Low-carbon cement and preparation method thereof

Abstract

The invention belongs to the field of building materials, and provides low-carbon cement and a preparation method thereof. The low-carbon cement comprises the following components in parts by mass: 15-47 parts of cement clinker, 0.5-7 parts of gypsum, 47-71 parts of an auxiliary cementing material, 0.1-11 parts of a hardening and tempering component and 0-0.1 part of a grinding aid, the hardening and tempering component comprises one or more of a lime-gypsum mixture, sulphoaluminate cement and waste concrete recycled micro powder. According to the low-carbon cement provided by the invention, the use amount of clinker can be remarkably reduced, and CO2 emission in the cement production process is reduced. Meanwhile, the strength of the cement is guaranteed while the carbon emission is reduced.

Description

Technical Field

[0001] The present invention relates to the field of building materials, and in particular to low-carbon cement and a preparation method thereof. Background Art

[0002] Portland cement is widely used in infrastructure construction and maintenance due to its exceptional compressive properties. However, the production of traditional Portland cement produces significant amounts of carbon dioxide (CO2), posing a significant challenge to climate change, environmental protection, and sustainable development. Limestone decomposition during the clinker manufacturing stage of Portland cement production is the primary source of CO2 emissions, accounting for over 70% of total emissions from the entire cement production process.

[0003] Therefore, given the structural composition of cement's carbon emissions, reducing clinker usage is a key approach to developing new, green, low-carbon, and environmentally friendly cements. By using industrial waste materials like fly ash and slag as auxiliary cementitious materials to partially replace clinker and produce low-clinker cement, not only can carbon emissions from the cement industry be significantly reduced, but it can also process industrial waste on a large scale, contributing to the comprehensive utilization of resources.

[0004] However, existing low-carbon (low-clinker) cement formulas cannot guarantee cement strength due to the low clinker content. Therefore, further research is needed to determine how to reduce cement carbon emissions while ensuring cement strength. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that it is impossible to simultaneously reduce cement carbon emissions and ensure cement strength, thereby providing a low-carbon cement and a preparation method thereof.

[0006] To this end, the present invention provides the following technical solutions:

[0007] The present invention provides a low-carbon cement comprising the following components in parts by weight:

[0008] 15-47 parts of cement clinker, 0.5-7 parts of gypsum, 47-71 parts of auxiliary cementitious materials, 0.1-11 parts of conditioning components and 0-0.1 parts of grinding aids;

[0009] The conditioning components include one or more of lime-gypsum mixture, sulphoaluminate cement and waste concrete recycled fine powder.

[0010] In the present invention, gypsum is ground together with cement clinker, so that the gypsum can be evenly distributed in the cement clinker, effectively suppressing the flash setting phenomenon. When the cement is subsequently used, the sulfate ions formed by dissolving the gypsum can react with the tricalcium aluminate produced by the hydration of the cement clinker to form ettringite, thereby delaying the rapid hydration of the cement, extending the initial setting time and final setting time of the cement, and improving the workability of the cement slurry, which is beneficial to the construction operation.

[0011] Gypsum, on the other hand, acts as a tempering component, acting as an activation agent when mixed with lime. During the grinding process after mixing, the solid waste in the auxiliary cementitious material undergoes an amorphous transformation due to the distortion of the mineral lattice on the particle surface during mechanical fine grinding. The silicoaluminate components then become active, and subsequently hydrate in the CaO-CaSO4-H2O system during cement application to form C-(A)-SH (hydrated calcium aluminosilicate gel) and AFt (ettringite), which contribute to strength.

[0012] The average specific surface area in the present invention is measured with reference to GB / T8074-2008 “Determination of specific surface area of cement by Blaine method”.

[0013] In an optional embodiment, the cement clinker comprises silicate cement clinker; the gypsum comprises one or both of desulfurized gypsum and anhydrite; the average specific surface areas of the cement clinker and gypsum are 350-400m 2 / kg; the auxiliary cementitious material includes slag; the auxiliary cementitious material also includes one or more of fly ash, sandstone, limestone and pozzolanic mixed materials; the pozzolanic mixed materials include one or two of volcanic ash and burnt clay; the grinding aid includes one or more of triethanolamine, triisopropanolamine, ethylene glycol, propylene glycol, glycerol, polymeric alcohol amine, polymeric polyol, sodium fatty acid and calcium chloride; the lime in the lime-gypsum mixture is quicklime, and the gypsum in the lime-gypsum mixture is one or two of desulfurized gypsum and anhydrite.

