A CEMENTITIOUS MATERIAL BASED ON CALCINATED CLAY AND ITS PREPARATION PROCESS
The development of a cement material using calcined clay, an alkaline activator, and specific raw materials addresses the environmental and performance issues of traditional cement, resulting in a low-carbon, high-strength cement solution.
Patent Information
- Application Number
- FR2023015405
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-10-27
- Filing Date
- 2023-12-28
- Publication Date
- 2025-05-02
AI Technical Summary
The production of traditional cement contributes significantly to environmental pollution, particularly due to high carbon dioxide emissions, and cement materials based on calcined clay face issues with degradation of initial resistance and limited application scope.
A cement material based on calcined clay is developed, incorporating an alkaline activator and specific raw materials such as calcined clay, steel slag, and cement clinker, which are mixed and ground to produce a cement material with enhanced mechanical properties and reduced carbon footprint.
The proposed cement material achieves improved mechanical properties, including increased compression resistance, and significantly reduces energy consumption and carbon emissions, thus addressing the environmental and performance limitations of traditional cement materials.
Abstract
Description
Title of the invention: A CEMENTITIOUS MATERIAL BASED ON CALCINED CLAY AND METHOD FOR PREPARING THE SAME Technical field
[0001] The present invention relates to the field of construction materials, and specifically to a cementitious material based on calcined clay and its preparation process. STATE OF THE ART
[0002] With the continuous development of urbanization, the demand for cement is increasing, however, cement production aggravates environmental pollution. According to statistics, the production of one ton of cement generates about 0.86 tons of carbon dioxide (CO2). Currently, the total global cement production is 3.6 billion tons, the CO2 emissions of the cement industry account for 5~8% of the total amount of human-made CO2 released, it is estimated that in 2030, the annual cement production will reach 5 billion tons, the huge amount of CO2 released will aggravate the greenhouse effect. To achieve the emission peak and carbon neutrality, it is urgent to solve the environmental pollution problem caused by cement.
[0003] Calcined clay is an industrial clay obtained by heating a waste clay raw material between 700°C and 850°C. When used to make a cementitious material, it not only makes efficient use of waste clay, but compared with conventional cement clinker, it reduces energy consumption and carbon emissions during its production process. In addition, calcined clay has a high volcanic ash activity, the interaction between calcined clay and clinker or ordinary Portland cement benefits the further production of CO3-AFM phase and C-(A)-SH gel in the system, therefore the produced calcined clay cement materials have a smaller pore diameter than Portland cement, which benefits the development of mechanical properties.
[0004] For these purposes, Chinese patent CN 116409948 A provides a low-carbon cementitious composite material with recycled cement powder, its preparation method and applications, in which small amounts of calcined clay and recycled cement powder are added to cement clinker to prepare the low-carbon cementitious composite material, however once the calcined clay is incorporated into the cement, although its subsequent hardness is significantly increased, it presents a problem of degradation of the initial strength.
[0005] Therefore, it is necessary to provide a cementitious material with low energy consumption and high early strength, this cementitious material being capable of fully utilizing the characteristics of low energy consumption, low carbon emissions and high volcanic ash activity of calcined clay. CONTENT OF THE INVENTION
[0006] To this end, the aim of the present invention is to provide a cementitious material based on calcined clay and its preparation method, capable of solving the previous problems of degradation of the initial strength and low scope of application of cementitious materials based on calcined clay.
[0007] In order to solve the above-mentioned problems, the present invention uses the technical scheme below:
[0008] A cementitious material based on calcined clay and its preparation process, comprising the following steps:
[0009] Each component of base material is taken and mixed with an alkaline activator, after grinding, a cementitious material based on calcined clay is obtained.
[0010] Said base materials are selected from one or more of the following elements, calcined clay, steel slag, slag, cement clinker, gypsum: and / or, said alkaline activator comprises one or more elements from calcium formate, calcium lignosulfonate, sodium sulfate, calcium chloride, sodium carbonate, sodium silicate and sodium hydroxide.
