retention time is 1-30 seconds.