[0014] Limiting the average specific surface area of cement clinker and gypsum to the above range helps to improve the strength of cement and ensure workability.

[0015] In an optional embodiment, the average specific surface areas of the auxiliary cementitious material and the tempering component are 350-550 m 2 / kg.

[0016] In an optional embodiment, the auxiliary cementitious material includes slag, and the average specific surface area of the slag is 450-550m 2 / kg; when fly ash is included in the auxiliary cementitious material, the average specific surface area of the fly ash is 600-800m 2 / kg; when the auxiliary cementitious material includes sandstone, the average specific surface area of sandstone is 350-400m 2 / kg; when the auxiliary cementitious material includes pozzolanic mixed materials, the average specific surface area of the pozzolanic mixed materials is 600-800m 2 / kg; when limestone is included in the auxiliary cementitious material, the average specific surface area of the limestone is 350-400m 2 / kg.

[0017] In an alternative embodiment, when the tempering component includes sulphoaluminate cement, the average specific surface area of the sulphoaluminate cement is greater than 350 m 2 / kg; when the conditioning component includes waste concrete recycled fine powder, the average specific surface area of waste concrete recycled fine powder is 600-800m 2 / kg; when the conditioning component includes a lime-gypsum mixture, the average specific surface area of the lime-gypsum mixture is 350-400m 2 / kg.

[0018] Limiting the average specific surface area of the tempering component and the supplementary cementitious material to the above range is helpful to improve the activation effect between the tempering component and the supplementary cementitious material. A too small specific surface area may result in low activity of the supplementary cementitious material, fewer surface nucleation sites, and insufficient effect of the tempering component. A too large specific surface area may result in too rapid hydration reaction and too fast setting time, affecting the hydration process of the cement.

[0019] The present invention also provides a method for preparing the low-carbon cement, comprising the following steps:

[0020] The components are mixed and ground to obtain the low-carbon cement.

[0021] In an optional embodiment, the mixing and grinding of the components comprises:

[0022] (1) mixing cement clinker and gypsum and then performing a first grinding to obtain a mixture;

[0023] (2) subjecting the auxiliary cementitious material and the tempering component to a second grinding, and mixing the mixture obtained in step (1) after the second grinding to obtain the low-carbon cement;

[0024] Optionally, a grinding aid is added during the second grinding process.

[0025] In an optional embodiment, the average specific surface area of the mixture in step (1) is 350-400m 2 / kg.

[0026] In an optional embodiment, the second grinding of the auxiliary gelling material and the tempering component in step (2) comprises:

[0027] (2.1) Mixing the auxiliary cementitious material and the tempering component and then grinding them;

[0028] Alternatively, (2.2) the auxiliary cementitious material and the tempering component are ground separately.

[0029] In an optional embodiment, the average specific surface area of the mixture obtained by grinding in step (2.1) is 350-550m 2 / kg.

[0030] In an optional embodiment, in step (2.2), the auxiliary cementitious material includes slag, and the average specific surface area of the ground slag is 450-550m 2 / kg; when fly ash is included in the auxiliary cementitious material, the average specific surface area of the fly ash after grinding is 600-800m 2 / kg; when the auxiliary cementitious material includes sandstone, the average specific surface area of the ground sandstone is 350-400m 2 / kg; When the auxiliary cementitious material includes pozzolanic mixed materials, the average specific surface area of the ground pozzolanic mixed materials is 600-800m 2 / kg; when limestone is included in the auxiliary cementitious material, the average specific surface area of the ground limestone is 350-400m 2 / kg.