[0011] Preferably, said alkaline auxiliary activator comprises calcium formate, sodium hydroxide and sodium silicate in a mass ratio of 1-3: 9-11: 0.3-0.8.
[0012] Said alkaline activator represents a mass content of 0.1-10% of said base material; preferably, said alkaline activator represents a mass content of 5-7% of said base material; and / or said alkaline activator is in solid state, the solid content of the alkaline activator is 95-100%.
[0013] Said base material comprising, in mass percentage: 30-60% calcined clay, 3-30% steel slag, 30-60% slag, 4-25% cement clinker and 0-5% gypsum.
[0014] Preferably, said base material comprises, in mass percentage, the following raw materials: 30-60% calcined clay, 3-5% steel slag, 30-60% slag, 4-6% cement clinker and 0.5-2% gypsum.
[0015] In said calcined clay A12O3> 15%, Al / Si > 0.3, CaO < 3%, SO3 < 3%; preferably, in said calcined clay the content of said calcined clay in A12O3 is > 20%, the index of the compressive strength activity at 28 days is greater than 80%; more preferably, the chemical composition of said calcined clay comprises, in mass percentage: A12O3: 25-40%, SiO2: 60-75%, K2O + Na2O < 3%, CaO + MgO < 5%, SO3< 3%.
[0016] Said steel slag is a slag aggregate composed of calcium, iron, silica and magnesium oxides from the steel industry, in said steel slag, the mass content of CaO is 30-60%, the mass content of SiO2 is 10-30%, the mass content of MgO is 2-20%, the mass content of Fe2O3 is 10-40%; preferably, the chemical composition of said steel slag comprises, in mass percentage: CaO: 38-50%, Fe2O3: 25-35%, SiO2: 14-20%, MgO: 4.5-12%, MnO: < 5%, Al2O3: 1-10%, CaF2 < 2%, SO3 < 5%.
[0017] Said slag is ground granulated blast furnace slag or air-cooled blast furnace slag; and / or, said cement clinker is Portland cement clinker meeting the requirements of GB / T 21372 "Portland Cement Clinker"; and / or said gypsum is at least one of desulfurization gypsum, mirabilite gypsum, phosphogypsum and titanium gypsum.
[0018] Before being mixed, said base material undergoes a drying treatment, and / or the powder obtained after grinding must still be sieved by a sieve with pores of 60-100 pm, the weight of sieving residue of said powder is 0-10%.
[0019] Said cement clinker and said calcined clay are all dry materials, the water content of which in the product on the market is less than 1%, no further explanation being necessary.
[0020] Said alkaline activator is also a solid, its water composition is mainly water of crystallization, chemically bound water / hydroxyl group, furthermore the quantities used are very small, water control is not necessary.
[0021] The present invention further provides a cementitious material based on calcined clay.
[0022] Beneficial effects of the present invention
[0023] 1. The present invention provides a cementitious material based on calcined clay comprising a base material and an alkaline activator, said base material comprising, in mass percentage: 30-70% calcined clay, 0-30% steel slag, 10-70% slag, 0-25% cement clinker and 0-5% gypsum, with the combination of the calcined clay and the slag in the proportions specified above, then coupled with the alkaline activator, as well as the combination of many raw materials and the alkaline activator, the cementitious material has the advantages of rapid strength formation and high final strength, overcoming the defects of long setting and slow hydration reaction of other cementitious materials based on calcined clay, and achieves a marked increase in the compressive strength of the cementitious material.
[0024] 2. The present invention provides a cementitious material based on calcined clay, the alkaline activator comprises one or more of calcium formate, calcium lignosulfonate, sodium sulfate, calcium chloride, sodium carbonate, sodium silicate and sodium hydroxide, particularly when the alkaline auxiliary activator comprises calcium formate, sodium hydroxide and sodium silicate in a mass ratio of 1-3:9-11:0.3-0.8.
[0025] 3. The present invention provides a cementitious material based on calcined clay, the alkaline activator represents a mass content of 0.1-10% of the base material; in particular when the alkaline activator represents a controlled mass content of 5-7% of the base material, it is possible to further stimulate the reaction between the cementitious components, and thus to increase the resistance of the cementitious material to fracture and the compressive strength.
