A cementitious composition including: a binder containing (a) 60-94%, by weight, of at least one pozzolanic material; (b) at least 0.5% calcium sulfoaluminate (CSA), by weight; (c) 1.2-11% by weight, expressed as SO.sub.3, of at least one inorganic sulfate selected from the group of sulfates consisting of a calcium sulfate hemihydrate, an anhydrous calcium sulfate, a calcium sulfate dihydrate, a sodium sulfate, and a sodium calcium sulfate; and (d) a total sulfate content of at least 3%, by weight, expressed as SO.sub.3, the cementitious composition including, at most, 3% natural lime, the cementitious composition including, at most, 10% alumina cement, the contents of the composition being calculated on a dry, aggregateless basis.

A method for producing supplementary cementitious material (SCM). The method comprises: contacting an input stream with a mechano-thermal activation aid; thermally treating the input stream to form a thermally treated input stream; and cooling the thermally treated input stream and obtaining supplementary cementitious material. The method may further comprise carbonating the thermally treated input stream. The method may further comprise modification of a network structure by the mechano-thermal activation aid. A composition comprising a calcium silicate hydrate bond; a supplementary cementitious material; and a mechano-thermal activation aid. The composition may further comprise a carbonate. The composition may further comprise a biomass.

A process for the manufacturing of a cement substitute may include: mixing an alkaline aluminosilicate containing material with at least one aluminosilicate hydrate containing material, and heating the thus obtained mixture to a calcination temperature of below 800 C. to form a calcined product comprising a reactive amorphous phase having the alkali ions bound therein. The process may further comprise a step of cooling the calcined product to a desired temperature. A cement substitute is obtainable by this process. The cement substitute includes a reactive amorphous phase of co-calcined alkali aluminosilicate containing material and aluminosilicate hydrate, containing material having alkali ions bound therein. The alkali ions are preferably sodium ions.

A process for the manufacturing of a cement substitute may include: mixing an alkaline aluminosilicate containing material with at least one aluminosilicate hydrate containing material, and heating the thus obtained mixture to a calcination temperature of below 800 C. to form a calcined product comprising a reactive amorphous phase having the alkali ions bound therein. The process may further comprise a step of cooling the calcined product to a desired temperature. A cement substitute is obtainable by this process. The cement substitute includes a reactive amorphous phase of co-calcined alkali aluminosilicate containing material and aluminosilicate hydrate, containing material having alkali ions bound therein. The alkali ions are preferably sodium ions.

The present application pertains to the cementing engineering technical field and reveals a cement system for ultra-high temperature resistance with excellent pumpability performance, as well as its preparation method. This cement system comprises a solid component and a liquid component. The solid component is comprised of a weight percentage of 14-70% cement, 3-80% silica sand, 3-80% fly ash, and 3-80% slag powder. The liquid component includes water and additives. This high-temperature resistant cement system exhibits stable performance with a thickening time generally exceeding 6 hours. The initial consistency ranges from 23.8 Bc to 33.6 Bc, exhibiting good pumpability performance. Furthermore, the system maintains stable strength and water permeability during the curing periods from 2 days to 90 days. The high-temperature resistant cementing system provided by this application can overcome the problems of long-term strength retrogression and address issues associated with high initial consistency, pumping difficulty, and short thickening time.

A cementitious composition including: a binder containing (a) 60-94%, by weight, of at least one pozzolanic material; (b) at least 0.5% calcium sulfoaluminate (CSA), by weight; (c) 1.2-11% by weight, expressed as SO.sub.3, of at least one inorganic sulfate selected from the group of sulfates consisting of a calcium sulfate hemihydrate, an anhydrous calcium sulfate, a calcium sulfate dihydrate, a sodium sulfate, and a sodium calcium sulfate; and (d) a total sulfate content of at least 3%, by weight, expressed as SO.sub.3, the cementitious composition including, at most, 3% natural lime, the cementitious composition including, at most, 10% alumina cement, the contents of the composition being calculated on a dry, aggregateless basis.

The present invention relates to a cement compound. The invention also relates to a method for producing such a cement compound. More in particular, the present invention relates to a cement compound comprising at least a reactive glass compound, an alkaline activator and a filler, and optionally additives, said reactive glass compound comprising at least 35 wt % CaO, at least 25 wt % SiO.sub.2 and at least 10 wt % Al.sub.2O.sub.3, and optionally other oxides.

A production method of carbon dioxide fixing sludge fine powder as a low-carbon binder. Water is added to residual concrete or returned concrete to form it into a slurry, gravel and sand are separated and removed therefrom, fine sand is separated and removed from the sludge water by a wet cyclone to obtain concentrated sludge water, and the concentrated sludge water is dehydrated to obtain a sludge cake. The sludge cake is put into a rotary drum, hot air and highly concentrated carbon dioxide are supplied into the rotary drum, the carbon dioxide is fixed and is crushed and dried to obtain carbon dioxide fixing sludge fine powder. Alternatively, the sludge cake is crushed and fractured to obtain sludge fine powder. This sludge fine powder is exposed to highly concentrated carbon dioxide to obtain carbon dioxide fixing sludge fine powder.

The present invention relates to the manufacture of aggregates from mine tailings, and to the use of said aggregates, pellets and/or fine aggregates in engineering applications as fillers, bases and sub-bases or in concrete mixtures.

By preparing a raw material mixture comprising CaO raw material, SiO.sub.2 raw material and waste material, and having a content of Al.sub.2 O.sub.3 after heating at 1000 C. of 5.0 mass % or less, and calcining at a calcination temperature of 1350 C. to 1600 C., it is possible to efficiently use waste materials as a part of raw materials, and to obtain a calcined product that comprises almost an equivalent amount of -2CaO.Math.SiO.sub.2 as conventional can be obtained.