[0031] In an optional embodiment, in step (2.2), when the tempering component includes sulphoaluminate cement, the average specific surface area of the ground sulphoaluminate cement is greater than 350 m 2 / kg; when the conditioning component includes waste concrete recycled fine powder, the average specific surface area of the ground waste concrete recycled fine powder is 600-800m 2 / kg; when the conditioning component includes a lime-gypsum mixture, the average specific surface area of the ground lime-gypsum mixture is 350-400m 2 / kg.

[0032] The technical solution of the present invention has the following advantages:

[0033] 1. The present invention provides a low-carbon cement comprising the following components in parts by weight: 15-47 parts of cement clinker, 0.5-7 parts of gypsum, 47-71 parts of auxiliary cementitious material, 0.1-11 parts of a tempering component, and 0-0.1 parts of a grinding aid; the tempering component comprises one or more of a lime-gypsum mixture, sulphoaluminate cement, and recycled fine powder from waste concrete.

[0034] The low-carbon cement proposed in the present invention can significantly reduce the amount of clinker used, reduce CO2 emissions during the cement production process, and at the same time ensure that the cement has good strength.

[0035] The tempering components selected in the present invention are easy to obtain, low in cost, and highly feasible. The present invention uses a lime-gypsum mixture as a tempering component. During the grinding process after co-addition, the solid waste in the auxiliary cementitious material undergoes an amorphous transformation due to the mineral lattice distortion on the particle surface during mechanical fine grinding, and the silicoaluminate components exhibit an active state. Subsequently, a hydration reaction occurs in the CaO-CaSO4-H2O system during cement application to generate C-(A)-SH (hydrated calcium aluminosilicate gel) and AFt (ettringite), thereby generating strength. Sulphoaluminate cement is used as a tempering component to exert its early rapid hydration effect and improve the early strength of the cement. Waste concrete recycled micropowder is used as a tempering component to release CSH seeds (hydrated calcium silicate seeds) to induce the bridging oxygen bond breakage of SiO2 and Al2O3, promote the dissociation and repolymerization of the active silicoaluminate components, and thus improve the strength of the cement.

[0036] By limiting the amount of each component within the scope of the present invention, the present invention can ensure an appropriate content of gypsum (including gypsum ground together with cement clinker, gypsum in the lime-gypsum mixture as a tempering component, and gypsum contained in other cement components (for example, gypsum is also added to sulphoaluminate cement during the production process, so sulphoaluminate cement also contains gypsum)), effectively adjust the strength of the consolidated body, promote the hydration of silicon-containing components while ensuring the formation and stability of AFt (ettringite), and facilitate the formation of C-(A)-SH (hydrated calcium aluminosilicate gel), thereby avoiding the risk of excessive growth of AFt (ettringite) and excessive expansion caused by the addition of too much gypsum.

[0037] 2. Auxiliary cementitious materials include one or more of fly ash, slag, sandstone, limestone and volcanic ash mixed materials.

[0038] The low-carbon cement proposed by the present invention effectively utilizes industrial solid waste, reduces the cost and environmental risks of solid waste disposal, and also reduces the consumption of natural resources in producing silicate cement clinker.

[0039] 3. The present invention provides a method for preparing the low-carbon cement, comprising the following steps: mixing and grinding the components to obtain the low-carbon cement. The mixing and grinding of the components comprises: (1) mixing cement clinker and retarder and then performing a first grinding to obtain a mixture; (2) performing a second grinding on the auxiliary cementitious material and the tempering component, and after the second grinding, mixing them with the mixture obtained in step (1) to obtain the low-carbon cement. The second grinding of the auxiliary cementitious material and the tempering component in step (2) comprises: (2.1) mixing the auxiliary cementitious material and the tempering component and then grinding them; or, (2.2) grinding each component of the auxiliary cementitious material and the tempering component independently.

[0040] When preparing low-carbon cement, the present invention can either independently grind each component to control the particle size distribution, or grind the components after mixing to control the total particle size to ensure activity. The former has a better effect, and the latter has a simple process. Both methods can achieve the preparation of cement.

[0041] 4. The present invention controls the specific surface area of the material after the second grinding, and can significantly increase the surface activity of the auxiliary gelling material through lattice distortion, thereby promoting the increase of C-(A)-SH (hydrated calcium silicate aluminate gel) and the improvement of strength.