[0026] 4. The present invention provides a cementitious material based on calcined clay, the percentage contents of each component of the base material are maintained at: 30-60% calcined clay, 3-30% steel slag, 30-60% slag, 4-25% cement clinker and 0-5% gypsum, preferably, percentage contents of each component of the base material are maintained at: 30-60% calcined clay, 3-30% steel slag, 30-60% slag, 4-25% cement clinker and 0-5% gypsum, preferably, which further increases the performance of the cementitious material. More preferably, the percentage contents of each component of the base material are maintained at: 30-60% calcined clay, 3-5% steel slag, 30-60% slag, 4-6% cement clinker and 0.5-2% gypsum, which allows to considerably increase the compressive strength of the obtained cementitious material and results in a compressive strength at 3 days, 7 days and 28 days in water of 20.1-35.6 MPa, 24.2-46.1 MPa, 34.5-65.8 MPa respectively.
[0027] 5. The present invention provides a cementitious material based on calcined clay, in which the control of the chemical contents and compositions of the base material promotes a relatively optimal ratio of the chemical substances of the components of the cementitious material, which further increases the compressive strength and safety of the cementitious material.
[0028] 6. The present invention provides a method for preparing cementitious material Based on calcined clay, this process is simple, its energy consumption is low, solidification is fast, strength is high and its applications are wide; the preparation process is easy, saving production costs and energy, and environmentally friendly due to low carbon emissions; from the technical, economic and environmental points of view, the present invention has great social, economic and environmental benefits, its feasibility is high and it is suitable for wide dissemination. METHODS OF IMPLEMENTATION
[0029] The embodiments provided below are intended for a better understanding of the present invention, they are not limited to the preferred embodiments, and do not constitute a limit to the content or scope of protection of the present invention, any product identical or similar to the present invention inspired by the present invention or obtained by combining the present invention with another prior technical characteristic is covered by the scope of protection of the present invention.
[0030] The concrete experimental steps or conditions not mentioned in the embodiments can be carried out according to the common experimental steps or conditions described in documents relating to the present technical field. The reagents or apparatuses for which the manufacturer is not mentioned are all common reagent products obtained on the market.
[0031] Embodiments 1-10 provide a cementitious material based on calcined clay, their compositions are shown in Table 1, the cementitious materials of each embodiment are prepared according to the following steps:
[0032] Each component of base material is taken according to Table 1, mixed with the alkali activator, the prepared materials are mixed and ground homogeneously to be sieved on a sieve whose pore diameter is 80 qm, and the weight of sieving residue of the powder is 10%, the cementitious material based on the calcined clay is thus obtained.