[0042] In summary, the present invention reduces the amount of clinker used and ensures the strength of low-carbon cement while reducing carbon emissions by coordinating the auxiliary cementitious material system, using tempering components, controlling the specific surface area, and other means. DETAILED DESCRIPTION

[0043] The following examples are provided for a better understanding of the present invention and are not intended to limit the best mode of implementation. They do not limit the content and scope of protection of the present invention. Any product identical or similar to the present invention obtained by anyone under the guidance of the present invention or by combining the features of the present invention with other prior arts shall fall within the scope of protection of the present invention.

[0044] Specific experimental steps or conditions not specified in the examples can be carried out according to the conventional experimental steps or conditions described in the literature in this field. The reagents or instruments used without specifying the manufacturer are all conventional reagents that can be purchased commercially.

[0045] In the embodiment of the present invention, the Portland cement clinker was purchased from Pingyi Zhonglian Cement Co., Ltd.

[0046] Desulfurized gypsum and anhydrite were purchased from Pingyi Zhonglian Cement Co., Ltd.; quicklime was purchased from Tianjin Damao Chemical Reagent Factory;

[0047] Fly ash, slag, sandstone and limestone were purchased from Pingyi Zhonglian Cement Co., Ltd. Among the pozzolanic mixed materials, volcanic ash was provided by Yunnan Tianshan Cement Co., Ltd., burnt clay was provided by China National Materials Construction Co., Ltd., sulphoaluminate cement was purchased from Tangshan Polar Bear Building Materials Co., Ltd., waste concrete recycled micropowder was purchased from Anhui Haidun Building Materials Co., Ltd., and triethanolamine was purchased from Tianjin Damao Chemical Reagent Factory.

[0048] Example 1

[0049] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0050] 15 parts of cement clinker (Portland cement clinker), 5 parts of gypsum (anhydrite), 68.97 parts of auxiliary cementitious materials (18.5 parts of fly ash, 47.97 parts of slag, 0 parts of sandstone, 2.5 parts of limestone and 0 parts of pozzolanic mixed materials), 11 parts of tempering components (11 parts of lime-gypsum mixture (including 6 parts of quicklime and 5 parts of anhydrite), 0 parts of sulphoaluminate cement, 0 parts of waste concrete recycled fine powder) and 0.03 parts of grinding aid (triethanolamine).

[0051] The preparation method comprises the following steps:

[0052] The cement clinker and gypsum are mixed and ground to obtain an average specific surface area of 400m 2 / kg mixture; after mixing the auxiliary cementitious material and the tempering component, add the grinding aid and grind to an average specific surface area of 550m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0053] Example 2

[0054] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0055] 18.4 parts of cement clinker (Portland cement clinker), 0.5 parts of gypsum (desulfurized gypsum), 71 parts of auxiliary cementitious materials (15 parts of fly ash, 40 parts of slag, 1 part of sandstone, 5 parts of limestone and 10 parts of pozzolanic mixed materials (volcanic ash)), 10 parts of tempering components (0 parts of lime-gypsum mixture, 5 parts of sulphoaluminate cement, 5 parts of waste concrete recycled fine powder) and 0.1 parts of grinding aid (triethanolamine).

[0056] The preparation method comprises the following steps:

[0057] The cement clinker and gypsum are mixed and ground to obtain an average specific surface area of 400m 2 / kg of mixture; after mixing the auxiliary cementitious material and the tempering component, add the grinding aid and grind to an average specific surface area of 500m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0058] Example 3

[0059] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0060] 28.2 parts of cement clinker (Portland cement clinker), 1.2 parts of gypsum (desulfurized gypsum), 68.6 parts of auxiliary cementitious materials (10 parts of fly ash, 48 parts of slag, 0 parts of sandstone, 5 parts of limestone and 5.6 parts of pozzolanic mixed materials (volcanic ash)), 2 parts of tempering components (0 parts of lime-gypsum mixture, 2 parts of sulphoaluminate cement, 0 parts of waste concrete recycled fine powder) and 0 parts of grinding aid (triethanolamine).