[0033] [Tables 1] Base material Alkaline reagent Calcined clay Steel slag Slag Cement clinker Gypsum Sodium carbonate Calcium lignosulfonate Sodium hydroxide Sodium silicate Calcium formate Calcium chloride Implementation method 1 40 24 30 5 1 6 0.5 0 0 0 0 Implementation method 2 40 24 30 5 1 6 0 0 0 0.5 0 Implementation method 3 40 24 30 5 1 4 0 0 0 0.5 0 Implementation method 4 40 24 30 5 1 0 0 1 5.0 0.5 0 Implementation method 5 60 4 30 5 1 0 0 1 5.0 0.5 0 Embodiment 6 60 30 4 5 1 0 0 1 5.0 0.5 0 Embodiment 7 30 24 40 5 1 0 0 1 5.0 0.5 0 Embodiment 8 30 4 60 5 1 0 0 1 5.0 0.5 0 Embodiment 9 30 14 40 15 1 0 0 1 5.0 0.5 0 Embodiment 10 70 0 10 25 5 0 0 1 5.0 0.5 0 Comparison 1 40 24 30 5 1 0 0 0 0 0 6.5 Comparison 2 40 24 30 5 1 0 0 0 0 0 0 Composition of cementitious material (kg)
[0034] Wherein, the Embodiments and Comparisons utilize the chemical components of calcined clay of Table 2
[0035] [Tables2] Materials A12O3 SiO2 Na2O Fe2O3 CaO k2o so3 Calcined clay 26.36 70.27 0.01 0.8 0.18 1.47 0.33 Chemical components (%) of calcined clay
[0036] Wherein, Embodiments 1-9 and Comparisons 1-2 utilize the steel slag chemical components of Table 3
[0037] [Tables3] Materials CaO SiO2 MgO Fe2O3 CaF2 MnO A12O3 so3 Losses Steel slag 38.71 15.55 5.9 26.48 0.02 2.29 3.72 0.32 3.11 Chemical components (%) of steel slag
[0038] Wherein, the embodiments and comparison utilize the slag chemical components of Table 4
[0039] [Tables4] Materials CaO SiO2 MgO A12O3 MnO Fe2O3 SO3 Slag 38.44 30.52 9.11 16.32 0.52 0.31 2.27
[0040]
[0041] Chemical components (%) of slag Wherein, the embodiments and comparison use the cement clinker chemical components of Table 5 [Tables5] Materials CaO MgO A12O3 SiO2 TiO2 Fe2O3 K2O Losses Cement clinker 64.82 3.37 4.11 20.77 0.36 3.36 0.88 1.96 Chemical components (%) of cement clinker
[0042] Wherein, the embodiments and comparison utilize the gypsum chemical components of Table 6
[0043] [Tableauxô] Material X A12O3 SiO2 P2O5 SO3 K2O CaO Fe2O3 MgO Other Losses Gypsum 1.74 2.46 0.02 47.6 0.26 35.13 0.47 0.47 1.66 10.02 Chemical components (%) of gypsum
[0044] Compressive strength tests and stability tests are carried out on the cementitious materials obtained in Embodiments 1-10 and Comparisons 1-2.
[0045] Compressive strength tests: mixing and forming are carried out in accordance with the provisions of GB / T17671-1999 “Method for measuring the strength of cement mortar (ISO standard)”, and then cured in water: the mortar sample is cured at 20°C ± 2°C in a curing box equipped with a membrane and the relative humidity of which is not less than 90%, the membrane is removed after 1 day, the sample without membrane is placed in water at 20°C ± 1°C for 28 days, the compressive strength is measured.
[0046] Stability test: According to the standard “Test method on the requirements of normal consistency, hardening time and stability of Portland cement” (GB / T1346-2011), the Le Chatelier method is used to measure the hardening time and stability of the cementitious materials of Embodiments 1-10.
[0047] The test results are shown in Tables 7 and 8.
[0048] Table 7 Compressive strength at 3, 7 and 28 days of the cementitious materials obtained in Embodiments 1-10 and Comparison 1-2.
[0049] [Tables?] Compressive strength 3d / MPa 7d / MPa 28d / MPa Embodiment 1 21.1 26.3 37.5 Embodiment 2 22.3 27.1 38.7 Embodiment 3 20.5 24.8 35.4 Embodiment 4 25.5 36.8 52.6 Embodiment 5 34.5 43.3 61.8 Embodiment 6 20.4 24.2 34.5 Embodiment 7 25.9 37.6 53.7 Embodiment 8 35.6 46.1 65.8 Embodiment 9 26.9 38.9 55.5 Embodiment 10 20.1 26.3 34.5 Comparison 1 5.6 12.5 18.6 Comparison 2 1.5 5.5 7.2
[0050] The calcined clay-based cementitious materials obtained in the embodiments of the present invention have a 3-day compressive strength > 20.0 MPa, a 7-day compressive strength > 24.0 MPa, a 28-day compressive strength > 35.0 MPa.