[0061] The preparation method comprises the following steps:

[0062] The cement clinker and gypsum were mixed and ground to obtain an average specific surface area of 380m 2 / kg of mixture; Grind each component of the auxiliary cementitious material and the tempering component independently until the average specific surface area of the fly ash is 800m 2 / kg, the average specific surface area of slag is 450m 2 / kg, the average specific surface area of limestone is 400m 2 / kg, the average specific surface area of the volcanic ash mixed material is 800m 2 / kg, the average specific surface area of sulphoaluminate cement is 400m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0063] Example 4

[0064] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0065] Cement clinker (Portland cement clinker) 33 parts, gypsum (anhydrite) 4.7 parts, auxiliary cementitious materials 57.3 parts (fly ash 0 parts, slag 56 parts, sandstone 0 parts, limestone 0 parts and pozzolanic mixed materials (volcanic ash) 1.3 parts), tempering components 5 parts (lime-gypsum mixture 0 parts, sulphoaluminate cement 0 parts, waste concrete recycled fine powder 5 parts) and grinding aid (triethanolamine) 0 parts.

[0066] The preparation method comprises the following steps:

[0067] The cement clinker and gypsum are mixed and ground to obtain an average specific surface area of 400m 2 / kg of mixture; after mixing the auxiliary cementitious material and the tempering component, grind them to an average specific surface area of 550m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0068] Example 5

[0069] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0070] Cement clinker (Portland cement clinker) 37 parts, gypsum (desulfurized gypsum) 7 parts, auxiliary cementitious materials 53 parts (fly ash 15 parts, slag 25 parts, sandstone 5 parts, limestone 5 parts and pozzolanic mixed materials (burned clay) 3 parts), tempering components 3 parts (lime-gypsum mixture 0 parts, sulphoaluminate cement 0 parts, waste concrete recycled fine powder 3 parts) and grinding aid (triethanolamine) 0 parts.

[0071] The preparation method comprises the following steps:

[0072] The cement clinker and gypsum were mixed and ground to obtain an average specific surface area of 380m 2 / kg of mixture; Grind each component of the auxiliary cementitious material and the tempering component independently until the average specific surface area of the fly ash is 600m 2 / kg, the average specific surface area of slag is 550m 2 / kg, the average specific surface area of sandstone is 400m 2 / kg, the average specific surface area of limestone is 380m 2 / kg, the average specific surface area of the volcanic ash mixed material is 600m 2 / kg, the average specific surface area of recycled fine powder from waste concrete is 800m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0073] Example 6

[0074] This embodiment provides a low-carbon cement comprising the following components in parts by weight:

[0075] 47 parts of cement clinker (Portland cement clinker), 5.9 parts of gypsum (desulfurized gypsum), 47 parts of auxiliary cementitious materials (10 parts of fly ash, 25 parts of slag, 2 parts of sandstone, 5 parts of limestone and 5 parts of pozzolanic mixed materials (burned clay)), 0.1 parts of tempering components (0 parts of lime-gypsum mixture, 0 parts of sulphoaluminate cement, 0.1 parts of waste concrete recycled fine powder) and 0 parts of grinding aid (triethanolamine).

[0076] The preparation method comprises the following steps:

[0077] The cement clinker and gypsum were mixed and ground to obtain an average specific surface area of 350m 2 / kg of mixture; after mixing the auxiliary cementitious material and the tempering component, grind them to an average specific surface area of 400m 2 / kg, then add the above-mentioned mixed materials and mix them evenly to obtain low-carbon cement.

[0078] Comparative Example 1

[0079] This comparative example provides a cement that is substantially the same as Example 1, except that the mass fraction of the tempering component is 16.8 parts ((16.8 parts of lime-gypsum mixture (including 11.8 parts of quicklime and 5 parts of anhydrite), 0 parts of sulphoaluminate cement, and 0 parts of waste concrete recycled fine powder)).

[0080] The preparation method is the same as that in Example 1.

[0081] Comparative Example 2

[0082] This comparative example provides a cement that is substantially the same as Example 3, except that it does not contain a tempering component.

[0083] The preparation method is substantially the same as that of Example 3, except that no tempering component is added.