[0051] [Tables8] Sample Curing time (min) Stability (Le Chatelier method) Initial time Final time Distance increase in mm Result Implementation method 1 130 260 0.5 Compliant Implementation method 2 110 180 1.5 Compliant Implementation method 3 160 330 1.5 Compliant Implementation method 4 65 125 1.0 Compliant Implementation method 5 55 75 1.5 Compliant Implementation method 6 100 155 0.5 Compliant Implementation method 7 55 85 1.0 Compliant Implementation method 8 50 70 1.5 Compliant Implementation method 9 60 85 1.5 Compliant Implementation method 10 260 450 0.5 Compliant
[0052] Hardening time and stability of the cementitious materials obtained in Embodiments 1-10.
[0053] The results show that Embodiments 1-10 all meet the provisions of GB175-2020, and can be used for cement.
[0054] Of course, the above-mentioned embodiments are only examples intended to clarify the operations, and do not constitute a limitation to the embodiments. Based on the above-mentioned description, the person skilled in the art can make various forms of modifications and variations. It is neither necessary nor possible to describe all the possibilities here. All modifications and variations which are obviously inspired therefrom are covered by the scope of protection of the creation of the present invention.
Claims
Claims
1. A cementitious material based on calcined clay, characterized in that it comprises a base material and an alkaline activator, said base material comprising, in mass percentage: 30-70% calcined clay, 0-30% steel slag, 10-70% slag, 0-25% cement clinker and 0-5% gypsum.
2. A calcined clay-based cementitious material according to claim 1, characterized in that said alkaline activator comprises one or more of calcium formate, calcium lignosulfonate, sodium sulfate, calcium chloride, sodium carbonate, sodium silicate and sodium hydroxide; preferably, said alkaline activator comprises calcium formate, sodium hydroxide and sodium silicate in a mass ratio of 1-3: 9-11: 0.3-0.
8.
3. A calcined clay-based cementitious material according to claim 1, characterized in that said alkaline activator represents a mass content of 0.1-10% of said base material; preferably, said alkaline activator represents a mass content of 5-7% of said base material.
4. A calcined clay-based cementitious material according to claim 1, characterized in that said base material comprises, in mass percentage, the following raw materials: 30-60% calcined clay, 3-30% steel slag, 30-60% slag, 4-25% cement clinker and 0-5% gypsum.
5. A calcined clay-based cementitious material according to claim 4, characterized in that said base material comprises, in mass percentage, the following raw materials: 30-60% calcined clay, 3-5% steel slag, 30-60% slag, 4-6% cement clinker and 0.5-2% gypsum.
6. A cementitious material based on calcined clay according to claim 1, characterized in that in said calcined clay, A12O3 >15%, Al / Si > 0.3, CaO < 3%, SO3 < 3%; preferably, in said calcined clay the content of said calcined clay in A12O3 is > 20%, the index of compressive strength activity at 28 days is greater than 80%; more preferably, the chemical composition of said calcined clay comprises, in mass percentage: A12O3: 25-40%, SiO2: 60-75%, K2O + Na2O < 3%, CaO + MgO < 5%, SO3 < 3%.
7. A calcined clay-based cementitious material according to claim 1, characterized in that in said steel slag, the mass content of CaO is 30-60%, the mass content of SiO2 is 10-30%, the mass content of MgO is 2-20%, the mass content of Fe2O3 is 10-40%; preferably, the chemical composition of said steel slag comprises, in mass percentage: CaO: 38-50%, Fe2O3: 25-35%, SiO2: 14-20%, MgO: 4.5-12%, MnO: < 5%, Al2O3: 1-10%, CaF2 < 2%, SO3 < 5%.
8. A calcined clay-based cementitious material according to claim 1, characterized in that said slag is ground granulated blast furnace slag or air-cooled blast furnace slag; and / or, said cement clinker is Portland cement clinker; and / or said gypsum is at least one of desulfurization gypsum, mirabilite gypsum, phosphogypsum and titanium gypsum.
9. A calcined clay-based cementitious material according to any one of claims 1-8, characterized in that each component of the base material is taken and mixed with the alkaline activator, the calcined clay-based cementitious material is obtained after grinding.
10. A cementitious material based on calcined clay according to claim 9, characterized in that the powder obtained after grinding must be further sieved in a sieve with pores of 60-100 qm, the sieving residue weight of said powder is 0-10%.