[0084] Comparative Example 3

[0085] This comparative example provides a cement that is substantially the same as Example 5, except that it does not contain a tempering component.

[0086] The preparation method is substantially the same as that of Example 5, except that no tempering component is added.

[0087] Comparative Example 4

[0088] This comparative example provides a cement that is substantially the same as Example 4, except that it does not contain a tempering component and the mass fraction of cement clinker (Portland cement clinker) is 73 parts.

[0089] The preparation method is substantially the same as that of Example 4, except that no tempering component is added.

[0090] The formulations of different cements in Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1.

[0091] Table 1 Formula of different cements (unit: mass parts)

[0092]

[0093]

[0094] Experimental example

[0095] Compressive strength tests were conducted on mortar prepared with the low-carbon cement in Examples 1-6 and the cement in Comparative Examples 1-4 in accordance with GB / T 17671-1999, "Test Method for Cement Mortar Strength (ISO Method)." Mortars were prepared with a water-cement ratio of 0.5 to form 40 mm × 40 mm × 160 mm mortar specimens. Standard curing was followed, and the 3-day and 28-day compressive strengths of the different mortar specimens were measured. The compressive strength test results for the different mortar specimens are reported in Table 2. Furthermore, the total carbon emission factors for the components used in the low-carbon cement in Examples 1-6 and the cement in Comparative Examples 1-4 were calculated, and the results are reported in Table 2. The calculation is based on the following: Portland cement clinker is 860kg CO2 eq / t, anhydrite is 32.8kg CO2 eq / t, desulfurized gypsum is 105.3kg CO2 eq / t, sulfoaluminate cement is 800kg CO2 eq / t, slag is 109kg CO2 eq / t, fly ash is 34.5CO2 eq / t, limestone is 430kg CO2 eq / t, waste concrete recycled fine powder is 30kg CO2 eq / t, quicklime is 1190kg CO2 eq / t, sandstone is 46.5kg CO2eq / t, burnt clay is 482kg CO2 eq / t, pozzolana is 280kg CO2 eq / t, and triethanolamine is 790kgCO2 eq / t.

[0096] Table 2 Performance test results of different cements

[0097]

[0098]

[0099] It can be seen from Table 2 that the 3d compressive strength of the low carbon cement prepared in Examples 1 to 6 reaches 20.3MPa-23.3MPa, the 28d compressive strength reaches 44.6MPa-49.9MPa, and the total carbon emission factor is between 282.86CO2eq / t-487.67CO2eq / t. The early strength (3d compressive strength) of the low carbon cement obtained in Examples 1 to 6 is significantly higher than that of the cement obtained in Comparative Examples 1 to 3. And compared with the cement obtained in Comparative Examples 1 to 3, the 28d compressive strength of the low carbon cement obtained in Examples 1 to 6 is also greatly improved. Regarding Comparative Example 4, its compressive strength is equivalent to that of the low carbon cement prepared in Examples 1 to 6, but its carbon emission factor reaches 511.39CO2eq / t. It can be seen that the low carbon cement obtained under the specific composition and dosage ratio of the present application can ensure that the cement has excellent strength while reducing carbon emissions.

[0100] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A low carbon cement, characterized in that: Contains the following components in parts by mass: 15-47 parts of cement clinker, 0.5-7 parts of gypsum, 47-71 parts of auxiliary cementitious materials, 0.1-11 parts of conditioning components and 0-0.1 parts of grinding aids; The conditioning components include one or more of lime-gypsum mixture, sulphoaluminate cement and waste concrete recycled fine powder.

2. The low carbon cement according to claim 1, characterized in that At least one of the following conditions is met: (1) The cement clinker comprises Portland cement clinker; (2) The gypsum includes one or both of desulfurized gypsum and anhydrite; (3) The average specific surface areas of the cement clinker and gypsum are 350-400m 2 / kg; (4) The auxiliary cementitious material includes slag; Optionally, the auxiliary cementitious material further comprises one or more of fly ash, sandstone, limestone and pozzolanic mixed materials; Optionally, the pozzolanic mixed material includes one or both of volcanic ash and burnt clay; (5) The grinding aid includes one or more of triethanolamine, triisopropanolamine, ethylene glycol, propylene glycol, glycerol, polymeric alcohol amine, polymeric polyol, sodium fatty acid and calcium chloride; (6) The gypsum in the lime-gypsum mixture is one or both of desulfurized gypsum and anhydrite.

3. The low carbon cement according to claim 1 or 2, characterized in that: The average specific surface areas of the auxiliary gelling material and the tempering component are 350-550m 2 / kg.

4. The low carbon cement according to claim 2, characterized in that At least one of the following conditions is met: (1) Auxiliary cementitious materials include slag, the average specific surface area of slag is 450-550m 2 / kg; Optionally, when fly ash is included in the auxiliary cementitious material, the average specific surface area of the fly ash is 600-800m 2 / kg; Optionally, when the auxiliary cementitious material includes sandstone, the average specific surface area of the sandstone is 350-400m 2 / kg; Optionally, when the auxiliary cementitious material includes a pozzolanic mixed material, the average specific surface area of the pozzolanic mixed material is 600-800m 2 / kg; Optionally, when the auxiliary cementitious material includes limestone, the average specific surface area of the limestone is 350-400m 2 / kg; (2) When the tempering component includes sulphoaluminate cement, the average specific surface area of sulphoaluminate cement is greater than 350m 2 / kg; (3) When the tempering component includes waste concrete recycled fine powder, the average specific surface area of waste concrete recycled fine powder is 600-800m 2 / kg; (4) When the tempering component includes a lime-gypsum mixture, the average specific surface area of the lime-gypsum mixture is 350-400m 2 / kg.

5. The method for preparing low carbon cement according to any one of claims 1 to 4, characterized in that: The following steps are involved: The components are mixed and ground to obtain the low-carbon cement.

6. The method for preparing low carbon cement according to claim 5, characterized in that: The mixing and grinding of the components comprises: (1) mixing cement clinker and gypsum and then performing a first grinding to obtain a mixture; (2) subjecting the auxiliary cementitious material and the tempering component to a second grinding, and mixing the mixture obtained in step (1) after the second grinding to obtain the low-carbon cement; Optionally, a grinding aid is added during the second grinding process.

7. The method for preparing low carbon cement according to claim 6, characterized in that: The average specific surface area of the mixture in step (1) is 350-400m 2 / kg.

8. The method for preparing low carbon cement according to claim 6, characterized in that: The second grinding of the auxiliary gelling material and the tempering component in step (2) comprises: (2.1) Mixing the auxiliary cementitious material and the tempering component and then grinding them; Alternatively, (2.2) the auxiliary cementitious material and the tempering component are ground separately.

9. The method for preparing cement according to claim 8, characterized in that: The average specific surface area of the mixture obtained by grinding in step (2.1) is 350-550m 2 / kg.

10. The method for preparing low carbon cement according to claim 8, characterized in that: At least one of the following conditions is met: (1) In step (2.2), the auxiliary cementitious material includes slag, and the average specific surface area of the ground slag is 450-550m 2 / kg; Optionally, in step (2.2), when the auxiliary cementitious material includes fly ash, the average specific surface area of the ground fly ash is 600-800m 2 / kg; Optionally, in step (2.2), when the auxiliary cementitious material includes sandstone, the average specific surface area of the ground sandstone is 350-400m 2 / kg; Optionally, in step (2.2), when the auxiliary cementitious material includes a pozzolanic mixed material, the average specific surface area of the ground pozzolanic mixed material is 600-800m 2 / kg; Optionally, in step (2.2), when the auxiliary cementitious material includes limestone, the average specific surface area of the ground limestone is 350-400m 2 / kg; (2) In step (2.2), when the tempering component includes sulphoaluminate cement, the average specific surface area of the ground sulphoaluminate cement is greater than 350 m 2 / kg; (3) When the tempering component includes waste concrete recycled fine powder, the average specific surface area of the ground waste concrete recycled fine powder is 600-800m 2 / kg; (4) When the tempering component includes a lime-gypsum mixture, the average specific surface area of the ground lime-gypsum mixture is 350-400m 2 / kg.

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